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. 

 t Hairs more especially above. 

 Avena flavescens is very similar to Gynosurus, but is 

 evidently hairy, and A. pratensis also comes here. 

 t+ Hairs abundant on both surfaces. 

 Holcus lanatus. Very hairy above and below, and 

 at the margins. Slight keel with sclerenchyma band : 

 isclerenchyma 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). 



Kosleria 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 



