How Pollen Works

Flower Power and Pollination

In this flower, the stamen ring the carpel, of which the stigma and style portions are both visible.
In this flower, the stamen ring the carpel, of which the stigma and style portions are both visible.

Some plants -- the angiosperms -- evolved to take the pollination process a step further. These are the flowering plants, and not only do they produce seeds, they also flower and produce protective fruits. These reproductive safety nets are also better at luring mobile organisms into assisting them successfully complete their life cycles; in fact, many evolved in tandem with the creatures who pilot the pollination process. In terms of species, angiosperms are the most prolific type; many species of trees and shrubs, along with all manner of fruits, vegetables, grains, cacti and wildflowers are considered angiosperms [source: Raven].

So let's look at how this works in your typical flower and dig down a little deeper into the development of pollen in general. Pollen grains are created through the process of meiosis, during which cells divide and grow in number. The grains of pollen are often located in pollen sacs on the ends of the stamen (the male parts of the flower), which typically surround the carpel (the female parts of the flower). The stamen generally come in two sections: the two-lobed anther, which house the pollen sacks, and the filament, the stalk on which the anther perch. Each grain gradually develops a tough outer wall to shelter it during its journey.

Once it's deposited at its destination, grains of pollen settle on a flower's stigma -- the entrance to the ovary. Like with the gymnosperms, germination and pollen-tube formation follow fertilization, but this time both sperm are used. While one fertilizes the egg cell, the other is tasked with fertilizing another cell that will develop into the endosperm, which is what growing plant embryos consume before and during the sprouting process.

Different flowers grow in different configurations, and while many, in fact the majority of angiosperms, carry both stamen and carpal components, some do not. For those species, male and female reproductive parts can be found on different flowers of the same plant -- similar to how many gymnosperms' pinecones are commonly configured. Or, in some cases, each particular plant specimen may feature only one or the other, varying the process slightly.