As with animals, the individual male and female sex cells contained within flowers are called gametes.
The male gamete is contained within small granular storage structures called pollen. Pollen is produced at the end of a slender stalk, or filament, on a structure called an anther. Together anther and filament form the male component of the flower, or stamen.
The female component, or pistil, consists of three parts: an ovary—usually at the base of the flower— from which arises a stalk called the style, bearing a sticky landing pad called a stigma to which pollen adheres.
The ovary of a flower contains one or more unfertilized ovules. Upon fertilization an ovule joins with sperm to form a single cell called the zygote. The entire structure of the flower is adapted with this process as the goal. As this zygote grows, it divides into a multicelled structure that we recognize as a seed. In some plants, ovary walls, called the pericarp, enlarge to form a fruit containing the seeds. These fruits may be soft and fleshy like an apple, or dry and hard like a walnut. Whatever its form, without fertilization, fruit will not develop. In fruits that contain multiple seeds, all ovules must be fertilized for the fruit to reach its maximum size.
In addition to the structures listed above, a flower may have other parts. Some of these include a series of short green leaves, called sepals, which form a protective calyx around an unopened flower bud. The petals, or corolla, together with the sepals, form the flower’s perianth. The entire flowering structure is borne on the receptacle of the pedicel, or flower stalk.
It is worth noting that while all plants reproduce, not all plants flower. Primitive plants such as mosses and ferns produce spores in a reproductive process similar to that of fungi.