Ovules of a cactus flower. Coloured scanning electron micrograph (SEM) of the ovary of an orchid cactus (Epiphyllum sp.) flower showing ovules (eggs, light green) attached to a funicle (stalk, green). Ovules consist of an embryo sac containing an ovum (egg cell). This is the female gamete. This is surrounded by tissue known as the nucellus, which provides nutrition for the egg. If fertilised by pollen (the male gamete), this egg becomes a seed.