14 C. chordorrhiza L. Spikelets 3 - 5, aggregated into a head, ovate, sessile: perig. ovate, acuminate, subrostrate, convex above, equaling the broad, ovate and acute glume; st. branching towards the base and sending out roots at the joints; spikes rarely bearing only stamens. - Marshes, N. Y., common (Sartwell), Mich. (Cooley.)
15 C. Leavenworthii Dew. Spikelets 4 to 6, small, ovate, sessile, bracteate, aggregated into an oblong head, the lower sometimes separated a little; perig. ovate, broad, short, convex above, abruptly short-beaked, slightly bifid, glabrous, scabrous on the edge, scarcely twice longer than the short, ovate, acute glume; culm rarely If high, slender, leafy towards the base; lvs. narrow, flat; whole plant pale green. - Ky. (Short) to Ala. (Wood), Fla. (Chapman) and La. (Leavenworth.)
16 C. cephaloidea Dew. Spikelets 4 - 6, ovate, aggregated closely, sessile and bracteate; perig. ovale, obtusish; bifid, scabrous on the margin, plano-convex, very diverging in maturity, about twice as long as the short, ovate, obtusish glume. - Dry fields, not abundant, but common over New England and New York. In hedges it is often four feet long, and subrostrate, leafy towards the base. (C. sparganoides, β. Carey.)
17 C. muricata L. Spikelets about 5, ovate, sessile, approximate, bracteate, lower one3 sometimes remotish; perig. ovate-lanceolate, plano-convex, 2-toothed, horizontal, scabrous on the margin, sometimes longer than the ovate-lanceolate glume. - Fields near Boston (Green, Curtis), and common in Arc. Am.
18 C. sparganioides Muhl. Spikelets 7 - 10, ovate, rather distant, bracteate, sessile; perig. ovate, acute, compressed, diverging, acuminate, 2-toothed, scabrous on the margin, nearly twice the length of the ovate, acute, or mucronate glume; st. about 2f high, with long, striate leaves.
β. ramea Dew, has one branch or more at the base, with several spikelets in the place of the lower spikelet, and is the C. divulsa of Pursh. - About cultivated and moist fields, common.
19 C. rosea Beak. Spikelets 3 - 5, subremote, sessile, alternate, stellate, even before maturity, lowest long-bracteate; perig. oblong-lanceolate, 5 - 12, convex above, scabrous on the margin, 2-toothed, very diverging, or even reflexed, twice, as long as the ovate-obtuse glume; st. 8 - 16' high.
β. radiata Dew. Spikelets distant, about 3-flowered, with setaceous bracts; perig. oblong, acute; st. 4 - 8' high, flaccid or lax, setaceous, with very narrow leaves. - Common in pastures and moist woods; the variety is about woods, or open places in woods.
20 C. retroflexa Muhl. Spikelets about 4, ovate, alternate, subapproximate, sessile, bracteate and stellate in maturity: perig. ovate, acutish, 2-toothed, sub-scabrous or smooth on the margin, reflexed and spreading, about equal to the ovate and acute glume; st. about a foot high. - Readily distinguished from the preceding. Woods and pastures, not abundant. (C. rosea, β. Tourn.)
21 C. disperma Dew. Spikelets 3 or 4, erect, subapproximate, lowest bracteate; perig. 1 or 2, rarely 3, ovate, obtuse, nerved, plano-convex, short-beaked, glabrous, twice longer than the ovate, acute, submucronate glume; st. slender, 5 to 12' high, flexile, in tufts of several, with narrow and linear leaves. - Wet woods, N. Eng. to Wis. (C. tenella, Carey, Boott., not of Ehrh.). - The species is common in N. Eur., but had never been recognized in this country, when described, 1824.
22 C. vulpinoidea Mx. Spikelets ovate-oblong, obtuse; spike decompound, bracteate, conglomerate; perig. ovate, acuminate, densely imbricate, bifid, tripli-nerved, diverging, a little shorter than the ovate-cuspidate glume; st. obtusely triangular, round and leafy towards the base. - Common in fields. (C. multiflora Muhl.)
β. microsperma Dew. Spikelets closely aggregated, whole spike less compact; perig. more convex, shorter, less acuminated into a beak, very abundant. - Grows with the other, in dry and moist situations. (C. microsperma Wahl.)
23 C. setacea Dew. Spikelels ovate, alternate, obtuse, conglomerate, bracteate; perig. ovate-lanceolate, acuminate, compressed, bifid, some diverging, about equal to the ovate-lanceolate, awned glume; st. 2f high, acutely triangular, scabrous above and striate. - Wet places, not abundant
24 C. teretiuscula Good. Spikelets ovate, acute, sessile, decompound, brownish, lower one bracteate; perig. ovate, acute, convex and gibbous, scabrous on the edge, spreading, longer than the ovate, acute glume; fr. brown; st. 18 to 36' high, leafy towards the root. - Wet places, common, in tufts.
25 C. stipata Muhl. Spike often decompound; spikelets oblong, aggregated, numerous, bracteate; perig. ovate-lanceolate, round at the base, plano-convex, nerved, bifid, subscabrous on the margin, diverging, twice longer than the ovate-lanceolate glume; st. thick, acutely triquetrous, concave on the sides. - Wet places and marshes, abundant.
26 C. Crus-Corvi Shuttl. (Boott. Illus. No. 04.) Spike decompound, subpani-culate, commonly largo, and branching below; spikelets ovate, numerous, aggregated, sessile; perig. short-ovate, very long-rostrate, veined, convex-concave, often horizontal, thrice longer than the ovate, acute glume; culm leafy; lvs. rough-edged; plant light green. - River swamps, Wis. to Ohio and Fla. (C. Halei Dew. C. sicaeformis Boott.)
27 C. vulpina L. Spike long, large, decompound, forming densely aggregated heads, often with single but close and oval spikelets, and often less compacted; perig. ovate, broad, tapering into a 2-toothed beak, often diverging in ripening, a little longer and narrower than the ovate, acute glume; culm large, strong and rough. - Ohio (Sullivant) to Nebraska (Hayden).
28 C. alopecoidea Tuckerman. (B. t. p. 67.) Spike compound, rather loose, spikelets 8 to 10, aggregated into an oblong head, bracteate, sessile; perig. ovate, plano-convex, scarcely nerved, acuminate, serrulate on the edge, bifid, subros-trate, a little longer than the ovate and acuminate glume; st. triquetrous, scabrous on the edges. - Moist woods, Penn. and N. Y. (Sartwell).