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rhynchospore blanc, white beak-rush, white beaksedge

brownish beak-rush, brownish beaksedge, capitate beak rush, rhynchospore à petites têtes

Habit Plants perennial, densely cespitose, 6–75 cm; rhizomes mostly absent. Plants perennial, cespitose, 20–100 cm; rhizomes absent.
Culms

erect to curved, leafy, obscurely trigonous to nearly terete, few ribbed, slender.

arching-ascending, leafy, obtusely trigonous, slender;

principal leaves overtopped by inflorescence;

blades flat, to 3 mm, apex tapering, trigonous.

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.

terminal and axillary, clusters 1–5 or more, compact, turbinate or hemispheric, 1–1.5 cm wide;

peduncles progressively shorter distally on culm;

bracteal leaves mostly exceeding subtended compounds.

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.

rich deep brown, rarely pale brown, lanceellipsoid, 3.5–4(–5) mm;

fertile scale elliptic, 2.7–3 mm, apex acute or rounded, midrib shortexcurrent or not.

Flowers

perianth bristles 10–12, slightly overtopping tubercle, retrorsely barbellate or rarely smooth, base often setose.

perianth absent.

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–)2–3(–5) per spikelet, (2–)2.5–3 mm;

body redbrown with pale central disc, stipitate, lenticular, obovoid, 1.2–1.5 × 0.7–1(–1.2) mm, margins pale, wirelike, surfaces slick;

tubercle triangular-subulate, (0.8–)1–1.2(–1.6) mm.

Principal

leaves mostly overtopped by culm;

blades narrowly linear to filiform, proximally flat, 0.5–1.5 mm, apex tapering, trigonous.

Rhynchospora alba

Rhynchospora capitellata

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 Moist to wet meadows, swales, seeps, stream banks, flatwoods, fens, and bogs
Elevation 0–2000 m (0–6600 ft) 0–1600 m (0–5200 ft)
Distribution
from FNA
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
[WildflowerSearch map]
[BONAP county map]
from FNA
AL; AR; CA; CT; DC; DE; FL; GA; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; NC; NH; NJ; NY; OH; OR; PA; RI; SC; TN; TX; VA; VT; WI; WV; NB; NS; ON; QC
[WildflowerSearch map]
[BONAP county map]
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.)

Rhynchospora capitellata occurs infrequently in the lower Gulf coastal plain (in Florida, only north) and intergrades with R. glomerata. Forms with antrorsely barbellate bristles are referred to forma controversa (S. F. Blake) Gale; those with smooth bristles are named forma discutiens (C. B. Clarke) Gale (S. Gale 1944). Occasional forms with trigonous fruits occur.

Bruce Sorrie (pers. comm.) believes that many of the southern coastal plain records for Rhynchospora capitellata are based on examples of a neglected taxon, R. leptocarpa (Chapman) Small (J. K. Small 1933), and he wishes to reinstate it. Occurring in semi-shady moist sites in steepheads, or from seeps and shallows along blackwater streams, the plants are mostly distinguished by the tall, lax habit; the many distant, small clusters of light brown or tan spikelets; and the softer, more lax foliage. Measures of spikelets, fertile scales, perianth, achenes, and fruit tubercles show a strong overlap with those of southern examples of R. capitellata. The long, lax culm habit, the softer and paler foliage, and the paler spikelets could well be ecologic responses, or the plants could indeed represent a geographic variant.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 23, p. 214. FNA vol. 23, p. 210.
Parent taxa Cyperaceae > Rhynchospora Cyperaceae > Rhynchospora
Sibling taxa
R. baldwinii, R. brachychaeta, R. breviseta, R. caduca, R. californica, R. capillacea, R. capitellata, R. careyana, R. cephalantha, R. chalarocephala, R. chapmanii, R. ciliaris, R. colorata, R. compressa, R. corniculata, R. crinipes, R. curtissii, R. debilis, R. decurrens, R. divergens, R. elliottii, R. eximia, R. fascicularis, R. fernaldii, R. filifolia, R. floridensis, R. fusca, R. globularis, R. glomerata, R. gracilenta, R. grayi, R. harperi, R. harveyi, R. indianolensis, R. inexpansa, R. inundata, R. knieskernii, R. kunthii, R. latifolia, R. macra, R. macrostachya, R. megalocarpa, R. megaplumosa, R. microcarpa, R. microcephala, R. miliacea, R. mixta, R. nitens, R. nivea, R. odorata, R. oligantha, R. pallida, R. perplexa, R. pineticola, R. pleiantha, R. plumosa, R. punctata, R. pusilla, R. rariflora, R. recognita, R. scirpoides, R. solitaria, R. stenophylla, R. thornei, R. torreyana, R. tracyi, R. wrightiana
R. alba, R. baldwinii, R. brachychaeta, R. breviseta, R. caduca, R. californica, R. capillacea, R. careyana, R. cephalantha, R. chalarocephala, R. chapmanii, R. ciliaris, R. colorata, R. compressa, R. corniculata, R. crinipes, R. curtissii, R. debilis, R. decurrens, R. divergens, R. elliottii, R. eximia, R. fascicularis, R. fernaldii, R. filifolia, R. floridensis, R. fusca, R. globularis, R. glomerata, R. gracilenta, R. grayi, R. harperi, R. harveyi, R. indianolensis, R. inexpansa, R. inundata, R. knieskernii, R. kunthii, R. latifolia, R. macra, R. macrostachya, R. megalocarpa, R. megaplumosa, R. microcarpa, R. microcephala, R. miliacea, R. mixta, R. nitens, R. nivea, R. odorata, R. oligantha, R. pallida, R. perplexa, R. pineticola, R. pleiantha, R. plumosa, R. punctata, R. pusilla, R. rariflora, R. recognita, R. scirpoides, R. solitaria, R. stenophylla, R. thornei, R. torreyana, R. tracyi, R. wrightiana
Synonyms Schoenus albus, Dichromena alba, Phaeocephalum album, R. luguillensis, Triodon albus Schoenus capitellatus, Phaeocephalum glomeratum var. minus, R. capitellata var. leptocarpa, R. capitellata var. minor, R. glomerata var. minor, R. leptocarpa
Name authority (Linnaeus) Vahl: Enum. Pl. 2: 236. (1805) (Michaux) Vahl: Enum. Pl. 2: 235. (1805)
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