A Morphometric Approach in South American Stipoids with Plumose and Pappus-like Awns

Abstract

Abstract—Within grasses, the tribe Stipeae is highly specialized by the presence of only one fruit per spikelet and characterized by the diversity in the ornamentation of the floret. Our aim was to analyze similarities and differences based on multi- and univariate analyses among closely related species in American Stipeae: Jarava species with plumose-like awns and species of Pappostipa with pappus-like awns. Ordination analyses (principal coordinate analysis and cluster analysis) were used to determine major groupings, while significant differences among groups were tested by multivariate analysis of variance (MANOVA) and univariate analysis based on generalized linear models (GLM). Based on morphological similarities, we delimited five groups. The presence of a small floret characterized Jarava annua, J. media, and J. plumosula, although J. annua was clearly distinguished by the distribution of hairs in the awn column. Jarava subplumosa and J. psylantha were characterized by the pubescence of the culm, the length of the floret callus, the length of the awn subule, and the length of the awn hairs. Pappostipa was distinctive by having hairs only in the awn column that resemble a pappus while Jarava neaei + J. pogonathera presented the longest inflorescences and hairs only on the awn subule, resembling a feather. As a result, we present a key to taxa and descriptions to characterize and identify species within the Jarava-Pappostipa group with plumose and pappus-like awns.