Article

The field and laboratory studies about Gagea bohemica (Zauschn.) Schult. & Schult. f., G. chrysantha Schult. & Schult. f. s. l., G. granatellii (Parl.) Parl., G. lutea (L.) Ker-Gawl., G. fragifera (Vill.) Ehr. Bayer & G. Lòpez are carried on community structure, phenology and reproductive biology. The studied species show differences in terms of community characteristics (species composition, structure), time and duration of flowering, and seed production. The species of rocky environment (G. granatellii and G. bohemica) show the highest number of vegetative individuals with respect to the flowering ones, the shortest duration of flowering and the lowest seed-set. It appears as a consequence of the low resource availability. The species of meadows (G. chrysantha, G. fragifera and G. lutea) appear instead to suffer overall the biological competition for resources and pollinators. Gross morphological analysis of the pollen grains revealed that deformed pollen is more abundant in triploid (G. chrysantha, G. granatellii) and heptaploid (G. fragifera) species, compared to the tetraploid (G. bohemica) and the hexaploid (G. lutea) ones. Seed production was very low. There is a positive correlation between amount of morphologically regular pollen and number of produced seeds. In most of the studied species we observed a trend to increase the seed production in individuals with many flowers; probably this is the result of a strategy aimed diminishing the effects of pollen- and pollinator-limitation.