The Genus Psilotrichum Blume (Amaranthaceae) in South India

The genus Psilotrichum was established by Blume in 1826 to include a single species, P. trichotomum Bl. He described the new genus as "Calix 3-bracteatus (Bracteis non spinescentibus), 5-partitus, foliosis lanceolatis, aequalibus. Stamina 5, basi in cyathulum edentulum convata. Antherae biloculares. Stylus indivisus, stigmate capito. Capsula evalvis, monosperma, inclusa calicis foliolis conniventibus nudis". P. trichotomum Bl. was later shown to be conspecific with a species described by Roxburgh (Fl. Indica 2: 502. 1824) two years earlier, and included in the genus Achyranthes as A. ferruginea Roxb. Moquin-Tandon (1849) transferred it to the genus Psilotrichum as P. ferrugineum (Roxb.) Moq., and it is accepted as the type species of the genus. The name Psilotrichum is derived from the Greek, Psilos meaning naked and trichus, in three parts (Nayar, 1985), coming under the family Amaranthaceae. Amaranthaceae, popularly called 'amaranth family, is a moderately large family with 77 genera and over 840 species (Müller & Borsch, 2005). It is a pantropical family with some genera or species reaching the warmer temperate regions. Nearly one third of the genera of the family are monotypic. The genus can be distinguished from other genera of Amaranthaceae by its two-chambered anthers, pseudostaminodia alternating with fertile (and sometimes sterile) filaments; stigma capitate; inflorescence of solitary or multiple, axillary or terminal globose heads usually without subtending leafy bracts. The genus was treated with confusion in several regional floras which are devoid of updated nomenclature and citation of type specimens. A key to the taxa are provided along with illustration of 2 species to facilitate identification of the taxa.