The location of nectaries and nectar secretion in the flowers of Allium giganteum Regel

Abstract

In the flowers of Allium there are found septal nectaries; in particular species, their outlet can be located in different parts of the ovary. The inflorescences of these plants are a rich source of nectar for insects. The location and structure of septal nectaries in the flowers of Allium giganteum Regel were investigated. Light and scanning electron microscopy was used. The septal nectaries were found to be located in the lower part of the ovary and in the gynophore on which the ovary is borne. Nectar is secreted into the nectary slits from which it flows through the ducts to three openings located in the upper part of the gynophore, from whence it gets outside in the vicinity of the expanded parts of the filaments. Sugar concentration in the nectar of A. giganteum averaged 54.5%, while sugar weight per flower was determined to be 0.36 mg. When converted into sugar weight per inflorescence, numbering more than 2,000 flowers, it was 771.7 mg.