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1 Sheaths loose, membranaceous, and fragile on the ventral side, septate-nodulose and usually mottled or striped with green and white on the dorsal side; widest leaves 3-10 mm. | |
3 Basal internodes of the inflorescence usually < 1 cm long, and usually < 2× as long as the spikes; bodies of perigynia with wing < 0.1 mm wide | |
3 Basal internodes of the inflorescence usually >2 cm long, at least 2× as long as the spikes; bodies of perigynia with wing 0.1-0.2 mm wide | |
2 Bodies of pistillate scales 2.2-4.4 mm long, 1.2-2.4 mm wide, mostly > ½ as long as the perigynia, apex acuminate to awned. | |
1 Sheaths tight on the ventral side, neither septate-nodulose nor mottled with green and white on the dorsal side. | |
6 Inflorescence ovoid in outline, the spikes densely aggregated, nearly indistinguishable except by the projecting setaceous bracts which subtend each spike. | |
8 Pistillate scales (excluding the awns) shorter than the perigynium body; culms not greatly exceeding the leaves | |
8 Pistillate scales (excluding the awns) as long as or exceeding the perigynium body; culms much exceeding the leaves | |
6 Inflorescence spicate-racemose, the individual spikes readily distinguishable (often separated by an exposed internode of the axis). | |
9 Pistillate scales green, hyaline, or pale tan; [native in our area (except C. austrina and C. muricata ssp. lamprocarpa), common and widespread in our area]. | |
10 Spikes with 8-20 perigynia; pistillate scales scarious-white (rarely brown) with green-veined center. | |
5 Perigynia corky-thickened in the lower 1/3 to 1/2 at maturity. | |
14 Leaves 0.5-3 mm wide; perigynia not > than 4.0 long, beaks 0.3-1.2 mm long. | |
17 Average perigynium width ≥ 1.3 mm; average spongy portion of the perigynium ≥ 1.1 mm long; perigynium base distinctly nerved, bulging on the ventral surface, making the perigynium biconvex in cross-section; perigynium 2-2.5× as long as wide; perigynium gradually narrowed to a short beak; leaves 1-3 mm wide | |
17 Average perigynium width < 1.3 mm; average spongy portion of the perigynium < 1.1 mm long; perigynium base nerveless, flattened on the ventral surface, making the perigynium planoconvex in cross-section; perigynium ca. 3× as long as wide; perigynium narrowed to a conspicuous beak; leaves 0.75-1.5 mm wide | |
20 Base of perigynium cuneate to rounded; distance from base of perigynium to base of achene 0.1-0.5 mm; [primarily of the Mountains in our area on dry soils] | |
20 Base of perigynium rounded to truncate; distance from base of perigynium to base of achene 0.5-0.9 mm; [widespread in our area, soils typically mesic to wet] | |