Diversity:  grass-like, often perennial tufted (caespitose) herbs - ca. 100 genera and 5,000 species.

Distribution:  Worldwide, but mostly in moist, cool places in the north temperate zone with extensions into the tropical highlands.  The Texas flora includes 15 genera and 207 species in Texas with five endemic species representing four genera (see also North American taxa; 27 genera and 843 species).

Floral structure:

 flowers often unisexual

Significant features:  Small, reduced flowers on grass-like (tufted or caespitose) plants but differing from the 'true' grasses (Poaceae) by having stems (known as 'culms' in this order) that are often triangular and solid (usually pithy) with leaves 3-ranked or arranged in 3 rows corresponding to the 'sides' of the angular stems.  Sheathing leaf bases of the Cyperaceae are also often 'closed' or firmly connected to the culm. Reproductive structure also differs from the Poaceae in that each flower, often unisexual, is subtended by only a single bract.  Clusters of florets, known as 'spikelets' for both families, are not subtended by pairs of 'sterile' bracts (glumes) in the Cyperaceae and some genera of the family show a perianth that is modified to form a series of bristles or scales.  The fruit is single-seeded, often a triangular or lenticular (lens shaped) achene or nutlet that, is some genera, carries features that are essential for identification to both genus and species.

stem section - Carex	Eleocharis inflorescences at anthesis with bracts - pistillate above, staminate below	Cyperus inflorescence of 'spikelets - flowers perfect

diagram -plant in flower	C. cherokeensis plant	diagram - generic key character	pistillate inflorescence, perigynia, bracts

More information on the Cyperaceae