keys to the vascular plants of east texas - Botanical Research ...

RHYNCHOSPORA/CYPERACEAE
621
Lipocarpha aristulata (Coville) G.C. Tucker, (bearded or awned), AWNED HALFCHAFF SEDGE.
Spikelet-like spikes 1–5(–8) mm long; floral scales widest near middle; inner hyaline scale 0.5–
0.8 mm long. Disturbed wet soils, exposed shorelines, usually sandy soils; Comal and Travis
(Turner et al. 2003) cos. near sw margin of East TX; also range map given by Friedland (1941)
clearly showed this taxon within East TX (counties not specified); scattered in w 2/3 of TX; w
U.S. from MI, MO, and TX w to the Pacific coast. Jun–Nov. [Hemicarpha aristulata (Coville)
Smyth, Hemicarpha micrantha (Vahl) Pax var. aristulata Coville]
Lipocarpha drummondii (Nees) G.C. Tucker, (for its discoverer, Thomas Drummond, 1780–1835,
Scottish botanist and collector in North America), DRUMMOND’S HALFCHAFF SEDGE, COMMON
HEMICARPHA. Spikelet-like spikes 1–5(–6) mm long; floral scales widest beyond middle. Disturbed
wet soils, exposed shorelines, usually sandy soils; Smith (BRIT), Bastrop, Harrison, Lee,
Leon, Travis, and Tyler (Turner et al. 2003) cos.; also Gulf Prairies and Marshes and e Cross Timbers
and Prairies; c U.S. from OH s to TX w to NE and AZ. May–Nov. [Hemicarpha drummondii
Nees, H. micrantha (Vahl) Pax var. drummondii (Nees) Friedl.]
Lipocarpha micrantha (Vahl) G.C. Tucker, (small-flowered), SMALL-FLOWER HALFCHAFF SEDGE.
Spikelet-like spikes 1–3(–5) mm long; floral scales widest at or beyond middle. Moist sandy
soils, seasonally wet areas, exposed shorelines; Brazos, Harrison, Henderson (BRIT), and Lee
(Turner et al. 2003) cos.; also Gulf Prairies and Marshes (Calhoun Co.—BRIT), Cross Timbers
and Prairies (Bosque, Hood, and Parker (BRIT) cos.) and Trans-Pecos; s Canada and widespread
in the U.S. except the n Rocky Mt. area. Mar–Oct. [Hemicarpha micrantha (Vahl) Pax,
Hemicarpha micrantha var. minor (Schrad.) Friedl., Scirpus micranthus Vahl]
RHYNCHOSPORA Vahl
BEAK-RUSH, HORNED-RUSH, BEAK SEDGE, WHITE-TOP
Tufted or clump-forming, sometimes rhizomatous perennials (rarely annuals), glabrous or with
scabrous-margined leaf blades; culms (= stems) triangular in cross section; leaves basal and
cauline; spikelets narrowly ovoid to fusiform or roundish, usually brownish or white (in a few
species) or dark brown to nearly black (in a few species), usually 1–few-flowered, in loose or
compact clusters, in spike-like or open panicles, or in a head-like cluster, the inflorescence with
1–few leafy bracts; scales of spikelets spirally arranged, the lower (1–)2–3 usually sterile; uppermost
1–2 florets usually without pistil; perianth of bristles or absent; achenes flattened to lenticular
to nearly round in cross section, with a conspicuous tubercle or “beak” (= hardened and
persistent style base) at the apex (hence the name BEAK-RUSH).
AA genus of over 250 species nearly cosmopolitan in distribution, with greatest diversity in the
New World tropics; they are mostly plants of sunny places with wet, acidic soils (Kral 2002c).
Temperate North America is rich in species, with ca. 60 in the se U.S. (Tucker 1987). According to
Yatskievych (1999), species of this genus “are generally considered poor forage for livestock. The
tiny sharp teeth along the leaf margins are composed of silica, and they make the plants relatively
unfit for consumption.” However, many marshland species provide food for migratory waterfowl
(Kral 2002c). In the key and descriptions presented here, the measurements given for achenes do
not include the tubercles. (Greek: rhyncos, a snout, and spora, a seed, from the beaked achenes)
REFERENCES: Gale 1944; Godfrey & Wooten 1979; Nixon & Ward 1982; Thomas 1984, 1992;
Tucker 1987; Kral 1999, 2002c; Bridges & Orzell 2000.
1. Scales of spikelets white; bracts below inflorescence with white base, the white zone conspicuous
or inconspicuous; perianth bristles absent (section Dichromena, previously segregated as
the genus Dichromena).
2. Bracts exceeding spikelets 1–2(–3) in number, very narrow, mostly filiform; white zone on
bract only at the very base, not longer than spikelets, inconspicuous; rhizomes absent; leaf
blades 3–15 mm long, ca. 1(–2) mm broad basally, narrower (arcuate-filiform) distally ____________ R. nivea