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The paper studies the synflorescence structure and flowering biology of the biennial monocarpic wetland plant Oenanthe aquatica. This species has a set of adaptations to prevent self-pollination, including generation of a pseudanthium, andromonoecy, intra- and interfloral protandry, and a specific sequence of flowering within its umbels. The synflorescence of O. aquatica is a panicle of umbels. The size of perfect and male flowers consistently decreases as the order of synflorescence axes grows. The size-related differences between perfect and staminate flowers on axes of the same branching order consist only in the length of their calyx abaxial teeth, corolla diameter, width of abaxial petals, length and width of anthers, and length and height of stylopodium. We have identified two arrangements of staminate flowers in O. aquatica: male flowers are located at the periphery or in the center of the umbellets. The share of staminate flowers in umbels increases as an axis order grows. The female phase of flowers on axes of one order occurs simultaneously within entire synflorescences with the male phase of flowers on axes of the next order, which might mean geitonogamy. Perfect flowers live for five to seven days, while staminate flowers function for no more than one day.

Изучена половая структура 47 ценопопуляций диэцичной Potentilla bifurca в степном, лесостепном и высокогорном поясах на территории шести провинций Алтае-Саянской горной области. По половому спектру выделено два типа ценопопуляций: с равным соотношением половых форм и с преобладанием женских особей. Полицентричность особей P. bifurca, однополовость рамет в пределах одной сложно устроенной особи, значительное преобладание вегетативного размножения над семенным, высокая скорость разрастания определяют специфику половой структуры ценопопуляций данного вида Sexual structure of 47 populations of dioecious Potentilla bifurca in the steppe, forest-steppe and alpine zones in the six provinces of the Altai-Sayan mountain region was studied. Based on the sexual spectrum the populations were divided into two types: with an equal sex ratio and with a predominance of females. Specificity of sexual structure of populations of the species is determined by polycentricity of P. bifurca individuals, unisexual ramets within one complex individual, significant predominance of vegetative propagation over seed reproduction, and high rate of proliferation