Development and ultrastructure of Cucurbita pepo nectaries of male flowers

The development of the nectary of the male flower of Cucurbita pepo L. was studied from 5 d before to 2 d after anthesis. The nectary consists of parenchyma that stores starch in the presecretory stages, and epidermis. An hour before nectar secretion begins, the starch is hydrolyzed. The nectar exudes from the stomata and forms a continuous layer on the nectary surface. During anthesis the nectar may all be collected by pollinators or some or all of it may remain in the nectary and be successively resorbed. The nectary parenchyma stores material for synthesizing the sugar component of nectar and stores similar material again after nectar resorption. It is also responsible for nectar production and secretion. The epidermis is actively involved in the reabsorption process. The resorption of nectar is a phenomenon that allows the plant to recover invested energy. Few observations on this phenomenon have hitherto been published.