132 A TEXT-BOOK OF GRASSES 
In genera with many-flowered spikelets the rachilla is of 
course elongated, while in 1-flowered spikelets it is reduced 
so that the floret seems to be terminal. It often extends 
beyond the insertion of the upper floret in many-flowered 
spikelets but is usually hidden by the upper lemmas. In 
1-flowered spikelets the rachilla may extend beyond the 
base of the floret. It then appears as a slender sometimes 
“plumose bristle or stalk pressed against the palea. This 
extension of the rachilla sometimes bears a rudimentary 
second floret. The first internode of the rachilla above 
the glumes is sometimes elongated, forming a stipe to the 
floret. This stipe may be developed into a sharp-pointed 
callus, which at maturity aids in seed-dispersal (Stipa, 
Aristida). Usually the internodes of the rachilla between 
the florets are short, the florets being closely imbricated; 
but, occasionally, they are elongated, the florets being 
rather distant, as in Senites. 
A peculiar jointing of the rachilla is to be observed in Festuca 
subuliflora Scribn. in which there is an articulation midway between 
the distant florets. This is probably due to ‘a downward elongation 
of the callus, surrounding and becoming grown to the rachilla, 
which has likewise become elongated so that the joint is still at the 
base of the callus.” * 
* Piper, Contr. U.S. Nat. Herb. 10:36. 1906. 
