Research directed by C. Daehler (UH Botany) with funding from the Kaulunani Urban Forestry Program and US Forest Service

Information on Risk Assessments
Original risk assessment

Leucaena leucocephala (leucaena, wild tamarind, lead tree)

Answer

1.01

Is the species highly domesticated?

y=-3, n=0

n

1.02

Has the species become naturalized where grown?

y=-1, n=-1

y

1.03

Does the species have weedy races?

y=-1, n=-1

y

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

y

2.04

Native or naturalized in regions with tropical or subtropical climates

y=1, n=0

y

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

3.02

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

n=0

n

3.03

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

n=0

y

3.04

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

n=0

y

3.05

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

n=0

n

4.01

Produces spines, thorns or burrs

y=1, n=0

n

4.02

Allelopathic

y=1, n=0

n

4.03

Parasitic

y=1, n=0

n

4.04

Unpalatable to grazing animals

y=1, n=-1

n

4.05

Toxic to animals

y=1, n=0

n

4.06

Host for recognized pests and pathogens

y=1, n=0

n

4.07

Causes allergies or is otherwise toxic to humans

y=1, n=0

n

4.08

Creates a fire hazard in natural ecosystems

y=1, n=0

n

4.09

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

y=1, n=0

n

4.1

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

y=1, n=0

y

4.11

Climbing or smothering growth habit

y=1, n=0

n

4.12

Forms dense thickets

y=1, n=0

y

5.01

Aquatic

y=5, n=0

n

5.02

Grass

y=1, n=0

n

5.03

Nitrogen fixing woody plant

y=1, n=0

y

5.04

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

y=1, n=0

n

6.01

Evidence of substantial reproductive failure in native habitat

y=1, n=0

n

6.02

Produces viable seed.

y=1, n=-1

y

6.03

Hybridizes naturally

y=1, n=-1

y

6.04

Self-compatible or apomictic

y=1, n=-1

y

6.05

Requires specialist pollinators

y=-1, n=0

n

6.06

Reproduction by vegetative fragmentation

y=1, n=-1

n

6.07

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

See left

2

7.01

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

y=1, n=-1

n

7.02

Propagules dispersed intentionally by people

y=1, n=-1

y

7.03

Propagules likely to disperse as a produce contaminant

y=1, n=-1

n

7.04

Propagules adapted to wind dispersal

y=1, n=-1

n

7.05

Propagules water dispersed

y=1, n=-1

n

7.06

Propagules bird dispersed

y=1, n=-1

7.07

Propagules dispersed by other animals (externally)

y=1, n=-1

n

7.08

Propagules survive passage through the gut

y=1, n=-1

y

8.01

Prolific seed production (>1000/m2)

y=1, n=-1

n

8.02

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

y=1, n=-1

y

8.03

Well controlled by herbicides

y=-1, n=1

n

8.04

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

y=1, n=-1

y

8.05

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

y=-1, n=1

Total score:

15

Source

Notes

1.01

No evidence.

1.02

Native to the neotropics and widely naturalized throughout the tropics including Hawaii.

Wagner,W. L., D. R. Herbst & S. H. Sohmer. 1990. Manual of flowering plants of Hawaii.University of Hawaii at Press. Honolulu.

1.03

'By the late 19th century subsp. leucocephala had spread or been introduced through Asia and Africa, and it is now pantropical, recorded from the majority of tropical and subtropical countries. Subsp. leucocephala is an aggressive colonizer of disturbed sites and is spreading naturally. It has been recorded as a weed in more than 20 countries scattered across all continents except Europe and Antarctica.' It is a weed of open (often coastal) habitats, semi-natural, disturbed, degraded habitats, other ruderal sites (e.g. roadsides, abandoned fields and waste ground) and occasionally agricultural land where it has been planted as a shade tree over cocoa. It is not one of the world's worst weeds and it is not known to invade undisturbed closed forest habitats. However, in many areas it has formed dense monospecific thickets...

CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International.

2.01

L. leucocephala is essentially a tropical species requiring warm temperatures of 25-30°C for optimum growth, tolerating temperature maxima as high as 48°C and with poor cold tolerance and significantly reduced growth during cool winter months in subtropical areas. Native to the neotropics and widely naturalized throughout the tropics: Hawaii.

Wagner,W. L., D. R. Herbst & S. H. Sohmer. 1990. Manual of flowering plants of Hawaii.University of Hawaii at Press. Honolulu.

2.02

2.03

1) The altitudinal range is the main difference between subspecies leucocephala and glabrata. They grow from sea level to, respectively, 500 and 1500 m.
2)Approximate limits north to south: 30°N to 16°N. Vegetation types: coastal plant communities; dry forests; secondary forests. Altitude range: 0 - 2000 m

1)http://members.lycos.co.uk/WoodyPlantEcology/docs/web-sp7.htm 2)CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International.

2.04

Native to the neotropics and widely naturalized throughout the tropics including Hawaii.

Wagner,W. L., D. R. Herbst & S. H. Sohmer. 1990. Manual of flowering plants of Hawaii.University of Hawaii at Press. Honolulu.

2.05

This species has been introduced in several countries throughout the world.

CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International.

3.01

Native to the neotropics and widely naturalized throughout the tropics including Hawaii.

Wagner,W. L., D. R. Herbst & S. H. Sohmer. 1990. Manual of flowering plants of Hawaii.University of Hawaii at Press. Honolulu.

3.02

No evidence.

3.03

(1)In the Marquesas Islands farmers consider the species as an agricultural weed which is nearly impossible to uproot completely.
(2)Listed as a serious weed in West Polynesia, New Guinea, and as principal weed in Hawaii and Ghana.

(1)http://members.lycos.co.uk/WoodyPlantEcology/docs/web-sp7.htm (2)Holm, L, Pancho, J.V.,Herberger,J.P. and Plucknett, D.L. 1979. A geogrpahical atlas of world weeds. John Wiley and sons. New York.

3.04

(1)It is spreading naturally and is considered a weed and a threat to native plants in some areas. (2)L. leucocephala invades cleared areas and forms dense thickets. In the Hawaiian islands it sometimes becomes the dominant part of the vegetation at low altitude (0 - 300 m) on dry and disturbed sites. In the Marquesas Islands the tree is spreading into native disturbed forest. (3)This thornless tree forms dense thickets, excluding all plants. It is grown for fodder, but unless severely grazed or controlled, it spreads rampantly throughout adjacent areas (4)Only 86, less than 2% of the total, have become serious pests of native ecosystems. Of these, the most significant are Andropogon virginicus, Clidemia hirta, Lantana camara, Leucaena leucocephala, Melinis minutiflora, Myrica faya, Passiflora mollissima, Pennisetum clandestinum, P. setaceum, Psidium cattleianum, Rubus argutus, and Schinus terebinthifolius. [no elaboration; the species is not subsequently discussed]

(1)http://www.issg.org/database/species/search.asp?sts=sss&st=sss&fr=1&sn=Leucaena+leucocephala&rn=&hci=-1&ei=38&x=24&y=8 (2)http://members.lycos.co.uk/WoodyPlantEcology/docs/web-sp7.htm (3)Smith, C.W. 1985. Impact of alien plants on Hawai'i's native biota. In: Charles P. Stone and J. Michael Scott, eds.. Hawai'i's Terrestrial Ecosystems: Preservation and Management. Cooperative National Park Resources Studies Unit, University of Hawaii, Honolulu. (4)http://www.botany.hawaii.edu/faculty/cw_smith/impact.htm [no elaboration]

3.05

No evidence.

4.01

No

Wagner,W. L., D. R. Herbst & S. H. Sohmer. 1990. Manual of flowering plants of Hawaii.University of Hawaii at Press. Honolulu.

4.02

No evidence.

4.03

No evidence.

4.04

1)an excellent protein source for cattle fodder, consumed browsed or harvested, mature or immature, green or dry 2)Used as forage

1)http://www.hort.purdue.edu/newcrop/duke_energy/Leucaena_leucocephala.html 2)http://members.lycos.co.uk/WoodyPlantEcology/docs/web-sp7.htm

4.05

1)Seeds and young leaves yield 4 percent of mimosine, which causes loss of hair in non-ruminant animals, especially in horses, mules, donkeys and hogs.2) Horses, feeding on the tree, lose their hairs. -- (this is a cosmetic problem that does not seem to occur unless animals are forced to eat large quantities over time)

1)http://www.hort.purdue.edu/newcrop/duke_energy/Leucaena_leucocephala.html 2)http://members.lycos.co.uk/WoodyPlantEcology/docs/web-sp7.htm

4.06

Pests recorded
Insect pests:
Acanthoscelides
Araecerus fasciculatus
Araecerus levipennis
Cathartus quadricollis
Heteropsylla cubana
Statherotis
Fungus diseases: Camptomeris leucaenae
(2) Coffee is the common host of Araecerus fasciculatus.

CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International. (2)http://www-infocris.iaea.org/IDIDAS/w3.exe$IDIDASShow?ID=57

4.07

'Its leaves and seeds are used for direct human consumption in some areas of Central America and Southeast Asia.'

Smith, F.W., Berg P.J., Gonzalea et al. 1992. Foliar symptoms of nutrient disorders in the tropical shrub legume Leucaena leucocephala. Division of Tropical Crops and Pastures Technical Paper No 32. CSIRO. Australia.

4.08

It regenerates rapidly from basal shoots after fire. There is also a flush of new seedlings produced following fire, but whether this is the result of normal germination or breaking dormancy by fire is not known. In mature monotypic stands fire is suppressed because of the low fuel load.

http://www.botany.hawaii.edu/faculty/cw_smith/leu_leu.htm

4.09

Light-demanding species.

CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International.

4.1

1) The leadtree thrives on a wide range of soils, but the most rapid growth is on deep clay soils which are fertile, moist and alkaline. It tolerates aluminum and soils low in iron and phosphorus. It grows best on neutral or alkaline soils, but does poorly on acidic latosols unless Mo, Ca, S and P are added. Its deep root system permits it to tolerate many soil types, from heavy soils to porous coral. 2)Soil types: acrisols; alkaline soils; calcareous soils; ferralsols; karst soils; limestone soils

1)http://www.hort.purdue.edu/newcrop/duke_energy/Leucaena_leucocephala.html 2)CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International.

4.11

It is not a vine.

4.12

'This seedy thornless tree can form dense monospecific thickets and is difficult to eradicate once established, rendering extensive areas unusable and inaccessible, and threatening native plants in some areas.'

http://www.issg.org/database/species/search.asp?sts=sss&st=sss&fr=1&sn=Leucaena+leucocephala&rn=&hci=-1&ei=38&x=24&y=8

5.01

5.02

5.03

It is a nitrogen fixing tree.

CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International.

5.04

6.01

No evidence.Introduced seed weevil kills many seeds in the pod.

6.02

Germination rates vary from 5% to 90%.

http://members.lycos.co.uk/WoodyPlantEcology/docs/web-sp7.htm

6.03

1)hybridization with other species of the genus occurs readily 2) L. leucocephala may also form spontaneous interspecific hybrids when brought into contact with other species of Leucaena in cultivation. Useful hybrids between L. leucocephala and other tetraploid species such as L. diversifolia (hybrid KX3) and L. pallida (hybrid KX2) have been produced... No evidence of natural hybridization.

1)http://members.lycos.co.uk/WoodyPlantEcology/docs/web-sp7.htm 2)CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International.

6.04

L. leucocephala is self-fertile and produces prodigious quantities of seed from the first year, more or less continuously throughout the year….' 'L. leucocephala is a self-compatible tetraploid of probable hybrid origin...'

CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International.

6.05

The flowers are self-fertile, and most seed results from self-pollination.'

http://www.ecoport.org/

6.06

No evidence.

6.07

Flowering starts within a year of germination and after two years trees produce fruits all year round.'

http://members.lycos.co.uk/WoodyPlantEcology/docs/web-sp7.htm

7.01

The propagules do not have any means of attachment.

7.02

widely planted in dry areas for multiple purposes (wood, forage, erosion control, etc)

7.03

Seeds glossy brown, ellipsoid or ovoid, laterally flattened, 6-9 mm long, 3.5-5.5 mm wide, 0.8-2 mm thick, with a pleurogram ca. 4 mm long and 1.5 mm wide.' - as seeds are large they are less likely to be introduced as a produce contaminant.

Wagner,W. L., D. R. Herbst & S. H. Sohmer. 1990. Manual of flowering plants of Hawaii.University of Hawaii at Press. Honolulu.

7.04

7.05

7.06

The seeds are dispersed by rodents and granivorous birds and can also be spread in cattle manure.' -- (BIRD dispersal occurs only very rarely. Birds rarely visit, the rare visits from granivorous birds are not species that cache)

http://www.hear.org/pier3/leleu.htm

7.07

7.08

can also be spread in cattle manure.'

http://www.hear.org/pier3/leleu.htm

8.01

(1)L. leucocephala is self-fertile and produces prodigious quantities of seed from the first year, more or less continuously throughout the year… (2)'Seeds glossy brown, ellipsoid or ovoid, laterally flattened, 6-9 mm long, 3.5-5.5 mm wide, 0.8-2 mm thick, with a pleurogram ca. 4 mm long and 1.5 mm wide.' (3)Prolific seed producer. (4)There are about 20 seed in 18 cm long pod that are borne in clusters of about 20.

(1)CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International. (2)Wagner,W. L., D. R. Herbst & S. H. Sohmer. 1990. Manual of flowering plants of Hawaii.University of Hawaii at Press. Honolulu. (3)http://www.hear.org/pier3/leleu.htm (4)http://members.lycos.co.uk/WoodyPlantEcology/docs/web-sp7.htm

8.02

Hard seed coat requires scarification for good germination.

8.03

Difficult to control and variable results have been reported. Basal bark or cut-stem treatment with 10%-20% Garlon 4 has been reported to be effective while others report only partial success with 40% Garlon4. 25% has been effective on trees <3" DBH, while larger trees were not killed. Large trees must be completely girdled for frill/girdle applications.

http://edis.ifas.ufl.edu/BODY_WG209

8.04

(1) 'It regenerates rapidly from basal shoots after fire. There is also a flush of new seedlings produced following fire, but whether this is the result of normal germination or breaking dormancy by fire is not known. In mature monotypic stands fire is suppressed because of the low fuel load.' (2)' It resprouts vigorously after coppicing or pollarding.
(3)'It regrows from cut stumps and it can be grown from cuttings. It regenerates rapidly from basal shoots after fire. New seedlings often rapidly re-establish stands after fire or other disturbance.'

(1)http://www.botany.hawaii.edu/faculty/cw_smith/leu_leu.htm (2)CAB International, 2000. Forestry Compendium Global Module. Wallingford, UK: CAB International. (3)http://www.hear.org/pier3/leleu.htm

8.05

In Hawai'i an introduced beetle larvae destroys seeds and nearly all pods are infested. Since 1983, the psyllid Heteropsylla cubana from Cuba has been rapidly spreading westward throughout the Pacific and tropical Asia. Particularly in dry regions it results in total defoliation, death of terminal shoots and inhibits flowering, and repeated attacks result in tree death. 

http://members.lycos.co.uk/WoodyPlantEcology/docs/web-sp7.htm