Pacific Island Ecosystems at Risk (PIER)


Agave americana


RISK ASSESSMENT RESULTS: High risk, score: 12


Australian/New Zealand Weed Risk Assessment adapted for Hawai‘i.
Information on Risk Assessments

Agave americana L. Family - Agavaceae. Common Names(s) - American agave, American century plant, centuryplant ,Maguey americano .

Answer

Score

1.01

Is the species highly domesticated?

y=-3, n=0

n

0

1.02

Has the species become naturalized where grown?

y=1, n=-1

1.03

Does the species have weedy races?

y= 1, n=-1

2.01

Species suited to tropical or subtropical climate(s) (0-low; 1-intermediate; 2-high) – If island is primarily wet habitat, then substitute “wet tropical” for “tropical or subtropical”

See Append 2

2

2.02

Quality of climate match data (0-low; 1-intermediate; 2-high) see appendix 2

2

2.03

Broad climate suitability (environmental versatility)

y=1, n=0

n

0

2.04

Native or naturalized in regions with tropical or subtropical climates

y=1, n=0

y

1

2.05

Does the species have a history of repeated introductions outside its natural range?

y=-2, ?=-1, n=0

y

3.01

Naturalized beyond native range y = 1*multiplier (see Append 2), n= question 2.05

y

2

3.02

Garden/amenity/disturbance weed y = 1*multiplier (see Append 2)

n=0

n

0

3.03

Agricultural/forestry/horticultural weed y = 2*multiplier (see Append 2)

n=0

n

0

3.04

Environmental weed y = 2*multiplier (see Append 2)

n=0

y

4

3.05

Congeneric weed y = 1*multiplier (see Append 2)

n=0

y

2

4.01

Produces spines, thorns or burrs

y=1, n=0

y

1

4.02

Allelopathic

y=1, n=0

n

0

4.03

Parasitic

y=1, n=0

n

0

4.04

Unpalatable to grazing animals

y=1, n=-1

n

-1

4.05

Toxic to animals

y=1, n=0

4.06

Host for recognized pests and pathogens

y=1, n=0

n

0

4.07

Causes allergies or is otherwise toxic to humans

y=1, n=0

4.08

Creates a fire hazard in natural ecosystems

y=1, n=0

n

0

4.09

Is a shade tolerant plant at some stage of its life cycle

y=1, n=0

4.10

Tolerates a wide range of soil conditions (or limestone conditions if not a volcanic island)

y=1, n=0

y

1

4.11

Climbing or smothering growth habit

y=1, n=0

n

0

4.12

Forms dense thickets

y=1, n=0

y

1

5.01

Aquatic

y=5, n=0

n

0

5.02

Grass

y=1, n=0

n

0

5.03

Nitrogen fixing woody plant

y=1, n=0

n

0

5.04

Geophyte (herbaceous with underground storage organs -- bulbs, corms, or tubers)

y=1, n=0

n

0

6.01

Evidence of substantial reproductive failure in native habitat

y=1, n=0

n

0

6.02

Produces viable seed.

y=1, n=-1

y

1

6.03

Hybridizes naturally

y=1, n=-1

y

1

6.04

Self-compatible or apomictic

y=1, n=-1

y

1

6.05

Requires specialist pollinators

y=-1, n=0

n

0

6.06

Reproduction by vegetative fragmentation

y=1, n=-1

y

1

6.07

Minimum generative time (years) 1 year = 1, 2 or 3 years = 0, 4+ years = -1

See left

2

0

7.01

Propagules likely to be dispersed unintentionally (plants growing in heavily trafficked areas)

y=1, n=-1

n

-1

7.02

Propagules dispersed intentionally by people

y=1, n=-1

y

1

7.03

Propagules likely to disperse as a produce contaminant

y=1, n=-1

n

-1

7.04

Propagules adapted to wind dispersal

y=1, n=-1

y

1

7.05

Propagules water dispersed

y=1, n=-1

y

1

7.06

Propagules bird dispersed

y=1, n=-1

n

-1

7.07

Propagules dispersed by other animals (externally)

y=1, n=-1

n

-1

7.08

Propagules survive passage through the gut

y=1, n=-1

n

-1

8.01

Prolific seed production (>1000/m2)

y=1, n=-1

8.02

Evidence that a persistent propagule bank is formed (>1 yr)

y=1, n=-1

8.03

Well controlled by herbicides

y=-1, n=1

8.04

Tolerates, or benefits from, mutilation, cultivation, or fire

y=1, n=-1

n

-1

8.05

Effective natural enemies present locally (e.g. introduced biocontrol agents)

y=-1, n=1

Total score:

12

Supporting data:

Notes

Source

1.01

(1)several cultivars exist [no evidence of serious loss of competitive ability]

(1)Riffle, R. L. 1998. The Tropical Look. An Encyclopedia of Dramatic Landscape Plants. Timber Press, Portland, OR.

1.02

1.03

2.01

(1)The natural distribution of A. americana is difficult to discern, but evidence suggests that the species originated in northeastern Mexico. It is often cultivated elsewhere in Mexico and in arid regions throughout the tropics, including the Mediterranean, Australia, Asia, and the islands of the Atlantic.

(1)Staples, G. W. and D. R. Herbst. 2005. A Tropical Garden Flora. Plants Cultivated in the Hawaiian Islands and Other Tropical Places. Bishop Museum Press. Honolulu, HI

2.02

(1)The natural distribution of A. americana is difficult to discern, but evidence suggests that the species originated in northeastern Mexico. It is often cultivated elsewhere in Mexico and in arid regions throughout the tropics, including the Mediterranean, Australia, Asia, and the islands of the Atlantic.

(1)Staples, G. W. and D. R. Herbst. 2005. A Tropical Garden Flora. Plants Cultivated in the Hawaiian Islands and Other Tropical Places. Bishop Museum Press. Honolulu, HI

2.03

(1)hardy in zones 9 through 11 and marginal in zone 8a.

(1)Riffle, R. L. 1998. The Tropical Look. An Encyclopedia of Dramatic Landscape Plants. Timber Press, Portland, OR.

2.04

(1)The natural distribution of A. americana is difficult to discern, but evidence suggests that the species originated in northeastern Mexico. It is often cultivated elsewhere in Mexico and in arid regions throughout the tropics, including the Mediterranean, Australia, Asia, and the islands of the Atlantic.

(1)Staples, G. W. and D. R. Herbst. 2005. A Tropical Garden Flora. Plants Cultivated in the Hawaiian Islands and Other Tropical Places. Bishop Museum Press. Honolulu, HI

2.05

(1)The natural distribution of A. americana is difficult to discern, but evidence suggests that the species originated in northeastern Mexico. It is often cultivated elsewhere in Mexico and in arid regions throughout the tropics, including the Mediterranean, Australia, Asia, and the islands of the Atlantic.

(1)Staples, G. W. and D. R. Herbst. 2005. A Tropical Garden Flora. Plants Cultivated in the Hawaiian Islands and Other Tropical Places. Bishop Museum Press. Honolulu, HI

3.01

(1)Abstract: A number of large-growing species of Agave L. (Agavaceae) have become firmly established as part of the introduced flora of parts of the Algarve, southern Portugal, particularly close to human settlements. Two species, which include at least four taxa, Agave americana L. ssp americana, A. americana var marginata Trel., A. salmiana Otto ex Salm-Dyck var salmiana and A. salmiana var ferox (K. Koch) Gentry, recorded in southeastern Portugal are briefly discussed here, their residence status is determined, and a key to aid in their identification and that of other cultivated forms of Agave americana is provided. In addition, a putative hybrid between A. americana ssp americana and A. salmiana var salmiana is recorded here for the first time. The nomenclature of the naturalized species of Agave is updated to reflect current usage. The four naturalized Agave taxa are compared to A. franzosinii Baker, which is widely cultivated along the Mediterranean coast of Europe. (2)Native in Texas only on gravelly hills in extreme south Texas, but naturalized elsewhere in the state and in warm regions throughout the world. (3)Cultivated and naturalized throughout the Mediterranean and the Canary Islands. From Mexico. (4)Abstract: In alpha-taxonomic terms the Eastern Cape Province of South Africa, which includes the entire Albany Centre of Endemism, is one of the richest succulent plant regions in the world. The mild climate of the region is also suitable for the cultivation of a number of exotic succulents, several of which have escaped into the natural flora, subsequently becoming naturalised. The five species of Agave L. recorded for the Eastern Cape are here described and illustrated as part of compiling a Flora for the region. The species are Agave angustifolia Haw. var. angustifolia, A. americana L. var. americana, A. sisalana Perrine, A. vivipara L. var. vivipara and A. wercklei F.A.C.Weber ex Wercklé. A key is provided to assist with the identification of the five species.

(1)Smith, G. F. and E. Figueiredo. 2007. Naturalized species of Agave L. (Agavaceae) on the southeastern coast of Portugal. Haseltonia 13 :52-60. (2)Nokes, J. 2001. How to Grow Native Plants of Texas and the Southwest. University of Texas Press, Austin, TX. (3)http://www.floracyberia.net/spermatophyta/angiospermae/monocotyledoneae/agavaceae/agave_americana.html [Accessed 12 Nov 2009] (4)Smith, G.F., Walters, M., Figueiredo, E. & Klopper, R.R. 2008. Naturalised species of Agave L. (Agavaceae) in the Eastern Cape Province of South Africa, Bradleya, vol. 26: 33-40.

3.02

[environmental weed] (1)Punta Entinas-Sabinar is a dune field where Agave americana is spreading, interfering with the dominant native species, Juniperus phoenicea (Cupressaceae), and H. soechas . Dunes are 7– 8 m tall and the valleys in between are highly saline. At the valley bottoms clumps of Pistacea lentiscus (Plantaginaceae) and other halophytes like Limoniun spp. (Plumbaginaceae) or Inula crithmoides (Asteraceae) are present, but no agaves are found. There are no records of the history of A. americana at this site, but it probably was introduced for sand dune stabilization. (2)Fourteen species were the most prominent invaders in the Nama-Karoo Biome (Appendix 3). Prosopis spp. (P. glandulosa var. torreyana, P. velutina and their hybrids) were the most prominent species with a prominence value of 60.6, followed by Atriplex inflata (sponge-fruit saltbush) and Opuntia ficus-indica with values of 21 and 14 respectively. The remaining top ten prominent invaders were, in order, Salsola kali/tragus (Russian tumbleweed), Azolla filiculoides (red water fern), Nicotiana glauca (wild tobacco), Atriplex nummularia (old man saltbush), Schinus molle (pepper tree), Agave americana (American agave) and Solanum elaeagnifolium (silverleaf bitter-apple).

(1)Badano, E. I. and F. I. Pugnaire. 2004. Invasion of Agave species (Agavaceae) in south-east Spain: invader demographic parameters and impacts on native species. Diversity and Distributions 10: 493–500. (2)Henderson, L. 2007. Invasive, naturalized and casual alien plants in southern Africa: a summary based on the Southern African Plant Invaders Atlas (SAPIA). Bothalia 37,2: 215–248.

3.03

[environmental weed. See 3.04]

 

3.04

(1)Punta Entinas-Sabinar is a dune field where Agave americana is spreading, interfering with the dominant native species, Juniperus phoenicea (Cupressaceae), and H. soechas . Dunes are 7– 8 m tall and the valleys in between are highly saline. At the valley bottoms clumps of Pistacea lentiscus (Plantaginaceae) and other halophytes like Limoniun spp. (Plumbaginaceae) or Inula crithmoides (Asteraceae) are present, but no agaves are found. There are no records of the history of A. americana at this site, but it probably was introduced for sand dune stabilization. (2)Fourteen species were the most prominent invaders in the Nama-Karoo Biome (Appendix 3). Prosopis spp. (P. glandulosa var. torreyana, P. velutina and their hybrids) were the most prominent species with a prominence value of 60.6, followed by Atriplex inflata (sponge-fruit saltbush) and Opuntia ficus-indica with values of 21 and 14 respectively. The remaining top ten prominent invaders were, in order, Salsola kali/tragus (Russian tumbleweed), Azolla filiculoides (red water fern), Nicotiana glauca (wild tobacco), Atriplex nummularia (old man saltbush), Schinus molle (pepper tree), Agave americana (American agave) and Solanum elaeagnifolium (silverleaf bitter-apple).

(1)Badano, E. I. and F. I. Pugnaire. 2004. Invasion of Agave species (Agavaceae) in south-east Spain: invader demographic parameters and impacts on native species. Diversity and Distributions 10: 493–500. (2)Henderson, L. 2007. Invasive, naturalized and casual alien plants in southern Africa: a summary based on the Southern African Plant Invaders Atlas (SAPIA). Bothalia 37,2: 215–248.

3.05

(1)Agave sisalana. The weedy behavior is due to vegetative growth, allowing the species to colonize large areas and replace the native vegetation with its rosettes.

(1)Weber, E. 2003. Invasive plants of the World. CABI Publishing, CAB International, Wallingford, UK.

4.01

(1)Succulent, large, stemless, subwoody, to 2 m high before flowering. Leaves simple, spirally arranged in a basal rosette, blade lanceolate, 100 200 x 12-25 cm, margins with black prickles 7-10 mm long and a black terminal spine 3-5 cm long, surface waxy white, in cultivars often variegated with cream stripes....best kept away from foot traffic because of the spiny leaf margins. The sharp tip may be clipped to prevent injury.

(1)Whistler, W. A. 2000. Tropical ornamentals: a guide. Timber Press, Portland, Oregon.

4.02

(1)when the plant dies after flowering, it returns valuable organic matter to infertile soils [no evidence of allelopathy]

(1)Nokes, J. 2001. How to Grow Native Plants of Texas and the Southwest. University of Texas Press, Austin, TX.

4.03

(1)No evidence

(1)Weber, E. 2003. Invasive plants of the World. CABI Publishing, CAB International, Wallingford, UK.

4.04

(1)Members of this genus are rarely if ever troubled by browsing deer[233]. (2)The ferocious cluster of basal leaves protects…from browsing animals (3)American aloe leaves alone are not sufficient for a maintenance ration. Although American aloe is palatable and can form a portion of the daily ration, it must be supplemented by sufficient Lucerne hay, meal, etc. to prevent paralysis, which can be experienced if American aloe leaves alone are fed continuously. It has however been shown that American aloe leaves can, to a large extent, take the place of silage, mangels etc, as the succulent portion of the ration. For fodder the leaves are chopped against the stem so that as much as possible of the thick fleshy portion is used, as this is the most palatable part. The fibrous points and edges of the leaves are removed and the leaves are chaffed in pieces not larger than 50 × 100 mm. A hand chaff-cutter or chopping knives are suitable for this purpose. Leaves are usually harvested from 4 - to 6 -year old plants. A yield of from 120 tons of leaves per hectare can be expected annually from America alone and that on relatively poor soils.

(1)http://www.pfaf.org/database/plants.php?Agave+americana [Accessed 12 Nov 2009] (2)Nokes, J. 2001. How to Grow Native Plants of Texas and the Southwest. University of Texas Press, Austin, TX. (3)G.C. De Kock. Drought resistant fodder shrub crops in South Africa. http://www.ilri.org/InfoServ/Webpub/Fulldocs/Browse_in_Africa/Chapter43.htm [Accessed 12 Nov 2009]

4.05

(1)Dermatologic poison yes Livestock poison no (2)Poisonous if a quantity are fed to ruminants.

(1)http://www.crescentbloom.com/plants/specimen/AE/Agave%20americana.htm [Accessed 12 Nov 2009] (2)The Nature Conservation Corporation – 2006. Invasive Alien Vegetation Management Manual. http://www.eskom.co.za/content/AnnxC.pdf [Accessed 17 Nov 2009]

4.06

(1)Pest resistance: no serious pests are normally seen on the plant (2)Agave Snout Weevil (Scyphophorus acupunctatus) The adult weevil attacks many species of agave. The very large Agave americana or century plant is more susceptible to weevil damage than the smaller species. The adult weevil is about ½ inch (12 mm) in length, is brownish-black and has a dull body (Fig. 16). The adult female enters the base of the plant to lay eggs. Decay microbes also enter through this injury and as the tissue rots, the plant has a wilted appearance. Infested plants soon collapse and die (Fig. 17). The larvae (grubs) develop in the dying plant and infect other hosts nearby. Agave snout weevil also infests the canes of several Yucca species. Control of the agave snout weevil is difficult. Selecting species that are less susceptible and typically smaller than the century plant is helpful, especially in areas where the problem has occurred previously. With rare or special specimens, chemical prevention using a broad-spectrum insecticide applied in spring is often effective in reducing damage. [other than Agave spp, which are not native to Hawaii, and not economically important, not an alternate host of important pests or pathogens]

(1)http://hort.ifas.ufl.edu/shrubs/AGAAMEB.PDF [Accessed 12 Nov 2009] (2)Kelly, J. and M. Olsen. 2008. Problems and Pests of Agave, Aloe, Cactus and Yucca. Cooperative Extension College of Agriculture and Life Sciences The University of Arizona Tucson, Arizona.

4.07

(1)Contact with the fresh sap can cause dermatitis in sensitive people...The heart of the plant is very rich in saccharine matter and can be eaten when baked[2, 92, 183]. Sweet and nutritious, but rather fibrous[213]. It is partly below ground[85]. Seed - ground into a flour and used as a thickener in soups or used with cereal flours when making bread[92]. Flower stalk - roasted[92, 95]. Used like asparagus[183]. Sap from the cut flowering stems is used as a syrup[177] or fermented into pulque or mescal[183]. The sap can also be tapped by boring a hole into the middle of the plant at the base of the flowering stem[213]...The sap of agaves has long been used in Central America as a binding agent for various powders used as poultices on wounds[254]. The sap can also be taken internally in the treatment of diarrhoea, dysentery etc[254]. The sap is antiseptic, diaphoretic, diuretic and laxative[21, 218, 240]. An infusion of the chopped leaf is purgative and the juice of the leaves is applied to bruises[218]. The plant is used internally in the treatment of indigestion, flatulence, constipation, jaundice and dysentery[238]. The sap has disinfectant properties and can be taken internally to check the growth of putrefactive bacteria in the stomach and intestines[21]. Water in which agave fibre has been soaked for a day can be used as a scalp disinfectant and tonic in cases of falling hair[21]. Steroid drug precursors are obtained from the leaves[238]. A gum from the root and leaf is used in the treatment of toothache[218]. The root is diaphoretic and diuretic[240]. It is used in the treatment of syphilis[218, 240]. All parts of the plant can be harvested for use as required, they can also be dried for later use. The dried leaves and roots store well[238]. [in most cases, people would not be allergic to plant] (2)Sap of the plant will leave a nasty rash. (3)Dermatologic poison yes (4)People who have allergies to plants in Agavaceae family should be cautious in using agave. Contact dermatitis after exposure to the sap of Agave americana has been reported in rare cases.

(1)http://www.pfaf.org/database/plants.php?Agave+americana [Accessed 12 Nov 2009] (2)http://davesgarden.com/guides/pf/go/55351/ [Accessed 12 Nov 2009] (3)http://www.crescentbloom.com/plants/specimen/AE/Agave%20americana.htm [Accessed 12 Nov 2009] (4)http://www.wellness.com/reference/herb/agave-agave-americana/dosing-and-safety [Accessed 12 Nov 2009]

4.08

(1)Here are some attractive succulents capable of serving as firebreaks: Agave americana (Century Plant). "A big, blue, thug-like plant that grows anywhere, with no care at all," Baldwin said. "Here in the Southwest, it's the plant most people think of when they hear the word `agave,' but there are many small agaves better suited to residential gardens." (2)Succulent, large, stemless, subwoody, to 2 m high before flowering.

(1)http://www.wral.com/lifestyles/house_and_home/story/2004351/ [Accessed 12 Nov 2009]

4.09

(1)Century plants prefer dry situations in full sun. (2)Light requirement: plant grows in part shade/part sun...It grows best in full sun but can adapt to shade.

(1)Staples, G. W. and D. R. Herbst. 2005. A Tropical Garden Flora. Plants Cultivated in the Hawaiian Islands and Other Tropical Places. Bishop Museum Press. Honolulu, HI (2)http://hort.ifas.ufl.edu/shrubs/AGAAMEB.PDF [Accessed 12 Nov 2009]

4.10

(1)The species is drought resistant and shows a broad tolerance to different soil types.

(1)Weber, E. 2003. Invasive plants of the World. CABI Publishing, CAB International, Wallingford, UK.

4.11

(1)Succulent, large, stemless, subwoody, to 2 m high before flowering. Leaves simple, spirally arranged in a basal rosette, blade lanceolate, 100 200 x 12-25 cm, margins with black prickles 7-10 mm long and a black terminal spine 3-5 cm long, surface waxy white, in cultivars often variegated with cream stripes.

(1)Whistler, W. A. 2000. Tropical ornamentals: a guide. Timber Press, Portland, Oregon.

4.12

(1)A single individual can form dense, impenetrable stands that eliminate native vegetation.

(1)Weber, E. 2003. Invasive plants of the World. CABI Publishing, CAB International, Wallingford, UK.

5.01

(1)Terrestrial

(1)Weber, E. 2003. Invasive plants of the World. CABI Publishing, CAB International, Wallingford, UK.

5.02

(1)Agavaceae

(1)Whistler, W. A. 2000. Tropical ornamentals: a guide. Timber Press, Portland, Oregon.

5.03

(1)Agavaceae

(1)Whistler, W. A. 2000. Tropical ornamentals: a guide. Timber Press, Portland, Oregon.

5.04

(1)Where invasive, the plant persists and spreads by abundant suckering from the root crown [not a true geophyte]

(1)Weber, E. 2003. Invasive plants of the World. CABI Publishing, CAB International, Wallingford, UK.

6.01

(1)No evidence

(1)Weber, E. 2003. Invasive plants of the World. CABI Publishing, CAB International, Wallingford, UK.

6.02

(1)Fruits are oblong short-beaked capsules of 4-5 cm length. Seeds are brown or shiny black, 7-8 mm long and 5-6 mm wide.

(1)Weber, E. 2003. Invasive plants of the World. CABI Publishing, CAB International, Wallingford, UK.

6.03

(1)The hybrid between Agave americana and Agave salmiana is commonly encountered in southeastern Portugal. It produces numerous offsets by means of underground runners to form small, impenetrable thickets...It is noteworthy that extensive natural (Gentry 1967) and artificial (Trager 2006) hybridization between species of Agave have been documented...The hybrid between A. americana and A. salmiana is an interesting case, as it is possible that these hybrid plants that are currently found in Portugal, originated there, rather than having been introduced as aliens from Mexico. It is furthermore unlikely that the hybrid came about in Portugal as a result of a deliberate crossing event performed by humans. Both parents flower freely in Portugal, and spontaneous hybridization as a result of casual visits by pollination vectors would be imminently possible. Also, at least in Mexico, the flowering times of the two species overlap substantially (Gentry 1982). Since the hybrid is also known from Mexico (Gentry 1982), where the parents are indigenous, it essentially does not lack a “native” region (Pyšek and others 2004). It may therefore be appropriate to also regard this hybrid simply as a naturalized plant.

(1)Smith, G. F. and E. Figueiredo. 2007. Naturalized species of Agave L. (Agavaceae) on the southeastern coast of Portugal. Haseltonia 13 :52-60.

6.04

(1)self-pollinated At5 and Aa (Agave americana) plants produced bery few fruits and seeds. [low seed production in self-pollinated plants, but still able to produce some seeds]

(1)Escobar-Guzman, R. E., F. Z. Hernandez, K. G. Vega, and J. Simpson. 2008. Seed production and gametophyte formation in Agave tequilana and Agave americana. Canadian Journal of Botany 86: 1343-1353.

6.05

(1)The flowers are hermaphrodite (have both male and female organs) and are pollinated by Lepidoptera (Moths & Butterflies), bats.

(1)http://www.pfaf.org/database/plants.php?Agave+americana [Accessed 12 Nov 2009]

6.06

(1)Where invasive, the plant persists and spreads by abundant suckering from the root crown.

(1)Weber, E. 2003. Invasive plants of the World. CABI Publishing, CAB International, Wallingford, UK.

6.07

(1)Flowers infrequently, after 15 to 30 years of growth, not a century as the name would imply [but see reference 2] (2)Where invasive, the plant persists and spreads by abundant suckering from the root crown. [although species does not sexually reproduce for a long time, it is able to reproduce vegetatively after 1 year]

(1)Whistler, W. A. 2000. Tropical ornamentals: a guide. Timber Press, Portland, Oregon. (2)Weber, E. 2003. Invasive plants of the World. CABI Publishing, CAB International, Wallingford, UK.

7.01

(1)Fruits are oblong short-beaked capsules of 4-5 cm length. Seeds are brown or shiny black, 7-8 mm long and 5-6 mm wide [no means of external attachment]

(1)Weber, E. 2003. Invasive plants of the World. CABI Publishing, CAB International, Wallingford, UK.

7.02

(1)native to Mexico but is widely cultivated for its attractive foliage and as a novelty.

(1)Whistler, W. A. 2000. Tropical ornamentals: a guide. Timber Press, Portland, Oregon.

7.03

(1)Fruits are oblong short-beaked capsules of 4-5 cm length. Seeds are brown or shiny black, 7-8 mm long and 5-6 mm wide [no evidence]

(1)Weber, E. 2003. Invasive plants of the World. CABI Publishing, CAB International, Wallingford, UK.

7.04

(1)Flotation of bulbils or fruits is possible. Trelease (1913) reported this for cultivated Agave americana L. Also possible is wind dispersal of the wafer-thin seeds. Agave seedlings apparently from wind-borne seeds colonize coral stone ruins in Antigua. Beyond wind and waves, circumstantial evidence points to human-mediated dispersal as discussed below.

(1)Rogers, G. K. 2000. A Taxonomic Revision of the Genus Agave (Agavaceae) in the Lesser Antilles, with an Ethnobotanical Hypothesis. Brittonia 52(3): 218-233.

7.05

(1)Flotation of bulbils or fruits is possible. Trelease (1913) reported this for cultivated Agave americana L. Also possible is wind dispersal of the wafer-thin seeds. Agave seedlings apparently from wind-borne seeds colonize coral stone ruins in Antigua. Beyond wind and waves, circumstantial evidence points to human-mediated dispersal as discussed below.

(1)Rogers, G. K. 2000. A Taxonomic Revision of the Genus Agave (Agavaceae) in the Lesser Antilles, with an Ethnobotanical Hypothesis. Brittonia 52(3): 218-233.

7.06

(1)Fruits are oblong short-beaked capsules of 4-5 cm length. Seeds are brown or shiny black, 7-8 mm long and 5-6 mm wide [not fleshy-fruited]

(1)Weber, E. 2003. Invasive plants of the World. CABI Publishing, CAB International, Wallingford, UK.

7.07

(1)Fruits are oblong short-beaked capsules of 4-5 cm length. Seeds are brown or shiny black, 7-8 mm long and 5-6 mm wide [no means of external attachment]

(1)Weber, E. 2003. Invasive plants of the World. CABI Publishing, CAB International, Wallingford, UK.

7.08

(1)Fruits are oblong short-beaked capsules of 4-5 cm length. Seeds are brown or shiny black, 7-8 mm long and 5-6 mm wide [no evidence of ingestion]

(1)Weber, E. 2003. Invasive plants of the World. CABI Publishing, CAB International, Wallingford, UK.

8.01

(1)26936 (16744-37128) black seeds per plant [clusters of plants could potentially reach high seed densities]

(1)Escobar-Guzman, R. E., F. Z. Hernandez, K. G. Vega, and J. Simpson. 2008. Seed production and gametophyte formation in Agave tequilana and Agave americana. Canadian Journal of Botany 86: 1343-1353.

8.02

(1)Storage Behaviour: Orthodox [field seed bank longevity unknown] (2)Wounding of the seed coat greatly increased germination efficiency for both A. tequilana and A. americana. Peña-Valdivia et al. (2006) previously reported accelerated germination in scarified A. salmiana seeds; however, a biological basis for the need for scarification under natural conditions is unclear. Seeds from most Agave species are normally distributed by the wind as capsules open to release them and not by birds or other animals. Mechanical damage however could occur once they have reached the ground owing to the movement of animals or the activities of insects. [scarification requirements may lead to creation of a persistent seed bank]

(1)Liu, K., Eastwood, R.J., Flynn, S., Turner, R.M., and Stuppy, W.H. 2008. Seed Information Database (release 7.1, May 2008) http://www.kew.org/data/sid (2)Escobar-Guzman, R. E., F. Z. Hernandez, K. G. Vega, and J. Simpson. 2008. Seed production and gametophyte formation in Agave tequilana and Agave americana. Canadian Journal of Botany 86: 1343-1353.

8.03

(1)Specific control methods for this species are not available. Smaller rosettes may be dug out but all roots must be removed to prevent regrowth. (2)Table 2. Changes in target alien plant populations with treatment; most effective treatments used in Hawai`i Volcanoes National Park...Agave americana...Most Effective Treatment Used...Herbicide...5% Garlon 4 [this reference suggests herbicides are effective, but other references disagree] (3)Difficult to control using herbicides. (4)Inject 2ml of MSMA (MSMA 720g/l) into the bole of the plant - 2l per 1000 plants. It is recommended that stout gloves be warn whilst working with this species as the “teeth’” can cut & the sap irritates the skin.

(1)Weber, E. 2003. Invasive plants of the World. CABI Publishing, CAB International, Wallingford, UK. (2)Tunison, J. T. and N. G. Zimmer. 1992. Success in controlling localized alien plants in Hawaii Volcanoes National Park. Pp. 506-524 in C. P. Stone, C. W. Clifford & J. T. Tunison (eds). Alien plant invasions in native ecosystems of Hawaii. Management and research. Cooperative National Park Resources Studies Unit University of Hawaii, Honolulu. (3)http://www.emrc.org.au/displayfile-ID-57812.asp [Accessed 12 Nov 2009] (4)The Nature Conservation Corporation – 2006. Invasive Alien Vegetation Management Manual. http://www.eskom.co.za/content/AnnxC.pdf [Accessed 17 Nov 2009]

8.04

(1)The most effective means of control is removal of the entire plant, including roots, by hand. At present these infestations largely consist of small plants and the removal of all plants is achievable with relatively little investment of labour. [does not benefit from cutting, but does spread vegetatively

(1)Ecoscape (Australia) Pty Ltd. 2005. North Cottesloe Coastal Natural Areas Management Plan. http://www.cottesloecoastcare.org/publications/North_Cott_%20Man_%20Plan.pdf [Accessed 17 Nov 2009]

8.05

(1)One pest, locally called the agave snout beetle, causes serious damage or death to plants by burrowing inside the crown where the mealy grubs feed. Growers try to expel them by forcing a stream of water into the burrows or applying a contact insecticide to the exit holes, where it can trickle inside.

(1)Staples, G. W. and D. R. Herbst. 2005. A Tropical Garden Flora. Plants Cultivated in the Hawaiian Islands and Other Tropical Places. Bishop Museum Press. Honolulu, HI


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