Aristida 



Agrostideae 



139 



Map 243 

 Aristida tuberculosa Nutt . 



50 



Map 244 



Aristida dichotoma Michx 



Glumes mostly 4-5 mm long; lemmas (exclusive of awns) generally 4-5 mm 



long, their central awns usually 5-15 mm long 3. A. longespica. 



Glumes mostly 6-11 mm long; lemmas (exclusive of awns) generally 6-8 mm 

 long, their central awns usually 15-25 mm long. 

 Plant annual, 20-40 cm high; first glume shorter than or equaling the second. 



4. A. intermedia. 



Plant perennial, 40-70 cm high; first glume generally longer than the second. 



5. A. purpurascens. 



Lemmas (exclusive of awns) more than 12 mm long. 



Central awn of lemma about 20 mm long, lateral awns much shorter, usually 



1.5 mm long 6. A. ramosissima. 



Central awn of lemma about 25-70 mm long, lateral awns usually about 5-10 mm 

 shorter than the central one 1. A. oligantha. 



1. Aristida tuberculosa Nutt. Map 243. Local in the northwestern part 

 of the state where it grows in almost pure sand on old beaches and low 

 dunes. 



Mass. to Ga. and Miss, near the coast ; around the southern end of Lake 

 Michigan, and locally in Wis., 111., Iowa, and Minn. 



2. Aristida dichotoma Michx. Map 244. Infrequent to frequent in the 

 southern half of the state. It is usually a common plant where it is found. 

 It prefers hard, white clay soil in abandoned and fallow fields, on washed 

 slopes, and along clayey roadsides. 



All the species of this genus, when found in habitats similar to those 

 just mentioned, are known in Indiana as poverty grasses. 



This species is often confused with A?*istida longespica from which it 

 may be separated by its dichotomously branched culms, its shorter terminal 

 panicles, its tighter second glume, the coiled central awn, and its straight 

 lateral awns being 1 mm long. In the other species the glumes are usually 

 much looser and the lateral awns of the lemma are much longer, diverging, 

 or widely spreading. 



This species was reported from Marshall County by Clark but there is 

 no verifying specimen. 



Maine to Mich. (Hemes) and e. Kans., southw. to s. Fla. and Tex. 



