D. Sammataro, E. H. Erickson, Jr. And M. B. Garment
Honeybees (Apis mellifera) exercise distinct foraging preferences among sunflower (Helianthus annuus) seed-parent lines and hybrid cultivars. Floral nectaries of over 100 sunflower cultivars/species were examined and compared to develop correlations between particular anatomical characteristics and honeybee predilection. The nectary, as revealed by light, scanning and transmission electron microscopy, may be circular or a 4- to 8-sided ring surrounding the base of the style directly above the ovary. Size of the nectary and number and placement of stomata differed among the genotypes and species studied. Florets of highly attractive genotypes had larger nectaries with more stomata than florets of less attractive ones. Results suggest that nectary characteristics may be heritable and that it may be possible through breeding to alter the relative attractiveness of plants to honeybees.