80 CLASSIFICATION ACCORDING TO [CH. 
grooves. The lower girders may not fuse laterally into a 
continuous band of sclerenchyma below (Fig. 18). 
The folded lower leaves of F. rubra and F. heterophylla come here 
also. For the flatter leaves of F. duriuscula see p. 78 and compare 
Fig. 27. 
The epidermal cells in this series have sinuous thickened walls, 
and here and there small tooth-like hairs. 
Nardus also comes here (see Fig. 26). 
(2) There are stomata below, but fewer than on the upper 
surface. Motor-cells usually conspicuous between the 
ridges. 
* Stronger bundles with girders of sclerenchyma 
joining them to the epidermis, at least below. 
© Hairs sparse or none. 
Cynosurus cristatus. Mid-rib obsolete, except the 
strong vascular bundle. Ridges low and rounded, with 
2—4 flanking stomata, and well developed motor-cells 
in furrows. Secondary vascular bundles with strong 
girders below, the smaller bundles sheathed only and 
isolated. Each ridge with slight sclerenchyma above. 
A few stiff short hairs above, and the leaves are con- 
volute. Ridges about twice the height of the leaf-thick- 
ness between (Fig. 16). 
Agropyrum repens. Mid-rib and margin with strong 
sclerenchyma-groups: ridges unequal, low and rounded, 
and each vascular bundle girdered. A few pointed hairs 
above, and motor-cells in all the grooves. A slight keel, 
stomata on both surfaces. 
Agropyrum caninum. All the bundles have girders. 
Slight keel. Marginal sclerenchyma. Few, very short, 
hard, hooked asperities above and below. Ridges low, 
