Pacific Island Ecosystems at Risk (PIER)


Xanthosoma robustum


RISK ASSESSMENT RESULTS: Evaluate, score: 3


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

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

Xanthosoma robustum Schott ; Xanthosoma roseum (Elephant ear, giant 'ape)

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

n

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

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

n

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

n

3.04

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

n=0

n

3.05

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

n=0

y

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

y

4.1

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

y=1, n=0

n

4.11

Climbing or smothering growth habit

y=1, n=0

n

4.12

Forms dense thickets

y=1, n=0

n

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

n

5.04

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

y=1, n=0

y

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

6.04

Self-compatible or apomictic

y=1, n=-1

6.05

Requires specialist pollinators

y=-1, n=0

y

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

3

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

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

y

8.03

Well controlled by herbicides

y=-1, n=1

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:

3

Supporting data:

Notes

Source

1.01

No evidence

1.02

p.14 "As early as 1993, one of us (KW) pointed out that a large aroid of the “elephant ear” type, widespread in the Hawaiian Islands as a naturalized plant, was missing from the Manual. Two similar-sized aroid species having this habit of growth are abundant in sunny places along roadsides, in pastures, wet meadows, and forest margins in mesic habitat. Both are called by the Hawaiian name ‘ape; Neal (1965) identified one as Alocasia macrorrhiza1 (L.) Schott and the other as Xanthosoma robustum Schott [Syn. X. roseum Schott]"

An Overlooked Naturalized Aroid for the Hawaiian Flora

G.W. STAPLES (Hawaii Biological Survey, Bishop Museum, 1525 Bernice St., Honolulu HI 96817,

USA) and K.R. WOOLLIAMS1 (Waimea Arboretum and Botanical Garden, 59–864 Kamehameha

Hwy., Haleiwa, HI 96712, USA) http://hbs.bishopmuseum.org/pdf/op49.pdf

1.03

No evidence

2.01

(1)Native: NORTHERN AMERICA Mexico [s.] SOUTHERN AMERICA Mesoamerica: Costa Rica; Guatemala; Honduras; Nicaragua (2) Xanthosoma robustum Schott. is a native of southern Mexico and Central America.

(1)http://www.ars-grin.gov/cgi-bin/npgs/html/tax_search.pl?Xanthosoma+robustum (2)TI: Antibacterial hydroperoxysterols from Xanthosoma robustum. AU: Kato,-T; Frei,-B; Heinrich,-M; Sticher,-O SO: Phytochemistry. 1996; 41(4): 1191-1195 ; 11 ref..

2.02

2.03

Ecology Xanthosoma is a plant of tropical rainforest regions, requiring average daily temperatures above 21°C, preferably between 25—29°C, being not tolerant of frost. [characteristics of the genus]

Jansen, P.C.M. & Premchand, V., 2003. Xanthosoma Schott. [Internet] Record number 3245 from TEXTFILE On-line. Flach, M. & Rumawas, F. (Editors). PROSEA (Plant Resources of South-East Asia) Foundation, Bogor, Indonesia. http://www.proseanet.org. Accessed: Tuesday, 01 June 2004.

2.04

(2)Native: NORTHERN AMERICA Mexico [s.] SOUTHERN AMERICA Mesoamerica: Costa Rica; Guatemala; Honduras; Nicaragua (3) Xanthosoma robustum Schott. is a native of southern Mexico and Central America.

(2)http://www.ars-grin.gov/cgi-bin/npgs/html/tax_search.pl?Xanthosoma+robustum (3)TI: Antibacterial hydroperoxysterols from Xanthosoma robustum. AU: Kato,-T; Frei,-B; Heinrich,-M; Sticher,-O SO: Phytochemistry. 1996; 41(4): 1191-1195 ; 11 ref..

2.05

(1)present in Hawaii (2)bulbs for sale in Loisiana

(1)http://www.canoeplants.com/ape.html (2)http://www.durionursery.com/

3.01

p.14 "As early as 1993, one of us (KW) pointed out that a large aroid of the “elephant ear” type, widespread in the Hawaiian Islands as a naturalized plant, was missing from the Manual. Two similar-sized aroid species having this habit of growth are abundant in sunny places along roadsides, in pastures, wet meadows, and forest margins in mesic habitat. Both are called by the Hawaiian name ‘ape; Neal (1965) identified one as Alocasia macrorrhiza1 (L.) Schott and the other as Xanthosoma robustum Schott [Syn. X. roseum Schott]"

An Overlooked Naturalized Aroid for the Hawaiian Flora
G.W. STAPLES (Hawaii Biological Survey, Bishop Museum, 1525 Bernice St., Honolulu HI 96817,
USA) and K.R. WOOLLIAMS1 (Waimea Arboretum and Botanical Garden, 59–864 Kamehameha
Hwy., Haleiwa, HI 96712, USA) http://hbs.bishopmuseum.org/pdf/op49.pdf

3.02

No evidence

3.03

on "List of Weeds Recorded in Coatepec Mexico" based on survey of roadsides, urban vacant lots, streets, sugar cane and coffee plantations [no indication that it is an economic pest]

http://www.scs.leeds.ac.uk/pfaf/relations/weeds.html

3.04

No evidence

3.05

(1) Xanthosoma sagittifolium was listed on Category II [Species that have shown a potential to disrupt native plant communities. These species may become ranked as Category I, but have not yet demonstrated disruption of natural Florida communities.] on the List of Florida's Most Invasive Species
(2) Xanthosoma violaceum was listed on Appendix B [Potential environmental weed species that do not have histories as weeds outside Australia] of the Candidate Species for Preventative Control.

(1) Florida Exotic Pest Plant Council. FLEPPC 1999 List of Florida's Most Invasive Species. Internet: http:// www.fleppc.org/99list.htm
(2) Candidate Species for Preventative Control. National Weeds Program. S. Csurhes and R. Edwards. Queensland Department of Natural Resources, January 1998. ISBN 0 6422 1409 3
Internet: http://www.deh.gov.au/biodiversity/invasive/weeds/potential/appendix-b-x.html

4.01

No evidence of such structures.

4.02

No evidence

4.03

No evidence

4.04

The plant is grown as an ornamental and the leaves are eaten like a spinach.

http://www.theresarosado.com/VivaMexico/Malanga.html

4.05

No evidence

4.06

Did not find any associated pest or pathogens.

4.07

(1)Poisoning caused by consumption of plant material from the elephant ear plant. Poisonous Ingredient oxalic acid asparagine, a protein found in this plant Note: Leaves and stems are the most dangerous if eaten in quantity. [not likely eaten in quantity] (2) Medicinally, the juice from freshly cut stems can be an antidote on the skin to itchy stinging plants such as ko/sugar cane and nettle. In the old days, the leaves of `ape and of ti were used to wrap a fevered person for comfort, and because it was said the bitter sap of `ape would frighten away negative spirits. ... Not a favored food, `ape was eaten only in times of famine when other foods were scarce. [this refers to Colocasia, not Xanthosoma]
(3) p.162 "In Guatemala, young leaves are cooked and eaten, but the roots are siad to be poisonous" [poeple not likely to be poisoned[

(1) http://www.nlm.nih.gov/medlineplus/ency/article/002867.htm (2)http://www.canoeplants.com/ape.html

(3) Neal, M.C. (1965) In Gardens of Hawaii. Bernice p. Bishop Museum Special Publicatio 50. Bishop Museeum Press, Honolulu. 924pp. p.162

4.08

thrives in slightly moist shady well composted soil

http://www.canoeplants.com/ape.html

4.09

(1)Xanthosoma will grow in full sun or partial shade (2)Xanthosoma Tolerates sun or shade

(1)http://www.suite101.com/article.cfm/shade_gardening/95670 (2)http://www.landsendtexotics.co.nz/cat_aroids.shtml

4.1

It grows best on deep, well-drained, fertile soils, within a pH range of 5.5—6.5. [chracterisitics of the genus]

Jansen, P.C.M. & Premchand, V., 2003. Xanthosoma Schott. [Internet] Record number 3245 from TEXTFILE On-line. Flach, M. & Rumawas, F. (Editors). PROSEA (Plant Resources of South-East Asia) Foundation, Bogor, Indonesia. http://www.proseanet.org. Accessed: Tuesday, 01 June 2004.

4.11

Not a climber.

http://www.emilycompost.com/elephant_ear.htm

4.12

No evidence

5.01

Terrestrial

5.02

Araceae

5.03

No evidence

5.04

This is a tuberous bulb plant growing from 3 - 5 feet. … In areas where they must be taken up for the winter, keep the tubers dry while dormant. Divide in the spring when setting out.

http://www.emilycompost.com/elephant_ear.htm

6.01

No evidence

6.02

(1) forum discussion of seed germination of Xanthosoma species (2) a congener X. sagittifolia was listed as recalcitrant in seed storage behavior

(1) http://forums.gardenweb.com/forums/load/aroid/hpgal051344005155.html (2) http://arjournals.annualreviews.org/doi/pdf/10.1146/annurev.ecolsys.31.1.107?cookieSet=1

6.03

No evidence

6.04

No evidence

6.05

'The inflorescence it has consists of a Spadix or stalk (male flowers on top, female flowers on the bottom and a string of sterile flowers in between) and a Spathe, or modified leaf that covers the Spadix. Occasionally, light will trigger the inflorescence to heat (up to 42 degrees Celsius at times), and release a strong scent that attracts scarab beetles. The beetles enter the inflorescence chamber and remain there for 24 hours. The pollen that the beetle carries rubs off and pollinates the female flowers. The beetles will mate and consume the sterile flowers. When climbing back out of the chamber, pollen from the male flower rubs off on the beetles for them to fly to the next open inflorescence for the process to begin again.

http://www.cloudforestalive.org/tour/lesson.f1ml?lid=591

6.06

In areas where they must be taken up for the winter, keep the tubers dry while dormant. Divide in the spring when setting out. [this is not natural fragmentation]

http://www.emilycompost.com/elephant_ear.htm

6.07

[minimum estimate for a large herbaceous perennial growing from a tiny seed]

7.01

No evidence

7.02

It is used in modern times as a landscaping plant due to its tropical appearance and ability to provide shade in a garden.

http://www.canoeplants.com/ape.html

7.03

No evidence

7.04

"Fruit a berry, crowned by the impressed stigma, many-seeded. Seed ovoid, grooved longitudinally." [characteristics of the genus]

Jansen, P.C.M. & Premchand, V., 2003. Xanthosoma Schott. [Internet] Record number 3245 from TEXTFILE On-line. Flach, M. & Rumawas, F. (Editors). PROSEA (Plant Resources of South-East Asia) Foundation, Bogor, Indonesia. http://www.proseanet.org. Accessed: Tuesday, 01 June 2004.

7.05

No evidence

7.06

(1)"Fruit a berry, crowned by the impressed stigma, many-seeded. Seed ovoid, grooved longitudinally." [characteristics of the genus] (2)fruits in bunches of 2 to 4 burst open at maturity [implies not bird dipersed or fleshy]

(1)Jansen, P.C.M. & Premchand, V., 2003. Xanthosoma Schott. [Internet] Record number 3245 from TEXTFILE On-line. Flach, M. & Rumawas, F. (Editors). PROSEA (Plant Resources of South-East Asia) Foundation, Bogor, Indonesia. http://www.proseanet.org. Accessed: Tuesday, 01 June 2004. (2)http://www.theresarosado.com/VivaMexico/Malanga.html

7.07

No evidence

7.08

(1)"Fruit a berry, crowned by the impressed stigma, many-seeded. Seed ovoid, grooved longitudinally." [characteristics of the genus] (2)fruits in bunches of 2 to 4 burst open at maturity [implies not bird dipersed or fleshy]

(1)Jansen, P.C.M. & Premchand, V., 2003. Xanthosoma Schott. [Internet] Record number 3245 from TEXTFILE On-line. Flach, M. & Rumawas, F. (Editors). PROSEA (Plant Resources of South-East Asia) Foundation, Bogor, Indonesia. http://www.proseanet.org. Accessed: Tuesday, 01 June 2004. (2)http://www.theresarosado.com/VivaMexico/Malanga.html

8.01

[unlikely - rarely fruits]

8.02

In areas where they must be taken up for the winter, keep the tubers dry while dormant. Divide in the spring when setting out.

http://www.emilycompost.com/elephant_ear.htm

8.03

No evidence of being controlled for.

8.04

(1)"if the cormels have not been harvested they start suckering" [ability to sucker] (2)You can chop up a bulb into 10 pieces and each piece will start a new plant. [Xanthosoma sagittarium]

(1)Jansen, P.C.M. & Premchand, V., 2003. Xanthosoma Schott. [Internet] Record number 3245 from TEXTFILE On-line. Flach, M. & Rumawas, F. (Editors). PROSEA (Plant Resources of South-East Asia) Foundation, Bogor, Indonesia. http://www.proseanet.org. Accessed: Tuesday, 01 June 2004. (2)http://plantsdatabase.com/go/2218

8.05

Don’t know


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