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 grass is watery places, ponds, ditches. The rootstock is stout, branched, creeping, and rooting. The plant is soft, bright-green, and limp. The stems are long, prostrate or floating, bent below, then erect, flattened smooth, finely furrowed, leafy, sometimes much-branched. The leaves are flat, linear-lance-shaped, blunt, the upper ones short. The panicle is long, pyramidal, with a stout, grooved rachis, with whorled branches, in alternate threes and fives, divided, slender, spreading. The spikelets are 2- or 3-5-flowered, more or less solitary, stalked, green and purple. The empty glumes are green, broad at the tip, the nerves obscure. The flowering glumes are purplish, smooth, with green nerves. The anthers are white. The plant is 6-12 in. high, flowering in May and June, and is a herbaceous perennial.
The habitat of this plant is watery places, marshes, stream-sides. The rootstock is stout, creeping. The stems are stout, smooth, finely furrowed, slightly flattened. The leaves are long, rough-edged, and rough on the keel, flat, acute, more or less erect. The sheaths are long and smooth, round in section. The ligule is short. The panicle is large, erect, much-branched, the branches rough. The spikelets are oblong, blunt, yellowish-green and purple, 5-10-flowered. The glumes are rough. The flowering glumes are blunt, rigid, 5-9, entire. The empty glumes are short, shining. The plant is 2-6 ft. high, flowering in July and August, and is a herbaceous perennial.
The habitat of this plant is watery places. The rootstock is stout, creeping. The stem is stout, branched, round in section, floating' or creeping, ascending, smooth, rooting below. The leaves are pale-green, acute, short, the upper long and floating. The sheaths are long, flattened. The ligule is broad, acute. The panicle is simple or branched, one-sided, long, the branches ascending, rough, simple, the lower paired. The spikelets are green, appressed, erect, linear, 7-12-flowered, the flowers lance-shaped, oblong, acute. The empty glumes are unequal, with torn tips, the flowering glumes are rough, with ragged tips. The anthers are five times as long as broad. The plant is 1-4 ft. high, flowering in July and August, and is a herbaceous perennial.
The habitat of this plant is similar to that of the last, stagnant water and wet places. It has been regarded as a variety of the last, from which it differs in the spreading fruiting spikelets. The stem is ascending, rooting below. The leaves are bluish-green, blunt, plaited when young. The ligule is short. The sheaths are rough and furrowed. The panicle is much branched, compound, with simple rough branches, the lowermost in fives, smooth, erect in flower, spreading in fruit. The spikelets are linear, 7-20-flowered, the florets oval-oblong, acute. The flowering glumes are twice as long as broad. The lower palea is blunt, 3-lobed. The anthers are three times as long as broad, cream-coloured, brown when empty. The plant is in flower between June and August, and is a herbaceous perennial.
Poa palustris, L. ( = P. serotina, Ehrh.). - The habitat of this plant is marshy places, and the plant is very rare. The stem is tufted, smooth, ascending. The leaves are narrow, pointed, roughish. The root is fibrous or creeping, with short stolons. The sheaths are smooth. The ligule is oblong and acute. The panicle is large, with rough, ascending to spreading branches, the lower more or less whorled in fives. The spikelets are ovate, acute. The flowers are 2-5, webbed. The lower palea is obscurely 5-veined, hairy on the keel and margins towards the base. The plant is 1-3 ft. high, flowering from June to August, and is a herbaceous perennial.