This section is from the book "British Wild Flowers - In Their Natural Haunts Vol5-6", by A. R. Horwood. Also available from Amazon: A British Wild Flowers In Their Natural Haunts.
The habitat of this plant is pastures and waste places, grassy places. The plant has the grass habit. The stem is more or less prostrate below, rooting, then erect, with long prostrate stolons. The leaves are flat, sometimes rough, with smooth rough sheaths. The ligule is long and acute. The panicle is branched or lobed, green or yellowish, compact after flowering, spreading in flower. The florets seldom have awns. The empty glumes are large and rigid, the flowering glumes are 5-nerved, and rarely awned. The plant is 6 in. to 2 ft. in height, flowering between July and September. The plant is a herbaceous perennial.
Meadows and marshy places are the habitat in which this plant is found. The habit is prostrate, then ascending, rooting at the nodes, with stoles. The stems are smooth, with smooth sheaths, the ligule blunt, and short. The panicle is long, spreading, narrowly egg-shaped, branched below. The empty glumes are egg-shaped, smooth, red or purple and green, the flowering glumes are blunt, shorter, 3-nerved, three times as long as the 2-nerved palea. The awn is short or absent. There are 3 stamens, a short style, and a feathery stigma. The fruit is enclosed in the glume, and is round and smooth. It is 1-1 1/2 ft. in height. It flowers in June and July, and is a herbaceous perennial.
The habitat of this grass is meadows, fields, copses, and waysides. The habit is erect. The root is fibrous. The plant is softly downy. The stems are tufted, ascending, with numerous leaves. The latter are flat, downy, with the upper sheaths swollen, and the knots softly hairy. The ligule is short. The panicle is pale-green or pink, the branches twice or thrice divided. The spikelets are oblong. The upper glume is blunt, rough, the empty glume acute, with strong nerves, and the awn is included in the glume, with a smooth or rough tip (not so long as in H. mollis). There is no awn in the lower florets. There are 3 stamens, and the stigmas are stalkless and feathery. The height is 1-2 ft. It is in flower from June to August. The plant is a herbaceous perennial.
Yellow Oat Grass(Trisetumflavescens,Beauv.). - The habitat of this grass is dry pastures and fields. The habit is erect. The stem is smooth. The radical leaves are hairy, flat, with hairy sheaths. The ligule is blunt and fringed with hairs. The panicle is open, much-branched, half-whorled, spreading, hair-like, yellow. The spike-lets are numerous, with 3-4 florets, yellow, shining, glistening. There are 3 spreading awns (hence the generic name) in the flowering glumes, and the empty glumes are egg-shaped, with a long point. The outer palea has 2 terminal bristles. The rachis is hairy. The styles are distinct. The stigmas are feathery. The fruit is furrowed with a downy tip, and enclosed in the flowering glume and palea. It is 1-1 1/2 ft. high. The flowers open in June and July, and give a yellow tinge to the meadows. It is a herbaceous perennial.