Using Propagule Size to Identify the Cyperaceae of Northwestern Pennsylvania: Carex, Eleocharis, Cyperus, Scirpus and Eriophorum

摘要

The Cyperaceae (or the Sedge Family) are a large taxonomic group of about 5,000 species that are classified into some 104 genera. Of these, Carex is the largest genus with about 2,000 species (Goetghe-beur 1998). Distributed worldwide, the Cyperaceae are annual or perennial grass-like herbs with 3-ranked leaves and usually solid stems (or culms). Most of the species are characteristic of moist habitats. The fruit is an achene, a single-seeded, indehis-cent dry fruit with the seed free from the pericarp, except for the placenta (Walters and Keil 1975). Sedges are distinguished from grasses (Poaceae) by their closed leaf-sheath, the 3-ranked arrangement of leaves, and the fact that each flower (floret) is subtended by a single scale; from rushes (Juncaceae) by the absence of the liliaceous, 6-parted perianth; and from both families by the fact that the fruit is an achene rather than a caryopsis (Poaceae) or a capsule (Juncaceae).