Flower closure enhances pollen viability in Crocus discolor G. Reuss

Abstract

Repetitive flower closure (nyctinasty) is influenced by various regulatory mechanisms, but its ultimate function remains unclear. It is hypothesized that closed corolla may protect a plant's reproductive organs against various unfavourable environmental conditions. We investigated if repetitive flower closure enhances pollen viability and prevents pollen loss in an early spring flowering species, Crocus discolor, occurring in open grasslands of submontane to subalpine zones of the Western Carpathian Mountains. Artificially interrupted temporal petal closure resulted in lower pollen viability, but it had no effect on the pollen availability in flowers. The latter result suggests that wind did not cause pollen loss from open flowers, but whether closed corolla may protect reproductive organs from being damaged by hail or rain remains to be tested. Closing corolla may serve as a pollen protection mechanism, particularly in early flowering plants facing harsh environmental conditions.