Olivia Judson has a great piece in The New York Times today about the sex lives of plants. Plants, just like the rest of us, have, over millions of years, worked out strategies of sex and reproduction that successfully perpetuate their kind, but, as Judson points out, the plants' sex lives come with some unique obstacles.
The most obvious obstacle is that the plant can't move around to find another of its kind to hook up with and so it has to depend on intermediaries. Flowers are the plants' vehicle for delivering their sperm and egg cells to the appropriate recipients and they essentially have two ways of getting those precious bits of matter to combine and make a new plant.
One of their allies in reproduction is the wind. It is a bit quirky and unpredictable it is true, but about ten percent of flowering plants do use the wind to spread their pollen. Since the wind goes its own way and is a bit unreliable, wind-pollinated plants tend to produce huge quantities of pollen as anyone who lives in pine country can attest. Very soon now our air will be turning yellow with mass amounts of pine pollen and people will be suffering from itchy eyes and tickling noses for the duration of the pine sexual orgy.
The other ninety percent of flowering plants take a more direct and intimate route to pollination by attracting individual pollinators like bees and various other members of the insect family and birds such as hummingbirds. The flowers attract these pollinators by offering them something they need - food in the form of nectar. In the process of consuming the nectar, the little pollinators pick up bits of pollen which they then carry to the next plant, completing the cycle of fertilization. It's a win-win situation.
It's interesting, but probably irrelevant, that the plants that use bees as their pollinators are also attractive to humans because they are bright and colorful and they smell good. But it's important to remember that all of this color and scent is for the bees or the other pollinator insect. It isn't for us.
Even so, we can be very grateful that these creatures are such efficient pollinators and that plants vie for their attention. In the process, the Earth has bloomed and our lives have been made a lot more colorful and pleasant.