MANUAL OF THE GRASSES OF THE UNITED STATES 633 



Culms glabrous; sheaths not viscid-spotted; spikelets 2.2 to 2.9 mm. long, sparsely 

 pubescent . 104. P. recognitum. 



Culms pilose with ascending hairs, the nodes densely pubescent; sheaths conspicu- 

 ously viscid-spotted; spikelets 1.8 to 2.2 mm. long, densely pubescent. 



105. P. MUNDUM. 



Spikelets ovate, that is, broadest below the middle. 



Sheaths or some of them hispid, rarely glabrous; autumnal phase with crowded branch- 

 lets 106. P. SCABRIUSCULUM. 



Sheaths glabrous; autumnal phase sparingly branching 107. P. cryptanthum. 



16. Cormnutata 

 Plants glaucous, glabrous; basal blades conspicuously ciliate; vernal culms usually solitary. 



110. P. MUTABILE, 



Plants not glaucous. 



Blades nearly linear, that is, with parallel margins; first glume about half as long as the 



spikelet 112. P. equilaterale. 



Blades lanceolate. 



Culms crisp-puberulent ; blades usually rigid, symmetrical, rarely more than 10 mm. 



wide; spikelets about 2.5 mm. long 108. P. ashei. 



Culms glabrous or softly puberulent; blades firm or lax; spikelets 2.7 to 3.2 mm. long. 

 Culms erect, or autumnal phase leaning; blades symmetrical, broadly cordate. 



109. P. COMMUTATUM. 



Culms decumbent; blades usually asymmetrical and falcate, narrowed to the scarcely 

 cordate base 111. P. joorii. 



17. Latifolia 

 Sheaths strongly papillose-hispid, at least the lower and those of the branches. 



113. P. CLANDESTINUM. 



Sheaths glabrous or softly villous. 



Nodes glabrous; spikelets 3.4 to 3.7 mm. long 114. P. latifolium. 



Nodes bearded; spikelets 4 to 4.5 mm. long 115. P. boscii. 



Subgenus 3. Eupanicum 

 la. Plants annual. 

 Inflorescence consisting of several more or less secund spikelike racemes; fruit transversely 



rugose 3. Fasciculata. 



Inflorescence a more or less diffuse panicle. 



Spikelets tuberculate 13. Verrucosa. 



Spikelets not tuberculate. 



First glume not more than one-fourth the length of the spikelet, truncate or triangu- 

 lar-tipped 4. DlCHOTOMIFLORA. 



First glume usually as much as half the length of the spikelet, acute or acuminate. 

 Blades linear ; spikelets more than 1.7 mm. long, the second glume and sterile lemma 



pointed beyond the fruit 5. Capillaria. 



Blades ovate-lanceolate; spikelets about 1.3 mm. long, the second glume and sterile 



lemma not pointed beyond the fruit 7. Trichoidea. 



lb. Plants perennial. 

 2a. Spikelets short-pediceled along one side of the rachises, forming spikelike racemes 

 (compare Agrostoidia with 1-sided but not spikelike panicle branches). 

 First glume nearly equaling the sterile lemma. 



Racemes spreading; fruit not more than one-third the length of the spikelet. 



17. Gymnocarpa. 



Racemes appressed; fruit nearly as long as the spikelet 15. Obtusa. 



First glume much shorter than the sterile lemma. 

 Fruit transversely rugose. 



Nodes glabrous — 1. Geminata. 



Nodes bearded 2. Purpurascentia. 



Fruit not rugose 16. Hemitoma. 



2b. Spikelets in open or sometimes contracted or congested panicles (somewhat 1-sided 

 in Agrostoidia). 



Fruit transversely rugose (obscurely so in P. plenum) 8. Maxima. 



Fruit not transversely rugose. 



Spikelets villous 14. Urvilleana. 



Spikelets glabrous. 



Sterile palea enlarged and indurate at maturity, expanding the spikelet. Blades 



