68 POACEAE 



upper one staminate. Empty glumes keeled, usually shorter than the lemma. 

 Lemma 3-nerved, pilose on the nerves and the margins, entire or 2-toothed at 

 the apex. Palet shorter, 2-keeled. Styles short; stigmas plumose. 



Second empty glume 1-nerved. 1. T. rnulicus. 



Second emptj glume 3-5-nerved. 2. T. elonpatus. 



1. T. muticus (Torr.) Nash. Stem 2-5 dm. tall, glabrous; leaf-blades 

 2-12 cm. long, 2-3 mm. u'ide, usually involute when dry, scabrous; panicle nar- 

 row, 6-15 cm. long; spikelets 6-9-flowered, 10-12 mm. long; lemma 4-5 mm. 

 long, obscurelv and irregularlv lobed at the obtuse or rounded apex, not mucron- 

 ate. Hills: Tex.— Colo.— Ariz.; Alex. Son. Je-0. 



2. T. elongatus (Buckley) Nash. Stem 3-10 dm. tall, scabrous; leaf -blades 

 erect or ascending, 4-25 cm. long, 2-3 mm. wide, long-acuminate, scabrous; 

 panicle narrow, 12-25 cm. long; spikelets 8-10-flowered, 10-14 mm. long; lemma 

 5-6 mm. long, obtuse or minutely 2-toothed, mucronate. Plains: Mo. — Colo. 

 — Ariz. — Tex. Austral — Son. Je-N. 



54. DIPLACHNE Beauv. 



Tall tufted perennials. Panicles composed of several long spike-like or 

 raceme-like branches. Spikelets hnear, sessile or nearlj' so, the flowers perfect 

 or the uppermost staminate. Emptj' glumes persistent, keeled, acute, unequal. 

 Lemma larger, 2-toothecl and mucronate or short-awTied between the teeth. 

 Palet hyahne, 2-nerved and 2-keeled. Styles distinct; stigmas plumose. 



1. D. acuminata Nash. Tufted perennial; stem 3-6 dm. high; leaf-blades 

 erect, 1-3 dm. long, 3-4.5 mm. wide, scabrous; racemes numerous, erect or ascend- 

 ing, the longer 7-15 cm. long; spikelets 10-12 mm. long; empty glumes 8-11 mm. 

 long; lemma 6-7 mm. long, acuminate; awn 0.75-1.33 mm. long. Wet or moist 

 ground: Ark. — Neb.— Colo. Plain. Je-Au. 



55. REDFIELDIA Vasey. Blow-out Grass, S.a.nd-grass. 



Tall perennials, with long creeping scaly rootstocks. Panicles diffuse, with 

 long capillary branches. Spikelets numerous, 1-3-flowered, the flowers perfect. 

 Empty glumes about equal, 1-nerved. Lemma large, compre.ssed-keeled, with 

 a basal ring of hairs, 3-nerved, awn-pointed or acute. Palet shorter, 2-nerved. 

 Styles long; stigmas short, plumose. 



1. R. flexuosa (Thurber) Vasey. Stem 4-12 dm. high; leaf-blades 3-6 dm. 

 long, 2-4 mm. wide, usuallv involute; panicle 2-5 dm. long; spikelets about 6 

 mm. long, 1-3-flowered; lemma scabrous, twice as long as the acute glabrous 

 empty glumes. Sand hills: S.D. — Okla. — ^Colo. — Wyo. Plain. Au-S. 



56. KOELERIA Pers. June Grass. 



Tuftpcl annuals or perennials. Panicles narrow, contracted, spike-like. 

 Spikelets numerous, crowded, 2-5-flowered, the flowers perfect or the uppermost 

 one or two staminate, shining. Empty glumes narrow, unequal. Lemma similar 

 to the second, the upper ones gradually smaller. Palet hyaline, 2-keeled, 2-toothed. 

 Styles very short; stigmas plumose. 



1. K. gracilis Pers. Stem 3-6 dm. high, slender, glabrous up to the inflores- 

 cence; leaf-blades narrow, 1-2 mm. wide, usually involute, glabrous or the lower 

 short-pilose, 4-12 cm. k)ng; ])anicle si)ike-like, 4-15 cm. long; sjiikelets shining, 

 pale; empty glumes lanceolate, acute, scabrous; lemma similar, more hyaline 

 and slightlv shorter. A', cristata, in part. A', nitida Nutt. Prairies and plains: 

 111.— Tex.— Calif.— B.C.; Eur. Plain— Suhmont. Jl-S. 



57. ERAGROSTIS Beauv. Stixk-guass, Skunk-grass. 

 Tufted annuals or perennials, sometimes prostrate or creeping; some species 

 dioecious. Spikelets numerous, singly or in fascicles, 2-many-flowered, the 

 flowers perfect or unisexual. Empty glumes unequal. Lennna large, 3-nerved, 

 usually broad. Palet shorter, prominently 2-nerved and 2-keeled, often incurved 

 and persistent on the rachis. Stamens 2 or 3. Styles short; stigmas plumose. 



