Andromonoecy in Colchicum steveni (Liliaceae) frequency, phenology and reserve allocation

Colchicum stevenii, an autumnal geophyte in Israel, was found to be andromonecious. Examination of the phenomenon in relation to the corm size, flowering rank, flower size, and habitat indicated that hermaphrodite flowers are larger and have a greater dry weight than male flowers. Within each individual, hemaphrodite flowers always appear at the beginning of the flowering sequence, whereas male flowers appear at the end. Smaller corms produce fewer and smaller flowers, but with a high percentage of male flowers. Populations in dry habitats have smaller corms and relatively more male flowers, and fewer and smaller flowers per individual plant, in comparison with populations of more humid habitats. The adaptive value of "sequential andromonecy" is discussed. The results are in accord with the hypothesis that under stressful conditions the individual plant allocates more reserve to male flowers.