v] LEAF-STRUCTURE 81 
and motor-cells poorly developed between. Few stomata 
on lower surface. Very like A. repens, but the principal 
ridges are more prominent below and those nearer the 
mid-rib have asperities. 
A. junceum resembles Psamma, but the ridges are 
much lower, and there are a few stomata on the under 
surface (Fig. 24). 
©® Leaf obviously hairy. 
+ Hairs more especially above. 
Avena flavescens is very similar to Cynosurus, but is 
evidently hairy, and A. pratensis also comes here. 
tt Hairs abundant on both surfaces. 
Holcus lanatus. Very hairy above and below, and 
at the margins. Slight keel with sclerenchyma band: 
sclerenchyma at margin slight. Ridges rounded, about 
twice as high as thickness between. Stomata more 
abundant above. Cuticle very thin and leaf soft. All 
bundles except the mid-rib with girders. Motor-cells 
fairly well developed between the ridges (Fig. 15). 
Kelerva cristata. Very hairy on both surfaces. 
Ridges irregular, the largest flat and high, the others 
rounded or triangular. Vascular bundles isolated, and 
the sclerenchyma reduced to a few cells in a single layer 
beneath the epidermis at the apex of each ridge and 
below the bundle. Motor-cells well developed in each 
furrow. Stomata more numerous above. 
*& No girders to the vascular bundles. 
Lolium perenne. Ridges numerous’ and unequal. 
Vascular bundles sheathed and isolated—i.e. devoid of 
W. 6 
