or less flattened (or in transection broadly triangular) rachises; zone of abscission 

 at the base of the spikelet below the callus; spikelets attached in 2 rows abaxially 

 on the rachis, strongly dorsally compressed, each with one perfect floret, solitary 

 or paired or at the bases of the raceme in racemelets of 3 (in extralimital species 

 the basal racemelets have up to 15 spikelets in 2 rows along the abaxial side of 

 a flattened rachilla, the "raceme" then being a small panicle), commonly the 

 uppermost spikelets solitary even when the lower ones are paired and the 

 pedicelled one slightly larger than the sterile one of the same pair; first glume 

 truncate, about 0.1 mm. long, discolored, closely investing the minute swollen 

 portion of the rachilla below the second glume, the swelling and the glume con- 

 stituting the "callus"; second glume as large as the spikelet, abaxial, marginally 

 often revolute; sterile lemma toward the rachis, nearly as large as the second 

 glume; fertile lemma abaxial, thin-cartilaginous but not indurate, stramineous, 

 elliptic-oblong, shorter than the second glume, marginally revolute and clasping 

 the palea of the same texture, surficially with microscopic transverse rugae or 

 puncticulate and apically mucronate or with an antrorsely scabrous awn. 



About 20 species in warm regions. The spikelet measurements given below do 

 not include the "callus". 



1. Plant perennial (but flowering the first year); foliage essentially glabrous; 

 spikelets slightly acuminate or usually merely tapered to a point, 

 usually with a purplish tinge; fertile lemma with an awn 0.9-1.5 

 mm. long 1. E. punctata. 



1. Plant annual; foliage finely pubescent (as seen under a lens), rarely glabrate; 

 spikelets distinctly acuminate to a very fine point, usually greenish; 

 fertile lemma with an awn 0.3-0.8 (-1) mm. long.. ..2. E. contracta. 



1. Eriochloa punctata (L.) Desv. Fig. 140. 



Tufted weak perennial but flowering the first year: culms 3-10 dm. long, 

 2-5 mm. thick, commonly geniculate and stoloniform basally, distally ascending, 

 leafy; ligule a fringe about 1 mm. long; blades (3-) 10-27 cm. long, 3-10 mm. 

 broad, mostly flat or folded, essentially glabrous; panicle dense and elongate 

 with numerous broadly overlapping ascending racemes; pedicels merely scabrous, 

 without any longer hairs; spikelets solitary or paired or in threes, 4-6 mm. long, 

 tapered to the slightly or not acuminate apex, purplish when mature; fertile lemma 

 with an awn 0.9-1.5 mm. long. 



Tight loamy moist soil near ponds or seasonally muddy areas, in marshes 

 and on river banks in s.e. Tex. and coastal parts of the Rio Grande Plains, 

 frequent, spring-fall; warmer parts of Am., n. to La. and Tex. 



Some plants seem intermediate between this species and E. contracta. 



2. Eriochloa contracta Hitchc. Prairie cupgrass. Fig. 140. 



Tufted annual; culms 2-8 dm. long, 1-4 mm. thick, geniculate and infrequently 

 shortly stoloniform basally, mostly ascending, leafy; ligule a fringe 1-2 mm. long; 

 blades 3-20 cm. long, 2-6 mm. broad, mostly flat or folded, or eventually 

 involute, shortly pubescent (like the sheaths); panicle narrow, with overlapping 

 erect racemes; pedicels scabrous and also apically with some long erect cilia 

 a third to half as long as the spikelet; spikelets solitary or paired, (3.1-) 3.7-4 

 (-5) mm. long, somewhat shaggy-pubescent, acuminate to a long fine point, 

 greenish to stramineous at maturity; fertile lemma with an awn 0.3-0.8 (-1) mm. 

 long. 



Tight loamy usually seasonally moist soil near swales in prairies and at edges 

 of fields and roadsides and lawns, in ditches, marshy areas and wet depressions, 

 in Okla. (Nowata Co.) and s.e. Tex. and Rio Grande Plains n. to. n.-cen. Tex., 

 infrequent w. to e. Plains Country, and Ariz. (Santa Cruz, Pima and Yuma cos), 

 spring-fall; Neb. s. to Tex. and La., w. to Colo, and Ariz.; adv. in Mo. and Va, 



285 



