144 POACEAE 



white hairs, the apex acuminate, entire or slightly 2-toothed, the awn terminal or aripiii 

 between the minute teeth. Stamens 3. Styles short, distinct. 



1. Brioneuron pilosum (Buckl. ) Nash. Stems densely tufted, 0.4-3 dm. tall, naked 

 above : leaf-sheaths sparingly pilose at the summit ; blades erect, folded, linear, obtuse or 

 abruptly acutish at the apex, thick, with broad white serrulate margins, papillose-hirsute, 

 especially beneath, the basal numerous, 2-8 cm. long, those on the stem usually 3 cm. 

 long or less : panicle racemose or nearly so, 1-3 cm. long : spikelets 3-8, crowded, 1-1.5 

 cm. long, about 5 mm. broad, the empty scales acuminate, 1-nerved, the flowering scales, 

 exclusive of the awn, 5.5-6 mm. long, acuminate, entire or slightly toothed at the apex, 

 the internerves pilose at the base, the nerves pilose on the lower and the midnerve 

 also above the middle, the longer hairs about 2 mm. long, the awn 1-1.5 mm. long. 



In dry gravelly soil, Kansas and Colorado to Texas and Arizona. Summer. 



99. TRIPLASIS Beauv. 



Perennial grasses, with very narrow flat or convolute leaf-blades and terminal con- 

 tracted or open somewhat branched panicles. Spikelets shortly pedicellate, 2-6-flowered, 

 the flowers perfect or the upper staminate, the glabrous rachilla articulated between the 

 flowers, the internodes long. Scales 4-8, membranous, the 2 lower empty, keeled, acute 

 shorter than the rest, the flowering scales distant on the rachilla, dorsally rounded at the 

 base, 3-nerved, the lateral nerves pilose, deeply 2-lobed at the apex, the lobes obtuse, acute 

 or acuminate, each with a glabrous or pubescent awn arising between the lobes, the callus 

 long and subulate ; palet shorter than the scale, compressed, 2-keeled, the keels long-ciliate. 

 Stamens 3. Styles short, distinct. Stigmas plumose. 



Flowering scale % as broad as long or more, with a shorter straight awn 3 mm. long 



or less. 

 Lobes of the flowering scale rounded or truncate at the irregularly and minutely 



toothed apex ; awn less than 2 mm. long. 1. T. purpurea. 



Lobes of the flowering scale acute or acutish at the apex ; awn 2.5-3 mm. long. 2. T. intermedia. 

 Flowering scale !/ 5 as broad as long, its lobes acuminate, pointed, the awn longer 



than the scale, 6 mm. in length or more, recurved, at least when dry. 3. 1. Americana. 



1. Triplasis purpurea (Walt.) Chapm. Stems tufted, 2-8 dm. tall: leaf -sheaths 

 rough ; blades 15 cm. long or less, 1-3 mm. wide, rough : panicle finally exserted, its 

 branches in 1's or 2's, 4 cm. long or less : spikelets on short hispidulous pedicels: scales 

 4 or 5 ; the 2 outer empty, acuminate ; flowering scales about 4 mm. long, 1.75 mm. wide 

 when spread out, divided about ^ way down, the lobes rounded or truncate at the irregularly 

 and minutely toothed apex, the awn equalling or a little exceeding the lobes, pilose on the 

 lower half, less than 2 mm. long, straight, [T. sparsiflora Chapm.] 



In sandy soil, usually along the coast, Ontario to Florida and Texas. Also along the Great Lakes 

 and from Missouri and Nebraska southward. Summer. SAND GRASS. 



2. Triplasis intermedia Nash. Stems densely tufted, 4-8 dm. tall, slender: leaf- 

 sheaths very rough, papillose-hirsute toward the base with long ascending hairs ; blades 

 13 cm. long or less, involute when dry, rough, hirsute above : panicle finally exserted, its 

 branches in l's-3's, pubescent at the base, rough, the larger ones 2-4 cm. long : spikelets on 

 short pubescent pedicels, 8-10 mm. long ; scales 5 or 6 ; the 2 outer empty, acuminate ; 

 flowering scales 4.5 mm. long and 1.5 mm. wide when spread out, divided from \-% their 

 length, the lobes acute to somewhat obtuse, the awn 2.5-3 mm. long, straight, much exceed- 

 ing the scale. 



In dry sandy soil, southern peninsular Florida. Summer. 



3. Triplasis Americana Beauv. Stems tufted, 3-8 dm. tall, slender, puberulent : 

 leaf-sheaths smooth ; blades 15 cm. long or less, less than 2 mm. wide, smooth, the upper 

 surface minutely pubescent : panicle finally exserted, its branches single or in pairs, 3 cm. 

 long or less : spikelets on short hispidulous pedicels ; scales 4 or 5 ; the 2 outer empty, 

 acuminate ; flowering scales about 5 mm. long and 1 mm. broad when spread out, divided to 

 the middle, the lobes subulate, acuminate, pointed, the awn much exceeding the scale, usu- 

 ally reflexed, at least when dry, pilose for about f its length, 6-8 mm. long. 



In dry sandy soil along the coast, North Carolina to Florida and Texas. Summer. 



100. REDFIELDIA Vasey. 



Tall perennial grasses, with long narrow leaf-blades and a terminal ample diffuse pan- 

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

 Scales 3-5, acute, the 2 outer empty, about equal in length, the remaining scales com- 

 pressed-keeled, larger, each furnished with a basal ring of hairs, 3-nerved, the middle 



