Floral Anatomy
by Nancy C. Pratt and Alan M. Peters
Flowers
can be either male or female or both. In some species, different
plants within a population produce either male or female flowers.
In others, a single plant produces only male flowers part
of the year then only female flowers in another part of the
year. Still others display both male and female flowers on
the same plant. By far the most common arrangement is having
both male and female parts within each flower. No two species
of plant have identical floral anatomy, but this diagram illustrates
a typical flower with both male and female parts.
The stamen is the male part, producing pollen (made up of spermlike cells and protein) on its anthers. The pistil, the female part, either receives pollen from the same flower--in which case, the flower self pollinated--or from a different flower of the same species--cross pollinated. A pollen grain, whether blown by the wind or carried by an animal, lands on the stigma, which is a receptacle for the style, a long tube that empties into the ovary. The pollen grain then develops a pollen tube that grows down the style to reach the ovary. It then releases the male gamete, which passes down the tube to fertilize an ovule in the ovary. The fertilized ovule develops into a seed and the ovary eventually becomes the fruit.
Return to Pollination
(ZooGoer 24(4) 1995. Copyright 1995 Friends of the National Zoo. All rights reserved.)
