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

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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]

Chinese: bai hua niu jiao gua

English: French cotton, Prince-of-Wales crown, Sodom apple, Sodom's milkweed, akund, apple of Sodom, auricula-tree, cabbagetree, calotrope, camelweed, giant milkweed, kapoktree, madar, mudar, roostertree, rubber bush, rubbertree, small crownflower, swallowwort

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

Spanish: algodón de seda, bomba, calotropis

Habit:  shrub/tree

Description:  "A large shrub or small tree of 2-4 m height, with a white latex and smooth, grey-green stems and a thick, soft bark.  The plant has a deep taproot of 3-4 m length.  The simple and opposite leaves are 8-25 cm long, 4-14 cm wide, ovate, thick and waxy.  They have a short pointed tip at the end and a heart-shaped base partly clasping the stem.  The white and purple flowers have five lobes, are more or less tubular, and 2-3 cm in diameter.  Fruits are grey-green, fleshy or dry capsules of 8-12 cm length and 6-8 cm width.  They contain numerous small, brown and flattened seeds of 8-10 mm length and c. 5 mm wideth, with long white hairs attached at one end"  (Weber, 2003; p. 80).

"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	Hawai‘i (Big) Island	introduced invasive	Parker, James L./Parsons, Bobby (2012) (pp. 56-57) Voucher cited: J. Parker & R. Parsons, J. Franklin BIED97 (BISH)
State of Hawaii Hawaiian Islands	Kaho‘olawe Island	introduced invasive	Starr, Forest/Starr, Kim (2012) (p. 87) Vouchers cited: Starr 101228-1 (BISH), Starr 101229-1 (BISH)
State of Hawaii Hawaiian Islands	Kaua‘i Island	introduced invasive cultivated	Starr, Forest/Starr, Kim/Loope, Lloyd L. (2004) (p. 20) Misidentified as Calotropis gigantea. Voucher cited: Starr & Starr 020226-3 (BISH)
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	Kaua‘i Island	introduced invasive	Starr, Forest/Starr, Kim (2012) (p. 87) Voucher cited: Starr & Starr 020226-3 (BISH)
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	Ni‘ihau, Lehua Islet	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.
State of Hawaii Hawaiian Islands	Maui Island	introduced invasive cultivated	Starr, Forest/Starr, Kim/Loope, Lloyd L. (2003) (p. 25) Misidentified as Calotropis gigantea. Vouchers cited: (East Maui) Starr & Martz 010309-1 (BISH), Starr & Martz 010503-2 (BISH); (West Maui) Starr & Martz 010701-1 (BISH)
State of Hawaii Hawaiian Islands	Maui Island	introduced invasive	Starr, Forest/Starr, Kim (2012) (p. 87) Vouchers cited: (East Maui) Starr & Martz 010503-2 (BISH); (West Maui) Starr & Martz 010701-1 (BISH)

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)
Central America Central America (Pacific rim)	Costa Rica (Republic of)	introduced invasive	U.S. Dept. Agr., Agr. Res. Serv. (2013) Naturalized
Central America Central America (Pacific rim)	El Salvador (Republic of)	introduced invasive	U.S. Dept. Agr., Agr. Res. Serv. (2013) Naturalized
Central America Central America (Pacific rim)	Guatemala (Republic of)	introduced invasive	U.S. Dept. Agr., Agr. Res. Serv. (2013) Naturalized
Central America Central America (Pacific rim)	Honduras (Republic of)	introduced invasive	U.S. Dept. Agr., Agr. Res. Serv. (2013) Naturalized
Central America Central America (Pacific rim)	Nicaragua (Republic of)	introduced invasive	U.S. Dept. Agr., Agr. Res. Serv. (2013) Naturalized
Central America Central America (Pacific rim)	Panama (Republic of)	introduced invasive	U.S. Dept. Agr., Agr. Res. Serv. (2013) Naturalized
China China	China (People's Republic of)	introduced cultivated	Zhengyi, Wu/Raven, Peter H./Deyuan, Hong (2013) Cultivated for medicine in S. Guangdong, Guangxi, S. Yunnan.
Mexico Mexico	Mexico (United Mexican States)	introduced invasive	U.S. Dept. Agr., Agr. Res. Serv. (2013) Naturalized
Thailand Thailand	Thailand (Kingdom of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)
United States (west coast) United States (west coast states)	USA (California)	introduced invasive	U.S. Dept. Agr., Agr. Res. Serv. (2013) Naturalized
Vietnam Vietnam	Vietnam (Socialist Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)

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).