Micromorphological studies on Heracleum L. (Apiaceae) in Poland with emphasis on ovary ornamentations and trichomes

The ovary surface ornamentation, pilosity and hair types were observed under SEM in Polish taxa of the genus Heracleum: H. sphondylium subsp. sphondylium and subsp. sibiricum, H. pubescens (ephemerophyte from two new localities), H. mantegazzianum and H. sosnowskyi. Diff erences of taxonomic signifi cance were found in the pilosity and ornamentation of the ovary surface. Pilosity of ovaries supports intraspecies variation reported to date in H. sphondylium, but these features are not correlated with any other characters in either subspecies. The ovary surface was either rugose with secondary striations or smooth. The ovaries were glabrous (in H. sphondylium subsp. sibiricum) and more or less densely covered by hairs in the other taxa. Examined taxa exhibit a considerable homogeneity of trichome structure, they are nonglandular, but diff er in their size and shape, with several diff erent types distinguished for: macrohairs, setae, prickles and papillae. The microsculpturing of trichomes varies from smooth, striate to tuberculate. Results of this study provided data on new qualitative traits of ovary epidermal structure, which may be used in identifi cation of Heracleum specimens.