Plants evolved pollen as a reproductive means more than 375 million years ago, and since then, they haven't looked back [source: Dunn]. A large portion of the plant life that's spread far and wide across the planet today displays this evolutionary ingenuity. The main reason pollen -- and by extension the process of pollination -- is so important, is because it means plants don't have to rely on water to transport the biological components necessary for fertilization. Plants that bear pollen also tend to offer protection to their offspring after fertilization in the form of hard seeds -- and in some cases, those seeds are even nestled inside fleshy fruits.
Pollen grains are, in essence, plant sperm. Or perhaps more technically, sperm sedans. Inside, they contain the male portion of DNA needed for plant reproduction. There's great variation when it comes to the size of pollen grains, and there's no correlation between the size of the plant and the size of the pollen it produces. Large plants might generate some of the tiniest grains of pollen, while diminutive plants may yield pollen that puts those to shame. Pollen grains may not look like much; to the naked eye, they often look like dusty specks, but upon closer inspection, they take an endless array of fascinating shapes with all manner of textures and features.
Whether conical, spherical, cylindrical or some other fantastical shape, many grains of pollen resemble something else, be it coral, succulent, seashell or sea anemone. Some grains are dotted with little spikes; others have weblike surfaces. Still more appear enshrined in ropey tangles, while others sport delicate dimples or have ribs that resemble the stripes on a watermelon.
Many of these unique adaptations are to help the pollen get where it needs to go -- namely, its own species' female counterpart. Surface features help grains cling to different modes of transportation, such as bird feathers, bee legs or animal fur. Or they help pollen sail through the air on appendages that resemble airplane wings or hot air balloons. Some of these features even help a pollen grain perform successfully when it reaches its destination. We'll discuss what happens when that happy event occurs on the next page.