44 



FIRST BOOK OF GRASSES 



between the teeth or lobes of a bidentate (2-toothed) 

 apex (see floret above, seen from the back). 



In these three spikelets, as in all but a few of the 

 grasses of the oat tribe, the florets fall from the 

 glumes which remain on the pedicel. In velvet 



grass, Notholcus lanatus (Fig. 

 34), the spikelet falls entire. 

 The articulation of the spikelet, 

 taken throughout the grass 

 family, is so nearly uniform for 

 related genera that it is relied 

 on to differentiate large series. 

 (See Lesson II, on inflorescence) . 

 There are exceptions to the 

 mode of articulation character- 

 istic of the group as a whole 

 in the^ case of a few genera in 

 Such exceptions are puzzling 

 to the beginner, leading him astray in using keys. 

 We must learn to observe all the characters of the 

 inflorescence and base our judgment on the sum total 

 of the characters, remembering that " Nature does 

 as she pleases" and rejoicing that in grasses she at 

 least pleases to keep invariably to the 2-ranked 

 arrangement of the spikelets. (See the summary of 

 Lesson II). In Lesson IV, Figs. 18 and 19, we 

 observed spikelets in which the florets were of two 

 kinds. In Notholcus lanatus the lower floret is per- 

 fect and awnless and the upper is staminate and 

 bears a hook-like awn from the back (Fig. 34, B, 



Fig. 34. A, spikelet of 

 Notholeus lanatus; B, 

 pair of florets. 



three of our tribes, 



