438 BRITISH FLOWERING PLANTS chap. 



Warnstorf found those near Ruppin did not do so till 

 between 10 and 11. 



A. agrestis. — The flower arrangements are as in the 

 preceding species. 



Lagurus 



L. ovatus. — In this species the long silky hairs do 

 not fall with the fruit, but Hildebrand suggests that 

 they catch the wind, with the result that the plant is 

 violently waved about, and thus the fruits are thrown 

 to some distance. 



Apera 



A. Spica-venti. — The flowers, which are borne in a 

 large pyramidal panicle, open about 6 a.m. 



GtASTRIDIUM 



The genus derives its name from the inflated base of 

 the barren glumes. 



G. lendigerum occurs in maritime sandy marshes in 

 South Wales and the southern portion of England. 



Psamma (Marram G-rass) 



P. arenaria. — This is the common grass of our sand 

 dunes. It is very valuable in binding the sand together 

 by its long creeping stems, and thus preparing for other 

 plants. 



AiRA 



A. csespitosa opens, according to Kerner, between 

 6 and 7 A.M. 



A. flexuosa. — The flowers are homogamous, with 

 bluish-black anthers. 



A. canescens. — In this species the awn is pointed, and 

 has a minute tuft of hairs about the middle. 



