Pacific Island Ecosystems at Risk (PIER)

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Ageratum houstonianum
Mill., Asteraceae
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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Other Latin names:  Ageratum mexicanum Sims

Common name(s): [more details]

Chinese: xiong er cao

English: ageratum, blue billygoat weed, bluemink, flossflower, goatweed, Mexican ageratum

Fijian: botebotekoro, mbotembotekoro, sogovanua, songovanua

French: ageratum du Mexique

Hawaiian: maile hohono, maile honohono, maile kula

Spanish: agérato

Habit:  herb

Description:  "Annual, usually erect and often much branched, the stems leafy throughout, pilose or villous with spreading hairs; leaves opposite, on rather long, slender petioles, very thin, broadly deltoid-ovate, mostly 4-8 cm long, obtuse or acute, generally shallowing cordate at the base, coarsely crenate, thinly villous-hirsute, not punctate beneath; corymbs terminal on the branches, often compound, glandular-hirtellous and villous with several-celled hairs; heads numerous lavender or pale blue, 8 mm broad, about 75-flowered; phyllaries narrowly lanceolate or linear, entire, herbaceous, long-attenuate, ciliolate, usually purplish toward the apex, 2-costate, glandular-puberulent; achenes black, lustrous, commonly hispidulous, at least on the angles, 1.2 mm long; pappus scales 5, lanceolate, fimbriate-margined, long-setiferous, about equaling the corolla" (Nash & Williams, 1976; p. 39).

"Coarse herb, semiprostrate toward base and with ascending branches 0.3-1 m high...  The corolla lobes and styles are pale blue to purple."  (Smith, 1991; pp. 296-297).

Description from the Flora of China online.
Description from the Flora of North America online.

Habitat/ecology:  In Hawai‘i, "naturalized in a wide variety of disturbed habitats, especially along trails and roadsides, 40-1,300 m" (Wagner et al., 1999; p. 256). In Fiji, "sometimes cultivated and also naturalized at elevations from near sea level to 1,127 m in open places, along roadsides, on river banks, and on cleared upland slopes and crests"  (Smith, 1991; pp. 296-297). In New Guinea, "established in a few localities above 1000 m" (Henty & Pritchard, 1975; p 63).

Propagation:  Seed

Native range:  Mexico, central America and the West Indies (Wagner et al., 1999; p. 256); cultivated and naturalized (GRIN).

Presence:

Pacific
Country/Terr./St. &
Island group
Location Cited status &
Cited as invasive &
Cited as cultivated &
Cited as aboriginal introduction?
Reference &
Comments
Fiji
Fiji Islands
Viti Levu Island introduced
invasive
cultivated
Smith, Albert C. (1991) (pp. 296-297)
Vouchers cited: Parks 20625, Parks 20626, Smith 5019, DA 2729, DA 8530, DA 11114, DA 10371, Vaughan 3246, DA 11327, DA 11123, DA 12117
French Polynesia
Marquesas Islands
Nuku Hiva (Nukahiva) Island introduced
invasive
Florence, J./Chevillotte, H./Ollier, C./Meyer, J.-Y. (2013)
Adventice
French Polynesia
Society Islands
Huahine Island introduced
invasive
cultivated
Welsh, S. L. (1998) (p. 69)
Voucher cited: Fosberg 63009
French Polynesia
Society Islands
Tahiti Island introduced
invasive
cultivated
Welsh, S. L. (1998) (p. 69)
Voucher cited: Fosberg 64999
French Polynesia
Society Islands
Tahiti Island introduced
invasive
Florence, J./Chevillotte, H./Ollier, C./Meyer, J.-Y. (2013)
Vouchers cited: J. Florence 3287 (PAP), J. Florence 6626 (PAP)
Adventice
French Polynesia
Austral (Tubuai) Islands
Raivavae (Raevavae) Island introduced
invasive
Florence, J./Chevillotte, H./Ollier, C./Meyer, J.-Y. (2013)
Adventice
State of Hawaii
Hawaiian Islands
Hawai‘i (Big) Island introduced
invasive
Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 256)
State of Hawaii
Hawaiian Islands
Kaua‘i Island introduced
invasive
Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 256)
State of Hawaii
Hawaiian Islands
Maui Island introduced
invasive
Oppenheimer, Hank L./Bartlett, R. T. (2000) (p. 2)
East Maui. Voucher cited: Oppenheimr H69910 (BISH)
State of Hawaii
Hawaiian Islands
O‘ahu Island introduced
invasive
Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 256)
Voucher cited: Garber 95 (BISH)
Japan (offshore islands)
Ogasawara (Bonin) Islands
Bonin (Ogasawara) Islands introduced
Kato, Hidetoshi (2007)
New Caledonia
New Caledonia Archipelago
Île Grande Terre introduced
MacKee, H. S. (1994) (p. 31)
Vouchers cited: MacKee 31210, Fallen 176 (NOU), Fukuoka et al. C-90, H. Brinon 267 (NOU), Toutain 3570 (NOU)
New Zealand (offshore islands)
Kermadec Islands
Raoul Island introduced
invasive
Sykes, W. R. (1977) (p. 85)
New Zealand (offshore islands)
Kermadec Islands
Raoul Island introduced
invasive
Webb, C. J./Sykes, W. R./Garnock-Jones, P. J. (1988) (p. 206)
"Common on Raoul and nearby islets. Waste places and disturbed areas".
Papua New Guinea
Papua New Guinea (eastern New Guinea Island)
Papua New Guinea (eastern New Guinea Island) invasive
Henty, E. E./Pritchard, G. H. (1975) (p. 63)
Established in a few localities above 1000 m.
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)
Australia (continental) introduced
invasive
U.S. Dept. Agr., Agr. Res. Serv. (2013)
Naturalized
Australia
Australia (continental)
Queensland introduced
invasive
Queensland Herbarium (2002) (p. 1)
China
China
China (People's Republic of) introduced
invasive
cultivated
Zhengyi, Wu/Raven, Peter H./Deyuan, Hong (2013)
Anhui, Fujian, Guangdong, Guangxi, Guizhou, Hainan, Hebei, Jiangsu, Nanhai Zhudao, Shandong, Sichuan, Yunnan, Zhejiang
"Grasslands, roadsides, slopes in valleys; 100-1500 m. Cultivated and naturalized".
China
China
Hong Kong introduced
invasive
Wu, Te-lin (2001) (p. 273)
On farmland or in wasteland.
Ecuador (Mainland)
Ecuador
Ecuador (Republic of) (continental) introduced
invasive
U.S. Dept. Agr., Agr. Res. Serv. (2013)
Naturalized
Guatemala
Guatemala
Guatemala (Republic of) introduced
invasive
U.S. Dept. Agr., Agr. Res. Serv. (2013)
Naturalized
Honduras
Honduras
Honduras (Republic of) native
U.S. Dept. Agr., Agr. Res. Serv. (2013)
Indonesia
Indonesia
Indonesia (Republic of)   Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. (1979) (p. 10)
Japan
Japan
Japan (country) introduced
Mito, Toshikazu/Uesugi, Tetsuro (2004) (p. 189)
Mexico
Mexico
Mexico (United Mexican States) native
U.S. Dept. Agr., Agr. Res. Serv. (2013)
Chiapas, Hidalgo, Jalisco, Morelos, Nayarit, Oaxaca, Veracruz
New Zealand
New Zealand
New Zealand (country) introduced
cultivated
Webb, C. J./Sykes, W. R./Garnock-Jones, P. J. (1988) (p. 206)
Perú
Perú
Perú (Republic of) introduced
invasive
U.S. Dept. Agr., Agr. Res. Serv. (2013)
Naturalized
Taiwan
Taiwan Island
Taiwan Island introduced
invasive
Ching-I Peng, ed. (2013)
"A common weed from low to middle elevations throughout Taiwan".
Thailand
Thailand
Thailand (Kingdom of) introduced
invasive
U.S. Dept. Agr., Agr. Res. Serv. (2013)
Naturalized
Also reported from
Country/Terr./St. &
Island group
Location Cited status &
Cited as invasive &
Cited as cultivated &
Cited as aboriginal introduction?
Reference &
Comments
United States (continental except west coast)
United States (other states)
United States (other states) introduced
invasive
U.S. Dept. Agr., Agr. Res. Serv. (2013)
Naturalized
United States (continental except west coast)
United States (other states)
USA (Florida) introduced
invasive
U.S. Dept. Agr., Agr. Res. Serv. (2013)
Naturalized


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This page was created on 24 MAR 2005 and was last updated on 19 FEB 2013.