Dec. IS, 1914 



Seeds oj Agropyron 



279 



importance to warrant its use as a determining character. No rachilla 

 of A . repens has been found which had the hirsute character of A . smithii 

 (fig. I, B) or the pilose character of A. tenerum (fig. i, C). 



The rachilla of A. smilhii is characterized by hairs of the same gen- 

 eral shape as the hairs found on the rachilla of A. repens. They are, 

 however, larger and stronger and the number is noticeably greater. This 

 characteristic is fairly uniform. 



The rachilla of A . tenerum is characterized by hairs of a pilose nature. 

 They are long as compared with those of A . repens and A . smithii, and 

 may often be distinguished by this feature alone from these two species, 

 as the pilose nature has never 

 been observed on them. 

 However, an absolutely au- 

 thentic specimen of A . tenerum 

 has been examined which had 



a rachilla much resembling fl f-^^A AA 



that of A . repens. The hairs 



were short, but were not as |!V / J 'i \ \ /(i 



large as the base. Other r'l\ I f \ lit. 



characters on the seed, how- 

 ever, made it possible to place 

 it accurately in the species 

 tenerum. 



LEMMA 



Another distinguishing 

 character and one which is 

 reliable as to uniformity may 

 be found at the base of the 

 lemma on the ventral side of 

 theseed. In A.te nerum (figs . 

 2, C, and 3, C) there is a line 

 of hairs which extends from 

 the base of the rachilla on the 

 dorsal side of the seed around 

 and entirely across the face 

 of the lemma on the ventral 

 side near the base of the seed. 

 In some cases it may be 

 impossible to distinguish the 

 hairs on the middle of the 

 lemma, but the surface of the 

 lemma at this point is rough- 

 ened sufficiently so that it 

 character. 



The seed of A. repens (figs. 2, A, and 3, A) has no such characteristic 

 line of hairs, but the basal portion of the lemma is entirely smooth and 

 shiny. This character in the seed of A. smithii (fig. 3, B) is somewhat 

 variable and is therefore not of much value. Most commonly, however, 

 it is found that the ring of hairs extends part way around on either side, 

 and on the middle of the lemma there is a space which usually is eatirely 

 smooth. 



Fig. 2. — Side views of basal portions of seeds of Agropyron 

 spp.. showing the relative projection of the rachilla: A, 

 Aoropyron repens; B. .1. smilhii; C. A. tenerum. X 9. 



is noticeable. This is a fairly definite 



