Grass-like or rush-like herbs, easily distinguished from Grasses by the sheaths of the leaves, which in the Sedges are closed round the clum, not split. Flowers in spikes, each flower in the axil of a glume-like bract, either altogether without a perianth or with a few bristles or scales inserted below the ovary. Ovary 1-celled, becoming an achene (2-or 3-angled). Style 2- or 3-cleft. Stamens mostly 3, occasionally 2.
We shall describe one species of each of five genera.
The plant (Fig. 256) is from 4 to 10 inches in height. The culm is triangular, leafy towards the base, but naked above. At the summit there is an umbel the rays of which are unequal in length, and on each ray are clustered several fiat brown - coloured spikes, the scales of which are imbricated in two distinct rows. At the base of the umbel there are 3 leaves of very unequal length, forming a sort of involucre, and the base of each ray of the umbel is sheathed. In each spike every scale except the lowest one contains a flower in its axil. The flower (Figs. 257 and 258) is entirely destitute of perianth, and consists of 2 stamens and an ovary surmounted by a 2-cleft style, being consequently perfect. The plant is pretty easily met with in low wet places.
In this plant, which grows in muddy soil in tufts 8 to 14 inches in height, there is but a single spike at the summit of each slender culm, and the scales of the spikes, instead of being imbricated in 2 rows and thus producing a flat form, are imbricated all round. The scales are very thin in texture, with a midrib somewhat thicker, and are usually brownish in colour. Each of them contains a perfect flower in its axil. Instead of a perianth, there are 6 or 8 hypogynous barbed bristles. The stamens (as is generally the case in this Order) are 3 in number, and the style is usually 3-cleft. Observe that the style is enlarged into a sort of bulb at the base, this bulbous portion persisting as a fiattish tubercle on the apex of the achene. The culms are without leaves, being merely sheathed at the base.
A stout marsh-plant, 2 or 3 feet high, with a sharply triangular hollow-sided culm, and bearing at the base from 1 to 3 channelled or boat-shaped leaves. The rusty-looking spikes vary in number from 1 to 6, and are in a single sessile cluster which appears to spring from the side of the culm, owing to the 1-leaved involucre resembling the culm and seeming to be a prolongation of it. Each scale of the spike is 2-cleft at the apex, and bears a point in the cleft. The flowers are perfect, with 2 to 6 bristles instead of perianth, 3 stamens, and a 2-cleft style, but there is no tubercle on the apex of the achene. The culms of this plant spring from stout running rootstocks.
A common bog-plant in the northern parts of Canada, resembling Scirpus in the details as to spikes, scales, etc., but differing chiefly in this, that the bristles of the flowers are very delicate and become very long after flowering, so that the spike in fruit looks like a tuft of cotton. The culm of our plant is triangular, though not manifestly so, and its leaves are hardly, if at all, channelled. The spikes are several in number, and are on nodding peduncles, and the involucre consists of 2 or 3 leaves. Culm 15 or 20 inches high.
The species of the genus Carex are exceedingly numerous and difficult of study. The one we have selected (Fig. 259) is one of the commonest and at the same time one of the easiest to examine. In this genus the flowers are monoecious, the separate kinds being either borne in different parts of the same spike or in different spikes. The genus is distinguished from all the others of this Order by the fact of the achene being enclosed in a bottle-shaped more or less inflated sac, which is made by the union of the edges of two inner bractlets or scales. To this peculiar sac (Figs. 260 and 261) which encloses the achene the name perigynium is given. The culms are always triangular and the leaves grass-like, usnally roughened on the margins and on the keel. In the species under examination (which may be found in almost any wet meadow) the culm is some 18 inches high. The staminate spike (only one) is separate from and above the fertile ones, which are 2 or 3 in number, few- (5 to 8) flowered, and quite near together. The perigynia are very much inflated, that is, very much larger than the achene; they are distinctly marked with many nerves, and taper gradually into a long 2-toothed beak from which protrude the 3 stigmas. The bracts which subtend the spikes are leaf-like, and extend much beyond the top of the culm.