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Description:
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A systematic study of two complexes of closely related species within Eleocharis subg . Limnochloa was conducted to better define poorly understood species and to lay the foundation for a worldwide revision of this group . Research utilized scanning electron microscopy (SEM ) , study of more than 2300 herbarium specimens and types from 35 herbaria , multivariate analysis , and field studies in the southeast United States and Mexico . Examination of achene gross - and micromorphology using SEM indicated a relationship among the species of the Eleocharis mutata complex (comprising E . mutata , E . spiralis , and E . cellulosa ) , their distinctness from the E . acutangula complex (comprising E . acutangula s .l . and E . obtusetrigona ) and support the placement of all taxa studied within subg . Limnochloa . All species examined shared micromorphological characters typical of subg . Limnochloa . A systematic study of the worldwide morphological variation of E . mutata suggests it is represented by a single taxon throughout its distribution and is native to the New World and probably introduced in tropical Africa . The taxonomic relationship of Eleocharis mutata and E . spiralis was explored using discriminant analysis , PCA and phyto -geography , supporting the recognition of the two taxa as distinct at the rank of species . A systematic study of E . cellulosa suggests it is represented by a single taxon throughout its distribution , with an apparent Caribbean genotype distinguished by the presence of perianth bristles with retrorse spinules . A systematic study of the worldwide variation of E . acutangula s .l . resulted in its segregation into two infraspecific taxa , E . acutangula subsp . acutangula and E . acutangula subsp . breviseta , and two new South American species , E . neotropica and E . steinbachii . Nomenclatural history and lectotypification of certain taxa studied are discussed , and two basyionyms and two synonyms of accepted taxa are lectotypified . A taxonomic treatment is provided that includes a key , detailed descriptions and complete synonymy of each species , line drawings prepared from select specimens examined , and notes on habitat and distribution . Future research goals and needs are discussed . |