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

The seed micromorphology was studied in eight species of Xyris (Xyridaceae) with taxonomic purposes. The results show that the presence of longitudinal endotegmic ridges in the seed coat is a pattern for the genus and that the shape of these ridges differentiates among the species. The following characteristics are also useful to identify the species: shape and size of the seed, number of cell rows between the ridges, and the striation pattern of the seed coat. Based on these characteristics, a standard terminology is proposed to describe the seed coat in species of the genus. An identification key for the studied species is also provided.