Digraphis arundinacea. No keel. Marginal sclerenchyma conspicuous. A few asperities below. Leaf thin, and all the bundles joined to the epidermis above and below by girders (Fig. [14]). Stomata on both surfaces, fairly large: epidermal cells with plane walls. There may be a few irregular air cavities, especially near the mid-rib.
⊙⊙ Only the principal bundles girdered.
Arundo Phragmites. Ridges very numerous and low. No keel. Marginal sclerenchyma strong. Vascular bundles with sheaths of large colourless cells, a few of the strongest girdered below, but most have only sclerenchyma bands above and below. Motor-cells particularly large, between all the bundles. There are no conspicuous lacunæ. Hairs very rare. Epidermal cells small, with sinuous walls: all the cell-walls contain silica. Stomata on both faces, sunk, small and more difficult to see than in Digraphis, where the epidermal cells are plane walled, or nearly so.
Arundo Donax is very like A. Phragmites, but has larger bundles each with a horse-shoe shaped sclerenchymatous mass below, and larger lacunæ.
≡ ≡ Veins not more than 10-20 in each half lamina.
⊙ More or less conspicuously hairy. The smaller bundles isolated and devoid of girders.
Bromus sterilis. Girders to the stronger bundles only. Stiff hairs above and below. Motor-cells poorly developed between each pair of low ridges. No pronounced cuticle. A faint sclerenchyma-band at margin, and at apex of low rounded keel. Stomata on both faces.
Bromus arvensis. Similar to B. sterilis, with stiff hairs commoner below. Harsh in cutting.
B. giganteus shows no hairs, but I cannot distinguish the Bromes generally by the leaf anatomy.
Anthoxanthum odoratum. No keel, ridges obsolete, the stronger bundles only with girders. Motor-cells conspicuous between all the ribs. Marginal sclerenchyma, and that above and below the bundles, poorly developed. A few coarse hairs both above and below, and stomata on both faces. Leaf thin and narrow.
Hordeum murinum. Few girdered bundles, and sclerenchyma at margins poor. Hairs sparse and coarse.
Bromus asper, Brachypodium sylvaticum and Lagurus also come here.