Calotropis procera (Aiton) W.T.Aiton, Asclepiadaceae

Click on an image for links to BIGGER PICTURES

Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Risk assessment results: 

Reject, score: 8 (Go to the risk assessment (Australia))
High risk, score: 15 (Go to the risk assessment (Pacific))

Other Latin names:  Asclepias procera Aiton

Common name(s): [more details]

English: akund, apple of Sodom, auricula tree, calotrope, French cotton, giant milkweed, king's crown, madar, mudar, roostertree, rubber bush, small crownflower, Sodom apple, Sodom's milkweed, swallowwort

French: arbre à soie, arbre de soie, bois canon

Spanish: algodón de seda, bomba, calotropis

Habit:  shrub

Description:  "Spreading shrub or small tree to 4 m, exuding copious milky sap when cut or broken; leaves opposite, grey-green, large up to 15 cm long and 10 cm broad, with a pointed tip, two rounded basal lobes and no leaf stalk; flowers waxy white, petals 5, purple-tipped inside and with a central purplish crown, carried in stalked clusters at the ends of the branches; fruit grey-green, inflated, 8 to 12 cm long, containing numerous seeds with tufts of long silky hairs at one end"  (Kleinschmidt and Johnson, 1977; p. 147).

"Tall herb with sessile, obovate, glaucous leaves less than 2 times longer than broad; bud globular, flowers umbellate, violet; coronal spurs not recurved"  (Nicholson, 1991; p. 28).

"Shrubs, mostly less than 6 ft., but up to 15 ft.; similar to C. gigantea, but leaves oblong to elliptic, corolla usually about 1 in. across with lobes more erect, corona lobes glabrous or pubescent, and follicle 4-5 in. long"  (Bailey and Bailey, 1976; p. 206).

Habitat/ecology:  "Giant milkweed favors open habitat with little competition. This condition is most completely met in overgrazed pastures and rangeland. Other common habitats are beachfront dunes, roadsides, and disturbed urban lots. The species grows in dry habitat (150 to 1000 mm precipitation) and sometimes in excessively drained soils in areas with as much as 2000 mm of annual precipitation. Giant milkweed may be found in areas up to 1,000 m in elevation in India (Parrotta 2001). It roots very deeply and rarely grows in soils that are shallow over unfractured rock. Soils of all textures and derived from most parent materials are tolerated, as well as soils with high sodium saturation. Beachfront salt spray is not detrimental. Competition with tall weeds, brush, and especially grass weakens existing plants, and being overtopped and shaded by trees soon eliminates them"  (Wildland shrubs of the United States and its territories).

In Australia, "Found on roadsides, disturbed areas, watercourses, river flats and coastal dunes.  Thrives on poor soils particularly where overgrazing has removed competition from native grasses. It forms dense thickets which compete with native plant species and transforms the appearance of the savanna. Also hinders pastoralism by degrading pasture lands and making mustering difficult."  (Smith, 2002; pp. 28-29).

Propagation:  "Seeds spread by wind and water over large distances.  Local stands increased in size by suckering."  (Smith, 2002; pp. 28-29).

Native range:  "Giant milkweed is native to West Africa as far south as Angola, North and East Africa, Madagascar, the Arabian Peninsula, southern Asia, and Indochina to Malaysia (Rahman and Wilcock 1991)"  (Wildland shrubs of the United States and its territories).

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
State of Hawaii Hawaiian Islands	Hawai‘i (Big) Island	introduced invasive cultivated	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 238) Cultivated, possible escapes.
State of Hawaii Hawaiian Islands	Kaua‘i Island	introduced invasive	Wood, K. R. (2006) (pp. 15-16) Voucher cited: K.R. Wood 11614 (PTBG)
State of Hawaii Hawaiian Islands	Lāna‘i Island	introduced invasive	Oppenheimer, Hank (2008) (p. 23) Voucher cited: Oppenheimer, Perlman & Tangalin H10705 (BISH, PTBG)
State of Hawaii Hawaiian Islands	Lehua Island	introduced invasive	Wood, K. R./LeGrande, Maya (2006) (p. 19) Vouchers cited: K.R. Wood 11345 (BISH, PTBG, US), K.R. Wood 11533 (BISH, PTBG) Two plants seen.

Pacific Rim
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Australia Australia (continental)	Northern Territory	introduced invasive	Csurhes, S./Edwards, R. (1998) (p. 147)
Australia Australia (continental)	Queensland	introduced invasive	Smith, Nicholas M. (2002) (pp. 28-29)
Thailand Thailand	Thailand (Kingdom of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2009)
Vietnam Vietnam	Vietnam (Socialist Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2009)

Indian Ocean
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Seychelles Seychelles Islands	Frégate Island		Robertson, S. A./Todd, D. M. (1983) (p. 46) Voucher cited: Robertson 2731

Comments:  Reported as escaped from cultivation in Hawai‘i (Wagner et al., 1999; p. 238). A declared noxious weed in Western Australia and the Northern Territory (Smith, 2002; pp. 28-29).

Control: 

Physical:  "Manual removal should aim at removing as much of the taproot and lateral roots as possible to prevent resprouting".

Chemical:  "Actively growing seedlings and larger plants can be treated with a mixture of 2,4-D and picloram.  In the case of mature plants, herbicides may also be applied to the basal bark"  (Weber, 2003; p. 81).

Additional information:
Fact sheet from the Government of Queensland, Australia. (PDF format).
Fact sheet from "Wildland shrubs of the United States and its territories: thamnic descriptions" (PDF format).
Information from the World Agroforestry Centre's AgroForestryTree Database.

Additional online information about Calotropis procera is available from the Hawaiian Ecosystems at Risk project (HEAR).

Information about Calotropis procera as a weed (worldwide references) may be available from the Global Compendium of Weeds (GCW).

Taxonomic information about Calotropis procera may be available from the Germplasm Resources Information Network (GRIN).

References:

Bailey, L. H./Bailey, E. Z. 1976. Hortus third: A concise dictionary of plants cultivated in the United States and Canada. Macmillan, New York. 1290 pp.

Csurhes, S./Edwards, R. 1998. Potential environmental weeds in Australia: Candidate species for preventative control. Canberra, Australia. Biodiversity Group, Environment Australia. 208 pp.

Francis, John K., ed. 2009. Wildland Shrubs of the United States and its Territories: Thamnic Descriptions General Technical Report IITF-WB-1 U.S. Department of Agriculture, Forest Service International Institute of Tropical Forestry and Shrub Sciences Laboratory (online resource).

Kleinschmidt, H. E./Johnson, R. W. 1977. Weeds of Queensland. Govt. Printer. 469 p.

Nicholson, D. H. 1991. Flora of Dominica, part 2: Dicotyledoneae. Smithsonian Contributions to Botany 77.

Oppenheimer, Hank. 2008. New plant records from O‘ahu for 2007. In: Evenhuis, Neal L. and Eldredge, Lucias G., eds. Records of the Hawaii Biological Survey for 2007. Bishop Museum Occasional Papers 100:22-38.

Robertson, S. A./Todd, D. M. 1983. Vegetation of Frégate Island, Seychelles. In: Sachet, M. H., D. R. Stoddart, and F. R. Fosberg. Floristics and ecology of Western Indian Ocean islands. Atoll Research Bulletin No. 273. Smithsonian Institution, Washington. 253 pp.

Smith, Nicholas M. 2002. Weeds of the wet/dry tropics of Australia - a field guide. Environment Centre NT, Inc. 112 pp.

Staples, George W./Herbst, Derral/Imada, Clyde T. 2000. Survey of invasive or potentially invasive cultivated plants in Hawai‘i. Bishop Museum Occasional Papers No. 65. 35 pp.

U. S. Government. 2009. Integrated Taxonomic Information System (ITIS) (on-line resource).

U.S. Dept. Agr., Agr. Res. Serv. 2009. National Genetic Resources Program. Germplasm Resources Information Network (GRIN). Online searchable database.

Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. 1999. Manual of the flowering plants of Hawaii. Revised edition. Bernice P. Bishop Museum special publication. University of Hawai‘i Press/Bishop Museum Press, Honolulu. 1919 pp. (two volumes).

Weber, Ewald. 2003. Invasive plants of the World. CABI Publishing, CAB International, Wallingford, UK. 548 pp.

Wood, K. R. 2006. New plant records and rediscoveries within the Hawaiian Islands. In: Evenhuis, Neal L. and Eldredge, Lucias G., eds. Records of the Hawaii Biological Survey for 2004-2005. Part 2: Notes. Bishop Museum Occasional Papers 88:15-19.

Wood, K. R./LeGrande, Maya. 2006. An annotated checklist and new island records of flowering plants from Lehua Islet, Ni‘ihau, Hawai‘i. In: Evenhuis, Neal L. and Eldredge, Lucias G., eds. Records of the Hawaii Biological Survey for 2004-2005. Part 1: Articles. Bishop Museum Occasional Papers 87:19-29.