†† _Motor-cells inconspicuous and in two flanking lines, one on each side of the mid-rib._ _Poa trivialis._ Keel with sclerenchyma at its apex, and a small band of the same at the margins. Vascular bundles of three orders, isolated, without girders, but with a small band of sclerenchyma above and below. Ridges obsolete. Short hook-asperities above. No thickened cuticle. Other species of Poa also come here: I cannot distinguish them by the leaf anatomy; but _P. annua_, _P. compressa_, _P. nemoralis_ and _P. pratensis_ are devoid of the hooked asperities; _P. nemoralis_ has a thicker lamina than the rest, and girders to the secondary bundles. _P. annua_ agrees in the latter point. ** _Leaf not keeled: rolling up. Motor-cells distributed between the ridges._ † _Hairs none or rare, or at most a few asperities._ ≡ _Veins numerous, 30-40 on each half lamina. Motor-cells very large._ ⊙ _All vascular bundles with girders above and below._ _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.