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

Plant reproduction may experience distinct evolutionary and ecological dynamics depending on their flowering phenology. Consequently, floral traits might undergo divergence selection to adapt to the difference in the abiotic and the biotic environment, especially if these traits affect intensity of competition plants experience due to pollinators. The present study analyzed the plant floral display, floral rewards, and the pollination and breeding systems of two related species of Leucojum, the autumn-blooming L. autumnale and the spring-blooming L. trichophyllum. The aim of the current study is to compare reproductive aspects of L. autumnale and L. trichophyllum due to differing environmental conditions. Both species needed pollinators to reproduce sexually, with zero (L. trichophyllum) or low 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 studied population produced 1–4 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 Hymenoptera and those of L. trichophyllum only by two Coleoptera, which were most abundant at sunrise and sunset, whereas in the middle of the day, they visited Cistaceae flowers. This latter occurrence may represent a temporal niche partitioning rather than competition in relation to visiting hours, as the L. trichophyllum flowers offer a place for insects to spend the night, a period in which the flowers of the Cistaceae species have lost their petals.