Taxonomic Innovations in North American Eleocharis (Cyperaceae) S. Galen SmithDepartment of Biology, University of Wisconsin-Whitewater, Whitewater, Wisconsin 53190, U.S.A.ABSTRACT. Taxonomic innovations for the upcom-ing volume 23 of the Flora of'North America (FNA)are here published. Eleocharis quinquefJora (F. X.Hartman) 0. Schwarz. E. suksdorfiana Beauverd.and E. bernardina (Munz & 1. M. Johnston) Munz& I. M. Johnston are redefined. New taxa descriledare: E. occulta S. G. Smith, segregated from E. acu-tisquamata Buckley; E. biJida S. G. Smith, segre-gated from E. compressa Sullivant; E. torticulmis S.G. Smith, segregated from E. suksdorfiana: and E.acicularis (L.) Roemer & Schultes var. porcata S.G. Smith, confused with E. wolfii (Gray) Gray. Otherinnovations are: E. elliptica Kunth var. atrata(Svenson) S. G. Smith, comb. nov.; E. compressa var.acutisquamata (Buckley) S. G. Smith, stat. nov.: E.palustris (I,.) Roemer & Schultes var. vigens I. H.Bailey, lectotypified. Key words: Cyperaceae, Eleocharis, North America. Taxonomy in Eleocharis is confused because of morphological convergence in habit, vegetative re-production (tubers, bulbs. stolons, viviparous spikelets), and most structures including culms, leaf sheaths, spikelets and their scales. perianth bristles, style branches, tubercles, and achenes (Gonzalez-Elizondo & Peterson, 1997; Gonzalez-Elizondo et al., 1997: Roalson & Friar. 2000). This paper contains taxonomic innovations re-sulting from my work on the treatment of Eleocharisfor the upcoming volume 23 of the Flora of NorthAmerica (FNA) (Flora of North America EditorialCommittee, in press). Eleocharis is a worldwide genus comprisingabout 200 species (Gonzalez-Elizondo & Peterson,1997). The latest comprehensive taxonomic treat-ment for North America was done by Svenson(1957), who recognized 61 species. About 65 spe-cies will be recognized in the FNA treatment. Gon-zalez-Elizondo and Peterson (1997) provided a su-praspecific classification utilizing four levels oftaxonomic categories, which will be followed. Classification of Eleocharis is unusually difficultfor two main reasons: (1) The simple structure (un-branched aerial stems: only two leaves, which arebasal, sheathing, and without blades or with onlyrudimentary blades; and a single terminal spikeletwithout involucral bracts) provides relatively fewmacroscopic characters. (2) Eleocharis includesseveral extremely difficult species complexes need-ing taxonomic revision. Many of the species inthese complexes have never been precisely defined.Problems of species delimitation are probably duein part to interspecific hybridization, which hasbeen studied mainly in the E. palustris complex inEurope (Strandhede, 1965, 1966). Unstable chro-mosome structure, polyploidy, and aneuploidy as-sociated with diffuse-centromere chromosomes andaberrant meiosis and pollen development (Harms.1968. 1972; Strandhede, 1965, 1967) doubtlessalso contribute to taxonomic complexity. This paperresolves some of the taxonomic problems in the E.palustris complex, the E. tenuis-compressa complex.the E. quinqueflora complex (E. subg. ZinserlingiaT. V. Egerova), and the E. acicularis compex (E.subg. Scirpidium (Nees) Kukkonen) in North Amer-ica.A. TIH ELEOCHARtS IutL STRIS CoMPILEX The E. palustris complex comprises subgenus Eleocharis sect. Eleocharis ser. Eleocharis subser. Eleocharis (= E. ser. Eleocharis subser. Palustres Svenson). It is circumboreal and comprised of per-haps 10 to 15 species. All of the North American and Eurasian species are difficult to delimit. Strandhede (1965, 1966) studied extensively the 4 species of this complex in northern Europe. It is still poorly understood in North America, for which Svenson (1957) recognized 6 species. I recognize 7 species, which include all 4 European species. For Europe, Strandhede (1966) showed that interspe-cific hybridization and polyploidy are a major cause of taxonomic difficulties among the species recog-nized there, and by extrapolation it seems likely that hybridization and polyploidy are also important in North America. The most widespread and variable species in thiscomplex is the circumboreal E. palustris (I.) Roe-mer & Schultes, within which I am including theNorth American E. smallii Britton as a synonym.For North America, Strandhede (1967) distin-NovoN 11: 241-257. 2001.