Rhynchospora capillacea Torr.
Family: Cyperaceae
Rhynchospora capillacea image
Paul Rothrock  
Plants perennial, cespitose, 10-40 cm, wiry; rhizomes stoloniferous, slender, to 1.5 mm thick. Culms erect or curved, leafy, filiform, angularly few ribbed. Leaves ascending-excurved, overtopped by culm; blades filiform, involute, apex setaceous. Inflorescences: spikelet clusters 1-2(-3), often sparse, ellipsoid or narrowly turbinate, less than 1 cm wide; subtending foliaceous bracts exceeding compounds. Spikelets erect or ascending, pale red brown to brown, fusiform, 6-7 mm; fertile scales elliptic, 4 mm, apex rounded or acute, midrib short excurrent or not. Flowers: perianth bristles 6, overtopping tubercle base, mostly retrorsely barbellate, sometimes smooth [forma laeviseta (E. J. Hill) Fernald]. Fruits 1-4(-5) per spikelet, 2.5-3 mm; body pale brown, slender stipitate, ellipsoid, lenticular, 1.5-2 × 0.8-1 mm; surfaces longitudinally minutely striate, obscurely transversely low rugose, dotted; tubercle narrowly triangular subulate, flattened, 0.8-1.7 mm. Fruiting summer-fall. Moist to wet calcareous fens, seeps over limestones or calcareous rock, marsh meadows; 0-1000 m; Alta., Man., N.B., Nfld. and Labr., Ont., Que., Sask.; Ala., Ark., Conn., Ill., Ind., Iowa, Maine, Mass., Mich., Minn., Mo., N.H., N.J., N.Y., N.Dak., Ohio, Okla., Pa., R.I., S.Dak., Tenn., Tex., Vt., Va., Wis. The two beakrushes most commonly occurring in fens are Rhynchospora capillacea and R. capitellata.

Perennial herb with slender rhizomes, tufted 10 - 40 cm tall Leaves: alternate, three-ranked, ascending-curved, under 0.5 mm wide, thread-like with a bristly tip, parallel-veined, rolled inward marginally, with a sheathing base that encloses the stem. Sheaths opening at the top. Inflorescence: a terminal head of one or two spikelet clusters, under 1 cm wide, reverse cone-shaped or ellipsoid, subtended by leaf-like bracts. Bracts surpassing the inflorescence. Flowers: minute, subtended by a floral scale, lacking sepals and petals, bearing six bristles. Bristles surpassing achene. Stamens exserted. Pistil one. Style two-cleft. Fruit: a one-seeded achene, one to four per spikelet, thin-stalked, light brown with obscure lines, darker marginally, 1.5 - 2 mm long (not including tubercle), about 1 mm wide, ellipsoid with a narrowed base, biconvex, minutely streaked longitudinally, obscurely wrinkled, dotted. Tubercle to almost 2 mm long, thinly triangular, flattened. Culm: curved or upright, 10 - 40 cm long, very thin, wiry, overtopping leaves, angularly ribbed, solid, leafy. Spikelets: ascending or upright, brown to light reddish brown, 6 - 7 mm long, spindle-shaped. Floral scales spirally arranged and overlapping, to 4 mm long, elliptic with a rounded or pointed apex.

Similar species: No information at this time.

Flowering: late May to late August

Habitat and ecology: Characteristically found in very springy calcareous seepage banks. It is also found near Lake Michigan on the moist calcareous shores of interdunal ponds.

Occurence in the Chicago region: native

Etymology: Rhynchospora comes from the Greek words rhynchus, meaning beak, and spora, meaning seed, referring to the beaked achene. Capillacea means hair-like.

Author: The Morton Arboretum

From Flora of Indiana (1940) by Charles C. Deam
Local in marly, springy places in the lake area, usually associated with the preceding species [Rhynchospora alba] and with Scleria verticillata.


Indiana Coefficient of Conservatism: C = 10

Wetland Indicator Status: OBL

Cespitose; lvs involute, filiform, 0.2-0.4 mm wide; glomerules 1 or commonly 2, the terminal ovoid or oblong, with 2-10 erect or ascending spikelets, the lateral remote, subsessile, with 1-4 spikelets; bristles 6, retrorsely barbellate or seldom smooth, surpassing the achene; achenes elliptic- oblong to narrowly elliptic-obovate, 1.7-2.1 mm, scarcely (or less than) half as wide, conspicuously narrowed toward the base, pale (and often obscurely darker-lined) centrally, darker toward the margins; tubercle subulate- attenuate, 0.8-1.6 mm; 2n=26. Calcareous swamps, bogs, and shores; Nf. to Sask., s. to Va., Tenn., and Mo.

Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.

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