Panicum dichotomiflorum Michx., Poaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Common name(s): [more details]

Chinese: yang ye shu

English: bluegrass, fall panic grass, fall panicum, smooth witchgrass, western witchgrass

French: panic d'automne

Spanish: rapiente

Habit:  grass

Description:  "Geniculate or erect annuals 10-120 cm tall, usually glabrous; culms usually branched.  Ligule a ciliate membrane, 1-2 mm long; blades 10-50 cm long, 0.3-2 cm wide, flat, glabrous or sparsely pubescent.  Panicles 4-50 cm long, terminal and axillary; spikelets 2-.32 mm long, oblong-ovoid, acute, glabrous; first glume 0.6-1 mm long, 1/5 - 1/4 as long as spikelet, obtuse to truncate, 3-nerved, broadly clasping, second glume 7-nerved; first floret sterile or staminate, first lemma 7-nerved, first palea absent or as long as first lemma; second floret 1.7-2.1 mm long, acute, glossy, smooth; anthers 1.2-1.4 mm long"  (Wagner et al., 1999; p. 1568).

Description from GrassBase.

Habitat/ecology:  In Hawai‘i, "naturalized in mesic, disturbed areas, 120-1,220 m"  (Wagner et al., 1999; p. 1568).

Propagation:  Seed

Native range:  "Native to the Americas"  (Wagner et al., 1999; p. 1568).

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	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 1568)
State of Hawaii Hawaiian Islands	O‘ahu Island	introduced invasive	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 1568) Voucher cited: Lyman s.n. (BISH)

Pacific Rim
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Chile (continental) Chile	Chile (Republic of)		Hafliger, Ernst/Scholz, Hildemar (1980) (p. 80)
China China	China (People's Republic of)		Hafliger, Ernst/Scholz, Hildemar (1980) (p. 80)
Mexico Mexico	Mexico (United Mexican States)		Hafliger, Ernst/Scholz, Hildemar (1980) (p. 80)
New Zealand New Zealand	New Zealand (country)	introduced invasive	Edgar, E./Connor, H. (2000) (p. 559) "Weed of crops (especially maize, onions), and disturbed soil in orchards, gardens, roadsides, waste places and pasture".
Panama Panama	Panama (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Perú Perú	Perú (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Taiwan Taiwan	Taiwan Island		Hafliger, Ernst/Scholz, Hildemar (1980) (p. plate)

Additional information:
Identification information from the Virginia Tech Weed Identification Guide

Additional online information about Panicum dichotomiflorum is available from the Hawaiian Ecosystems at Risk project (HEAR).

Information about Panicum dichotomiflorum as a weed (worldwide references) may be available from the Global Compendium of Weeds (GCW).

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

References:

Edgar, E./Connor, H. 2000. Flora of New Zealand, vol. V: Gramineae. Manaaki Whenua Press. .

Hafliger, Ernst/Scholz, Hildemar. 1980. Grass weeds, vol. 1. CIBA-GEIGY Ltd., Basle, Switzerland. 142 pp. + plates.

U. S. Government. 2011. Integrated Taxonomic Information System (ITIS) (on-line resource).

U.S. Dept. Agr., Agr. Res. Serv. 2011. National Genetic Resources Program. Germplasm Resources Information Network (GRIN). Online searchable database.

Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. 1999. Manual of the flowering plants of Hawaii. Revised edition. Bernice P. Bishop Museum special publication. University of Hawai‘i Press/Bishop Museum Press, Honolulu. 1919 pp. (two volumes).

Zhengyi, Wu/Raven, Peter H./Deyuan, Hong. 2011. Flora of China (online resource).