O gênero Zornia Gemelin (Leguminosae - Papilinoideae) no Estado do Pará: considerações taxonômicas.

Abstract

The family Leguminosae Adans., with about 650 genera and 18,000 species is, together with Compositae and Orchidaceae, one of the largest phanerogamic families. The genus Zornia Gmel. (Leguminosae-Papilionoideae) is composed of two subgenera, four sections and 33 species, and has a wide distribution throughout continental South America. It currently contains 124 species, 17 subspecies and 54 varieties and one sub-variety, of which 12 occur in Brazil. In the present work six species and one variety which occur in the state of Pará were studied: Zornia brasiliensis Vogel, Z. curvata Mohl.; Z. cryptantha Arech.; Z. diphylla (L.) Pers.; Z. latifolia Sm. var. latifolia; Z. marajoara Huber; Z. tenuifolia Moric. The genus occurs in the savannas and similar regions in the tropics and sub-tropics of the world. In terms of life form, species of the genus are herbs or bushes, perennial, with alternate b1- or tetra-foliate leaves, the inflorescences are in terminal or auxiliary spikes, with the number of flowers varying from 1 to 20 per inflorescence. The sessile flowers are subtended by two bracts, the calyx is tubular, and the corolla is typically papilionaceous. The fruit is a typical articulated loment subtended by persistent floral elements, and is usually hispid and reticulated. The species of the genus occurring in Pará are considered to be forage and medicinal herbs. This study was to update the available information about the morphology and taxonomy of the species occurring in Pará state. The taxa and their respective geographic distributions are described, discussed and illustrated. Using the literature and herbarium material the geographical distributions of the species were plotted, and their flowering and fruiting patterns were studied. — À dichotomous key for the identification of the species is presented.