Rhynchospora caduca Elliott, Cyperaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Common name(s): [more details]

English: anglestem beaksedge

Habit:  herb

Description:  "Perennials with short-creeping rhizomes; culms loosely to moderately densely tufted, 60-120 cm tall, 1.8-3 mm in diameter near base, 3-4-nodose below the inflorescence, trigonous, smooth.  Leaves basal, a few cauline and well-spaced, herbaceous, linear, shorter than the culm, 3-6 mm wide; sheaths 2-5 cm long, the cauline ones green, the basal ones reddish brown or yellowish brown.  Inflorescences of 4-5 well-spaced, anthelate partial panicles, these decompound, 2-7 cm long, 1.5-3 cm wide, moderately dense, the peduncles exserted, branches numerous, 1-3 cm long, once or twice further branched, each bearing 3-5 spikelets, the lowest 2 leaf-like bracts longer than the subtending partial panicle, the upper bracts as long as or shorter than the subtending partial panicle; spikelets brown, solitary or in clusters of 2-3, subsessile, ovate, 3.5-4.5 mm long, ca. 2 mm wide, subterete; glumes 6-8, the middle 3-6 flower-bearing, 2-4 of them perfect, brown to rusty brown, ovate to broadly so, acute, membranous, margins hyaline, the slender and conspicuous midnerve prolonged into a straight mucro or short awn, the flower-bearing glumes 2.8-3.7 mm long, 2-3 mm wide; perianth bristles 6, longer than the achene (incl. the style base); style base deltoid, 0.6-0.8 mm high and wide, ciliate.  Achenes broadly obovate, lenticular, 1-1.6 mm long, 1-1.4 mm wide, transversely undulate-rugose and cancellate with longitudinally oblong cells"  (Wagner et al., 1999; p. 1428).

Habitat/ecology:  In Hawai‘i, "sparingly naturalized in wet, disturbed areas, 320-1,400 m" (Wagner et al., 1999; p. 1428).

Propagation:  Seed, rhizomes.

Native range:  Southern US

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. 1428) Voucher cited: Shinbara H110 (BISH)
State of Hawaii Hawaiian Islands	Kaua‘i Island	introduced invasive	Wagner, Warren L./Herbst, Derral R. (1995) (pp. 18-19) Voucher cited: Hume & Levine 332 (BISH, PTBG)
State of Hawaii Hawaiian Islands	Maui Island	introduced invasive	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (p. 1428)
State of Hawaii Hawaiian Islands	Moloka‘i Island	introduced invasive	Wysong, Michael/Hughes, Guy/Wood, K. R. (2007) (p. 4) Voucher cited: K.R. Wood & Hughes 10563 (PTBG)
State of Hawaii Hawaiian Islands	O‘ahu Island	introduced invasive	Wagner, Warren L./Shannon, Robynn K./Herbst, Derral R. (1997) (p. 56) Voucher cited: Takeuchi 8516 (BISH)

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., Agr. Res. Serv. (2011)

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

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

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

References:

Meyer, Jean-Yves. 2000. Preliminary review of the invasive plants in the Pacific islands (SPREP Member Countries). In: Sherley, G. (tech. ed.). Invasive species in the Pacific: A technical review and draft regional strategy. South Pacific Regional Environment Programme, Samoa. 190 pp.

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. 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).

Wagner, Warren L./Shannon, Robynn K./Herbst, Derral R. 1997. Contributions to the flora of Hawai‘i. In: Evenhuis, Neal L. and Miller, Scott, E., eds. Records of the Hawaii Biological Survey for 1996. Part 1: Articles. Bishop Museum Occasional Papers. 48:51-65.

Wysong, Michael/Hughes, Guy/Wood, K. R. 2007. New Hawaiian plant records for the island of Moloka‘i. In: Evenhuis, Neal L. and Eldredge, Lucias G., eds. Records of the Hawaii Biological Survey for 2006. Part 2: Notes. Bishop Museum Occasional Papers 96:1-8.