Taxonomic significance of cypselas morphology of tribe Heliantheae (Asteraceae) from Pakistan and Kashmir

In Asteraceae, the remarkable feature of cypsela plays a significant role in the taxonomic treatment of species. In this research, we aim to assess the significance of the micro-morphological diversity of cypsela at a lower taxonomic level, alongside its corresponding phylogeny. Cypselas of 11 taxa viz., Blainvillea acmella (L.) Philip., Eclipta prostrata (L.) L., Helianthus annuus L., Helianthus tuberosus L., Parthenium hysterophorus L., Sphagneticola calendulaceae (L.) Pruski, Sphagneticola trilobata (L.) Pruski, Verbesina encelioides (Cav.) Benth. Hook. f. ex A. Gray, Xanthium spinosum L., Xanthium strumarium L., and Zinnia elegans Jacquin were examined for the first time from the study area. Cypselas are usually isomorphic (except in Zinnia elegans), light to dark brown or blackish with a carbonized layer in the pericarp, often monotypic, oblanceolate to oblong or obovate. The characters including the size, surface, number of ribs, angle, apex, and appearance of awns, pappus, beak, and wings were evaluated. Studied taxa are grouped into two contrasting cypsela types (viz., Type I and Type II). Cypselas types with their species are presented through the artificial key. Thirteen qualitative and quantitative variables were utilized to construct cluster analysis, including hilum position, degree of pubescence (surface hair), apex, presence or absence of pappus and awns. The variations among these features were the cornerstone to delineating studied taxa. Here we report the cypsela morphological characteristics of 11 species from 8 genera of Heliantheae (Asteraceae) for the first time in Pakistan and Kashmir, using Stereomicroscopy and Scanning Electron Microscopy.