Carex L.-SEDGE

The wetlands and meadows of the mountain apparently provide excellent habitat for the sedges, as the genus is represented by 50 species. While most are to be found in meadows at middle elevations, they are by no means restricted to such habitats: some grow in forests and others on rocky slopes in the alpine zone. And while the plants range in size from small to huge, the only way to make clear identifications is to carefully examine details of the anatomy of the flowering parts, with a handlens certainly and preferably with a microscope. And, as if this were not enough of a challenge, a successful identification often depends upon having plants that are mature enough that the shape and size of the perigynium can be determined with accuracy.

The stems of Carex are triangular, often with sharp, raspy corners (hence, the old expression, "sedges have edges"). The leaves are thus in three ranks along the stems. The lowest leaf blades are often reduced to sheaths, while the upper blades may be flat, folded, or inrolled. Measurements of leaf width are made on the lower regular stem leaves.

Carex flowers are unisexual: each is male or female. The flowers of each sex may be in separate spikes, or they may form mixed spikes with one sex above the other. They are arranged in one to several spikes per stem. The words "androgynous" and "gynaecandrous" are used to indicate the relative position of the male and female flowers.

The former means "male above," and the latter "female above." These configurations are seen in Carex species at Mount Adams:

1. If there is a single spike per stem, the male flowers are always at the top (androgynous).
2. Where there are two or more spikes per stem, the terminal spike may be all male (androgynous) or all female (gynaecandrous). Some species have two or more terminal male spikes. In either case, the lower spikes are usually all female.
3. Where there are two or more spikes per stem, and the terminal spike is mixed, the species is androgynous if male flowers are at the top of the mixed spike and gynaecandrous if the top flowers are female. As in case 2, the lower spikes are usually all female.

Finally, in mixed spikes, there are almost always many more female than male flowers.

The male flowers typically have 3 stamens (although occasionally 2). The male spike, or portion of it, is usually more slender than the female portion; this feature alone helps to distinguish the two sexes. Even after flowering, remnant wispy anthers can often be found on at least a few flowers.

As noted above, each female flower is borne in a perigynium (plural, perigynia) formed of a modified bract. The details of the perigynium are very important in the Carex key-features such as shape, dimensions, color, and surface features of mature flowers must be ascertained under magnification. The perigynium may be blunt at the tip, but is more often extended to form a beak; the surface is sometimes hairy and may have distinctive veins or a winged margin. Within the perigynium is the ovary, which develops into an achene. The stigmas, numbering 2 or 3, protrude from a tiny opening at the top of the perigynium; here they are positioned to capture the wind-borne pollen. At the base of the perigynium is a scale, which more or less covers the perigynium. The color of this scale largely determines the overall hue of the spike.