Panicum Paniceae 151 



Annual or perennial grasses of various habit, foliage, and inflorescence ; 

 spikelets disarticulating below the glumes, arranged in open or compact 

 panicles, rarely racemose, 1- or 2-flowered, the lower flower usually repre- 

 sented by a sterile lemma and palea, the palea usually not developed or 

 rarely lacking, when 2-flowered the lower staminate only; glumes 2, 

 asually very unequal, the first smaller and often minute, the second 

 ;ypically equaling the sterile lemma, the latter of the same texture and 

 simulating a third glume ; stamens 3 ; fertile lemma chartaceous-indurate, 

 Lhe nerves obsolete, the margins inrolled and enclosing a palea of the 

 same texture. 



KEY TO SECTIONS OF INDIANA PANICUM. 



Basal leaves similar to those of the culm; plants not forming winter rosettes. 

 First glume truncate or triangular-tipped, usually about a fourth (rarely longer) 

 as long as the acute or acuminate glabrous spikelet; annual 



1. DlCHOTOMIFLORA, p. 156. 



First glume not truncate, more than a fourth as long as the spikelet, usually a third 

 to nearly half as long; annual or perennial. 

 Spikelets 2-5 mm long, smooth, or the keels more or less scabrous, but the spikelet 

 not warty. 



Annual 2. Capillaria, p. 156. 



Perennial. 



Spikelets on long pedicels in large, open panicles; plants with creeping root- 

 stocks 3. Virgata, p. 158. 



Spikelets on short pedicels, arranged close together in one-sided branches in 

 large panicles; plants without creeping rootstocks. .4. Agrostoidea, p. 158. 



Spikelets 1.8-2 mm long, warty 5. Verrucosa, p. 159. 



Basal leaves not similar to those of the culm; plants forming winter rosettes. 

 Culm leaves elongated, not over 5 mm (rarely 6 mm) wide, more than 20 times as 

 long as wide; spikelets 2.2-4 mm long, beaked in P. depauperatum and its 



variety; autumnal phase branching at the base 6. Depauperata, p. 160. 



Culm leaves not elongated (if elongated, glabrous on both surfaces with spikelets 2.2-3 



mm long, or the blades softly pubescent on both surfaces and the spikelets 1.8-2 



mm long) ; autumnal phase branching above the base or remaining simple. 



Plants with elongate foliage aggregated at the base, light green, softly pubescent, 



the basal leaves not in distinct rosettes in autumn; ligules nearly obsolete; 



spikelets 1.8-2 mm long; autumnal phase branching near the base, forming 



close, fiat tufts, with reduced panicles 7. Laxiflora, p. 161. 



Plants not as above. 



Uppermost leaves elongate, generally longest, stiff, widely spreading, 3-8 (10) 

 mm wide and up to 22 cm long, glabrous on both surfaces ; sheaths glabrous 

 or only the margins pubescent; spikelets 2.3-3 mm long 



8. BlCKNELLIANA, p. 162. 



Uppermost leaves and spikelets not as above. 



Culms glabrous or only the nodes pubescent; spikelets not over 3 mm long. 

 Ligules less than 1.2 mm long, usually nearly obsolete. 



Culms bearded at the nodes, at least the lower ones (rarely only the upper 



ones puberulent in P. mattamuskeetense) 9. Dichotoma, p, 162. 



Culms not bearded at the nodes. 



Spikelets more than 1.8 mm long 9. Dichotoma, p. 162. 



Spikelets less than 1.8 mm long 13. Sphaerocarpa, p. 170. 



Ligules 2-5 mm long 10. Spreta, p. 164. 



Culms and sheaths more or less strongly pubescent; if glabrous except the 

 nodes, the spikelets more than 3 mm long. 

 Ligules 2-5 mm long 11. Lanuginosa, p. 164. 



