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

614 CYPERACEAE/ISOLEPIS
perianth reaching at least to the base of blades of stalked-bladed perianth parts and often to
near their tips. Moist to wet areas, usually sandy or sandy-peaty soils; Burleson, Colorado, Harris,
Leon (BRIT), Freestone, Henderson, Madison, Robertson, and Van Zandt (Turner et al. 2003)
cos.; also Gulf Prairies and Marshes; se Canada and e U.S. w to MI and TX. Aug–Sep. [F. squarrosa
Michx. var. pumila Torr.] This species has often been considered a variety of F. squarrosa. However,
it is annual, never produces corm-like rhizome buds, and has much smaller anthers (0.5–
0.7 mm long) (Kral 1978).
Fuirena simplex Vahl, (unbranched), UMBRELLA SEDGE, WESTERN UMBRELLA-GRASS, WESTERN
UMBRELLA SEDGE. Plant 10–40(–100) cm tall; leaf sheaths glabrous or only the lowest hirsute;
leaf blades minutely scabrous or glabrous; spikelets 8–15(–20) mm long; bristles of perianth
reaching at least base of blades of stalked-bladed perianth parts. Aquatic or wet places. Jun–Oct.
This is a widespread variable species and is the most common Fuirena species in much of East
TX. Kral (1978) distinguished two varieties as follows: m/287
1. Plants nonrhizomatous, mostly annual, usually < 30 cm tall; anthers 0.5–0.6 mm long _________ var. aristulata
1. Plants rhizomatous, perennial, 20–40(–100) cm tall; anthers 0.9–1.2 mm long __________________ var. simplex
var. aristulata (Torr.) Kral, (bearded or awned). Widespread in TX; AR, KS, LA, MO, NE, NM, OK,
and TX. [F. squarrosa Michx. var. aristulata Torr.]
var. simplex. Rhizomes simple, lacking corm-like shoot buds. Reported to be an indicator of calcareous
seepage (Yatskievych 1999); widespread in TX; AR, KS, NM, OK, and TX.
Fuirena squarrosa Michx., (with recurved tips), HAIRY UMBRELLA SEDGE, HAIRY UMBRELLA-GRASS.
Rhizomatous perennial to 1 m tall, usually less, the rhizomes producing corm-like shoot buds;
leaf sheaths strongly hispid-hirsute; leaf blades with pubescence; spikelets 10–20 mm long;
bristles of perianth often reaching middle of blades of stalked-bladed perianth parts; anthers
ca. 1–1.3 mm long. Wet areas, often on sandy substrates; widespread in East TX; scattered elsewhere
in s 1/2 of TX; e U.S. from NY s to FL w to OK and TX. Jun–Oct. [F. hispida Elliott] According
to Kral (2002a), this species “is most similar to F. pumila in perianth except it is perennial; to
F. breviseta except its distal sheaths are hirsute, not glabrous; and to F. bushii except its perianth
blade is flatter and the anthers shorter.”
ISOLEPIS R. Br. BULRUSH, LATERAL BULRUSH
Small tufted annuals (or perennials?) 2–25(–40) cm tall, glabrous or nearly so; culms wiry, very
thin, 0.2–0.5 mm thick near base; leaves near base of culms; ligules absent; leaf blades rudimentary
to exceeding sheaths; inflorescences of 1–3(–10) sessile terete spikelets, appearing lateral,
with 1(–2), spreading to erect, modified leaf (= involucral bract) sometimes appearing like a
continuation of the culm; flowers 8–25 per spikelet; scales of spikelets spirally arranged, keeled,
awnless or very short-awned; perianth absent; stigmas usually 3; achenes trigonous to thickly
plano-convex, minutely papillose (this can sometimes be obscured by a whitish, wax-like, surface
layer), without a tubercle but with a minute beak.
AA cosmopolitan but predominantly s hemisphere genus of 69 species (Muasya & Simpson
2002; Smith 2002c), mostly of temperate and subtropical climates; when tropical, restricted to
mountains at higher elevations. Three species are reported for TX (Smith 2002c). Previously included
in Scirpus (e.g., Kartesz 1994) and according to some, better treated as a section or subgenus
in Scirpus in the broad sense. We are following Smith (1995, 2002c) and Jones et al. (1997) in
recognizing this segregate of Scirpus at the generic level. This approach is supported by phylogenetic
studies (e.g., Bruhl 1995; Muasya et al. 2000b) which suggest that Scirpus sensu lato is
polyphyletic. Recent molecular research (Muasya et al. 2001; Muasya & Simpson 2002) suggests
that Isolepis is more closely related to Cyperus than to Scirpus. The key to species is modified
from Smith (2002c). (Greek: isos, equal, and lepis, scale)