γ. secunda. Horse-mane Oats. Panicle 1-sided; awns short.

29. TRISE'TUM, L. (Lat. tria, three, setum, a bristle; a characteristic term.) Spikelet 2 - 5-flowered; glumes 2, shorter than the {lowers; lower palea with 2 bristles at the apex and a soft, flexuous awn from above the middle of the back; scales ovate; fruit coated, furrowed. - Very closely related to Avena.

1 T. palustre Torr. Culm erect, contracted at the nodes, slender, smooth, about 2f high; lvs. lance-linear, about 3 long, roughish, on smooth, striate sheaths; panicle oblong, contracted, nodding, yellowish-green; spikelets about 3" long, 2 - 3-flowered, middle flower abortive, upper one pedicellate, its lower palea ending in 2 setous teeth, and awned below the tip, lower one mostly awnless. - Wet meadows, Mass., N. Y. to Fla. May - July. (Avena, Mx. Aira pallens, Muhl.)

2 T. molle Kunth. Minutely and softly puberulent throughout; culm If high; lvs. narrow, 2 to 4' long; pan. contracted and spike-like, 2' long; awn at length de flexed, longer than the beardless flowers. - Mts. and rocks, N. H. to Mich, and Can. (Avena, Mx.) Scarcely differs from the foregoing, which is also sometimes downy.

3 T. purpurascens Torr. Culm leafy, 2f high; lvs. narrow-linear, keeled, 4 - 6' long, and with the sheaths smooth; panicle very simple, almost a raceme, few-flowered, 4 - 6' long; glumes 3 to 5-flowered, very unequal, entire; spikelets 6 to 8" long, lanceolate, terete, often purple, smooth; lower palea 7-veined, cleft into 2 bristly points at the apex; awn geniculate. - Mountain bogs, N. Eng. to Wis. and Can. June.

30. BROM'US, L. Brome Grass. (Gr. food; the name was anciently applied to Oats.) Spikelets 5 to ∞-flowered; glumes unequal, membranous, veined; lower pale 5 to 9-veined, convex or cari-nate on the back, awned from below the mostly bifid tip; upper pale ciliate on the 2 keels, often bifid; caryopsis linear, adherent to the upper pale. - Coarse grasses with flat lvs. and large, paniculate, nodding spikelets.

1 B. secalinus L. Smooth Cheat or Chess. Culm smooth, 2 to 4f high; lvs. lance-linear, 6 to 12' long, rough and some hairy above, on smoothish sheaths; pan. spreading in fruit, branches subsimple, with few nodding spikelets; spkl ovate, turgid, smooth, 7 to 10-flowered; fls. soon diverging and rather distinct, oblong, longer than the short, flexuous awn. - A handsome but worthless grass, in fields of wheat and other grains, and in waste grounds. Jn., Jl. § Eur.

2 B. mollis L. Downy Chess. Culm slender, some downy, 12 to 18'to 2f, lvs. flat, hairy both sides, lance-linear, on sheaths clothed with deflexed hairs; pan. erect, contracted in fruit; spikelets ovate, compressed, about 6-flowered, downy all over; fls. oblong, closely imbricated, not longer than their straight awn. - Wheat fields and waste grounds, rare. Lower pale 1/4 longer than the upper. Jn. § Eur. Varies in pubescence. (B. racemosus L. β. arvensis, Ed. 2.)

3 B. Kalmii Gray. Culm slender, 18' to 3f; lvs. and sheaths more or less hairy, sometimes excessively so; pan. simple, small, 3 to 4' long; spkl. drooping, closely 7 to 12-flowered, densely silky all over; lower glume 3-veined, upper 5; lower pale much longer than the upper, 5 to 7-veined, the awn 1/3 of its length. - Dry hilly woods, U. S. and Can. Jn., Jl (B. purgans Torr. nee L. fide Prof. Gray.)

4 B. unioloides Thunb. & Kth. Rescue Grass. Culm 18' to 3f, glabrous; lvs. smoothish, on sheaths more or less hairy or almost smooth; pan. large, 6 to 10' long, branches subsimple, whorled; spikelets smooth, lance-ovate, much compressed, 2-edged, 1' long, 1/3 as wide, 8 to 12-flowered; lower glume 3, upper 6-veined; lower pale 7 to 9-veined, much larger than the strongly 2-keeled upper, with scarcely any awn. - Cultivated at the South (in 1857) from seeds distributed by the government, but proved no better than our Chess, † Peru.

5 B. ciliatus L. Culm erect, smooth, 2 to 4f high; lvs. flat, some pubescent, C to 12' long, on sheaths more or less pilous with deflexed hairs; pan. large, erect, 5 to 8' long, finally nodding, branches in 2s and 4s, compound; spikelets at first lance-fusiform, 7 to 11 -flowered, the fls. soon separating; glume lower 1, upper 3-veined; peles compressed-carinate above, silky-haired near the margins, twice longer than the straight awn. - Damp woods along rivers, U. S. and Can. Jn., Jl. (B. Canadensis Mx. B. pubescens Muhl. B. purgans, Ed. 2.)

β. purgans. Pan. more open; spkl. silky-hairy all over. - Mid. and S. States.

6 B. tectoram L. Culm slender, 1 to 3f, pubescent above; lvs. pubescent; sheaths ciliate with few long hairs; pan. compound, at length 1-sided and nodding; pedicels capillary; spikelets linear-oblong, minutely downy, about 5-flowered; glumes lower 1-, upper 3-veined; lower pale 3-veined, carinate. scarious-edged, lance-subulate, scarcely as long as its awn. - N. York (Sartwell), Penn. (Jackson). (B. sterilis Torr.) §

31. TRICUS'PIS, Beauv. (Lat. tres, three, cuspis, a point; referring to the structure of the lower pale.) Spikelets terete or tumid, 3 to 9-flowered, upper flower abortive; glumes 2, unequal, awnless; pales 2, the lower larger, hairy-fringed along the keel and the 2 lateral veins, and ending in 3 short cusps or mucrones (the projecting veins and mid-vein) and 2 intermediate teeth, upper pale 2-toothed; stamens 1 to 3; stigmas plumous; caryopsis smooth, free, 2-horned. - Erect, simple. Fan. mostly with racemous branches.