Sexual structure of populations of some gynodioecic Thymus L. species (Lamiaceae)

We studied the sexual structure of populations of gynodioecic Thymus L. species - T. marschallianus Wildd., T. dimorphus Klok. et Shost., T. czernjaevii Klok. et Shost., T. talievii Klok. et Shost., T. guberlinensis Iljin. It was rather different. The first three species of the list are from the section Verticillati Klok., which includes steppe and mountain-steppe species. [Klokov, 1954]. These populations had a large rate of female plants (40 - 60 %) that differed from the populations of T. talievii (section Euserpyl-lum Klok., which includes forest, coniferous forest and tundra species) and T. guberlinensis (section Kotschyani Klok., which includes the species from dry and rocky slopes). We suppose that high rate of female plants of T. marschallianus, T. dimorphus and T. czernjaevii is closely connected with high variation of insects-pollinators in steppes. The plenty of pollinators not only promotes successful cross-pollination of androsteryle female plants and effective seed formation, but also maintains high quantity of such female plants in populations.