Polypogon interruptus Kunth, Poaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Common name(s): [more details]

English: ditch beard grass, ditch polypogon, ditch rabbitsfoot grass

Habit:  grass

Description:  "Perennials; culms tufted, 0.5-6 (-9) dm tall, sometimes decumbent at base and rooting at nodes.  Sheaths smooth to scaberulous, margins overlapping, thin; ligule translucent, firm, (1.5-) 3-7 (-9.5) mm long, nerved, puberulent, margins entire to lacerate, apex narrowed, obtuse, or truncate; blades flat, 2-5 (-9) mm wide, scabrous.  Panicles 2-9 (-15) cm long, interrupted, branches erect; glumes subequal, 1.7-2.5 mm long, keeled, hispidulous, apex narrowed abruptly into a terminal awn, sometimes minutely bifid, the awn (1-) 1.5-3 (-5) mm long; lemma narrowly lanceolate, (0.7-) 1-1.5 mm long, smooth, glossy, apex minutely bifid, awned from near apex, the awn ca. 3 mm long; palea similar and nearly as long as lemma.  Caryopsis pale brown, narrowly ovoid, 0.6-0.8 mm long"  (Wagner et al., 1999; p. 1585-1586).

Description and other information from World Grass Species database.

Habitat/ecology:  In Hawai‘i, "naturalized and common in wet sites such as along streams, roadside drainages, in wet forest, and near rock seeps, 0-1,980 m"  (Wagner et al., 1999; p. 1585).

Propagation:  Seed

Native range:  Western and southern South America, naturalized elsewhere (GRIN).

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. 1586)
State of Hawaii Hawaiian Islands	Kaua‘i Island	introduced invasive	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 1586)
State of Hawaii Hawaiian Islands	Kure Atoll	introduced invasive	Wagner, Warren L./Herbst, Derral R. (1995) (p. 24) Voucher cited: Saito s.n. (BISH)
State of Hawaii Hawaiian Islands	Kure Atoll	introduced invasive	Starr, Forest/Martz, Kim/Loope, Lloyd (2001) (p. 16) Common near quarters, on the runway, and in open areas.
State of Hawaii Hawaiian Islands	Maui Island	introduced invasive	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 1586) Voucher cited: Forbes 171.M (BISH)
State of Hawaii Hawaiian Islands	O‘ahu Island	introduced invasive	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 1586)
United States (other Pacific offshore islands) Midway Atoll	Midway Atoll	introduced invasive	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 1586)
United States (other Pacific offshore islands) Midway Atoll	Sand Island	introduced invasive	Starr, Forest/Starr, Kim/Loope, Lloyd (2008) (pp. B-12)

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)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Ecuador (Mainland) Ecuador	Ecuador (Republic of) (continental)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
Perú Perú	Perú (Republic of)	native	U.S. Dept. Agr., Agr. Res. Serv. (2011)
United States (west coast) United States (west coast states)	USA (Oregon)	native	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2011)
United States (west coast) United States (west coast states)	USA (California)	native	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2011)
United States (west coast) United States (west coast states)	USA (Washington)	native	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2011)

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)	native	U.S. Dept. Agr., Nat. Res. Cons. Serv. (2011)

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

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

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

References:

Starr, Forest/Martz, Kim/Loope, Lloyd. 2001. Botanical inventory of Kure Atoll. United States Geological Survey, Biological Resources Division, Haleakala Field Station, Hawai‘i. 22 pp.

Starr, Forest/Starr, Kim/Loope, Lloyd. 2008. Botanical survey of Midway Atoll. Prepared for: United States Fish and Wildlife Service. 27 pp. plus appendices.

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.

U.S. Dept. Agr., Nat. Res. Cons. Serv. 2011. The PLANTS Database. National Plant Data Center, Baton Rouge, LA 70874-4490 USA.

Wagner, Warren L./Herbst, Derral R. 1995. Contributions to the Flora of Hawai‘i. IV. New Records and name changes. In: Evenhuis, Neal L. and Miller, Scott, E., eds. Records of the Hawaii Biological Survey for 1994. Part 2: Notes. Bishop Museum Occasional Papers. 42:13-27.

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).