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

560 CYPERACEAE/CYPERUS
12. Achenes 0.6–1.5 mm long; spikelets usually 2.5–10 mm long; annuals or perennials,
not viscid.
13. Plants coarse rhizomatous perennials; leaves usually nodulose (= with knotlike
septa visible under a hand lens) owing to numerous cross veins between
the main veins; achenes 1–1.5 mm long, linear to linear-oblong ________ C. pseudovegetus
13. Plants small annuals; leaves not nodulose; achenes 0.6–1.1 mm long, elliptic to
oblong-ovate.
14. Scales of spikelets with 5–11 nerves, with long-acuminate, awn-like tips
(visible to the naked eye); plants with a persistent spice-like odor _______ C. squarrosus
(in part)
14. Scales of spikelets with at most 3 nerves, with pointed but not awn-like
tips; plants without a spice-like odor _____________________________ C. acuminatus
11. Scales of spikelets with the tips straight to slightly incurved.
15. Scales of spikelets minute, < 1 mm long, bead-like, rounded or broadly obtuse
apically; achenes 0.5–0.8 mm long, the surfaces finely granular __________________ C. difformis
15. Scales of spikelets larger, 1 mm or more long, variously shaped but not as above;
achenes various.
16. Plants small tufted annuals; culms (2–)6–15(–35) cm tall; achenes obovoid, from
ca. 3/4 as wide as long to nearly as wide as long _______________________ C. compressus
16. Plants perennials, rhizomatous or with thickened and/or hardened stem bases;
culms often taller; achenes variously shaped, ca. 1/2 as wide as long or narrower.
17. Scales of spikelets with 7–13 nerves (midnerve plus 3–6 nerves visible on
each side of scale), 1.8–4 mm long, not 2-keeled, with a single keel or broadly
rounded on the back; achenes 1.5–2.4 mm long.
18. Scales of spikelets with recurved to straight, awn-like or distinct, minute,
narrowly pointed apex 0.4–0.8 mm long (note: the basal scales are
often merely mucronulate, with apex to 0.2 mm long); plants viscid (=
sticky) when fresh; leaf blades involute (= with margins rolled) ________ C. oxylepis
(in part)
18. Scales of spikelets without awn-like or distinct narrowly pointed apex,
sometimes emarginate (= notched) apically, if mucronulate apex
present, this at most 0.3 mm long; plants viscid when fresh (C. elegans)
OR not so; leaf blades involute (C. elegans) OR not so.
19. Leaf blades involute; achenes obovoid, widest near the tip, usually
black with a thin, cellular, grayish-white overlay that tends to slough
off; plants viscid when fresh ___________________________ C. elegans (in part)
19. Leaf blades flat or V-shaped; achenes narrowly oblong to oblongellipsoid,
widest near the middle, variously colored but without a
grayish-white overlay; plants not viscid.
20. Longest inflorescence bract ascending; inflorescences usually
with 3–10 rays (= main branches); scales of spikelets only
slightly overlapping the adjacent scales on the same side of
the spikelet (giving margin of spikelet a distinctive serrate
outline); anthers 1–1.3 mm long _________________________ C. grayoides
20. Longest inflorescence bract horizontal to reflexed; inflorescences
unbranched or with 1–4 rays; scales of spikelets conspicuously
overlapping; anthers 0.3–1 mm long.
21. Leaf blades 0.5–2 mm wide; achenes narrowly oblong,
0.5–0.8 mm wide; anthers 0.8–1 mm long; scales of spikelets
yellowish to yellowish brown ______________________ C. filiculmis