The idea for this experiment comes from my wife, Nancy. I was sitting here at the computer, trying to decide what to write about when Nancy made a comment about how good the flowers on the table smelled. Nancy loves flowers, and always has lots of them around the house. That one whiff and this activity practically wrote itself.
If you are lucky enough to have flowers around your house, take a few minutes and smell them. If you don't have flowers around the house, you should be able to find a variety of flowers at your local grocery, hardware store, or nursery. Once you are surrounded by the flowers, take the time to sniff them, one by one. Keep track of your observations (sniffservations?) What did you notice?
You probably found that if you smell several different examples of the same kind of flower, they all smell pretty much the same. You also probably found that different varieties of flowers have very different smells. Why?
For that matter, why do flowers smell at all? What purpose does the smell serve? To answer that, think about what purpose the flower serves. The purpose of a flower is to get pollen cells from one plant to connect with the egg cells of another plant of the same species, in order to produce fertile seeds to make more plants.
The trick is to move the pollen from one plant to another. Different plants have different ways of doing that. Some rely on wind to blow the pollen from flower to flower. Others rely on water, but the vast majority of plants count on animals to do the work. Spend some time watching flowers in a garden, and you will see a wide variety of bees, butterflies, flies, beetles, hummingbirds, and other creatures busily pollinating the flowers.
How wonderful that those dedicated creatures spend their lives tirelessly helping the plants with no thought of payment or reward! Think again! That is about as likely as me coming over and begging for the privileged of mowing your lawn, and you can ask my Mom how I feel about mowing lawns.
OK, then why do those animals spend their time carrying pollen from flower to flower? Bribes! The flowers produce drops of sweet nectar as bait to convince the bees, butterflies, and other creatures to visit. The pollen is strategically placed so that in order to get to the nectar, the creature can't avoid bumping into some of the sticky pollen. It also bumps into the stigma, where pollen that is already on the little critter can stick to pollinate the flower.
Now that may all be interesting, but what does it have to do with the smell of the flowers? That smell is a way of advertising nectar, letting creatures know that there is good stuff available, but it is also a way of selectively advertising it. Rose pollen is no good for a gardenia. Gardenia pollen is no good for a dandelion.
Each flower needs pollen from a similar plant, so they have developed different colors, shapes, and smells to attract different pollinators. Bees, beetles, butterflies, and hummingbirds all have their favorites, which they visit more frequently. Having a unique color, shape or smell makes it more likely that a flower will get pollen from another of the same species.
Some flowers have smells that are not nice at all (at least to us.) A good example is Rafflesia, one of the world's largest flowers. Its flowers smell like rotten meat. Why? What self respecting animal would be attracted to rotten meat? Flies! What smells horrible to us smells like a wonderful meal to the flies. That greatly increases the probability that a fly will bring pollen from another Rafflesia, instead of some stinky old rose or gardenia.
The same idea works with people. Instead of the smell of flowers and carrying pollen, try using the smell of fresh baked cookies to get me to take out the trash. It works on me every time.