All Floras      Advanced Search
FNA Vol. 23 Page 45, 47, 48, 49, 50 Login | eFloras Home | Help
FNA | Family List | FNA Vol. 23 | Cyperaceae | Schoenoplectus

2. Schoenoplectus acutus (Muhlenberg ex Bigelow) Á. Löve & D. Löve, Bull. Torrey Bot. Club. 81: 33. 1954.

Scirpus acutus Muhlenberg ex Bigelow, Fl. Boston, 15. 1814

Rhizomes 5–15 mm diam. Culms cylindric, 1–4 m × 2–10 mm. Leaves 3–4, all basal; sheaths often dark reddish proximally, front membranous-translucent and splitting, orifice adaxially deeply V-shaped; blades 1–2, C-shaped to dorsiventrally flat in cross section, usually much shorter than sheath, distal blade 8–120 × 3–7 mm, margins often scabridulous. Inflorescences 2(–3) times branched, open or compact, branches 6(–18) cm; proximal bract usually erect, thickly C-shaped in cross section, 1–9 cm, margins sometimes scabridulous. Spikelets 3–190, solitary or in clusters of 2–8, never all solitary; scales reddish to orange-brown to straw-colored, often variable on same scale, usually wholly or partly straw-colored and prominently lineolate-spotted at 10X, scale or midrib often green when young, ovate, 3–4 × 2–3 mm, sparsely to often densely reddish or straw-colored spinulose-papillose distally or on most of surface, margins ciliate, hairs long, contorted, flanks veinless, apex acute to obtuse, notch 0.3–0.5 mm deep, awn on at least some scales in spikelet usually strongly contorted, 0.5–2 mm (often broken off). Flowers: perianth members (4–)6(–8), brown, bristlelike, equaling achene body or sometimes much shorter, rarely rudimentary, spinulose; anthers 2 mm; styles 2(–3)-fid. Achenes dark gray-brown, plano-convex or rarely weakly trigonous, obovoid, (1.5–)2–3 ´ 1.2–1.7 mm; beak 0.2–0.4 mm.

Varieties 2 (2 in the flora): North America, Mexico, possibly Eurasia, e Pacific Islands.

Plants of Schoenoplectus acutus var. occidentalis that have most styles 3-fid, most achenes trigonous, and culms very soft with large air cavities occur at lower elevations in California (mostly southern) and Baja California. In California they often grow on stream bars. They may deserve varietal status. The varieties intergrade throughout most of the west with var. occidentalis.

Schoenoplectus acutus hybridizes with Schoenoplectus tabernaemontani, S. heterochaetus, and S. californicus (see also S. tabernaemontani).

Although previously assumed to be restricted to North America, some specimens from Eurasia are probably Schoenoplectus acutus, and one very young specimen from Clipperton Island in the eastern Pacific is probably S. acutus var. occidentalis.

1 Styles 2-fid; achenes plano-convex; culms mostly very firm, air cavities in distal 1/4 mostly ca. 0.5 mm wide.   2a var. acutus
+ Some styles 3-fid; some achenes compressed, obtusely trigonous; culms firm to soft, larger air cavities in distal 1/4 1–2.5 mm wide.   2b var. occidentalis

Lower Taxa


Related Objects  
  • Distribution Map
  • Map

     |  eFlora Home |  People Search  |  Help  |  ActKey  |  Hu Cards  |  Glossary  |