The adaptive role of nectarial appendages in Colchicum

A few species within the genus Colchicum of the Colchicaceae family, a small group of species native to the transitional belt of the Mediterranean and the Middle East deserts, are characterized by unique morphological traits: nectarial appendages that occur at the base of the perianth segments and consist of two lamellae with teeth. The morphology of the nectarial appendages was measured in three species and in a new population with similar traits to this group for the first time. Nectarial appendages and nectar standing crop are larger for the inner whorl of perianth segments in all species, although the perianth segments are themselves usually smaller. Intact flowers received more ant visits in outer than in inner whorl perianth nectaries. Removal of the nectarial appendages resulted in an opposite trend, implying that these organs prevent ant access to nectaries. Ant access to flowers reduced nectar standing crop, which could reduce the fitness of the species assuming that ants do not pollinate. The role of nectarial appendages as nectar-theft deterrents is reinforced in light of the group's harsh habitat and flowering season.