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 marshes, pools, chiefly on moorlands. The plant has the rush habit. The rootstock (slightly creeping) is short, with one tuft of leaves and stems. The leafstalks are obliquely blunt. The stems are round in section. The sheaths are acute, leafless. The glumes are blunt, with narrow margins, the lowest glume the largest. There are 5-6 bristles. The stigmas are 3. The nuts are 3-angled, oblong to egg-shaped, conical, smooth, crowned with the broad-based, 3-angled style. The plant is 4-12 in. high, flowering in June and July, and is a herbaceous perennial.
The habitat of this plant is marshes and pools, peat)' pools, ditches, and ponds. The plant has the club-rush habit, but is floating. The stems are flattened, slender, branched, rooting from the lower nodes, and zigzag, leafy. The leaves are clustered, linear, slender, and on land the plant is tufted, with the leaves sheathed. The flowers have solitary, terminal, egg-shaped spikelets, pale and narrow. The flower-stalks are alternate, with a leaf below. The 4-8 glumes are oblong, bluntly-keeled, membranous at the border, the 2 outer larger, not so long as the spike, and enclosing it. The nut is plano-convex, inversely egg-shaped, flattened, blunt-pointed, pale, smooth. There are 2 stigmas, the styles forming a beak to the nut. The plant is 6-18 in. long, and flowers in June and July, being a herbaceous perennial.
The habitat of this plant is damp places in S.\V. England, etc, wet bogs in \V. Scotland. The plant has the Club-rush habit. The stem is threadlike (hence filifurmis). The plant closely resembles 5. setaceus, but is larger, paler, the leaves longer, 1-2, narrow, channelled. The flowers are in terminal spikes, the spikelets 1-3, or solitary, more or less terminal. The lower bract is shorter, longer than the spike, the glumes blunt, hardly short-pointed, greenish, with a brown spot on the upper part each side. The nut is nearly round, not furrowed, 3-angled, pale, shining, rough, dotted in lines. The plant is 2-8 in. high, flowering in July and August, and is a herbaceous perennial.
The habitat of this plant is wet boggy pastures and marshes. The rootstock is long. The stem is triangular, solitary, sheathed below. The leaves are flat, not so long as the stem, grass-like, keeled, with rough edges. There are 6-8 flowers in the spikelets, the outer glume in the lowest spikelet having an awl-like point longer than the spike, the spikelets being longer than the bracts. The bracts are leafy, long or short. The spikelets are brown. The lower glumes are ribbed, not so long as the spikelets, reddish-brown. There are 3-6 bristles, strong, persistent, with bent-down teeth. The nut is lenticular, shining, with a persistent style, pale. The plant is 4-10 in. high, flowering in June and July, and is a herbaceous perennial.