Report on invasive plant species in Kiribati

The Republic of Kiribati requested assistance from the US Department of Agriculture, Forest Service, Institute of Pacific Islands Forestry, to conduct a survey of invasive plant species of environmental concern. Similar surveys have been conducted in American Samoa, the Commonwealth of the Northern Mariana Islands, the Cook Islands, the Federated States of Micronesia, Niue, Palau, Samoa and Tonga. The survey was carried out in August and September 2003. We were requested to survey the islands of Tarawa, Abemama, Beru and Butaritari; however, difficulties with plane connections did not permit us to visit Beru and Maiana was substituted instead.

The objectives of the survey were to: (1) identify plant species presently causing problems, particularly in natural and semi-natural ecosystems; (2) identify species that, even though they are not presently a major problem, could spread more widely or are known to be problem species elsewhere; (3) confirm the absence of species that are a problem elsewhere and, if introduced to Kiribati, could be a threat there; and (4) make appropriate recommendations.

During our visit local experts⁽²⁾ showed us sites of known infestations and participated in the survey. We also had available copies of botanical surveys conducted in the past (see Appendix 9, References), particularly those conducted by Fosberg et al. and Thaman. The survey team inspected each island, focusing particularly on disturbed sites and sites where introductions are likely, including roadsides, airstrips, ports and cultivated and inhabited areas. Visual inspection and recording of known invasive and potentially invasive species along roads and trails accessible by car or motorbike was accompanied by more detailed inspection on foot at a variety of sites. Herbarium specimens (171 total) were collected for documentation or for later identification or verification of ‘new’, ‘significant’, taxonomically ‘difficult’ or unknown species. All voucher specimens are deposited in the Herbarium Pacificum at Bishop Museum.

The intent was only to conduct an overall survey and not an exhaustive survey of the weed flora of the islands. Given the limited duration and nature of the survey it is likely that some potentially invasive species, particularly those occurring in low numbers or cultivated in urban gardens, were overlooked. For the purpose of this survey, we have assumed that species recorded by previous surveys but not seen are still in existence. Periodic surveys and additional surveys of individual species and sensitive areas can and should be conducted as needed. This report summarizes our findings and makes some suggestions and recommendations for further action.

Invasive species occurring in or of threat to Kiribati have been grouped into five categories:

Species that are invasive elsewhere in the Pacific or in similar ecosystems but were not seen on our visit and are not reported in the literature as being present (648 species)
Species that are presently subjects of eradication programs (1 species).
Invasive species that are widespread or potentially serious problems (43 species).
Other species that are invasive or weedy elsewhere and are common, weedy or cultivated (74 species).
Native species (or Micronesian introductions) that exhibit aggressive behavior (8 species).

These species are listed in Appendix 1. Additional information about each species is located on an Internet site, http://www.hear.org/pier, and on the PIER-CD, copies of which have been made available to the Ministry of Environment, Lands and Agricultural Development.

1. Dangerous species not known to be on the islands of Tarawa, Abemama, Butaritari and Maiana

It is fortunate that a number of species that are troublesome on other Pacific islands or in similar ecosystems have yet to reach the islands of Tarawa, Abemama, Butaritari and Maiana. In fact, these islands have fewer weed species than any others surveyed so far in the Pacific, probably a combination of isolation and the atoll environment, which does not support the variety of species found on ‘high’ islands. Species not known to be present on the islands surveyed are listed in Appendix 1, Table 1. While quite a large number of these species would probably either not survive if introduced or would do poorly in atoll ecosystems, all are listed in the table for reference purposes. Listed species should receive high priority for exclusion from entry into the country and be promptly evaluated for eradication if found to be present. The following summarizes those likely to be of particular concern to atolls such as those surveyed.

Ardisia elliptica (shoebutton ardisia) is a problem species in the Cook Islands, Hawai‘i, French Polynesia, Samoa and Florida (US). It produces prolific fruit and crowds out other species in the forest understory. Birds, which eat the fruit, are a major factor in its spread.

Asparagus densiflorus (asparagus fern, sprengeri fern) and Asparagus setaceus (ornamental asparagus, climbing asparagus fern, plumosa) are commonly planted throughout the Pacific as ornamental plants. On several islands in Tonga, the thorny vines of Asparagus setaceus (ornamental asparagus, climbing asparagus fern) have become established in the forest understory, climbing into the canopy. Asparagus densiflorus has recently been found to be rather widespread in Hawai‘i on the island of Kaua‘i, where it is spreading along roadsides and invading secondary forest. It seems to have the ability to withstand herbicide treatments used to control vegetation along roads. The seeds of these species are bird-dispersed, and they can also spread vegetatively through root tubers from discarded plants.

Cardiospermum grandiflorum (balloon vine, heart seed) is very invasive on Rarotonga, Cook Islands, and is reported to be invasive in Australia as well.

Centella asiatica (Asiatic pennywort, Indian pennywort, marsh pennywort, pennyweed) is a pantropical weed. It is native or an early introduction throughout much of the Pacific, including the Marshall Islands, but apparently has not made it to Kiribati.

Chromolaena odorata (chromolaena, Siam weed) is a highly invasive pan-tropical weed. This species is a major problem for agriculture as well as the environment and will almost certainly make its appearance in Kiribati sooner or later. It was recently found on Majuro, Marshall Islands, where it is the subject of an eradication program. It has small, wind-dispersed seeds that can also travel on boots, clothing or used cars or equipment.

Chrysopogon aciculatus (Mackie’s pest, lovegrass) is indigenous or an early introduction to many Pacific islands. It is apparently not yet present on Kiribati. This is an aggressive, noxious weed that readily withstands trampling, poor soils and mowing. Its sharp seeds can penetrate flesh and work their way in, causing festering sores. Its spiked seeds are carried from place to place in fur, feathers, or clothing.

Clerodendrum chinense (Honolulu rose) is a shade-tolerant species. It primarily reproduces from root suckers and can form dense thickets, crowding out other species. It is a major pest species in Niue, American Samoa and Samoa and is present and invasive on a number of other Pacific islands. While it prefers moist, fertile soil and probably would not do well in Kiribati, it is a high-risk species that should not be introduced.

Clerodendrum quadriloculare (bronze-leaved clerodendrum) is an attractive ornamental commonly planted for that purpose throughout much of Micronesia. It is notorious for being a prolific producer of root suckers and, in fact, the plant is easily propagated by means of root cuttings. It has become widespread on Pohnpei, Federated States of Micronesia, and is in cultivation on Majuro, Marshall Islands. In Hawai‘i it is becoming a problem ornamental, producing numerous root suckers that appear some distance from the parent plant. It is a potential problem because of its ability to invade intact or relatively intact ecosystems.

Clidemia hirta (Koster’s curse) is a serious problem species in Hawai‘i and other Pacific locations, including Fiji, Palau, Samoa, the Solomon Islands and Vanuatu. It is shade tolerant and spread by birds.

Coccinia grandis (ivy or scarlet gourd) is a smothering vine that is a serious problem on Saipan, Commonwealth of the Northern Mariana Islands. The vines climb over trees and form such dense cover that the forest underneath is completely shaded out and destroyed. It is also invasive in Guam and Hawai‘i and is reportedly present in Fiji and Vanuatu. It is a vegetable commonly used in southeastern Asian cooking and the plant is often introduced for that reason. It readily spreads vegetatively through cuttings and, if fruit is present, by birds and probably pigs.

Crassocephalum crepidioides (thickhead, fireweed) is a common weed throughout much of the Pacific. The seeds are wind-dispersed.

Cryptostegia grandiflora (rubber vine, India rubber vine) is an aggressive woody climbing vine capable of growing over trees up to 15 m high. In the open, it forms impenetrable thickets. It has become a serious problem in northeastern Queensland, Australia, and is present in New Caledonia and Fiji.

Cuscuta campestris (golden dodder, field dodder) is a parasitic plant that is a serious agricultural and environmental weed. It is a prolific seed producer and is parasitic on a wide range of host plants, often killing them. It can also spread by means of stem fragments. It is abundant in Fiji, becoming quite common on Guam, and is present in the Marshall Islands (Majuro). It can be introduced as a contaminant in seed.

Dieffenbachia seguine (spotted dieffenbachia, dumb cane) is often introduced as an ornamental. This species can be invasive and difficult to remove in moist areas and has become a major problem in this regard in American Samoa and Samoa. It reproduces vegetatively and can thrive in dense shade, crowding out other species.

Dissotis rotundifolia (dissotis, pink lady) has been introduced to Pacific islands as an ornamental ground cover. It can form a dense mat, crowding out or excluding other species. This behavior was seen in Palau and Samoa. It is a problem species as well in Fiji, French Polynesia and Hawai‘i. Since it can reproduce vegetatively, mowing or slashing can spread it more widely or lead to very dense stands. Other members of the family Melastomataceae not presently in Kiribati should also be excluded.

Eichhornia crassipes (water hyacinth) is a well-known problem worldwide in freshwater lakes, ponds, marshes, ditches, canals and slow-moving streams. It reproduces both by seed and vegetatively.

Hemigraphis alternata (metal leaf, red ivy) is often introduced as an ornamental, forms dense low stands, invading under the forest canopy. It is shade tolerant, does well in the forest understory and can exclude other species. It is present in the Marshall Islands and a number of other locations in the Pacific, but the worst infestations were seen in Samoa.

Hippobroma longiflora (star of Bethlehem) is a small poisonous ornamental plant that has been introduced to a number of Pacific islands, including the Marshall Islands.

Hiptage benghalensis (hiptage) is a problem species in Hawai‘i and is reported to be a very invasive species on La Réunion and Mauritius. It is also becoming invasive in north Queensland, Australia. The seeds are wind-dispersed and it also can reproduce from cuttings.

Hyptis capitata (knobweed) is common in Guam and several other Pacific islands. The seeds adhere to fur and clothing and are also spread by water.

Hyptis pectinata (mint weed) is a serious weed of disturbed sites and agriculture. Its seeds stick to clothing and to the fur of animals and can also be spread by vehicles and machinery. It is on the Hawaii State noxious weed list, is a noxious weed in Fiji, is very prevalent in Samoa and is becoming so in Tonga.

Imperata cylindrica (blady grass, cogon grass), a very invasive grass, is a serious problem for both agriculture and the environment. It is on the U.S. Federal and State of Hawaii noxious weed lists. In Micronesia, it was introduced at the airports on Palau and Yap, where eradication efforts are presently underway. It is also present on Saipan and Tinian.

Indigofera suffruticosa (indigo) is established on many Pacific islands and is a major weed species in Tonga.

Ipomoea hederifolia (ivy-leaf morning glory, star ipomoea) is invasive in the Torres Strait islands and Cape York Peninsula, Australia, and is a weed of roadsides and agriculture on several Pacific islands.

Ipomoea quamoclit (star of Bethlehem, Cupid’s flower, cypress vine), sometimes introduced as an ornamental, is invasive in Fiji and north Queensland, Australia.

Macfadyena unguis-cati (cat’s claw climber) is an aggressive vine that climbs trees and also forms a dense mat on the ground. Control is difficult because it has tuberous roots and reproduces from stem fragments and cuttings. It is a problem species in Hawai‘i and eastern Australia (northern New South Wales and southeast Queensland). It is cultivated as an ornamental in the US, is spreading at several locations on Niue and is reported to be moderately invasive in New Caledonia (Meyer, 2000). Spread is through wind-dispersed seed, pieces and cuttings.

Melinis minutiflora (molasses grass) is both invasive and can cause a serious fire hazard. It has modified fire regimes on many islands where it has been introduced (D’Antonio and Vitousek, 1992). It forms dense mats, excluding other vegetation.

Merremia peltata (merremia) is a very aggressive vine at most of the locations throughout the Pacific where it is native or introduced. It has been introduced to several Pacific islands since World War II. It spreads both by seed as well as adventitious rooting from stems and pieces.

Merremia tuberosa (wood rose), a climbing, smothering vine, is notable for its aggressive behavior on Niue. It is also a problem species in Hawai‘i. It is often introduced as an ornamental or from discarded floral arrangements containing seeds.

Mikania micrantha (mile-a-minute weed), a smothering vine, is widespread throughout the Pacific and is a major pest wherever it occurs. It is spread both by seed (dispersed by wind, as a contaminant on vehicles and machinery or on clothing or in the hair of animals) and vegetatively from broken stem fragments. Each node of the stem can produce roots.

Mimosa diplotricha [=invisa] (giant sensitive plant) is a particularly nasty plant covered with thorns, forming dense tangles that are difficult to walk through. It is present in a number of South Pacific locations (American Samoa, Cook Islands (Aitutaki), Fiji, French Polynesia (Society Islands), New Caledonia, Niue, Papua New Guinea, Solomon Islands and Vanuatu). Barbed seed pods are carried by animals or on clothing.

Mimosa pudica (sensitive plant), a smaller plant than M. diplotricha with only small thorns, is common throughout the Pacific as a component of the weedy vegetation of roadsides and other disturbed areas. It forms a dense ground cover, preventing reproduction of other species. Bristles on the seed pod cling to fur and clothing. Sooner or later this species will undoubtedly show up in Kiribati.

Mucuna pruriens (cow itch, velvet bean) is often introduced as a cover crop or for livestock feed. It is a serious problem on Saipan and is considered a weed species in Mexico, Mozambique, Jamaica and Madagascar. While the utilis variety commonly used in agriculture lacks irritating hairs it can apparently revert to type over time.

Ocimum gratissimum (wild basil) is a weed species on a number of Pacific islands, but is particularly prevalent in the Cook Islands. O. basilicum (te marou, basil) is common on Tarawa and Abemama.

Paspalum conjugatum (T grass), an aggressive and persistent species, is found throughout the Pacific but was not seen in Kiribati. The small seeds are probably distributed by man and animals on clothing and fur. It also spreads by stolons. It prefers moist habitats.

Phyllostachys spp. and other running bamboos spread by means of rhizomes, as opposed to bamboos that grow in clumps, and are extremely difficult to control or remove. Phyllostachys nigra (black bamboo) is a problem species in Hawai‘i while Phyllostachys bissetii is extremely invasive on the island of Mangaia, Cook Islands.

Piper aduncum (spiked pepper) is invasive in Fiji, Papua New Guinea, the Solomon Islands, Indonesia and Malaysia. Its tiny seeds are dispersed by birds and flying foxes and can be introduced into new areas on machinery. Locally, it spreads by suckers, forming large clumps.

Piper auritum (eared pepper, also called "false kava") has been introduced to some Pacific islands as a fast-growing form of kava, but it is worthless in this regard. It is becoming widespread in Tonga and is presently subject of an eradication campaign on the island of Pohnpei, Federated States of Micronesia. It has also been introduced into Hawai‘i but the local kava growers association is working with the authorities to eradicate it there as well. See also SPC Pest Alert No. 19, False Kava. This species suckers profusely, forming large clumps, and produces many small seeds that can be spread by birds, rodents and bats and can also be introduced into new areas on machinery. Quarantine officers should be alert to its deliberate introduction, but with its very small seeds it might also be brought in inadvertently.

Schefflera actinophylla (octopus tree, umbrella tree) is a fast-growing, evergreen tree. It is a shade tolerant plant with bird-dispersed fruits that is capable of invading undisturbed forests. It is invasive in Hawai‘i, Micronesia and French Polynesia and is present in the Marshall Islands.

Schinus terebinthifolius (Christmas-berry, Brazilian pepper) is a major problem species in Hawai‘i was well as Florida (US) and the Indian Ocean islands of La Réunion and Mauritius. The fruits are very attractive to birds, aiding its spread. It is present, though not common, in Guam.

Senna tora (foetid cassia, stinking cassia, sicklepod, peanut weed) "occurs abundantly in open pastures and in pastures under coconuts, and is very common on roadsides and wasteland. It tolerates fairly low soil fertilities and moisture levels, but grows tallest where conditions are better, when it may form solid stands to the exclusion of all other plants" (Swarbrick, 1997). It is a weed in Fiji and especially prevalent on the island of ‘Eua, Tonga.

Sesbania grandiflora (hummingbird tree, scarlet wisteria tree) has been introduced as an ornamental on some Pacific islands. It was observed to be spreading outside of cultivation in American Samoa and Samoa.

Solanum capsicoides (cockroach berry, devil’s apple, soda apple) has been introduced to several South Pacific islands as an ornamental. It is becoming well established in Tonga, particularly on Vava’u. Although small, it is quite spiny and would probably be a problem for agriculture as well as a general nuisance. It produces large amounts of small, tomato-like fruit. Spread may be by birds or pigs or by humans who use the fruit in making ornamental wreaths.

Spathodea campanulata (African tulip tree) is often used as an ornamental tree. It is a major problem in Fiji, the Hawaiian Islands and several other places. The seeds are wind-dispersed and it also propagates from root suckers and cuttings. Large trees do not stand up well to wind.

Syngonium angustatum (arrowhead plant, goosefoot plant), a climbing aroid, is widely cultivated as an ornamental. It commonly escapes when cuttings are discarded. This species has the ability to spread in the deep shade of intact forests, forming a dense mat on the forest floor as well as climbing trees. It is difficult to eradicate as it is able to reproduce from a single node and stem and root fragments are easily overlooked. It is a problem species in American Samoa, is widespread in Hawai‘i and is quite invasive in Niue.

Tephrosia candida (white tephrosia) has become established on a number of Pacific islands, particularly the Cook Islands and Samoa (Savai‘i). It can form dense thickets, particularly in disturbed areas.

Thunbergia grandiflora (blue trumpet vine, Bengal trumpet) is an aggressive vine that can smother trees. Excellent examples of its potential can be seen in Koror, Palau. The plant forms large underground tubers and is difficult to eradicate because of regeneration from the tubers and root and stem fragments. It is a problem species in Australia (a noxious weed in Queensland) and Singapore. A similar species, Thunbergia laurifolia, is present in the Marshall Islands.

In addition to the grasses mentioned above, a number of other potentially invasive grass species are not yet present on these islands, including Andropogon gayanus, Andropogon glomeratus, Andropogon virginicus, Anthoxanthum odoratum, Arundo donax, Axonopus compressus, Axonopus fissifolius, Bothriochloa bladhii, Brachiaria eruciformis, Cenchrus brownii, Chloris divaricata, Chloris gayana, Chloris radiata, Chloris virgata, Coix lacryma-jobi, Cortaderia jubata, Cortaderia selloana, Cymbopogon refractus, Cyrtococcum oxyphyllum, Cyrtococcum patens, Cyrtococcum trigonum, Dactylis glomerata, Dichanthium annulatum, Digitaria bicornis, Digitaria ciliaris, Digitaria eriantha, Digitaria fuscescens, Digitaria horizontalis, Digitaria insularis, Digitaria sanguinalis, Digitaria violascens, Echinochloa colona, Echinochloa polystachya, Echinochloa stagnina, Eragrostis elongata, Eragrostis pilosa, Eragrostis tenuifolia, Eragrostis tremula, Eragrostis unioloides, Eriochloa procera, Holcus lanatus, Hymenachne amplexicaulis, Hyparrhenia rufa, Imperata conferta, Isachne globosa, Ischaemum indicum, Ischaemum polystachyum, Ischaemum rugosum, Ischaemum timorense, Microlaena stipoides, Oplismenus hirtellus, Panicum decompositum, Panicum repens, Paspalum dilatatum, Paspalum paniculatum, Paspalum urvillei, Pennisetum clandestinum, Pennisetum glaucum, Pennisetum setaceum, Rottboellia cochinchinensis, Saccharum spontaneum, Sacciolepis indica, Schizachyrium condensatum, Setaria barbata, Setaria italica, Setaria palmifolia, Setaria parviflora, Setaria pumila, Sorghum arundinaceum, Sorghum bicolor, Sorghum halepense, Sporobolus elongatus, Sporobolus pyramidatus, Themeda gigantea, Themeda quadrivalvis, Tripsacum latifolium, Urochloa glumaris, Urochloa humidicola, Urochloa mutica and Urochloa reptans. Grasses are easily introduced as contaminants in imported seed, imported sand and gravel or on used machinery, and by their nature tend to be invasive.

Likewise, a number of sedges are not present, including Cyperus cyperinus, Cyperus cyperoides, Cyperus difformis, Cyperus distans, Cyperus gracilis, Cyperus haspan, Cyperus iria, Cyperus ligularis, Cyperus pilosus, Eleocharis dulcis, Fimbristylis autumnalis, Fimbristylis littoralis, Fuirena umbellata, Kyllinga melanosperma and Kyllinga polyphylla. Kyllinga brevifolia is reported present only on Nonouti (Fosberg et al., 1987).

Weedy species that are present in similar atoll habitats in the Marshall Islands and thus would likely be weeds in Kiribati include Amaranthus spinosus (edlebur, needle burr, spiny amaranth, thorny pigweed), Bidens alba (beggar’s tick, Spanish needle; similar to B. pilosa already present), Conyza canadensis (butterweed, Canadian fleabane, hogweed), Crotalaria pallida (smooth rattlepod, striped crotalaria), Impatiens balsamina, Impatiens walleriana, Ipomoea triloba (little bell), Ludwigia hyssopifolia and Solanum americanum (American nightshade, black nightshade).

The best indicator that a species might be invasive is the fact that it is invasive elsewhere. However, each island ecosystem is unique and invasiveness cannot be predicted with certainty. A good strategy is to be extremely cautious and exclude the above species and other species known to be invasive or weedy elsewhere (although the best strategy is to exclude all species not shown by risk assessment to be of acceptable risk). Known problem species that have the potential to cause problems in tropical island ecosystems and are not yet present in Kiribati are listed in Appendix 1, Table 1. These species should be excluded through plant quarantine and, if establishment is detected, promptly evaluated for eradication. Species that are reported to be present in Fiji, Guam, Hawai‘i, the Marshall Islands, Nauru, Samoa or Tonga are listed in Appendix 2. These species would be of high risk of introduction from air and ship traffic between these points and Kiribati.

2. Species that are presently subjects of eradication programs

Agriculture Officers have made a practice of removing Datura metel (te uri ni tiana, datura, jimson-weed) whenever it is found. This seems to have been quite effective in reducing the population to very low numbers. We found a few specimens along a street in Betio (Tarawa) and near the dock on Abemama. It was previously reported on Butaritari (Fosberg et al., 1979) but was not seen there (perhaps eradicated).

We were told that adverse publicity had been given to Wedelia [=Sphagneticola] trilobata (Singapore daisy) on the radio (it was reportedly called a "killer weed") and that people were urged to remove it. One lady on Tarawa showed us where she had taken it out of her garden (although it was coming back from roots and remaining stems). This species is discussed further below.

3. Species that are invasive or have the potential to become so on the islands of Tarawa, Abemama, Butaritari and Maiana

A number of known invasive plants that cause trouble in similar ecosystems have been introduced into Tarawa, Abemama, Butaritari and Maiana (Appendix 1, Table 3). Some of these are already causing problems while others are not. Some are cultivated plants that have not (yet) escaped and their potential for causing damage is so far unknown. However, one of the best predictors of invasiveness is the behavior of the species elsewhere, and these are known troublemakers.

Invasive species already widespread

A number of invasive species are already widespread on the islands of Tarawa, Abemama, Butaritari and Maiana. Eradication or extensive control is out of the question for these species, but they may still warrant control in sensitive, natural and protected areas such as parks, reserves and conservation areas or in areas where they interfere with agriculture or are otherwise a nuisance.

Amaranthus dubius (te uekeueke, te mota, amaranth), Bidens pilosa (beggar’s tick), Blechum pyramidatum (green shrimp plant), Chamaesyce hirta (te tarai, te tarai Kutiaie, garden spurge), Chamaesyce hypericifolia (beach spurge, graceful spurge), Chamaesyce prostrata (te tarai, creeping splurge, prostrate spurge), Dentella repens (te uteute n Imatang), Phyllanthus amarus (te kaimatu), Senna occidentalis (te katia, coffee senna), Spermacoce assurgens (buttonweed), Spermacoce ernstii (buttonweed), Synedrella nodiflora (Cinderella weed), Tridax procumbens (coat buttons, tridax daisy) and Vernonia cinerea [=Cyanthillium cinereum] (ironweed, vernonia) are widespread ruderal weeds. Chamaesyce hirta, Chamaesyce prostrata, Phyllanthus amarus, Tridax procumbens and Vernonia cinerea were found on all the islands visited while the others were absent from one or more islands and should be subject to inter-island quarantine. However, Tridax procumbens was only found in a small area on Maiana and could easily be eliminated on that island.

Bryophyllum pinnatum [=Kalanchoë pinnata] (te ang, te kabekau [Butaritari]), life plant) is widespread on North Tarawa, common on Maiana and was seen at Baretoa village on Abemama. On Butaritari there is a large patch just east of the Tirua resthouse and some examples elsewhere. It reproduces vegetatively, is shade tolerant and can be invasive on the forest floor.

Cenchrus echinatus (te anti, te kateketeke, te uteute ae kateketeke, burgrass, sand-bur), with its sharp burs that detach easily from the spike and attach to clothing or animals, is widespread on all the islands visited. This species is very common throughout the Pacific and many tropical countries.

The sedges Cyperus compressus (flat sedge) and Cyperus rotundus (te mumute, nut sedge) are widespread on all the islands visited, while Eleocharis geniculata (te maunei) was found growing in very wet areas on Tarawa, Butaritari and Maiana.

Eustachys petraea is the most common grass, ubiquitous on all the islands visited.

Leucaena leucocephala (te kaitetua, leucaena) is common, as on most Pacific islands, but it is not as prevalent in Kiribati as it is in many other locations. It is often planted for soil enhancement. It was not seen on Maiana.

Pluchea carolinensis (te kaikare, te kare, sour bush) is found on Tarawa (along the airport and in areas to the south to and along the road to Temaiku) and on Butaritari (along the airstrip and main road). Pluchea indica (Indian fleabane, Indian pluchea, Indian camphorweed) is present on Butaritari, mostly near the coast. These are shrubby species with wind-dispersed seed. Pluchea carolinensis is naturalizing extensively on Tongatapu, Tonga, and is reported to be widespread but not presently abundant on Guam. These species may have been accidentally introduced as a result of military activity as both were also introduced to Penrhyn Island (Cook Islands) when an airfield was built there during the Second World War (Bill Sykes, pers. com.) and are commonly found in conjunction with other World War II airfields in the Pacific.

Ricinus communis (castor bean) is common along roadsides and in disturbed places on Tarawa and Butaritari but absent from Abemama and Maiana. This species is very weedy in Samoa and Tonga.

Russelia equisetiformis (te kaibaun, coralplant, fountainplant) is widespread on North Tarawa and Abemama and is also found on Butaritari and Maiana. It is also reported from Onotoa and Tabiteuea (Fosberg et al., 1979). It can form large clumps and thickets, excluding other vegetation. It is reported to be common in Fiji (Smith, 1991) and Niue (Sykes, 1970).

Stachytarpheta jamaicensis (te uti, blue porterweed, light blue snakeweed) is common on Tarawa, Abemama and Butaritari, while Stachytarpheta cayennensis [=urticifolia] (te uti, blue rat’s tail, dark blue snakeweed) is found with it on Tarawa and Butaritari. Stachytarpheta jamaicensis tends to favor more open areas while Stachytarpheta cayennensis will invade as an understory plant, particularly when there has been disturbance. The two can hybridize. Both species are common throughout the Pacific.

Tradescantia spathacea (te ruru ni, oyster plant, boat plant, boat lily, Moses in a boat) is cultivated on Tarawa and Butaritari, while T. zebrina (wandering jew) is planted as an ornamental on Tarawa. Both plants like sandy and rocky areas. They are somewhat shade tolerant and can invade into the forest understory. These plants are commonly spread from ornamental plantings and through the dumping of garden cuttings.

Turnera ulmifolia (te kakainea, yellow alder, sage rose) is widely planted and naturalized on all the islands as an ornamental. The seed is reported to be carried by ants (Staples et al., 2000) and the species is widely naturalized elsewhere in the tropics.

Waltheria indica, a pantropical weed, is widespread on Tarawa.

Invasive species of limited extent

The following species are limited in extent or have recently become established. Some of them are only in cultivation while others are more widespread. A number of these species are high priority candidates for control or eradication due to their invasive potential. Others should be monitored for possible future action, if necessary (see species-specific recommendations).

Acacia farnesiana (te kaibakoa, te aketia, Ellington curse, klu, sweet acacia) was not seen but is reported to be present in cultivation on Tarawa and Nikunau. This thorny shrub is a pest in Fiji, French Polynesia, New Caledonia, Solomon Islands and Vanuatu.

Allamanda cathartica (allamanda, yellow trumpet vine) is planted and naturalized on a number of Pacific islands. It was previously recorded on Tarawa (Fosberg et al., 1979) but was not seen in this survey. It is becoming invasive in northern Queensland, Australia, and Papua New Guinea. It has invaded forest and savanna in central Babeldaob, Palau.

Antigonon leptopus (coral vine, chain of love), a climbing vine often planted as an ornamental, is a widespread pest on Guam. A single example was seen in cultivation on Tarawa.

Cestrum nocturnum (night-flowering cestrum) is reported to be present in Tarawa (Swarbrick, 1997), probably in cultivation, but was not seen. This species has bird-dispersed seeds and is "abundantly naturalized in thickets and open forest" in Fiji (Smith, 1991) and elsewhere.

Cyperus involucratus [=alternifolius subsp. flabelliformis] (umbrella sedge) was seen only in cultivation at one location in Tarawa. It is often planted as an ornamental, but can be an invader in wet areas.

Epipremnum pinnatum cv. Aureum [=Scindapsus aureus] (pothos, money plant) was seen in cultivation in Tarawa. This tree-climbing species can invade the forest understory. It is a cultivar of a plant (Epipremnum pinnatum) native to the Solomon Islands (Smith, 1979) and widely cultivated. Since it only reproduces vegetatively from cuttings and pieces, the main concern is infestations that become established where they are not wanted. Its main method of spread is through discarded plants and garden cuttings.

Macroptilium atropurpureum (siratro, purple bushbean) was found in two locations on Tarawa; on a fence along the main road in downtown Betio and on a fence in the back road through the urbanized area of Bikenibeu. It could form dense infestations in disturbed areas if it spreads from these locations.

Malvastrum coromandelianum (false mallow, prickly malvastrum), a pantropical weed, is found on a number of Pacific islands as a "weed in waste places, gardens, canefields, and open fields and along roadsides" (Smith, 1981). It was collected in one location on Abemama and was previously reported by Swarbrick (1997), probably from Tarawa.

Panicum maximum (Guinea grass) was reported present in Kiribati by Swarbrick (1997) but no location was given (probably Tarawa). This grass can perpetuate a fire cycle. It seeds profusely and the seeds are dispersed by wind, birds, flowing water or as a contaminant. It can survive long periods of drought. Fire will sweep through stands of this grass but it regenerates rapidly from underground rhizomes. It is a problem species in Guam and Hawai‘i and is very prevalent in Samoa and Tonga, forming dense stands in open and disturbed areas. It is common in Fiji.

Only one small area of Passiflora foetida (te biku, love-in-a-mist) was noted on Tarawa. It is also reported to be present on Butaritari (var. gossypifolia, Fosberg et al., 1979) but was not seen there. It is quite prevalent on most Pacific islands, where it often forms a dense ground cover that prevents or delays the establishment of other species. However, it does not appear to be highly invasive in Kiribati. We were told it had been introduced to Abemama, but if so it is uncommon or no longer present as we did not see it.

Pennisetum polystachion (mission grass) is commonly found in disturbed areas. It is reported to be present on Butaritari (Fosberg et al., 1989) but was not seen there. It provides fuel for fires and readily spreads after fire, perpetuating a fire cycle. This species has seeds adapted for dispersal by wind and is frequently spread as a contaminant on vehicles and machinery.

Pennisetum purpureum (elephant grass) was collected along the road to Temaiku near the wetlands adjacent to the fishponds. It can form dense, perennial stands, particularly in mesic to wet areas. Thus it could readily spread in the wetlands where it is growing.

Prosopis pallida (mesquite) was reported to be present on Tarawa by Fosberg et al. (1979), probably in cultivation. It was not seen and may longer be present. In Hawai‘i, P. pallida is "a dominant component of the vegetation in low elevation, dry, disturbed sites, from the vegetation line behind beaches, on raised limestone reefs, dry slopes and gulches, and in degraded dry forest, 0-610 m" (Wagner et al., 1999). This species commonly produces large amounts of seed.

Solanum torvum (prickly solanum, devil’s fig) is a large spiny species of disturbed areas and fields that can form dense, impenetrable thickets. Its seeds are bird-spread. It was reported to be present on Tarawa and Abemama by Fosberg et al. (1979) and as a pest species in Kiribati by Swarbrick (1997), but was not seen. It is certainly an undesirable species and perhaps it has been eliminated over time. A leaf-eating chrysomelid beetle, Leptinotarsa undecimlineata, is reported to be host-specific as a control agent (Waterhouse and Norris, 1987).

Wedelia [=Sphagneticola] trilobata (Singapore daisy) has become a serious pest on many Pacific islands (Thaman, 1999) as well as in northern Australia. It is both planted and naturalized at a number of locations on Tarawa (there is a large patch on the hospital grounds in Bikenibeu, for example) and in several locations on Butaritari. It can form dense mats along roadsides and in disturbed areas and is a problem in agriculture. Control by chemical means is difficult and mechanical removal often leaves numerous nodes that freely root and rapidly spread. Mowing or slashing can make the problem worse unless done very frequently and very close to the ground. Unless controlled, the infestations in Kiribati are sure to spread until it is a widespread pest.

4. Other species that are known or listed as weedy or invasive elsewhere and are common, weedy or cultivated on the islands of Tarawa, Abemama, Butaritari and Maiana

A number of other common or weedy introduced species were noted. Many of these species, which might best be termed aggressive weeds, are mostly prevalent along roadsides or on disturbed sites. A number of them are found only in cultivation. Some of these species could become a problem in the future, since there is often a long lag time between introduction and when a species begins to cause serious impacts. These species (listed in Appendix 1, Table 4) should be monitored for spread and control measures instigated, if necessary.

Calotropis gigantea (te bumorimori, calotrope, crown flower) is found in cultivation on Tarawa. It is an invasive species in Timor and has naturalized in northwestern Australia.

Casuarina equisetifolia (te burukam, te katurina, casuarina, ironwood, Australian pine) is likely an early introduction to many islands in Kiribati. It is a salt-resistant species, grows well on atolls, and is often grown for its hard wood. However, it can exclude other species and is shallow-rooted. Where planted along the coast or on small islands it may promote beach erosion.

Cleome viscosa (tickweed, spider flower), an agricultural weed, was collected on Tarawa. It is common in Fiji and Samoa and may spread more widely.

Euphorbia cyathophora (te kabekau, painted spurge, wild poinsettia) is present on all the islands visited and particularly widespread on Tarawa. It is a common weed.

Although present on all the islands visited, Lantana camara (te kaibuaka, lantana) was seen only in cultivation or as a remnant of cultivation. While a serious pest in Fiji and Hawai‘i, lantana doesn’t seem to be a problem in Kiribati at the present time.

Pilea microphylla (artillery plant) is widespread on Tarawa and present on Butaritari. Sykes (1970) describes it as a "little succulent plant of rock crevices and fissures…where it is often very common. It also grows in the villages on coral walls and similar places, especially in shade or partial shade. These habitats are typical for this adventive species in many other tropical Pacific islands."

Portulaca oleracea (te boi, pigweed, purslane) is a common weed on all the islands visited.

Sida acuta (broom weed, spiny sida) is a pantropical weed that is a "major weed of pastures and roadsides" (Swarbrick, 1997). It is a weed on a number of Pacific islands and is reported to be present on Banaba (Fosberg et al., 1979). It was collected on Maiana.

Tecoma stans (yellow bells, yellow-elder, yellow trumpetbush) is widely cultivated. It is a serious invader of disturbed areas in Tonga and French Polynesia where it grows in dense stands, commonly with other weedy species. The seeds are wind-dispersed. Some naturalization was noted on Abemama and Butaritari, but otherwise this species seems to mostly stay where it is planted.

Gliricidia sepium (mother of cacao, quickstick) was seen on Tarawa, mostly in Bairiki, where one example of naturalization was noted.

In addition to Cenchrus echinatus, Eustachys petraea, Panicum maximum, Pennisetum polystachion and Pennisetum purpureum discussed above, other introduced grasses include Cenchrus ciliaris (buffelgrass), Cynodon dactylon (Bermuda grass), Dactyloctenium aegyptium (te uteute, beach wiregrass), Eleusine indica (goosegrass), Paspalum setaceum, Sporobolus indicus (smutgrass) and Urochloa [=Brachiaria] subquadripara (green summer grass, tropical signalgrass). Chloris barbata (swollen fingergrass), Melinis repens (Natal redtop), Paspalum fimbriatum (fimbriate paspalum), Paspalum scrobiculatum (rice grass), and Stenotaphrum secundatum (buffalo grass) were reported present by Swarbrick (1997) and/or Fosberg et al. (1987) but were not seen in this survey. Bamboos (te kaibaba) (Bambusa spp.) are also present. Unless there is a particular name for a grass species, the local name for grass, te uteute, is used.

The sedge Kyllinga nemoralis (white kyllinga) is reported present on Butaritari (Fosberg et al., 1987) but was not seen.

Some other weedy species noted or reported to be present include Achyranthes aspera (chaff-flower), Agave sisalana (te robu, sisal), Asclepias curassavica (milkweed), Clitoria ternatea (butterfly pea), Conyza bonariensis (hairy fleabane), Desmodium incanum (kaimi clover), Desmodium tortuosum (Spanish clover), Desmodium triflorum (tropical trefoil), Gloriosa superba (flame-lily), Gomphrena globosa (te motiti, te moteti, bachelor’s-button, globe amaranth), Hemigraphis reptans, Ipomoea aquatica (te Kang kong, te ruku, aquatic morning glory, kang kong), Jasminum sambac (te bitati, Arabian jasmine), Passiflora edulis (passion fruit), Physalis peruviana (te baraki, te bin, Cape gooseberry), Polygala paniculata (island snake-root) and Tacca leontopetaloides (arrowroot). Most of these were of limited extent or were reported in the literature but not seen.

These and some additional invasive plant species, mostly ruderal weeds or of agricultural concern, seen or reported to be present, are listed in Appendix 1, Table 4.

5. Native species (or Micronesian introductions) exhibiting aggressive behavior

Weedy native species (or more likely, Micronesian introductions) include Abutilon indicum (te kaura, te kaura ni, abutilon); Ludwigia octovalvis (te mam, willow primrose), commonly found in babai pits; Sigesbeckia orientalis (Indian weed, yellow-crown-head) and the grass Eragrostis amabilis (te uteute n’ aine, te uteute te aine, female grass, Japanese love grass).

Ipomoea violacea [=macrantha] (te ruku, moonflower), an aggressive vine, was found on North Tarawa (between Notoue and Taratai) and on Butaritari. We were told that it first became noticeable on Butaritari 3-4 years ago. Fosberg (1987) lists it as present on Tarawa, Nonouti, Tabiteuea and Onotoa but not Butaritari. Perhaps it was introduced to Butaritari from another island or merely became more prevalent there due to disturbance.

Tribulus cistoides (puncture vine) is a vine with a spiny fruit that is troublesome in coastal habitats in Hawai‘i. It is reported to be present only on Kiritimati Island.

General observations and recommendations

It was not the purpose of this survey to provide a review of policies and procedures for the management of exotic plant pests. However, the following observations and suggestions are offered as a review of good management practices. For a more in-depth treatment of the principles of invasive species management the publication "Invasive alien species: a toolkit of best prevention and management practices" is available.

Kiribati has laws and regulations in place that deal with quarantine and new introductions. The first line of defense against invasive species, and the most cost-effective, is to keep them out. Strict inspection at ports of entry is essential to prevent the entry of undesirable species. Plant quarantine officers should receive training to be familiar with both agricultural pests and those that threaten natural and semi-natural ecosystems. At a minimum, a list of known noxious species to be excluded should be developed and exclusion of these species should be backed by the force of law and regulation. Better yet is to employ the "precautionary principle" (as in Australia and New Zealand and under serious consideration by a number of other countries) to exclude all alien species not shown to be of acceptable risk. Risk assessment and management techniques can be used to assess the likelihood and effects of possible introductions and to develop exclusion and eradication strategies. The Secretariat of the Pacific Community has a Plant Protection Training Officer for Micronesia, Konrad Englberger, who provides assistance to strengthen quarantine operations.

In the case of new introductions, the ability to take prompt action is essential, as expanding infestations soon become uneconomical to control. Provision for emergency response procedures and funding mechanisms to deal with immediate problems should be in place.

Education of the public about the danger of introductions and encouraging the use of native or approved species needs to continue as a long-term campaign. People should be encouraged to take responsible actions such as following quarantine regulations, not dumping garden cuttings and reporting suspicious plants. There are many instances where an invasive plant started out as a pretty flower planted in a yard or garden. Public service announcements on radio can be used and "wanted" posters can be prepared for critical species. Education of schoolchildren is especially important, as this is the most impressionable age. Children can also have a notable effect on the actions of their parents. Prompt follow-up to public reports and inquiries is essential to maintain the credibility of a public education program. The public also needs to understand that the immediate eradication of a problem species, even if it involves the use of pesticides, may be better than living with a problem species forever.

Local nurseries and plant importers can be sources of new introductions. A positive approach is to work together to develop a "white list" of both native and non-native species that the public can be encouraged to plant. Likewise, gardening associations and other village and local groups can perform an important education function for their members in what species to avoid and can assist in reporting and controlling infestations of invasive plants. Needless to say, government agencies should lead the way by promoting the use of non-invasive species, especially those that are native to the country.

Many Pacific countries or individual islands have formed invasive species committees or working groups. Close and immediate coordination and cooperation between various government departments and other entities is essential when an invasive species problem is encountered, especially when there is a need to move quickly to eradicate an introduced species. Such a committee can be effective both for long-term strategic actions, such as review and strengthening of relevant laws and regulations, as well as short-term tactical and operational problems, such as action when a new species is found to have been introduced. Typically, an overall management plan is developed together with a prioritized action plan. Among other things, action planning addresses critical areas to protect, species subject to control or eradication and assignment of responsibility for specific control or eradication measures. Time, money and people are always in limited supply and must be directed to the places where they will do the most good. Economic analysis can be used to assess the costs and benefits of management strategies and prioritize action. Some recommendations are made below as to possible actions against individual plant species, but these should be tested against available resources and other priorities.

Foresters, conservation officers, extension agents and others that spend time in the field should be alert to new species that exhibit invasive behavior. Most pest species are deliberately or inadvertently introduced by the action or carelessness of people and tend to first become established on farms or in gardens, around houses and in disturbed areas. Suspicious plant species should be promptly reported. Periodically scheduled surveys can also be conducted for new or expanding infestations. An evaluation should be conducted for any new species that appears to be invasive or is known to be invasive elsewhere. Assistance by an expert who is familiar with the species and methods for its eradication or control should be requested if needed. Prompt action is essential, since once a species becomes widespread, control or eradication can be extremely costly or impossible. Assistance is also available on-line from experts through the Pacific Pestnet list-server.

Laws and regulations should be reviewed to make sure they are adequate to deal with new introductions. This includes the ability of government to require the control of noxious species on private or customary lands or to take action on private lands if the landowner cannot be located or does not take prompt action. If needed, model laws and regulations can be obtained from states and countries that have implemented them.

Steam cleaning or power washing of all used cars, trucks and equipment coming into Kiribati must be enforced. This is desirable not only from the standpoint of excluding invasive plants, but also insects and diseases. Especially suspect are roadbuilding machinery, military equipment and off-road vehicles. Quarantine inspectors should be especially vigilant to make sure used cars, trucks and equipment from Guam, Hawai‘i, Southeast Asia, Indonesia, New Guinea, Australia and the Philippines are clean as many dangerous weeds are present in these locations. Likewise, importation of sand, gravel, seed and other easily contaminated material from outside the country should be subject to restriction, inspection and monitoring.

Quarantine inspectors should closely inspect boots, camping equipment and other material for soil and seeds, particularly when they have been used in countries where small-seeded species are present. Certainly the belongings of anyone entering the country who answers in the affirmative to the question on the quarantine form regarding a recent visit to a forest or farm should be thoroughly inspected.

A number of species used in ornamental plantings are, at least to some degree, invasive. While many of these species have desirable ornamental or physical characteristics, planting exotics as opposed to native species is a policy question that needs to be carefully considered. Most species that naturalize to any extent will gradually spread throughout available and suitable habitat, given enough time. Existing exotic species should be monitored for spread and new introductions should be carefully assessed to minimize risk. Areas previously used for agricultural and forestry species trials as well as other areas where exotic species have been planted should be more thoroughly checked for dangerous species than was possible during this survey.

A risk-rating scheme would be useful in evaluating the various known and potential invasive species for their risk of introduction, spread and potential damage. The Institute of Pacific Islands Forestry is testing an adaptation of the Australian risk assessment system to the needs of the Pacific. A number of risk assessments developed using this system have already been posted on the PIER Internet site and CD. Eventually, it is our hope to rate all the species listed in the PIER database and provide this information to Pacific island countries. In the meantime, risk assessments can be performed on individual species to help evaluate their potential for invasion and spread.

Kiribati has set aside areas such as the North Tarawa Conservation Area to be maintained as a heritage for future generations and for the protection of native biodiversity and tourism values. Protection of such areas will involve a continuous and long-term effort, even on a small scale, due to the continuing pressure from invading species. Intact ecosystems are the most resistant to invasion and any measures that limit the amount of disturbance will help keep invasive species out.

Due to the limitation of time and money, we were only able to survey Tarawa and three outer islands (Abemama, Butaritari and Maiana). However, this probably gives a pretty good assessment of the typical weed flora of the Gilbert Islands. Two islands in the Line group, Kiritimati (Christmas) and Fanning are receiving tourist traffic from Hawai‘i and are thus at risk from the many invasive plant species there. These two islands should be surveyed in the near future.

The purpose of this survey was to give an overall assessment of the situation. In the short time available it was not possible to perform the evaluations that would be needed to justify control or eradication programs for individual species. For many species, therefore, our recommendations are provisional and must be subject to a more complete evaluation as to extent, invasiveness and the possibility of control or eradication. Technical assistance should be requested, if needed, to evaluate individual species.

Species-specific recommendations

Make every effort to keep out all the species listed in Appendix 1, Table 1. All of these are known invasive species elsewhere, and there is no sense in running the risk that they will act the same in Kiribati. As we are able to gather information on other species that might threaten tropical island ecosystems we will add them to the database. For those with Internet access, additional information and new listings can be found at http://www.hear.org/pier. The information is also available on the PIER-CD for local use. Assistance from experts in identifying and managing invasive species is also available by using the Pacific Pestnet list server.
Take special measures to keep out the species listed in Table A, to monitor for their occurrence and to eradicate them immediately if found. These are all well-documented problem species that have had a major impact on ecosystems and agriculture elsewhere. The potential impact of many of these species, if they are introduced and become established, can be severe.

Table A. Priority species for exclusion from Kiribati

Scientific Name	Common Names (abridged)	Family	Invasive in:
*Ardisia elliptica*	shoebutton ardisia	Myrsinaceae	Cook Islands, Hawai‘i, French Polynesia, Samoa, Florida (US).
*Amaranthus spinosus*	edlebur, needle burr, spiny amaranth, thorny pigweed	Amaranthaceae	Fiji, Hawai‘i and elsewhere
*Asparagus densiflorus*	asparagus fern	Liliaceae	Hawai‘i
*Asparagus setaceus*	climbing asparagus fern	Liliaceae	Tonga
*Bidens alba*	beggar’s tick, Spanish needle, cobbler’s pegs	Asteraceae	Hawai‘i, Marshall Islands, Palau and elsewhere
*Cardiospermum grandiflorum*	balloon vine; heart seed	Sapindaceae	Cook Islands (Rarotonga)
*Centella asiatica*	Asiatic pennywort	Apiaceae	Pantropical
*Chromolaena odorata*	chromolaena, Siam weed	Asteraceae	Pantropical
*Chrysopogon aciculatus*	Mackie’s pest, lovegrass	Poaceae	Many Pacific islands
*Clerodendrum chinense*	Honolulu rose	Lamiaceae	Samoa, Tonga and elsewhere
*Clerodendrum quadriloculare*	bronze-leaved clerodendrum	Lamiaceae	Federated States of Micronesia, Palau
*Clidemia hirta*	Koster’s curse	Melastomataceae	American Samoa, Fiji, Palau, Samoa
*Coccinia grandis*	ivy gourd, scarlet-fruited gourd	Cucurbitaceae	Hawai‘i, Saipan
*Conyza canadensis*	butterweed, Canadian fleabane, hogweed, horseweed	Asteraceae	Hawai‘i, Marshall Islands, Palau
*Crassocephalum crepidioides*	thickhead, fireweed	Asteraceae	Many Pacific islands
*Crotalaria pallida*	smooth rattlepod, striped crotalaria	Fabaceae	Fiji, French Polynesia, Hawai’i and elsewhere
*Cryptostegia grandiflora*	rubber vine, India rubber vine	Asclepiadaceae	Australia (Queensland)
*Cyperus ligularis*	rocket sedge, swamp flatsedge	Cyperaceae	Guam, Marshall Islands
*Cuscuta campestris*	golden dodder, field dodder	Cuscutaceae	Fiji, Marshall Islands and elsewhere
*Dieffenbachia seguine*	spotted dieffenbachia, dumb cane	Araceae	American Samoa, Samoa
*Dissotis rotundifolia*	dissotis, pink lady	Melastomataceae	Palau, Samoa
*Eichhornia crassipes*	water hyacinth	Pontederiaceae	Pantropical
*Erigeron bellioides*		Asteraceae	Guam, Hawai‘i, Marshall Islands
*Eugenia uniflora*	Surinam cherry	Myrtaceae	Cook Islands
*Hippobroma longiflora*	star of Bethlehem	Campanulaceae	Pantropical
*Hiptage benghalensis*	hiptage	Malpighiaceae	Australia (Queensland), Hawai’i, La Réunion, Mauritius
*Hyptis capitata*	knobweed	Verbenaceae	Guam
*Hyptis pectinata*	mint weed	Verbenaceae	Fiji, Samoa, Tonga
*Imperata cylindrica*	blady grass, cogon grass	Poaceae	Palau, Yap
Indigofera suffruticosa	indigo	Fabaceae	Tonga and elsewhere
*Ipomoea hederifolia*	ivy-leaf morning glory, star ipomoea	Convolvulaceae	Australia (Queensland), Fiji
*Ipomoea quamoclit*	star of Bethlehem, cypress vine	Convolvulaceae	Australia (Queensland),
*Kyllinga brevifolia*	green kyllinga, green water sedge	Cyperaceae	Marshall Islands and elsewhere
*Macfadyena unguis-cati*	cat’s-claw climber	Bignoniaceae	Hawai’i, Niue, New Caledonia
*Melinis minutiflora*	molasses grass	Poaceae	Hawai’i
*Merremia peltata*	merremia	Convolvulaceae	American Samoa, Cook Islands (Aitutaki), Samoa
*Merremia tuberosa*	wood rose	Convolvulaceae	Hawai’i, Niue
*Mikania micrantha*	mile-a-minute weed	Asteraceae	Many Pacific islands
*Mimosa diplotricha*	giant sensitive plant	Fabaceae	Fiji, Samoa and a number of other Pacific islands
*Mimosa pudica*	sensitive plant	Fabaceae	Many Pacific islands
*Mucuna pruriens*	cow itch, velvet bean	Fabaceae	Saipan
*Ocimum gratissimum*	wild basil		Cook Islands, pantropical
*Paspalum conjugatum*	T grass	Poaceae	Pantropical
Passiflora spp.	All Passifloraceae not already present	Passifloraceae	Pacific islands
Phyllostachys spp.	Running bamboos	Poaceae	Hawai’i (P. nigra), Cook Islands (P. bissetii)
*Piper aduncum*	spiked pepper	Piperaceae	Fiji, Papua New Guinea, Solomon Islands, Indonesia, Malaysia
*Piper auritum*	eared pepper, false kava	Piperaceae	Hawai’i, Pohnpei, Tonga
*Schinus terebinthifolius*	Christmas-berry, Brazilian pepper	Anacardiaceae	USA (Hawai’i, Florida)
*Senna tora*	sicklepod, peanut weed	Fabaceae	Fiji, Tonga
*Sesbania grandiflora*	hummingbird tree, scarlet wisteria tree	Fabaceae	American Samoa, Samoa
*Solanum capsicoides*	cockroach berry, devil’s apple, soda apple	Solanaceae	Hawai’i, Samoa, Tonga
*Syngonium angustatum*	arrowhead plant, goosefoot plant	Araceae	Niue
*Tephrosia candida*	white tephrosia	Fabaceae	Cook Islands, Palau, Samoa
*Thunbergia grandiflora*	blue trumpet vine, Bengal trumpet	Acanthaceae	Australia (Queensland), Palau, Singapore
All grasses	all other grass species not already present	Poaceae	Pantropical
All melastomes	all non-native melastomes	Melastomataceae	Hawai’i, etc.

Note: Appendix 1, Table 1 is a complete list of invasive and potentially invasive plant species not yet present in Kiribati.

The species listed in Table B, seen or reported to be only in cultivation, should be closely monitored for spread or, better yet, eradicated if there are only a few examples, as they are well-documented invasives elsewhere. They may behave similarly in Kiribati if they escape cultivation.

Table B. Cultivated species of possible threat to Kiribati

Scientific Name	Common Names (abridged)	Family	Present on:	Invasive in:
*Acacia farnesiana*	te kaibakoa, te aketia, Ellington curse, klu, sweet acacia	Fabaceae	Babeldaob	Fiji, French Polynesia, New Caledonia, Solomon Islands, Vanuatu
**Allamanda cathartica*	yellow trumpet vine	Apocynaceae	Tarawa	Australia (Queensland), Palau, Papua New Guinea
**Annona squamosa*	sugar apple, sweetsop,	Annonaceae	Tarawa	Nauru
*Antigonon leptopus*	chain-of-love, coral vine	Polygonaceae	Tarawa	Guam
*Asystasia gangetica*	Chinese violet, Philippine violet, coromandel	Acanthaceae	Tarawa, Butaritari	Australia (New South Wales), Indonesia, Malaysia
**Bryophyllum delagoense*	chandelier plant	Crassulaceae	Tarawa	Hawai’i
*Calotropis gigantea*	calotrope, crown flower, madar	Ascelepiadaceae		Australia (Northern Territory, north-west Western Australia), Timor
*Canna indica*	te riti, canna lily	Cannaceae	Tarawa	New Zealand
**Cestrum nocturnum*	night-flowering cestrum	Solanaceae	Tarawa	Cook Islands, French Polynesia, Samoa, Tonga
*Clitoria ternatea*	butterfly pea	Fabaceae	Tarawa	Fiji
*Cyperus involucratus*	umbrella sedge	Cyperaceae		Cook Islands, Tonga
*Epipremnum pinnatum cv. Aureum*	pothos	Araceae	Tarawa	Hawai’i, Niue, Samoa
*Gloriosa superba*	gloriosa lily	Liliaceae	Tarawa, Abemama	Hawai’i
**Hemigraphis reptans*		Acanthaceae	Butaritari	Hawai’i
*Ipomoea aquatica*	te kang kong, te ruku, aquatic morning glory, kang kong	Convolvulaceae	Tarawa, Abemama	Fiji
**Licuala grandis*	ruffled fan palm	Arecaceae	Tarawa	French Polynesia
*Momordica charantia*	bitter-melon	Cucurbitaceae	Tarawa	Fiji, Hawai’i
**Passiflora edulis*	passion fruit	Passifloraceae	Tarawa	New Zealand
*Tradescantia spathacea*	te ruru ni, oyster plant, boat plant, boat lily	Commelinaceae	Tarawa, Butaritari, Abaiang	Cook Islands, Niue, Tonga
*Tradescantia zebrina*	wandering zebrina, wandering jew	Commelinaceae	Tarawa	Cook Islands

*Reported present but not seen in this survey. Presumed to be in cultivation if present.
Note: See Appendix 1 for a complete list of plants with invasive potential.

All invasive plant species are not present on all islands. As would be expected, Tarawa has the most weedy species; there are significantly fewer on the outer islands. However, a few unique species occur on Butaritari. Maiana has the fewest invasive plants. Thus, there is the opportunity to prevent the movement and establishment of invasive plants on new islands, both through internal quarantine procedures and by surveying for and rapidly responding to new infestations. Table C (next page) shows species that should be subject to restrictions on inter-island movement or promptly eradicated if found on uninfested islands. Appendix 3 shows, for each island, all the invasive species present there. Because they have fewer invasive plants, exclusion of new species is especially important for the outer islands. Appendix 4 shows species present elsewhere in Kiribati that are not yet present in these islands.

Table C. Species that should be subject to inter-island quarantine

Scientific Name	Common name	Present on:
*Abutilon indicum*	te kaura, te kaura ni, albutilon	Tarawa, Banaba
*Acacia farnesiana*	te kaibakoa, te aketia, Ellington curse, klu, sweet acacia	Tarawa, Nikunau
*Achyranthes aspera*	chaff-flower	Tarawa
*Agave sisalana*	te robu, sisal	Tarawa, Abemama, Abaiang, Arorai, Nikunau
*Amaranthus dubius*	te uekeueke, te mota, amaranth	Tarawa, Abemama, Butaritari
*Amaranthus viridis*	te mota, green amaranth, pigweed, slender amaranth	Tarawa
*Antigonon leptopus*	chain-of-love, coral vine	Tarawa
*Asclepias curassavica*	milkweed	Tarawa, Butaritari
*Asystasia gangetica*	Chinese violet, Philippine violet, coromandel	Tarawa, Butaritari
Bambusa spp.	Bamboo; te kaibaba (Kiribati)	Butaritari
*Bidens pilosa*	beggar’s tick	Tarawa, Butaritari
*Blechum pyramidatum*	green shrimp plant	Tarawa, Butaritari
*Brassica juncea*	te kabiti, te kabiti n Tiaina, Chinese mustard, Indian mustard	Tarawa
*Bryophyllum pinnatum*	life plant, air plant, resurrection plant; te ang (Kiribati), te kabekau (Kiribati (Butaritari))	Tarawa, Abemama, Butaritari, Maiana
*Calyptocarpus vialis*		Tarawa
*Casuarina equisetifolia*	casuarina, ironwood, Australian pine, she-oak; te burukam, te katurina (Kiribati)	Tarawa, Abemama, Butaritari
*Catharanthus roseus*	rosy periwinkle	Tarawa, Abemama, Butaritari, Banaba, Nonouti, Onotoa, Tabiteauea
*Cenchrus ciliaris*	buffelgrass	Tarawa
*Cenchrus echinatus*	burgrass; te anti, te kateketeke, te uteute ae kateketeke (Kiribati)	Tarawa, Abemama, Butaritari, Maiana
*Cestrum nocturnum*	night-flowering cestrum	Tarawa
*Chamaecrista nictitans*	partridge pea	Tarawa
*Chamaesyce hirta*	asthma plant, garden spurge, pill-bearing spurge, hairy spurge	Tarawa, Abemama, Butaritari, Maiana
*Chamaesyce hypericifolia*	beach spurge, graceful spurge	Tarawa, Abemama, Butaritari
*Chamaesyce prostrata*	creeping splurge, prostrate spurge; te tarai (Kiribati)	Tarawa, Abemama, Butaritari, Maiana
*Chamaesyce thymifolia*	red caustic creeper, thyme-leafed spurge	Tarawa
*Chloris barbata*	swollen fingergrass	Tarawa, Abemama
*Cleome viscosa*	tickweed, spider flower	Tarawa
*Clitoria ternatea*	butterfly pea	Tarawa
*Conyza bonariensis*	hairy fleabane	Tarawa, Butaritari
*Crotalaria incana*	fuzzy rattlepod, woolly rattlepod	Tarawa
*Crotalaria retusa*	devil-bean, wedge-leaf rattlepod	Tarawa
*Crotalaria spectabilis*	showy rattlepod	Tarawa
*Cynodon dactylon*	Bermuda grass	Tarawa, Abemama
*Cyperus compressus*	flat sedge	Tarawa, Abemama, Butaritari, Maiana
*Cyperus involucratus*	umbrella sedge	Tarawa
*Cyperus rotundus*	nut grass, nutsedge; te mumute (Kiribati)	Tarawa, Abemama, Butaritari, Maiana
*Dactyloctenium aegyptium*	te uteute , beach wiregrass	Tarawa
*Datura metel*	te uri ni tiana, datura	Tarawa, Abemama, Butaritari, Abaiang, Tamana
*Dentella repens*	te uteute n Imatang (Kiribati (Butaritari))	Tarawa, Abemama, Butaritari, Makin
*Desmodium incanum*		Tarawa
*Desmodium tortuosum*	Florida beggarweed	Tarawa
*Desmodium triflorum*	tropical trefoil	Tarawa
*Eleocharis geniculata*	te maunei	Tarawa, Butaritari, Maiana, Marakei, Onotoa
*Eleutheranthera ruderalis*		Tarawa
*Eleusine indica*	goosegrass, wiregrass; te uteute, te uteute na banabana (Kiribati)	Tarawa, Abemama, Butaritari, Maiana
*Emilia sonchifolia*	purple sow thistle	Tarawa
*Epipremnum pinnatum cv. Aureum*	pothos	Tarawa
*Eragrostis amabilis*	Japanese love grass, female grass (Kiribati); te uteute n’ aine, te uteute te aine (Kiribati)	Tarawa, Abemama, Butaritari, Maiana
*Euphorbia cyathophora*	dwarf poinsettia, painted spurge; te kabekau (Kiribati)	Tarawa, Abemama, Butaritari, Maiana
*Eustachys petraea*		Tarawa, Abemama, Butaritari, Maiana
*Gliricidia sepium*	mother of cacao, quickstick, Mexican lilac	Tarawa
*Gloriosa superba*	gloriosa lily	Tarawa, Abemama, Butaritari
*Gomphrena globosa*	te motiti, te moteti, globe amaranth	Tarawa
Heliotropium procumbens var. depressum	four-spike heliotrope, slender heliotrope	Tarawa
*Hemigraphis reptans*		Butaritari
*Ipomoea aquatica*	aquatic morning glory, kang kong; te kang kong; te ruku (Kiribati)	Tarawa, Abemama
*Kyllinga brevifolia*	green kyllinga	Butaritari, Nonouti
*Kyllinga nemoralis*	white kyllinga	Butaritari
*Leucaena leucocephala*	te kaitetua, leucaena	Tarawa, Abemama, Butaritari, Kiritimati
*Ludwigia octovalvis*	willow primrose; te mam (Kiribati)	Tarawa, Abemama, Butaritari
*Macroptilium atropurpureum*	siratro, purple bushbean	Tarawa
*Malvastrum coromandelianum*	false mallow, prickly malvastrum	Tarawa?, Abemama
*Melinis repens*	Natal redtop, Natal grass	Tarawa
*Momordica charantia*	bitter-melon	Tarawa
*Ocimum basilicum*	te marou, sweet basil	Tarawa, Abemama
*Oldenlandia corymbosa*		Tarawa, Butaritari
*Panicum maximum*	Guinea grass	Tarawa
*Paspalum fimbriatum*	fimbriate paspalum	Tarawa
*Paspalum scrobiculatum*	rice grass	Tarawa
*Passiflora edulis*	passion fruit	Tarawa
*Passiflora foetida*	te biku, love-in-a-mist, stinking passionflower	Tarawa, Butaritari
*Pennisetum polystachion*	mission grass, feathery pennisetum	Butaritari
*Pennisetum purpureum*	elephant grass	Tarawa
*Phyllanthus amarus*	te kaimatu	Tarawa, Abemama, Butaritari, Maiana
*Physalis angulata*	annual ground cherry; te baraki, te bin (Kiribati)	Tarawa, Abemama, Butaritari, Maiana
*Physalis peruviana*	te baraki, te bin, Cape gooseberry	Butaritari
*Pilea microphylla*	artillery plant	Tarawa, Butaritari
*Pluchea carolinensis*	te kaikare, te kare, sour bush	Tarawa, Butaritari, Kiritimati
*Pluchea indica*	Indian fleabane, Indian pluchea	Butaritari, Banaba, Kiritimati
*Polygala paniculata*	island snake-root	Tarawa
*Portulaca oleracea*	pigweed, purslane; te boi (Kirbati)	Tarawa, Abemama, Butaritari, Maiana
*Ricinus communis*	castor bean	Tarawa, Butaritari
*Russelia equisetiformis*	coralplant, fountainplant; te kaibaun (Kiribati)	Tarawa, Abemama, Butaritari, Maiana
*Sansevieria trifasciata*	bowstring hemp, mother-in-law’s tongue	Tarawa, Butaritari
*Senna occidentalis*	te katia, coffee senna	Tarawa, Butaritari, Maiana
*Sida acuta*	broom weed, southern sida, spiny sida	Banaba, Maiana
*Sida rhombifolia*	arrow-leaf sida	Tarawa, Abemama, Butaritari, Kiritimati
*Sigesbeckia orientalis*	small yellow crown-beard, yellow crown-head	Tarawa
*Solanum torvum*	prickly solanum	Tarawa, Abemama
*Sonchus oleraceus*	sow thistle	Tarawa
*Spermacoce assurgens*	buttonweed	Tarawa, Abemama, Butaritari
*Spermacoce ernstii*		Tarawa, Abemama, Butaritari
*Sphagneticola trilobata*	Singapore daisy, wedelia	Tarawa, Butaritari
*Sporobolus indicus*	smutgrass	Tarawa
*Stachytarpheta cayennensis*	te uti, blue rat’s tail, dark-blue snakeweed	Tarawa, Butaritari
*Stachytarpheta jamaicensis*	te uti, blue porterweed, light blue snakeweed	Tarawa, Abemama, Butaritari
*Stenotaphrum secundatum*	buffalo grass	Tarawa
*Synedrella nodiflora*	Cinderella weed, porter bush	Tarawa, Butaritari
*Tecoma stans*	nei Karairai, yellow bells, yellow-elder, yellow trumpetbush	Tarawa, Abemama, Butaritari, Makin
*Tradescantia spathacea*	te ruru ni, oyster plant, boat plant, boat lily	Tarawa, Butaritari, Abaiang
*Tradescantia zebrina*	wandering zebrina, wandering jew, inchplant	Tarawa
*Tridax procumbens*	coat buttons, tridax daisy	Tarawa, Abemama, Butaritari, Maiana
*Turnera ulmifolia*	te kakainea, yellow alder, sage rose	Tarawa, Abemama, Butaritari, Maiana
*Urochloa subquadripara*	brachiaria, green summer grass, tropical signalgrass	Tarawa, Abemama
*Vernonia cinerea*	ironweed, little ironweed, vernonia	Tarawa, Abemama, Butaritari, Maiana
*Waltheria indica*		Tarawa

Note: See Appendix 4 for complete lists of species not yet present on each island or island group. Species are included in this table even though they may be present on all four of the islands visited in this survey as they may not yet be present on other Kiribati islands.

Table D shows the most serious invasive plant species in Kiribati and summarizes recommendations for their management. In a number of cases, more detailed information and recommendations follow in the island-specific recommendations.

Table D. Summary of management recommendations for invasive species present in Kiribati

Scientific Name		Common Names (abridged)	Family	Comments and recommendations
*†	*Acacia farnesiana*	te kaibakoa, te aketia, Ellington curse, klu, sweet acacia	Fabaceae	Discourage further planting, control outside of cultivation, destroy unwanted plants, inter-island quarantine.
†	*Agave sisalana*	te robu, te rob’, sisal, sisal hemp	Agavaceae	Discourage further planting, control outside of cultivation, destroy unwanted plants, inter-island quarantine.
†	*Allamanda cathartica*	allamanda, yellow trumpet vine	Apocynaceae	Discourage planting; remove if a problem, inter-island quarantine.
†	*Antigonon leptopus*	chain of love	Polygonaceae	Discourage further planting; work to eradicate over time, inter-island quarantine.
†	*Asystasia gangetica*	Chinese violet, Philippine violet, coromandel	Acanthaceae	Discourage further planting; work to eradicate over time. Inter-island quarantine.
	*Bryophyllum pinnatum*	te ang, life plant	Crassulaceae	Control outside of cultivation, consider eradication on islands with only small infestations such as Abemama and Butaritari.
	*Calotropis gigantea*	calotrope, crown flower	Ascelepiadaceae	Inter-island quarantine, monitor for spread.
	*Casuarina equisetifolia*	casuarina, ironwood, Australian pine	Casuarinaceae	Discourage planting on ocean shores, small islands and other areas subject to erosion.
	*Cestrum nocturnum*	night-flowering cestrum, queen (or lady) of the night	Solanaceae	Inter-island quarantine, control outside of cultivation.
	*Clitoria ternatea*	butterfly pea, Asian pigeonwings	Fabaceae	Inter-island quarantine, control outside of cultivation.
*†	*Cyperus involucratus*	umbrella sedge	Cyperaceae	Eradicate if only cultivated or of limited extent.
*†	*Datura metel*	te uri n tiaina, datura, jimson-weed	Solanaceae	Continue eradication.
	*Epipremnum pinnatum cv. Aureum*	pothos, money plant	Araceae	Discourage further planting, control outside of cultivation, destroy unwanted plants, inter-island quarantine.
	*Gliricidia sepium*	mother of cacao, quickstick, Mexican lilac	Fabaceae	Discourage further planting, control outside of cultivation, destroy unwanted plants, inter-island quarantine.
	*Gloriosa superba*	climbing-lily, flame-lily, glory-lily, gloriosa lily	Liliaceae	Discourage further planting, control outside of cultivation, destroy unwanted plants, inter-island quarantine.
	*Hemigraphis reptans*		Acanthaceae	Discourage further planting, control outside of cultivation, destroy unwanted plants, inter-island quarantine.
	*Ipomoea aquatica*	te kang kong, te ruku, aquatic morning glory, kang kong	Convolvulaceae	Control outside of cultivation, destroy unwanted plants.
	*Ipomoea violacea*	te ruku, moonflower	Convolvulaceae	This aggressive native species can be controlled locally as needed.
†	*Lantana camara*	te kaibuaka, lantana	Verbenaceae	Appears not to be spreading, but to be safe any unwanted plants could be eliminated.
*†	*Macroptilium atropurpureum*	siatro	Fabaceae	Eradicate observed infestations and any additional ones found.
*†	*Panicum maximum*	Guinea grass, green panic, buffalograss	Poaceae	Reported present on Tarawa but not seen; if a small infestation, consider eradication; Inter-island quarantine.
	*Passiflora foetida*	te biku, love-in-a-mist, stinking passionflower	Passifloraceae	Not common. Control or eradicate, as appropriate; inter-island quarantine.
	*Pennisetum polystachion*	mission grass, feathery pennisetum	Poaceae	Reported present on Butaritari but not seen; if a small infestation, consider eradication; Inter-island quarantine.
*†	*Pennisetum purpureum*	elephant grass, napier grass, merker grass	Poaceae	Evaluate for eradication.
*†	Prosopis pallida	mesquite, algaroba	Fabaceae	Reported present on Tarawa; eradicate if found.
	*Ricinus communis*	castor bean	Euphorbiaceae	Inter-island quarantine, control as needed on infested islands.
*†	*Solanum torvum*	prickly solanum, devil’s fig	Solanaceae	Reported present on Tarawa and Abemama but not found. Evaluate for eradication if found.
*	*Sphagneticola trilobata*	Singapore daisy	Asteraceae	Although there are a number of infestations on Tarawa, this species should be evaluated for eradication; eradication is strongly recommended on Butaritari; inter-island quarantine and prompt eradication if found on Abemama and Maiana.
	*Stachytarpheta jamaicensis*	te uti, blue porterweed, light blue snakeweed	Verbenaceae	Inter-island quarantine (not present on Maiana); control as needed on infested islands.
	*Tecoma stans*	yellow bells, yellow-elder, yellow trumpetbush	Bignoniaceae	Inter-island quarantine (not present on Maiana); monitor for spread on other islands and control as needed.
	*Tradescantia spathacea*	oyster plant, boat plant, boat lily, Moses in a boat	Commelinaceae	Discourage further planting and dumping; control outside of cultivation; inter-island quarantine.
	*Tradescantia zebrina*	wandering jew	Commelinaceae	Discourage further planting and dumping; control outside of cultivation; inter-island quarantine.
*†	*Tridax procumbens*	coat buttons, tridax daisy	Asteraceae	Eradicate small infestation on Maiana.

*High priority for eradication
† Eradication can probably be accomplished at low cost

Planting of a number ornamental species should be discouraged. Those observed or reported present include Allamanda cathartica (allamanda, yellow trumpet vine), Antigonon leptopus (chain of love), Asystasia gangetica (Chinese violet, Philippine violet, coromandel), Bryophyllum pinnatum (life plant), Calotropis gigantea (te bumorimori, calotrope, crown flower, madar;), Cestrum nocturnum (night-flowering cestrum), Clitoria ternatea (butterfly pea), Cyperus involucratus (umbrella sedge), Epipremnum pinnatum cv. Aureum (pothos), Gliricidia sepium (mother of cacao, quickstick), Gloriosa superba (gloriosa lily), Gomphrena globosa (te matiti, te moteti, globe amaranth), Hemigraphis reptans, Jasminum sambac (te bitati, Arabian jasmine), Lantana camara (te kaibuaka, lantana), Russelia equisetiformis (te kaibaun, coralplant, fountainplant), Tecoma stans(nei Karairai, yellow bells, yellow-elder), Tradescantia spathacea (oyster plant, boat plant, boat lily, Moses in a boat), Tradescantia zebrina (wandering jew), and Wedelia [Sphagneticola] trilobata (Singapore daisy). These are known or potential problem species when they escape cultivation. A good example of what can happen when ornamental species escape cultivation is Turnera ulmifolia (yellow alder, sage rose), planted extensively and widely naturalized. Of particular concern is Wedelia [Sphagneticola] trilobata, which has become a major pest on a number of Pacific islands.

Recommendations by Island

All islands

The following recommendations apply to all islands covered by this survey (Tarawa, Abemama, Butaritari and Maiana):

Scientific Name	Common name	Comments and recommendations
*Casuarina equisetifolia*	casuarina, ironwood, Australian pine	Discourage planting on ocean shores, small islands and other areas subject to erosion.
*Lantana camara*	te kaibuaka, lantana	Appears not to be spreading, but to be safe any unwanted plants could be eliminated.

Discourage further planting of ornamental plants that are known or suspected to be problem species. Discourage discarding of garden waste and cuttings. Many tropical species can reproduce vegetatively and dumping of garden waste can spread them to new areas.

Infrequent mowing or slashing may just spread weed species that reproduce vegetatively, including Tradescantia spathacea, T. zebrina and Wedelia [Sphagneticola] trilobata.

Limit burning and extinguish wildfires promptly. Fire destroys many native species, which are not well adapted to fire, and favors invasive species, many of which are fire-resistant, fire-promoting or are pioneer species that do well on burned and nutrient-poor sites. Burning favors invasive species by reducing competition, exposing mineral soil and destroying organic matter, making it difficult for native species to become re-established. Fire can promote the reproduction of fire-adapted species. Establishment of these species (and extirpation of native species) can fuel additional fires, leading to a destructive fire cycle. In any case, atoll soils are low in nutrients and nutrient cycling is very important. Fire interrupts the nutrient cycle as well as favoring weed species.

Disturbance, removal of competition and the exposure of mineral soil favor many invasive species. Undisturbed ecosystems are much more resistant to invasion and limiting roadbuilding, land clearing and other disturbance to the minimum necessary will help prevent the establishment and spread of invasive plant species.

Maintaining inter-island quarantine, voluntary or otherwise, is very important for the outer islands, as there are far fewer invasive and potentially invasive species on them than in Tarawa. When new species do become established on these islands (the presently small infestation of Tridax procumbens found on Maiana is a good example) they should be promptly eradicated, as some of them can spread very rapidly.

Following are management recommendations for the most serious invasive plant species on each island. Please see Appendix 3 for a complete list of invasive species on each island.

Tarawa

Scientific Name	Common name	Comments and recommendations
*Acacia farnesiana*	te kaibakoa, te aketia, Ellington curse, klu, sweet acacia	Reported to be present in cultivation but not seen. Discourage further planting, control outside of cultivation, destroy unwanted plants.
*Agave sisalana*	te robu, te rob’, sisal, sisal hemp	Discourage further planting, control outside of cultivation, destroy unwanted plants, inter-island quarantine.
*Allamanda cathartica*	allamanda, yellow trumpet vine	Reported present but not seen. If present, discourage planting; eradicate if a problem.
*Antigonon leptopus*	chain of love	Only seen in cultivation. Discourage further planting; work to eradicate over time.
*Asystasia gangetica*	Chinese violet, Philippine violet, coromandel	Only seen in cultivation. Discourage further planting; work to eradicate over time.
*Calotropis gigantea*	calotrope, crown flower	Only seen in cultivation. Monitor for spread. If necessary, control outside of cultivation or eradicate.
*Cestrum nocturnum*	night-flowering cestrum, queen (or lady) of the night	Reported present, probably in cultivation, but not seen. If present, monitor for spread; control outside of cultivation or eradicate if necessary.
*Clitoria ternatea*	butterfly pea, Asian pigeonwings	Only seen in cultivation. Monitor for spread, control outside of cultivation or eradicate.
*Cyperus involucratus*	umbrella sedge	Only seen in cultivation. Eradicate if only cultivated or of limited extent.
*Datura metel*	te uri n tiaina, datura, jimson-weed	Continue eradication.
*Epipremnum pinnatum cv. Aureum*	pothos, money plant	Only seen in cultivation. Discourage further planting, control outside of cultivation, destroy unwanted plants, eradicate if necessary.
*Gliricidia sepium*	mother of cacao, quickstick, Mexican lilac	Monitor for spread (one naturalized specimen noted). Discourage further planting, control outside of cultivation, destroy unwanted plants.
*Gloriosa superba*	climbing-lily, flame-lily, glory-lily, gloriosa lily	Only seen in cultivation. Discourage further planting, control outside of cultivation, destroy unwanted plants.
*Ipomoea aquatica*	te kang kong, te ruku, aquatic morning glory, kang kong	Reported present, probably in cultivation, but not seen. If present, control outside of cultivation, destroy unwanted plants.
*Ipomoea violacea*	te ruku, moonflower	Seen only on North Tarawa. This aggressive native species can be controlled locally as needed.
*Macroptilium atropurpureum*	siatro	Eradicate infestations in Betio and Bikenibeu and any additional ones found.
*Panicum maximum*	Guinea grass, green panic, buffalograss	Reported present but not seen. If present and a small infestation, consider eradication.
*Passiflora foetida*	te biku, love-in-a-mist, stinking passionflower	Not common. Monitor for spread and control or eradicate, as appropriate.
*Pennisetum purpureum*	elephant grass, napier grass, merker grass	Evaluate for eradication.
Prosopis pallida	mesquite, algaroba	Reported present, probably in cultivation, but not seen. Eradicate if found.
*Solanum torvum*	prickly solanum, devil’s fig	Reported present but not seen. Evaluate for eradication if found.
*Sphagneticola trilobata*	Singapore daisy	Although there are a number of infestations on Tarawa, this species should be evaluated for eradication, otherwise it will eventually be everywhere on the island.
*Tradescantia spathacea*	oyster plant, boat plant, boat lily, Moses in a boat	Discourage further planting and the dumping of plants or cuttings; control outside of cultivation.
*Tradescantia zebrina*	wandering jew	Discourage further planting and the dumping of plants or cuttings; control outside of cultivation.

North Tarawa

Because it is somewhat isolated and more lightly inhabited than South Tarawa, the weed flora of North Tarawa is somewhat different. While we didn’t have time to survey all of North Tarawa, we were able to survey a large enough area (Buota to Nabeina and Tabonibara to Taratai) to get what is probably a representative sample of the species and their relative abundance (See Appendix 5, Table 1).

A number of species present in South Tarawa (particularly cultivated species) are not present in North Tarawa. Thus, there is the opportunity to keep some species out by promptly extirpating them if they show up. On the other hand, several species (including Bryophyllum pinnatum (te ang, life plant) and Russelia equisetiformis (te kaibaun, coralplant, fountainplant) are much more abundant than in South Tarawa. Also found on North Tarawa was Ipomoea violacea (te ruku, moonflower), an aggressive native species also present on Butaritari. Appendix 5, Table 2 lists species present on South Tarawa that are not known to be present on North Tarawa.

North Tarawa has been set aside as a conservation area. To preserve the nature of this area, it may be appropriate to expend extra effort to exclude exotic species from this area and to control some of the invasive plant species that are present, as necessary and appropriate.

Scientific Name	Common name	Comments and recommendations
*Ipomoea violacea*	te ruku, moonflower	This aggressive native species can be controlled locally as needed.

Abemama

Scientific Name	Common name	Comments and recommendations
*Agave sisalana*	te robu, te rob’, sisal, sisal hemp	Discourage further planting, control outside of cultivation, destroy unwanted plants, inter-island quarantine.
*Bryophyllum pinnatum*	te ang, life plant	Only a few small infestations. Eradication recommended.
*Datura metel*	te uri n tiaina, datura, jimson-weed	Continue eradication.
*Gloriosa superba*	climbing-lily, flame-lily, glory-lily, gloriosa lily	Only seen in cultivation. Discourage further planting, control outside of cultivation, destroy unwanted plants.
*Ipomoea aquatica*	te kang kong, te ruku, aquatic morning glory, kang kong	Control outside of cultivation, destroy unwanted plants.
*Solanum torvum*	prickly solanum, devil’s fig	Reported present but not seen. Evaluate for eradication if found.

Butaritari

Scientific Name	Common name	Comments and recommendations
*Asystasia gangetica*	Chinese violet, Philippine violet, coromandel	Reported present, probably in cultivation, not seen. If present, discourage further planting; work to eradicate over time.
*Bryophyllum pinnatum*	te ang, life plant	A small number of infestations. Strongly consider eradication.
*Datura metel*	te uri n tiaina, datura, jimson-weed	Reported present but not seen, may have been eradicated. If found, eradicate.
*Hemigraphis reptans*		Reported present, probably in cultivation, but not seen. If present, discourage further planting, control outside of cultivation, destroy unwanted plants.
*Ipomoea violacea*	te ruku, moonflower	This aggressive native species can be controlled locally as needed.
*Passiflora foetida*	te biku, love-in-a-mist, stinking passionflower	Reported present but not seen. If present, monitor for spread and control or eradicate, as appropriate.
*Pennisetum polystachion*	mission grass, feathery pennisetum	Reported present but not seen. If present and a small infestation, consider eradication.
*Sphagneticola trilobata*	Singapore daisy	There are only a small number of infestations on Butaritari. Eradication is strongly recommended or else this species will eventually be everywhere on the island.
*Tradescantia spathacea*	oyster plant, boat plant, boat lily, Moses in a boat	Discourage further planting and the dumping of plants or cuttings; control outside of cultivation.

Maiana

Scientific Name	Common name	Comments and recommendations
*Tridax procumbens*	coat buttons, tridax daisy	Eradicate small infestation at the base of the radio tower and across the street in Tebangetua before it spreads all over the island.

Other islands

The following species are reported present on the islands listed. While we did not visit these islands, recommendations are based on the characteristics of the species and their behavior as seen in Kiribati or on other Pacific islands.

Scientific Name	Island(s)	Common name	Comments and recommendations
*Acacia farnesiana*	Nikunau	te kaibakoa, te aketia, klu, Ellington curse, sweet acacia	Discourage further planting, control outside of cultivation, destroy unwanted plants.
*Agave sisalana*	Abaiang, Arorai, Nikunau	te robu, te rob’, sisal, sisal hemp	Discourage further planting, control outside of cultivation, destroy unwanted plants.
*Bryophyllum pinnatum*	Tabiteuea	te ang, life plant	Status not known. If limited, consider eradication.
*Datura metel*	Abaiang, Tamana	te uri n tiaina, datura, jimson-weed	Continue eradication if still present.
*Lantana camara*	Nonouti	te kaibuaka, lantana	Eradicate if not common.
*Tradescantia spathacea*	Abaiang	oyster plant, boat plant, boat lily, Moses in a boat	Discourage further planting and the dumping of plants or cuttings; control outside of cultivation.

Appendix 1. Invasive species

Appendix 2. Invasive species present in Fiji, Guam, Hawai‘i, the Marshall Islands, Nauru, Samoa or Tonga but not present in Kiribati

Appendix 3. Invasive species by location

Appendix 4. Presence of invasive species within Kiribati

Appendix 5. Invasive species on North Tarawa

Appendix 6. Scientific name synonyms

Appendix 7. Background material and references

(1) Former Director, Pacific Southwest Research Station, USDA Forest Service (retired) and Botanist, Bishop Museum, Department of Natural Sciences, respectively.

(2) We would like to express our sincere appreciation for the hospitality, assistance and support of the following staff of the Ministry of Environment, Lands and Agricultural Development who assisted us with the field work: Tianeti I. Beenna (Senior Agricultural Officer), Rui Tibau (Agricultural Assistant stationed on Butaritari Island), Kaaea Katanga (Nurseryman on Maiana Island) and Kimaere Abiata (Agricultural Assistant stationed on Abemama Island).

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