Sedges

Sedges are superficially grass-like in their morphology, but they differ from the grasses (family Poaceae) in some important respects.

Most species of sedges are perennial plants, with only a few having an annual life cycle. Sedges are herbaceous, dying back to the ground surface at the end of the growing season but then re-growing the next season by sprouting from underground rhizomes or roots. One distinguishing characteristic of the sedge is its three-angled or triangular cross-section of the stem.

The flowers of sedges are small and have some reduced or missing parts. Referred to as florets, they are either male (staminate) or female (pistillate), although both Cottongrass in the Yukon. JLM Visuals. Reproduced by permission. sexes can be present in the same cluster of florets, or inflorescence. Usually, the staminate florets occur in a discrete zone at the top of the inflorescence, with the pistillate florets beneath. Sedges achieve pollination by shedding their pollen to the wind, which then carries these grains to the stigmatic surfaces of female florets. The fruits of sedges are dry, one-seeded achenes, sometimes enclosed within an inflated structure called a perigynium.

Wetlands are usually the habitat for various types of sedges. Sedges may occur as terrestrial plants rooted in moist ground or as emergent aquatic plants, often rooted in the sediment of shallow water at the edge of a pond or lake, but with the flowering stalk and some of their leaves emergent into the atmosphere. Some species of sedge can occur in habitats that are rather dry, as in the case of some arctic and alpine sedges.