Rhynchospora alba |
Rhynchospora cephalantha |
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rhynchospore blanc, white beak-rush, white beaksedge |
bunched beaksedge |
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Habit | Plants perennial, densely cespitose, 6–75 cm; rhizomes mostly absent. | Plants perennial, cespitose, 40–100(–150) cm; rhizomes absent. |
Culms | erect to curved, leafy, obscurely trigonous to nearly terete, few ribbed, slender. |
arching, leafy, obscurely and convexly trigonous, multi-ribbed, slender to stoutish. |
Inflorescences | clusters 1 or 2–3, then widely spaced, narrowly turbinate to hemispheric, 1.5–2.5 cm wide; subtending leafy bracts often exceeded by distal cluster. |
spikelet clusters 3–several, widely spaced, often equidistant, mostly hemispheric to globose, occasionally lobed, 1–2 cm thick; bracteal leaves much exceeding subtended inflorescence. |
Spikelets | pale brown to nearly white, ellipsoid, 3.5–5.5 mm, apex acute; fertile scales elliptic, 3–3.5(–4) mm, apex acute or acuminate, midrib excurrent as mucro. |
dark red-brown to dark brown, lanceellipsoid to ellipsoid, 4–5(–6) mm, apex acute; fertile scales elliptic, 3–3.5(–4.5) mm, apex acute, midribs 3, laterals indistinct. |
Flowers | perianth bristles 10–12, slightly overtopping tubercle, retrorsely barbellate or rarely smooth, base often setose. |
perianth bristles 6, reaching tubercle tip, retrorsely (rarely antrorsely) barbellate. |
Fruits | 1(–2) per spikelet, (2.3–)2.5–3 mm; body pale brown with paler center, stipitateobovoid, lenticular, 1.5–1.8(–2) × 0.9–1.2 mm; surfaces transversely striate, relatively smooth, rim narrow, flowing to tubercle base; tubercle narrowly triangularsubulate, 0.5–1.2 mm. |
1(–2) per spikelet, 3.5–4(–4.2) mm; body brown with pale center, obovoid distal to stipe, lenticular, 2–2.3 × 1–1.5(–2) mm; tubercle triangular-subulate, (1–)1.5–2 mm, at least 0.5 mm wide at base. |
Principal | leaves mostly overtopped by culm; blades narrowly linear to filiform, proximally flat, 0.5–1.5 mm, apex tapering, trigonous. |
leaves overtopped by culm; blades linear, flat proximally, 1.5–3 mm wide, apex tapering, trigonous. |
Rhynchospora alba |
Rhynchospora cephalantha |
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Phenology | Fruiting summer–fall. | Fruiting summer–fall. |
Habitat | Acid, sphagnous, boggy, open sites, poor fens, often on floating mats or peaty interstices of rocky shores | Sandy silts, sands, and peats of shores, boggy streams, seeps, savannas, and savanna bogs |
Elevation | 0–2000 m (0–6600 ft) | 0–200 m (0–700 ft) |
Distribution |
AK; CA; CT; DE; GA; ID; IL; IN; MA; MD; ME; MI; MN; NC; NH; NJ; NY; OH; OR; PA; RI; SC; TN; VA; VT; WA; WI; WV; AB; BC; MB; NB; NF; NS; NT; ON; PE; QC; SK; Fla(?); West Indies (Puerto Rico); South America(?); Eurasia
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AL; DE; FL; GA; LA; MD; MS; NC; NJ; NY; SC; TX; VA
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Discussion | The smooth-bristled Rhynchospora alba forma laeviseta Gale mostly occurs with the typical antrorsely barbellate type in Pennsylvania, the Great Lakes, British Columbia, Newfoundland, and Nova Scotia. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
North American plants referred to Rhynchospora axillaris (Lamarck) Britton [Phaeocephala axillare (Lamarck) House by N. L. Britton and A. Brown (1913) and J. K. Small (1933)] are actually R. cephalantha. A photograph of the type specimen of Schoenus axillaris Lamarck (from P) reveals what appears to be an immature top of S. glomeratus [R. glomerata (Linnaeus) Vahl]. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 23, p. 214. | FNA vol. 23, p. 212. |
Parent taxa | Cyperaceae > Rhynchospora | Cyperaceae > Rhynchospora |
Sibling taxa | ||
Synonyms | Schoenus albus, Dichromena alba, Phaeocephalum album, R. luguillensis, Triodon albus | R. cephalantha var. attenuata, R. cephalantha var. pleiocephala |
Name authority | (Linnaeus) Vahl: Enum. Pl. 2: 236. (1805) | A. Gray: Ann. Lyceum Nat. Hist. New York 3: 218. (1835) |
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