Phytologia (September 1994) 77(3): 141-297. REVIEW OF THE TAXONOMY OF ASTER SENSU LATO (ASTERACEAE: ASTEREAE), EMPHASIZING THE NEW WORLD SPECIES Guy L. Nesom Depaitment of Botany, University of Texas, Austin, Texas 78713 U.S.A. ABSTRACT The genus Aster (as tjrpilied by A. amellus L.) and its closest rel-atives comprise the subtribe Asterinae a. 3tr. These ca. 306 species in thirteen genera are primarily restricted to the Old World; Aater is the largest of these (with ca. 180 species) and is restricted to the Northern Hemisphere of the Old World, except for the seventeen species of Aater sect. Calimeridei (the A. harveyanus Kuntze group), which occurs in southeastern Africa, and A. alpinus L., which occurs in Asia and North America. The status of problematic, potentially generic-level Asian groups presently maintained within Aster s. str. is discussed. Boltonia is the only American genus hypothesized to be in the Asterinae. The New World species previously classified primarily within Aster are here ap-portioned among eleven previously described genera and two new ones, including the following (with number of species indicated): Almutaster (1), Ampelaster gen. nov. (1), Chloracantha (1), Canadanthus gen. nov. (1), Doellingeria (11 -three from North America, eight from Asia), Bucephalus (11), Eurybia (28), lonactis (5), Oclemena (3), Oreostemma (3), Psilactis (6), Sericocarpus (5), and Symphyotrichunu, including Vir-gulus (97). The status of Tonestus (eight species) within the Asterinae is considered, but it probably is best placed within the Solidagininae. A taxonbmic account is provided for infrageneric categories and all 181 species of these fourteen American genera (including Tonestus), with new combinations necessary to establish a complete nomenclature; mor-phological summaries are provided for all. The validity and typilication of the name Eurybia (Cass.) S.F. Gray is discussed in detail. Asian Asterinae are generally characterized by obovate, flattened, 2-nerved achenes commonly with glandular faces and are hypothesized to com-prise a monophyletic group. American species (the Symphyotrichinae) are generally characterized by their cylindric to fusiform, terete, multi-nerved, and eglandular achenes, but transitions to flattened and few-nerved achenes apparently have occurred in parallel with Asian taxa. 141
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