This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol1", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Perennial or sometimes annual, grass-like, usually tufted herbs, commonly growing in moist places. Inflorescence usually compound or decompound, paniculate, corymbose, or umbelloid, rarely reduced to a single flower, bearing its flowers singly, or loosely clustered, or aggregated into spikes or heads. Flowers small, regular, with or without bractlets (prophylla). Perianth 6-parted, the parts glumaceous. Stamens 3 or 6, rarely 4 or 5, the anthers adnate, introrse, 2-celled, dehiscing by a slit. Pistil superior, tricarpous, 1-celled or 3-celled, with 3-many ascending anatropous ovules, and 3 filiform stigmas. Fruit a loculicidal capsule. Seeds 3-many, small, cylindric to subglobose, with loose or close seed-coat, with or without caruncular or tail-like appendages.
Eight genera and about 300 species, widely distributed.
Leaf-sheaths open; capsule 1- or 3-celled, many-seeded; placentae parietal or axial.
Leaf-sheaths closed; capsule i-celled, 3-seeded, its placenta basal.