Autumn Leucojum autumnale L. and spring L. trichophyllum Schousb.: the same flower type for different seasons with a different pollination scenario

Abstract

Some reproductive aspects of plant species may be conditioned by their flowering phenology. This might affect both the diversity and abundance of pollinators and the plants that constitute the community and, in turn, influence the degree of competition for pollinators. This study analyzed the plant floral display, floral rewards, and the pollination and breeding systems of two related species of Leucojum with different flowering phenology, the autumn-flowering L. autumnale L. and the spring-flowering L. trichophyllum Schousb. The main aim was to discover differences between both species that could be modeled by their differing flowering phenology. Our results showed that both species needed pollinators to reproduce sexually, with zero (L. trichophyllum) or almost zero values (c. 7.7%; L. autumnale) for fructification after self-pollination vs. over 90% after natural pollination (both species). Their flowers opened in the morning and closed at night, and neither produced nectar, only pollen as reward to pollinators. Plants of the L. autumnale population studied produced 1 to 4 inflorescences per plant vs. only 1 in L. trichophyllum, and the former presented a greater density of flowers per surface unit. Leucojum autumnale flowers were visited by Himenoptera in the morning and those of L. trichophyllum only received visits from two Coleoptera, these being most abundant at sunrise and sunset, whereas in the middle of the day they visited Cistaceae flowers. This latter occurrence represents facilitation rather competition in relation to visiting hours.