CHANGE IN FLORAL NECTAR COMPONENTS FROM FRESH TO SENESCENT FLOWERS OFCAPPARIS-SPINOSA (CAPPARIDACEAE), A NOCTURNALLY FLOWERING MEDITERRANEAN SHRUB

We studied the nectar characteristics in relation to flower age of the summer flowering Mediterranean shrub Capparis spinosa in three locali ties in Southern Greece. Anthesis was nocturnal. Nectar volume, concen tration, and sucrose/hexose ratio varied with site, year, and between individual plants: amino acid concentration varied only with site. The sucrose/hexose ratio decreased considerably with flower age, while th e glucose/fructose ratio remained constant (ca. 1), implying that nect ar sucrose broke down in the course of anthesis. Sugar breakdown incre ased with water content of nectar. Amino acid concentration was strong ly age-dependent: It was low in fresh flowers, relatively high in midd le-aged ones (except aspartic acid that was extremely increased), and very high in senescent ones. We attribute the amino acid changes to ph enomena related to flower senescence in the dark.