Exploring floral morphoanatomy and embryology in wild populations of Chrysolaena flexuosa (Vernonia, Asteraceae): a contribution to understanding its ornamental potential

Abstract

Chrysolaena fexuosa (Sims.) H. Rob. is a South American species in the tribe Vernonieae, with potential ornamental value: it has attractive inforescences, is suitable for pot cultivation, and its cypselae are useful for dried fower arrangements. Apart from studies on the growth dynamics of this species under cultivation, chromosome number, DNA content, ploidy level, size, pollen viability, and the characterization of phenotypic and genetic variability, it is noteworthy that other aspects regarding the foral architecture, reproductive mode, and gametophyte formation of C. fexuosa have not yet been studied. For this reason, our study encompasses a foral morphoanatomical survey and a comprehensive assessment of gametophyte development in the species. As a result of this study, we report new foral morphotypes, confrming that the morphological variability of the species might be greater than speculated. The morphoanatomy of the androecium and gynoecium and the male and female gametophyte developmental characteristics are uniform in all the populations studied despite the diferent ploidy levels. Chrysolaena fexuosa has fve tetrasporangiate stamens of the dicotyledonous type of development; all the populations studied displayed a unilocular inferior ovary with a single anatropous, unitegumented, and tenuinucellar ovule. Given that all the embryo sacs observed were of the Polygonum-type development regardless of the ploidy level, we infer that the populations analyzed are fertile and undergo sexual reproduction. Our results not only contribute further research in the feld of breeding systems and propagation of this species, but also promote the successful introduction of C. fexuosa to the plant ornamental market.