GROWING CONDITIONS AND SEED PRODUCTIVITY OF <i>PINGUICULA VULGARIS</i> (LENTIBULARIACEAE) IN LENINGRAD REGION

Abstract

The growing conditions of Pinguicula vulgaris in the vicinity of the villages Pudost’ (floodplain meadow) and Glyadino (slope meadow, lowland spring fen) in the Leningrad Region were studied in detail, and the seed productivity of its plants was evaluated in these conditions for the first time. Despite a close geographical location and a general confinedness of both populations to the Izhora Upland (to the outcrops of carbonate rocks), they differ in an occupied area and its microtopography, the degree of shading of plants during daylight, and soil moisture (though of similar acidity), and also differ in the species composition of plant communities (richer in Pudost’ than in Glyadino). At the same time, regardless of the differences in growing conditions, the level of seed-setting in P. vulgaris plants in both populations during all the years of research was close and quite high (64–80% in Pudost’, 70–72% in Glyadino), that indicates a high potential for the renewal of the species in the populations by seed propagation. It is noted that the main factors limiting the size of Pinguicula populations in the Leningrad Region are the same as in its other populations of Northern Europe: intense settlement of territories by the species forming a layer with high closeness and height, trampling of soils, unfavorable weather conditions during flowering and fruiting of the plants significantly reducing their seed productivity. However, unlike some subarctic populations of P. vulgaris, where a decrease of seed productivity occurs due to low temperatures at the end of a short growing season and irregular reproduction (especially at the species moving into mountain conditions), in populations of the Leningrad Region (with a longer growing season and regular reproduction), it decreased mainly due to a long dry periods during flowering and fruiting of the plants.