VIVIPAROUS PLANTS. 169 
The grasses most commonly affected in this manner 
are Dactylis glomerata!, Poa bulbosa!, Poa annua !, 
P. trivialis !, pratensis !, alpina !, angustifolia, and laa, 

Fie. $1.—Portion of panicle of Aira vivipara and separate floret. 
Cynosurus cristatus, Festuca nemoralis, F. ovina!, Gly- 
ceria flutans !, Gl. aquatica, Aira alpina !, ceespitosa!, 
Phlewm phalaroides, Lolium perenne!, Alopecwrus pra- 
tensis !, Agrostis alba, Holeus mollis ! 
From an examination of the structure of viviparous 
erasses Von Mohl was led to the conclusion that the 
lower palea is to be considered as a bract, and not a 
perianthial leaf, because the base of the palea sur- 
rounds the stem or axis of the spikelet entirely, and 
both its margins cohere towards its lower extremity." 
A similar condition occurs not infrequently in 
Polygonum viviparum, and in Juncacew, Cyperacee, &c. 
1 Cited in ‘ Annals Nat. Hist.,’ 1845, vol. xv, p. 177. 
