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

CYPERACEAE
509
10. Scales of spikelets with short bristle-tip or bristle-tip absent; perianth of 1 thin
perianth scale, or of bristles, or perianth absent.
11. Spikelets (actually small spikelet-like spikes or heads of spirally arranged
single-flowered spikelets) 1–5(–8) mm long, sessile; each scale enclosing
a single, thin, inconspicuous perianth-like bracteole; plants very small, to
only 15(–20) cm tall; scales with 2 or 3 prominent veins (use strong hand
lens) _________________________________________________________ Lipocarpha
11. Spikelets 2.5–20 mm long, sessile or on distinct pedicels; each scale enclosing
a perianth of bristles or perianth absent; plants small to very large;
scales with only 1 prominent vein (the midrib).
12. Spikelets with a single fertile (= achene-producing) floret subtended
by ca. 2–5 empty scales (these lack achenes but can have an aborted
pistil or stamens); leaf margins scaberulous (= only slightly roughened,
almost smooth to the touch) to dangerously spinulose-serrulate (=
saw-toothed); inflorescences with numerous spikelets, these usually
in groups of 2–10 at the ends of short branches; perianth absent;
species rare in East TX __________________________________________ Cladium
12. Spikelets not as above, with 1–many fertile florets, each spikelet subtended
by at most 1 empty scale; leaf margins various; inflorescences
not as above; perianth absent or of bristles; including species common
and widespread in East TX.
13. Inflorescences usually either 1-sided or widely spreading or drooping;
perianth of bristles (except in Isolepis and Schoenoplectus
saximontanus); plants small to very large (to 5 m tall) (segregates
of Scirpus in the broad sense).
14. Inflorescences with 1(–2) spreading to erect modified leaf (involucral
bract) appearing like a continuation of the culm, the
inflorescences thus appearing lateral; culms with 1–3 leaves
near base OR without blade-bearing leaves.
15. Plants rhizomatous perennials 30–300(–500) cm tall; culms
2–20 mm thick near base; achenes smooth; perianth
bristles present; inflorescences with 1–150 or more
spikelets ____________________________________ Schoenoplectus
15. Plants tufted annuals or perennials 2–65 cm tall; culms
0.2–1.5 mm thick near base; achenes minutely papillose
(sometimes obscurely so) or with prominent, transverse,
wavy ridges; perianth bristles absent.
16. Achenes minutely papillose (this can sometimes be
obscured by a whitish wax-like layer); spikelets 2–10
mm long; inflorescences with 1–3 spikelets; plants 2–
25(–40) cm tall ____________________________________ Isolepis
16. Achenes with prominent, transverse, wavy ridges;
spikelets 5–20 mm long; inflorescences with1–10(–20)
spikelets; plants 9–65 cm tall _________________ Schoenoplectus
14. Inflorescences with 2 or more well-developed leaf-like involucral
bracts, the inflorescences appearing terminal; culms with
well-developed leaves.
17. Spikelets small, 3–10 mm long, 2–4 mm wide, very numerous;
scales of spikelets glabrous, not apically notched, awnless
or nearly so; achenes < 1.5 mm long; culms mostly
obscurely triangular ___________________________________ Scirpus