124 A TEXT-BOOK OF GRASSES 



154. The lemmas are the bracts of the spikelet above 

 the glumes. They ordinarily subtend flowers but some- 

 times are empty. The lemmas vary from 1 to many (as 

 many as 50 in Eragrostis) and except in Streptochaita are 

 in 2 ranks upon the rachilla. As is usually the case with 

 bracts, the lemma represents the leaf-base, the blade 

 not being developed. 



Streptochaeta is an anomalous Brazilian genus in which the 

 lemmas are spirally arranged. 



In the more primitive forms of grasses, the lemmas 

 are usually bract-like in appearance and in a general way 

 resemble the glumes, being greenish, keeled and nerved. 

 In more modified forms such as Andropogonese, the lemmas 

 are often thin and delicate, being entirely inclosed by the 

 enlarged and indurated glumes. On the other hand, the 

 lemma may be hardened, as in most Paniceae, where the 

 lemma of the fertile floret is hard, usually smooth and 

 nerveless. Modiflcation is carried to a greater extent in 

 the lemma than in any other organ of the grass plant. 

 For this reason the form of the lemma is of great impor- 

 tance in classification, its shape, texture and nerving being 

 uniform within definite limits in any given genus. In 

 those genera, such as Andropogon and its relatives, 

 Hilaria, Anthephora and the like, in which the glumes are 

 enlarged, indurated or otherwise specialized, the lemmas 

 are found to be thin or small or otherwise to show but 

 little modification. 



In grasses having unspecialized or but slightly modi- 

 fied glumes, as in most of the genera, the lemmas are 

 usually strongly characteristic. The lemma, whether 

 bearing a fertile flower or empty, as in the lower lemma in 

 most species of Paniceae, or modified into a cluster of 



