CHAPTER III.
GRASSES CLASSIFIED ACCORDING TO THEIR VEGETATIVE CHARACTERS.
I. Sheaths entire except where those of lower leaves are burst by branches, &c.
A. Aquatics with the sheaths reticulated, owing to large air-cavities. Leaves equitant, linear acute, often floating.
Glyceria fluitans (Br.). Floating sweet grass. Somewhat coarse, but useful pasture in water-meadows and fens. Sweet-tasting.
Section of sheathed leaves linear oblong; sheath striate or furrowed, keeled; leaf ribbed; ligule broad acute. Leaf-base with a yellow triangle. Smooth.
Glyceria aquatica (Sm.). Reed sweet grass. Especially given to growing in the water-courses and on banks instead of spreading in the water-meadows, &c. Sweet-tasting.
Section of sheathed leaves broadly naviculate; sheath smooth, no keel; leaf not ribbed, thick and inflated with large air-cavities; ligule short. Leaf-base with a brown triangle. Margins and keel rather rough.
These two species of Glyceria are distinguished by their shoot-sections and the ridges of the leaves of G. fluitans: they often occur in the same ditch.
They cannot readily be confused with others on account of their aquatic habit, and the characters given. The only other aquatic or semi-aquatic species are forms of Catabrosa, Digraphis, Arundo, Alopecurus geniculatus, Molinia cærulea and the rare Calamagrostis.
The ligule and flat shoots with closed sheaths alone suffice to distinguish it from the round and split sheathed Arundo Phragmites; and the round shoots of Digraphis, its split sheath and firm leaves, suffice to distinguish it.
Molinia also has a tuft of hairs instead of a ligule, and a split sheath, and its habit is different.
Alopecurus geniculatus, with its “kneed" shoots, has a totally different habit from Glyceria, and its very high ridges and want of visible air-chambers complete the diagnosis.
Catabrosa is a small creeping aquatic with very flaccid leaves, quite glabrous and soft. Also sweet-tasting.
B. Not aquatic, and devoid of visible air-chambers in leaf or sheath. Often perennial, i.e. having stolons or other branches with no rudiments of flowers in them, and with relics of old leaf-bases.