48 CLASSIFICATION ACCORDING TO [CH. 
with 5—6 white lines between, if viewed by transmitted 
light. Wet meadows. 
A. cespitosa cannot easily be mistaken for any other species. 
Alopecurus geniculatus is also a moisture-loving grass with strongly 
ridged leaves, but the interspaces are far less translucent and the 
whole habit is different. 
All the other species of Azra have involute and setaceous leaves, 
and even A. cespitosa is apt to roll in its leaves in mountain 
varieties, but they are easily flattened out, and show the ridges. 
Psamma arenaria, Beauv. (Sea Mat-grass). This is 
one of the most valuable “sand-binders,” its long matted 
rhizomes holding loose sand together. It is a sea-shore 
grass, of no use for fodder. It was formerly much used 
for mats and thatching. Leaves concave, long, narrow, 
erect, scabrid and glaucous above, and polished below: 
pungent. Ridges rounded, alternately high and low. 
Sheath long. Ligule very long and bifid. 
Elymus arenarius, L. (Sand lLyme-grass). Like 
Psamma, this is a “sand-binder” and of no use for 
fodder. Leaves concave, and eared at the base of the 
blade: ears pointed and tend to cross in front. Ligule 
very short and obtuse. Ridges flattened above, not 
seabrid. Apex of blade rolled, forming a hard spine. 
Psamma cannot easily be mistaken for the much less common 
Elymus, as it is not eared, and the ridges and ligule are very 
different. 
(1) Leaves not specially rigid and hard, and often thin ; 
glabrous, or shining below. Ridges less evident. 
*  Ligule very short or obsolete; blade firm but not 
hard, glabrous or nearly so, and shining below. 
Sheath often coloured red or yellow at the base. 
+ Sections of sheathed leaves narrow, oblong, owing 
to compression of shoots. Sheath nearly entire. 
