Floral nectary development and nectar secretion in three species of Passiflora were investigated with light and electron microscopy. The nectary ring results from the activity of an intercalary meristem. Increased starch deposition in the amyloplasts of the secretory cells parallels maturation of the nectary phloem. Large membrane‐bound protein bodies are observed consistently in phloem parenchyma cells, but their function is presently unknown. The stored starch serves as the main source of nectar sugars at anthesis. Plastid envelope integrity is maintained during starch degradation, and there is no evidence of participation of endoplasmic reticulum or Golgi in the secretion of pre‐nectar. It is concluded that in these starchy nectaries granulocrine secretion, commonly reported for floral nectaries, does not occur.
Extra‐floral nectaries of nine species of Passiflora were studied with light and electron microscopy prior to and during secretion. There is no evidence of ER or Golgi participation in the secretion of nectar. The vascular tissue supplying the nectary is characterized by companion and phloem parenchyma cells which are usually larger than the sieve elements, a configuration similar to that found in leaf minor veins. In the petiolar nectaries, large masses of membrane‐bound protein are commonly found in these cells. This protein is absent in laminar nectaries.
Petiolar, bracteolar, and stipular glands from two varieties of Passiflora foetida were studied by both light and electron microscopy. These glands have previously been called nectaries. They do resemble the sugar‐secreting glands of other Passiflora species with respect to their location and morphology. However, cytological studies together with chemical tests of the exudate support the view that the glands in the varieties studied actually secrete a resin‐like substance which possibly functions as an anti‐herbivore mechanism.
Petiolar, bracteolar, and stipular glands from two varieties of Passiflora foetida were studied by both light and electron microscopy. These glands have previously been called nectaries. They do resemble the sugar‐secreting glands of other Passiflora species with respect to their location and morphology. However, cytological studies together with chemical tests of the exudate support the view that the glands in the varieties studied actually secrete a resin‐like substance which possibly functions as an anti‐herbivore mechanism.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.