Phyllary characteristics of wild perennial Helianthus L. species

Abstract

Phyllaries or involucral bracts surround capitulum of Helianthus L. species, play an important role in dispersion, pollination, seed germination and may protect the inflorescences against predators and negative effects of environmental factors. The aim of this research was to conduct comparative micromorphological and anatomical analyses of phyllaries of 19 wild perennial Helianthus species. Plant material was hand-collected at the time of physiological maturity. For anatomical analyses cross-sections were obtained from the middle part of the phyllaries using cryotechnique procedure. Micromorphological observation, morphological and histological measurements of phyllaries were performed using light and scanning electron microscopy (SEM). Phyllaries are arranged in three or four circles. The analyzed species showed significant differences in the size of outer phyllary leaves.