These plants have evolved in scores of angiosperm families. Most species that have been studied secrete glucose, fructose, and sucrose plus some protein, amino acids, and organic acids. The cells of the extrafloral nectary have densely staining cytoplasm and an inconspicuous vacuole, and the nuclei are large. Characteristically, there are many plasmodesmata connecting these cells through radial and basal cell walls. Cytoplasm stains very densely because it has very high concentrations of ribosomes and mitochondia, along with quantities of rough and smooth endoplasmic reticulum with abundant vesicles.
Golgi apparatus tend to be more abundant in developing cells than when mature and secreting.
Phloem usually ends close to the nectary, and is the obvious source of the carbohydrates, but sugars must be transported across a few cells to reach the secretory layer. By some accounts, the sugar collects first beneath the cuticle before rupturing occurs. Experiments done on plants with extrafloral nectaries has dramatically shown how plants guarded by ants have high success, whereas without ants they can succub to very heavy foraging by other animals.