Abstract Polyploidy is often related with phenotypic variation, as observed in Herbertia lahue, a geophyte species. This study examined the H. lahue polyploid series and departure in cytogenetic, morphometric, and pollen data. Diploids (2n=2x=14) present bimodal karyotype with two long and five short chromosome pairs, while hexaploids (2n=6x=42) and octoploids (2n=8x=56) present a gradual decrease in chromosome size. All cytotypes have CMA+/DAPI- bands co-localized with 18S rDNA sites in the satellite region (no DAPI+ bands in any cytotype). Unlike diploids and octoploids, 5S rDNA interstitial sites in hexaploids are not in a syntenic position with 18S rDNA sites. Genome size is effective as an indirect predictor of the cytotypes since 2C-values increased according to ploidy level. The reduction in the number of the rDNA sites in polyploids associated with their lower 1Cx-values compared to diploids may suggest a genome downsizing process. Morphometric analysis revealed significant differences among cytotypes, and discriminant analysis identified three morphometric groupings corresponding to the cytotypes. The phenotypic variation observed in pollen grains, bulbs, and ovary characters suggested the gigas effect. Concluding, remarkable differentiation was observed at both genomic and phenotypic characters in all the cytotypes analyzed, suggesting a possible ongoing speciation process in H. lahue.

ABSTRACT South Brazilian grasslands are among the most species-rich grasslands worldwide yet they have been suffering ongoing degradation due to land-use. Little is known about the reproductive ecology of the native species of these grasslands. Thus, our goal was to characterize seed traits and germination requirements of three native species of the tribe Tigridieae (Iridaceae, Iridoideae) due to its richness in the Pampa biome and the contrasting morphology, cytogenetics, and geographic distributions of its representatives. We tested if closely related species possess similar seed traits and whether species with wider distributions have broader germination requirements. Seed production and mass were estimated, and morphological analyses, germination experiments and viability tests were performed. Principal component analysis (PCA) was used to describe correlations between seed traits and species’ distributions. Germination was assessed using time-to-event analysis and the Cox model. All seed traits differed among the analyzed species/cytotypes. Final germination percentage (FGP) averaged 39.1 % and with overall viability of 89.9 %. Germination tests showed that seeds benefit from negative photoblasty. Species/cytotypes with wider distributions and heavier and larger seeds generally had better germination performances than narrower distributed species/cytotypes with lighter and smaller seeds.