Aquatic and Wetland Vascular Plants of the Northern Great Plains

Cyperaceae - The Sedge Family

Mostly perennial, grasslike, rushlike or reedlike plants; stems trigonous or less often terete (or compressed), solid or pithy. Leaves in 3 vertical ranks or reduced mainly to sheathing at the base of the stem; leaf blades, when present, grasslike, elongate and parallel-veined, often strongly keeled; sheaths closed around the stem, sometimes splitting with age. Flowers much reduced, perfect or unisexual, each subtended by a bract (scale); perianth consisting of 1-many (often 6) small bristles or a single perianth scale, or the perianth lacking; stamens 3 or sometimes 1 or 2; ovary superior, 1-celled, 3-carpellary or less often 2-carpellary, sometimes contained in a saclike covering called the perigynium (Carex), ripening into an achene, the style trifid or bifid (stigmas 3 or 2), ovule 1, basally attached. Flowers and their subtending scales arranged in spikelets (termed spikes in Carex), the spikelets solitary as a single terminal or lateral spike, or the spikelets few to many and arranged in various types of inflorescences, the inflorescence often subtended by 1-several involucral bracts. A large family (third largest in our region) of which most members inhabit wet places.

Lead	Characteristic	Go To
1	Flowers unisexual; achene enclosed in a saclike perigynium which in turn is subtended by a scale.	Genus Carex
1	Flowers perfect or mostly so; achene naked, merely subtended by a scale and the perianth (if present).	Lead 2
2	Scales distichous in the spikelets.	Lead 3
2	Scales spirally arranged and overlapping in the spikelets.	Lead 4
3	Inflorescences terminal; achene not subtended by bristles.	Genus Cyperus
3	Inflorescences axillary; achene subtended by bristles.	Genus Dulichium
4	Style base persistent as a tubercle atop the achene, often swollen, differentiated in color and texture from the achene body, or if the style base appears confluent with and not differentiated from the achene body, then the spikelets solitary on leafless culms.	Lead 5
4	Style base persistent as a small beak, confluent with the achene body and not differentiated from it, or the style base not persistent on the achene; spikelets usually few to many, or if solitary, then on leafy culms.	Lead 7
5	Spikelets solitary on the culms; culms appearing leafless, the leaves reduced to basal sheathes.	Genus Eleocharis
5	Spikelets 1-several, culms leafy at the base, the leaves with narrow blades.	Lead 6
6	Fertile flowers or achenes usually only 1 or 2(-5) terminating each spikelet, most of the scales empty; achene lenticular, the tubercle prominent, beaklike, confluent with the achene body.	Genus Rhynchospora
6	Fertile flowers or achenes few to several per spikelet, all or nearly all of the scales with flowers or achenes; achene trigonous, the tubercle minute, mammillate, distinct from the achene body.	Genus Bulbostylus
7	Perianth of numerous, long, whitish or rufous bristles, greatly surpassing the scales and giving the spikelets a cotton tuft appearance.	Genus Eriophorum
7	Perianth of 1-6 small bristles or scales, or the perianth lacking.	Lead 8
8	Perianth of 1-6 small bristles or absent; plants mostly perennial.	Lead 9
8	Perianth of 1 or 3 scales, sometimes absent; plants annual.	Lead 10
9	Perianth absent; style base swollen above the attachment to the achene, readily deciduous.	Genus Fimbristylis
9	Perianth of 1-6 bristles, rarely absent; style base not swollen, often partly persistent as a beak on the achene.	Genus Scirpus
10	Perianth of 1 minute scale or sometimes absent; spikelets 5 mm or less long.	Genus Hemicarpha
10	Perianth of 3 stalked scales; spikelets more than 5 mm long.	Genus Fuirena