Gamochaeta pensylvanica (Willd.) Cabrera, Asteraceae

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Present on Pacific Islands?  yes

Threat only at high elevations?  no

Other Latin names:  Gnaphalium pensylvanicum Willd.

Common name(s): [more details]

English: Pennsylvania cudweed

Habit:  herb

Description:  "Annual, 10-40 cm tall, usually branched only at base; stems 1-few, erect or ascending.  Basal leaves mostly 0 at flowering, sometimes present and withered.  Lower cauline leaves apetiolate, sparsely tomentose on upper surface, densely tomentose on lower, more or less concolorous to somewhat discolourous, plane, usually obovate and long-cuneate, sometimes oblanceolate, obtuse to acute, mucronate, flat or slightly undulate, (10)-20-40-(60) x 3-8-(12) mm, upper cauline leaves similar but smaller, narrower and broader based, sometimes folded.  Capitula in dense terminal and axillary clusters; clusters usually forming dense terminal spikes at ends of branches and scattered below.  Involucral bracts oblong, obtuse to apiculate, 2.5-3 mm long; stereome green; lamina pale brown, gap and margins clear; outer bracts almost covered by hairs.  Achenes minutely papillate, 0.4-0.5 mm long"  (Webb et al., 1988; pp. 238-239).

Habitat/ecology:  On Raoul Island, "waste places coastal sites, scrubland" (Webb et al., 1988; pp. 238-239).

Propagation:  Seed

Native range:  Temperate and subtropical America.

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Japan (offshore islands) Bonin (Ogasawara) Islands	Bonin (Ogasawara) Islands	introduced	Kato, Hidetoshi (2007) As Gnaphalium pensylvanicum Willd.
New Caledonia New Caledonia	New Caledonia Islands		Swarbrick, John T. (1997) (p. 92)
New Zealand (offshore islands) Kermadec Islands	Raoul Island	introduced invasive	Webb, C. J./Sykes, W. R./Garnock-Jones, P. J. (1988) (p. 238) "Waste places, coastal sites, scrubland, local".

Pacific Rim
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Costa Rica Costa Rica	Costa Rica (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2007)
Guatemala Guatemala	Guatemala (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2007)
Honduras Honduras	Honduras (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2007)
Mexico Mexico	Mexico (United Mexican States)	native	U.S. Dept. Agr., Agr. Res. Serv. (2007)
Nicaragua Nicaragua	Nicaragua (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2007)

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

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

References:

Kato, Hidetoshi. 2007. Herbarium records of Makino Herbarium, Tokyo Metropolitan University. Personal communication.

Swarbrick, John T. 1997. Weeds of the Pacific Islands. Technical paper no. 209. South Pacific Commission, Noumea, New Caledonia. 124 pp.

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

Webb, C. J./Sykes, W. R./Garnock-Jones, P. J. 1988. Flora of New Zealand, Volume IV: Naturalised pteridophytes, gymnosperms, dicotyledons. Botany Division, DSIR, Christchurch. 1365 pp.