Xyridaceae of Viruá National Park, Roraima state, Brazil

Abstract

A taxonomic treatment of the Xyridaceae in the Viruá National Park is presented. Located in Roraima state, northern Brazil, the park comprises a mosaic of lowland vegetation types, including forests, wetlands, and one of the largest continuous areas of campinarana in the Brazilian Amazon Basin. Xyridaceae are represented in the park by 20 species in the genera Abolboda and Xyris. Although the four species of Abolboda are widespread, most of the Xyris species (75%) are endemic to Amazonian open vegetation formations, such as campinaranas and savannas. This study was based on field, herbarium, and scanning electron microscopy research. The taxonomic treatment includes identification keys to the genera and species, morphological descriptions, SEM images of seeds for Xyris species, iconography, geographic distribution and comments on the ecology of the species. The poorly known Xyris connosepala is synonymized in Xyris guianensis.

Floristic survey of herbaceous and subshrubby aquatic and palustrine angiosperms of Viruá National Park, Roraima, Brazil

“…We identified some specimens collected in this phytophysiognomies in Amazonas state and not yet deposited in any herbaria, which belong to such endemic species. In fact, endemic species of white-sand savannas were recently listed in other studies of the Viruá National Park (Cabral 2011, Dávila 2011, Azambuja 2012, Cangani 2012, Pessoa et al 2015, Mota et al 2015). Other taxa with a more restricted distribution are families, genera or species with concentrated richness or exclusive occurrence in northern South America, or only in the Guiana Shield, e.g.…”

“…and cited the VNP among the localities of its occurrence, and although we did not collect this species, it appears in our list. Pessoa et al (2015) and Mota et al (2015), respectively, held two taxonomic treatments with focus on Orchidaceae and Xyridaceae to this area, and we also included the aquatic and palustrine herbs and subshrubs cited by them in our list. When it was impossible to examine directly any specimen of the species treated, we cited the correspondent treatment.…”

Estudos taxonômicos das Xyridaceae no estado do Paraná, Brasil

“…Com cerca de 400 espécies, o gênero Xyris Gronov. ex L. é o maior da família, tendo sua amplitude de distribuição coincidente com a das Xyridaceae (Mota et al 2015;Wanderley 2017). As demais espécies estão incluídas em quatro pequenos gêneros confinados principalmente ao norte da América do Sul: Abolboda (23 spp.…”

Seed micromorphology and its taxonomic significance to Xyris (Xyridaceae, Poales)

“…The anatomy of the seeds was studied for species of Abolboda, Orectanthe (Carlquist 1960;Oriani and Scatena 2014) and Xyris (Weinzieher 1914;Rudall and Sajo 1999;Nardi et al 2015) and proved to be useful taxonomically. The importance of seed coat ornamentation for the taxonomy of Xyris has already been demonstrated in the literature (Wanderley 1992;Silva 2010;Mota et al 2015). Mota et al (2015), for example, analyzed the seed coat surface of 17 species of Xyris and used characteristics such as length and shape of seed, type of striae, and pattern of cross-lines to distinguish among species.…”

“…The importance of seed coat ornamentation for the taxonomy of Xyris has already been demonstrated in the literature (Wanderley 1992;Silva 2010;Mota et al 2015). Mota et al (2015), for example, analyzed the seed coat surface of 17 species of Xyris and used characteristics such as length and shape of seed, type of striae, and pattern of cross-lines to distinguish among species. It is worth pointing out that the knowledge of the ontogeny of the seed is very important for the analysis of micromorphology because it facilitates the understanding of the origin of the tissues responsible for seed coat ornamentation.…”