22 BASE, MARGIN, SURB'ACE [CH. 



bristle, and even flatter leaves may be so inrolled at the 

 tips as to have the apex prolonged into a sharp needle- 

 like pungent or spinescent point — e.g. Hordeum py^atense, 

 Avena j^'^^atensis to a slight extent, and pronounced in 

 Elymus, &c. In SesleHa the apex is rounded with a short, 

 sharp, prickle-like median projection (nmcronate). 



The passage of blade into sheath has already been 

 described, but the base of the blade may have its margins 

 projecting as horizontal shelves, like a Byron collar, round 

 the sides of the throat of the sheath, sometimes tinged 

 with yellow or pink — e.g. Lolium, Holcus, Bromus inermisy 

 Hordeum ; the ends of these may project as auricles or 

 ears — e.g. Festuca elatior, Elymus, Agropyrum, Antho- 

 ocanthum, Bromus asper, Hordeum, &c. In Festuca ovina 

 the ears are short, stiff, and erect (Fig. 13). 



The margin may be perfectly even, as in most grasses, 

 or it is more or less scahrid or scaherulous, as in Aira 

 ccespitosa, Poa maritima, Festuca elatior, Avena pratensis, 

 Agrostis, Milium, Phleum, Briza, the minute teeth {ser- 

 rulw) pointing up or down. 



The surface may be bright green, or glaucous, harsh, 

 hairy or glabrous, and is not uncommonly also scahrid, like 

 a file or emery-paper, and sometimes only when rubbed in 

 one direction up or down, owing to the minute teeth being 

 directed all one way. These teeth are developed on the 

 ridges. 



All our ordinary grass leaves are parallel-veined, and 

 the vascular strands (the veins) can usually be seen on 

 holding the leaf up to the light. In most cases the tissue 

 is raised over the veins, as ridges or " ribs," and according 



