A revision of the genus Malvastrum A. Gray (Malvaceae: Malveae)

Vita.The genus Malvastrum was described in 1849 by Asa Gray. His original intention was to segregate out certain members of Sida and Malva to leave those two genera more "natural" and clearly defined. The generic characters that he used to circumscribe Malvastrum were later found to encompass several otherwise dissimilar groups of species, and so Malvastrum became an artificial assemblage. During subsequent years over 300 names were published in Malvastrum. The major assemblages of related species have been previously removed in to previously published genera or have been given generic status (particularly the genera Acaulimalva Krapovickas, Anisodontea Presl, Malacothamnus Greene, Monteiroa Krapovickas, Nototriche Turczaninow, Tarasa Philippi, and Urocarpidlum Ulbrich). Previous revisions of these genera have left the remaining true Malvastrums without a complete treatment, and that has been the subject of the present study. Taxonomic decisions have been based upon herbarium specimens examined a t and loaned by the major domestic and foreign herb aria, upon examinations of locally cultivated individuals of most of the taxa, and upon field observations of the three Malvastrums in Texas. During this examination, the morphological characters of the specimens were recorded and compared, karyological preparations were made, and the phenology of living individuals was studied. After the full range of variation in the samples had been determined, a numerical analysis was undertaken to aid in constructing relationships among the taxa. The result has been to accept seven sections, 14 species, six subspecies, and two varieties in Malvastrum. The following primary contributions have been made: 1) the citation of all the names published in Malvastrum together with their present placement and disposition of types; 2) an analysis of the geographic distribution of Malvastrum together with an hypothetical account of the origin and subsequent dispersal of the species; 3)..