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

590 CYPERACEAE/ELEOCHARIS
35. Tubercle not constricted at its base, � continuous with achene, tapering
into achene so that the junction is not structurally distinct
(however, there can be a distinct color change); culms sometimes
elongating and their spikelets rooting to form new plants __________ E. rostellata
35. Tubercle constricted at its base, not continuous with achene, the junction
with achene clearly distinct structurally; culms not rooting at
tips (spikelets) to form new plants.
36. Achenes coarsely honey-combed reticulate (use hand lens or
dissecting scope).
37. Achenes 0.6–0.9 mm long; spikelets 3–6 mm long; leaf
sheaths purplish red basally; rhizomes purplish red ____________ E. tenuis
37. Achenes 1.2–1.7(–2.4) mm long; spikelets (4–)6–14 mm long;
leaf sheaths straw-colored to greenish basally; rhizomes not
purplish red ___________________________________________ E. tortilis
36. Achenes smooth to finely reticulate.
38. Scales of spikelets with long-pointed scarious tips, some or
all tips usually bifid or notched.
39. Rhizomes not easily observed, obscured by the persistent
dead culm bases; all (including lowermost) scales of
spikelets bifid _____________________________________ E. occulta
39. Rhizomes evident; lowermost scale of spikelets entire __ E. compressa
38. Scales of spikelets with rounded or broadly short-pointed tips
that are not bifid or notched (but sometimes split and thus
apparently bifid).
40. Plants annual, without rhizomes; achenes 0.5–0.6 mm
long; leaf sheaths usually pale brown to brownish or green
basally __________________________________________ E. brittonii
40. Plants perennial, with rhizomes; achenes 0.6–1.2 mm
long; leaf sheaths brownish to yellowish or often purplish
red basally.
41. Leaf sheaths usually yellowish to brownish basally;
spikelets 3–7(–9) mm long, usually proliferating vegetatively
(plantlets sprouting from the spikelets); tubercles
0.2–0.5 mm tall ___________________________ E. vivipara
41. Leaf sheaths usually purplish red basally (sometimes
brownish in E. albida); spikelets 4–14 mm long, not
proliferating vegetatively; tubercles 0.1–0.3 mm tall.
42. Apex of distal leaf sheath light-colored marginally,
angled to a point on one side but without
an abrupt tooth; achenes smooth under
magnification ________________________________ E. albida
42. Apex of distal leaf sheath with a red or brown
margin, � perpendicular to culm, usually with an
abrupt awl-shaped tooth on one side; achenes
often with minute patterning under magnification.
43. Scales of spikelets broadly rounded apically
(sometimes split and thus apparently notched);
tubercles ca. as tall as wide; culms spongy
internally; species widespread in East TX
_________________________________ E. montevidensis