Plowmanianthus, a New Genus of Commelinaceae with Five New Species from Tropical America

Abstract

Abstract A new Neotropical genus of Commelinaceae, Plowmanianthus, is described with five new species. Karyological and morphological data, as well as results of phylogenetic studies, support its inclusion in the subtribe Dichorisandrinae (tribe Tradescantieae) with four other genera (Cochliostema, Dichorisandra, Geogenanthus, and Siderasis). The occurrence of moniliform hairs along the distal margins of the petals is evidence of an even closer relationship with Cochliostema and Geogenanthus, this character being restricted in the family to these three genera. Plowmanianthus may be uniquely characterized as comprising small, perennial rosette herbs with usually one-cymed, axillary inflorescences borne among the lower leaves, an androecium reduced to three fertile stamens, annular, papillate stigmas, and uniseriate to partially biseriate seeds. Plants of the genus are shallowly rooted, the roots not penetrating deeper than the leaf-litter or humus-rich layers of their primary rainforest habitats. Plowmania...