Euphorbia milii Desm., Euphorbiaceae

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Present on Pacific Islands?  yes

Threat only at high elevations?  no

Risk assessment results:  Low risk (based on second screen), score: 1 (Go to the risk assessment)

Common name(s): [more details]

English: Christ's plant, Christ's thorn, crown of thorns

Spanish: corona de Cristo, corona del señ:or

Habit:  shrub

Description:  "Shrub to ca. 1.5 m tall, somewhat climbing, containing a milky sap, branches covered with spines.  Leaves alternate, crowded near the branch tips, simple, obovate to spatulate, to ca. 6 cm long, margins entire.  Flowers unisexual (plants monoecious), in clusters of cup-shaped structures known as 'cyathia'.  Each cluster has 2 bright red, broadly ovate bracts beneath, ca. 1.5 cm across.  Staminate flowers numerous in each cyathium, calyx absent; corolla absent; stamen 1.  Pistillate flowers 1 per cyathium; calyx absent; corolla absent.  Fruit a capsule; seed 1."  (McMullen, 1999; p. 134).

Habitat/ecology:  Arid lowlands in the Galápagos Islands (McMullen, 1999; p. 134).

Propagation:  Seed

Native range:  Madagascar; widely cultivated (GRIN).

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Commonwealth of the Northern Mariana Islands (US) Northern Mariana Islands	Rota Island	introduced	Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1979) (p. 138) Var. splendens
Cook Islands Southern Cook Islands	Aitutaki Atoll	introduced cultivated	McCormack, Gerald (2007)
Cook Islands Southern Cook Islands	Rarotonga Island	introduced cultivated	McCormack, Gerald (2007)
Ecuador (Galápagos Islands) Santa Cruz Group	Santa Cruz Island	introduced cultivated	Charles Darwin Research Station (2005)
Federated States of Micronesia Kosrae Island	Kosrae Island	introduced cultivated	Lorence, David H./Flynn, Tim (2005) (p. 14) cf. millii
Fiji Fiji Islands	Viti Levu Island	introduced cultivated	Smith, Albert C. (1981) (p. 569) As Euphorbia splendens. Voucher cited: DA 16236
French Polynesia Marquesas Islands	Nuku Hiva (Nukahiva) Island	introduced cultivated	Florence, J. (1997) (p. 65)
French Polynesia Society Islands	Moorea Island	introduced cultivated	Florence, J. (1997) (p. 65)
French Polynesia Society Islands	Raiatea (Havai) Island	introduced cultivated	Florence, J. (1997) (p. 65)
French Polynesia Society Islands	Tahiti Island	introduced cultivated	Florence, J. (1997) (p. 65)
French Polynesia Tuamotu Archipelago	Makatea (Ma‘atea) Island	introduced cultivated	Florence, J. (1997) (p. 65)
Guam Guam Island	Guam Island	introduced cultivated	Stone, Benjamin C. (1970) (pp. 374-375) Var. splendens. Rare in gardens.
Guam Guam Island	Guam Island	introduced	Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1979) (p. 138)
Marshall Islands Ralik Chain	Jaluit (Jãlwõj) Atoll	introduced	Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1979) (p. 138) Var. splendens
Marshall Islands Ralik Chain	Kwajalein (Kuwajleen) Atoll	introduced cultivated	Whistler, W. A./Steele, O. (1999) (p. 100)
Marshall Islands Ratak Chain	Arno Atoll	introduced cultivated	Vander Velde, Nancy/Vander Velde, Brian (2007) (p. 7) "Rare; single bush by residence in Arno village".
Marshall Islands Ratak Chain	Majuro (Mãjro) Atoll	introduced cultivated	Vander Velde, Nancy (2003) (p. 93)
Nauru Nauru Island	Nauru Island	introduced cultivated	Thaman, R. R./Fosberg, F. R./Manner, H. I./Hassall, D. C. (1994) (p. 130) Voucher cited: Hassall 178 (SUVA)
New Caledonia New Caledonia Archipelago	Île Grande Terre	introduced	MacKee, H. S. (1994) (p. 51) Voucher cited: MacKee 21259
Niue Niue	Niue Island	introduced cultivated	Yuncker, T. G. (1943) (p. 77) Var splendens. Voucher cited: Yuncker 9970 (BISH). Not seen by Sykes (1970) in 1965.

Indian Ocean
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Australia (Indian Ocean offshore islands) Christmas Island Group	Christmas Island	introduced cultivated	Swarbrick, J. T. (1997) (p. 114)

Comments:  Reported as possibly an invasive plant in the Galápagos Islands per Charles Darwin Research Station. The plant is poisonous and the sap can cause blistering of the skin (McMullen, 1999; p. 134).

Additional information:  Additional online information about Euphorbia milii is available from the Hawaiian Ecosystems at Risk project (HEAR).

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

References:

Charles Darwin Research Station. 2005. CDRS Herbarium records.

Florence, J. 1997. Flore de la Polynésie française, Vol. 1. Paris. Editions de l'Orstom, Institut Français de Recherche Scientifique pour le Développement en Coopération, Collection Faune et Flore Tropicales 34. 393 pp.

Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce. 1979. A geographical checklist of the Micronesian dicotyledonae. Micronesica 15:1-295.

Lorence, David H./Flynn, Tim. 2005. Checklist of the plants of Kosrae. Unpublished checklist. National Tropical Botanical Garden, Lawai, Hawai‘i. 23 pp.

MacKee, H. S. 1994. Catalogue des plantes introduites et cultivées en Nouvelle-Calédonie. Muséum National d'Histoire Naturelle, Paris, 164 p.

McCormack, Gerald. 2007. Cook Islands biodiversity and natural heritage. On-line database.

McMullen, C. K. 1999. Flowering plants of the Galápagos. Comstock Pub. Assoc., Ithaca, N.Y. 370 p.

Smith, Albert C. 1981. Flora Vitiensis nova: a new flora of Fiji. National Tropical Botanical Garden, Lawai, Kauai, Hawaii. Volume 2. 810 pp.

Stone, Benjamin C. 1970. The flora of Guam. Micronesica 6:1-659.

Swarbrick, J. T. 1997. Environmental weeds and exotic plants on Christmas Island, Indian Ocean: a report to Parks Australia. 101 pp. plus appendix.

Thaman, R. R./Fosberg, F. R./Manner, H. I./Hassall, D. C. 1994. The flora of Nauru. Smithsonian Institution, Washington. Atoll Research Bulletin 392:1-223.

U.S. Dept. Agr., Agr. Res. Serv. 2007. National Genetic Resources Program. Germplasm Resources Information Network (GRIN). Online searchable database.

Vander Velde, Nancy. 2003. The vascular plants of Majuro Atoll, Republic of the Marshall Islands. Smithsonian Institution, Atoll Research Bulletin No. 503:1-141.

Vander Velde, Nancy/Vander Velde, Brian. 2007. Arno plants [preliminary working listing of plant species]. Unpublished checklist, 13 pp.

Whistler, W. A./Steele, O. 1999. Botanical survey of the United States of America Kwajalein Atoll (USAKA) Islands. Prepared for Oak Ridge Institute for Science and Education and the U. S. Army Environmental Center. 111 pp.

Yuncker, T. G. 1943. The flora of Niue Island. Bishop Mus. Bull. 178. Bishop Museum Press, Honolulu. 126 pp.