No. 27. 

 PAPPOPHORUM APERTUM Mimro, in Herb. 



Plant perennial, loosely tufted with somewhat bulbous base. 



Culms erect, not branched, solid, terete, smooth, 18 to 30 inches tall. 



Leaves; radical few and small; from radical shoots, with slightly hispid 

 sheaths, and narrow, involute blades, -1 to 10 inches long; of culm 3 or 4; sheaths 

 nearly equaling or often exceeding internodes, slightly hispid; blade involute, his- 

 pid above, 2 lines wide with long tapering point, 6 to 10 inches long; ligule a rather 

 conspicuous, loose hairy fringe 1^ to 2 lines long. 



Inflorescence a close, linear, spike-like, panicle, 6 to 10 inches long, with short 

 branches below, none above, often included at base. 



Spikelets oblong, 3-nowered (upper one sterile), 2 lines long, on short hispid 

 pedicels less than ^ line long; first glume lanceolate acute, carinate, hyaline, mi- 

 nutely hispid on keel, 1-nerved, If lines long; second glume same but i line longer; 

 floral glumes vasiform, nearly square unrolled, pubescent especially below, 1 line 

 long, 7-nerved, each nerve terminating in a hispid awn 2 lines long, and alternat- 

 ing with these are 7 or 8 slightly smaller awns; sterile glume similar but half as 

 large and raised on an internode of the rachilla i line long; palet lanceolate, lacer- 

 ate at apex, 2-keeled, 1| lines long. 



Grain narrowly lanceolate, light brown, 1 line long, falling with the entire 

 spikelet, except the persistent empty glumes. 



Plate XXVII; a, spikelet; b, empty glumes; c, floral glume; d, palet; e, ster- 

 ile upper flowe 7 ' 



There is a variety of this species with much looser inflorescence, the lower 

 branches 1 to 2 inches long, flowering mostly to the base and subdivided; spikelets 

 purplish. 



Western Texas to Arizona. 



