these may project as auricles or ears—e.g. Festuca elatior, Elymus, Agropyrum, Anthoxanthum, 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 scabrid or scaberulous, as in Aira cæspitosa, Poa maritima, Festuca elatior, Avena pratensis, Agrostis, Milium, Phleum, Briza, the minute teeth (serrulæ) pointing up or down.

The surface may be bright green, or glaucous, harsh, hairy or glabrous, and is not uncommonly also scabrid, 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 to the height of these ridges the thinner parts between look like deep or shallow furrows (cf. Figs. 8-16 and Chapter IV.). If the leaf is held up to the light the ridges appear dark in proportion to their opacity—i.e. height or thickness—and the furrows light in proportion to the thinness of the tissues there. If the contrast is very great, as in Aira cæspitosa (Fig. 23), the furrows seem like transparent sharp lines, and when, as in Poa, which is practically devoid of ridges, the difference of thickness is small they appear merely as fine striæ. These characters must be determined on the fresh leaves, however, because the contraction in drying draws the ridges closer together and tends to obliterate the lines.