Opuntia monacantha (Willd.) Haw., Cactaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Risk assessment results:  Opuntia aurantiaca: Reject, score: 22 (Go to the risk assessment)

Opuntia robusta: Reject, score: 20 (Go to the risk assessment)

Opuntia monacantha: Reject, score: 20 (Go to the risk assessment)

Other Latin names:  Opuntia vulgaris auct. mult.

Common name(s): [more details]

Chinese: dan ci xian ren zhang

English: common prickly pear, drooping prickly pear

Habit:  cactus

Description:  "Shrubs or small trees up to 4 m tall, often with a definite trunk; joints glossy green when fresh, narrowly obovate to oblong-lanceolate, the base somewhat cuneate, 10-35 cm long, 7.5-12.5 cm wide, margins undulate toward apex.  Areoles with 1-2 (3) gray or yellowish to reddish brown spines with darker tips, 1-7.5 cm long, trunk areoles sometimes with 10 or more spines.  Flowers 7.5-10 cm long, 5-7.5 cm in diameter; outer perianth parts yellow with a reddish median stripe, 18-25 mm long, 12-15 mm wide, inner perianth parts yellow to orange, rotate, 25-40 mm long, 12-40 mm wide; staminal filaments green to white; style green, 12-20 mm long; stigma lobes 8-10, cream yellow.  Berries reddish purple, fleshy, conical to obovoid, 5-7.5 cm long, 4-5 cm in diameter" (Wagner et al., 1999; p. 420).

Habitat/ecology:  Dry sites.  In Fiji, "this species has become a frequent adventive as a perennial shrub 0.5-4 m high, often found in agricultural areas or on waste land near sea level" (Smith, 1981; p. 271).

Propagation:  Seed

Native range:  Southeastern South America.

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) Saipan	Saipan Island	introduced	Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1979) (p. 193) Opuntia sp.
Cook Islands Southern Cook Islands	Aitutaki Atoll	introduced cultivated	Space, James C./Flynn, Tim (2002) (p. 76) Opuntia sp.
Cook Islands Southern Cook Islands	Rarotonga Island	introduced cultivated	Space, James C./Flynn, Tim (2002) (p. 69) Opuntia sp.
Federated States of Micronesia Yap Islands	Yap (Waqab) Island	introduced	Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1979) (p. 193) Opuntia sp.
Fiji Fiji Islands	Fiji Islands	introduced invasive	Smith, Albert C. (1981) (p. 271) Opuntia vulgaris
Guam Guam Island	Guam Island	introduced	Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1979) (p. 193) Opuntia sp.
State of Hawaii Hawaiian Islands	O‘ahu Island	introduced invasive	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 420) Voucher cited: Judd s.n. (BISH)
Marshall Islands Ralik Chain	Kwajalein (Kuwajleen) Atoll	introduced cultivated	Whistler, W. A./Steele, O. (1999) (p. 99) Opuntia sp.
Nauru Nauru Island	Nauru Island	introduced cultivated	Thaman, R. R./Fosberg, F. R./Manner, H. I./Hassall, D. C. (1994) (p. 110) Opuntia sp.
New Caledonia New Caledonia	New Caledonia Islands		Swarbrick, John T. (1997) (p. 94) Opuntia sp.
New Caledonia New Caledonia	New Caledonia Islands	introduced invasive	Gargominy, Oliver/Bouchet, Philipe/Pascal, Michel/Jaffre, Tanguy/Tourneu, Jean-Christophe (1996) (p. 379) Opuntia sp. Espèces envahissantes (bosquets et fourrés) peu nombreuses mais difficiles à déterminer.
New Caledonia New Caledonia	New Caledonia Islands	introduced invasive	Tassin, Jacques (2005) Opuntia vulgaris
Niue Niue	Niue Island	introduced cultivated	Sykes, W. R. (1970) (p. 54) O. compressa? Voucher cited: CHR 169752
Palau Hatohobei Group	Tobi Island	introduced cultivated	Space, James C./Waterhouse, Barbara/Miles, Joel E./Tiobech, Joseph/Rengulbai, Kashgar (2003) (p. 110) Opuntia sp.
Palau Palau (Belau ) (main island group)	Angaur (Ngeaur) Island	introduced	Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1979) (p. 193) Opuntia sp.
Palau Palau (Belau ) (main island group)	Angaur (Ngeaur) Island	introduced cultivated	Space, James C./Waterhouse, Barbara/Miles, Joel E./Tiobech, Joseph/Rengulbai, Kashgar (2003) (p. 104) Opuntia sp.
Palau Palau (Belau ) (main island group)	Koror (Oreor) Island	introduced cultivated	Space, James C./Waterhouse, Barbara/Miles, Joel E./Tiobech, Joseph/Rengulbai, Kashgar (2003) (p. 98) Opuntia sp.
Palau Palau (Belau ) (main island group)	Ngercheu Island	introduced cultivated	Space, James C./Waterhouse, Barbara/Miles, Joel E./Tiobech, Joseph/Rengulbai, Kashgar (2003) (p. 108) (Carp Resort) Opuntia sp.
Palau Palau (Belau ) (main island group)	Ngerkebesang Island	introduced cultivated	Space, James C./Waterhouse, Barbara/Miles, Joel E./Tiobech, Joseph/Rengulbai, Kashgar (2003) (p. 98) Opuntia sp.
Palau Palau (Belau ) (main island group)	Peleliu (Beliliou) Island	introduced cultivated	Space, James C./Waterhouse, Barbara/Miles, Joel E./Tiobech, Joseph/Rengulbai, Kashgar (2003) (p. 106) Opuntia sp.
Philippines Philippine Islands	Philippine Islands	introduced invasive	Merrill, Elmer D. (1923) (p. 130) In sandy soil near the beach.
Samoa Western Samoa Islands	Upolu Island	introduced cultivated	Space, James C./Flynn, Tim (2002) (p. Field notes.) Opuntia sp.
Tonga Tongatapu Group	Tongatapu Island	introduced cultivated	Space, James C./Flynn, Tim (2001) (p. 54) Opuntia sp.

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)	Queensland	introduced invasive	Queensland Herbarium (2002) (p. 5) Also present and invasive: Opuntia aurantiaca (tiger pear), Opuntia imbricata (rope pear) and Opuntia tomentosa velvet tree pear)
China China	China (People's Republic of)	introduced invasive	Zhengyi, Wu/Raven, Peter H./Deyuan, Hong (2013) Seashores, slopes; sea level to 2000 m. Fujian, Guangdong, Guangxi, Yunnan.
New Zealand New Zealand	New Zealand (country)	introduced invasive	Webb, C. J./Sykes, W. R./Garnock-Jones, P. J. (1988) (p. 453) "Cliffs, sandy beaches".
Taiwan Taiwan Island	Taiwan Island	introduced invasive	Zhengyi, Wu/Raven, Peter H./Deyuan, Hong (2013) Seashores, slopes; sea level to 2000 m.

Comments:  Declared noxious weeds in Fiji and Samoa. O. vulgaris is moderately invasive in these two locations (Meyer, 2000).

Control:  There is detailed information about identification and control of opuntioid cacti--including Opuntia monacantha--in Managing opuntioid cacti in Australia: Best practice control manual for Austrocylindropuntia, Cylindropuntia, and Opuntia species produced by the Western Australian Agriculture Authority.