Each vascular bundle has a sheath, but is isolated. Sclerenchyma at tips of the ridges dense: smaller bands below: strong at margins. Lower cuticle strong. Leaf rolls up.
The flat upper leaves of Festuca rubra (Fig. [20]) and F. heterophylla are somewhat similar in type. They have stiff hairs on the ridges.
≡ ≡ Ridges not more than 2-3 times as high as the tissue between; each furrow with motor-cells, and each vascular bundle joined to epidermis above and below by a sclerenchyma girder.
Brachypodium pinnatum. Smooth. Ridges rounded. Hairs rare. The strong sclerenchyma girders below almost continuous laterally. Epidermal cells with sinuous thick walls, and a few tooth-hairs.
Note the differences from B. sylvaticum, p. [76.]
Melica nutans, M. uniflora, and Calamagrostis Epigeios also come here.
⊙⊙ Motor-cells confined to the innermost 2-4 furrows. Sclerenchyma in a continuous band just inside the thick cuticle below.
Festuca duriuscula. The ridges are only about half to one-third as high again as the thickness between, and the motor-cells in four series at the base of the three innermost ridges. Each ridge has only one isolated sheathed bundle, without girders. Stomata on the flanks of the ridges, and few in number. The sclerenchyma forms a thick band just inside the strong cuticle below. The leaf is conduplicate, not convolute.
This applies particularly to the more open leaves: the subulate leaves belong to the next type (see Fig. [27]).
Aira canescens and Spartina stricta also come here.
Psamma arenaria. Inrolled. Smooth below and devoid of keel, with sub-epidermal band of sclerenchyma, and similar tissue at the margin. Ridges of three sizes, the largest twice or three times as high as the leaf-tissue between is thick, all rounded above, and very hairy. Stomata above only. Motor-cells in each sinus not large. Vascular bundles isolated, without girders or bands of sclerenchyma.
Elymus is very like Psamma, but has a few stomata below and the sub-epidermal sclerenchyma is not continuous (see Fig. [25]).
✲✲ Leaves (subulate) not opening out, the upper surface represented by a groove or a few ridges above the angular or ovate solid section.
⊙ Section pentagonal or angular-ovate: sclerenchyma below in a continuous band.