Genus 6. 



GRASS FAMILY. 



9. Andropogon paucipilus Nash. Few-haired 

 Beard-grass. Fig. 272. 



Andropogon paucipilus Nash, in Britton, Man. 70. 1901. 



A glabrous perennial. Culms up to $1° tall, 

 sparingly branched above; blades erect, firm, usually 

 somewhat glaucous, long-acuminate, the lower 8'-i2' 

 long and 2i"-3i" wide; racemes in pairs, a's' 

 long, the rachis internodes glabrous, or the margins 

 with a few long weak crimped hairs; sessile spike- 

 lets lanceolate, about 5" long, acuminate, the first 

 scale sulcate on the back, the intercarinal space 

 2-nerved, the fourth scale with an imperfect awn 

 less than i its length ; pedicellate spikelets stami- 

 nate, a little smaller than the sessile ones, the first 

 scale g-nerved, not sulcate, the pedicels sparsely 

 pilose with long weak crimped hairs. 



In sand, Nebraska and Montana. Summer and fall. 



7. AMPHILOPHIS Nash, in Britton, Man. 

 71. 1901. 



Perennial grasses with usually flat leaf-blades and showy, often silvery white, 

 panicles, the axis short or elongated. Racemes usually numerous, the internodes of 

 the rachis and the pedicels with manifestly thickened margins, the median portion 

 thin and translucent, the margins ciliate with long hairs. Spikelets dorsally compressed. 

 Sessile spikelets of 4 scales, perfect, or rarely the lower pair or pairs staminate or empty; 

 first scale 2-keeled, the margins narrowly inrolled; second scale i-nerved; fourth scale stipe- 

 like, the blade wanting, merging into a usually geniculate perfect, rarely imperfect, awn, or 

 the awn rarely wanting. Pedicellate spikelets awnless, staminate and similar to the sessile 

 ones, or empty and smaller than them. Stamens 3. Styles distinct. Stigmas plumose. 

 [Greek, in reference to the hairs surrounding the spikelets.] 



A genus of about 15 species. Besides the following several others occur in the United States. 

 Type species : Andropogon Torreyanus Steud. 



i. Amphilophis saccharoides (Sw.) Nash. 

 Torrey's Beard-grass. Fig. 273. 



Andropogon saccharoides Sw. Prodr. 26. 1788. 

 Andropogon glaucns Torr. Ann. Lye. N. Y. I : 153. 1824. 



Not Muhl. 1817. 

 Andropogon Torreyanus Steud. Nomencl. Ed. 2, 93. 1841. 

 Andropogon saccharoides var. Torreyanus Hack, in DC. 



Monog. Phan. 6: 495. 1889. 



Culms erect, il°-3i° tall, simple or branched, gla- 

 brous, the nodes naked or barbed; sheaths glabrous, 

 rarely pubescent, more or less glaucous ; blades 3'-io' 

 long, 2"-4" wide, long-acuminate, smooth and gla- 

 brous towards the base, scabrous on margins and at 

 the apex, glaucous; racemes l'-ii' long, in a termi- 

 nal long-exserted panicle 2-4' long; joints of the 

 rachis with a thin translucent median line; outer- 

 most scale of sessile spikelet ii"-2" long, about 

 equalling the terminal hairs of the rachis-joints, 

 lanceolate, acute, pubescent at base with long silky 

 hairs; awn 4"-8" long, spiral, bent, scabrous; pedicel- 

 late spikelet reduced to a single narrow scale. 



In dry soil, Missouri to Kansas and Colorado, north- 

 ern South America, and in Jamaica. Feather Sedge- 

 grass. Aug.-Sept. 



8. SORGHASTRUM Nash, in Britton, Man. 71. 1901. 



Generally tall perennial grasses, with long narrow flat leaves and terminal decompound 

 panjcles. Sessile spikelets consisting of 4 scales, the two outer indurated and shining, the 

 inner hyaline, the fourth with a perfect, rarely imperfect, awn, and subtending a palet and 

 perfect flower, or the palet sometimes wanting. Pedicellate spikelets wanting. Stamens 3. 

 Styles distinct ; stigmas plumose. Grain free. [Greek, resembling Sorghum.] 



About 12 species, in temperate and tropical countries. Type species: Sorgastrum avenaceum 

 (Michx.) Nash. 



