This is a post for my sister, Emily, who is currently working at a camp in the mountains, teaching about nature to Los Angles middle-school kids. Apparently, she’s having trouble getting them interested in plants. Luckily, I love plants. So, this is only the beginning of my kid-friendly reasons that plants are awesome. In no particular order:
#1 Plants use showy colors, fragrances, and free food to entice insects and birds to help them have sex. Okay, you can say mate or reproduce if you are worried about the repercussion of talking about sex with 6th graders, but the point remains that when we talk about flowers, we’re talking about sex. Most plants, rooted to the soil, can’t get up and chase a mate, they can’t decide to mate with the male who sports the best display of tail feathers or the strength to win fights. They are stuck. Which is where the flowers come in.
Plants give away free food, pollen and nectar, because as the pollinators go from flower to flower, they spread the reproductive cells in the pollen around. Promiscuous sex! Flowers have evolved for the pollinators they want. Specific smells, colors, and shapes, all attract specific pollinators. This specificity matters, because, from a plant’s perspective, they don’t just want to spread themselves out every which way. Although some do produce tons of small, aerodynamic pollen, and let the wind do their work for them. However, the only pollen that succeeds is the pollen that arrives at another flower of the same species. So, the logic follows, that you’d want a pollinator to be committed to your species, and not totally promiscuous with all of the other types of flowers. For example:
So, Emily, and anyone else interested in educating kids about the awesomeness of plants, you can look at flowers and try to guess what types of pollinators they are trying to encourage.
#2 Seeds evolved with specific designs for dispersal.
So, this is what happens after the sex, right? Plants spread tons of pollen out into the world so that a few flowers can sexually reproduce. And it gets complicated here, because plenty of plants can self fertilize too, producing seeds without sexual genetic recombination, but we can skip that part with the 6th graders and just move on to the end result- seeds!!
Seeds!! The shape of seeds are the key to their success. Containing a baby plant embryo, a seed must find a successful home for the plant within to grow up, or die trying. How seeds travel the landscape to find themselves a new home can be fascinating. These pink plumes on the above shrub dry out and catch the wind, carrying the seeds out into the world.
Some seeds use the wind even more than just to cast them across the landscape. Stork’s bill, a common non-native flower in the Mojave desert, has seeds that look like little screws with sails, so that when the wind catches one just right, it screws into the soil, or your socks, or tent, or whatever is available.
So while tiny, light-weight seeds with sails often take flight, some seeds are big and heavy, encased in heavy tissues. Why? Because they taste delicious!! Everybody loves fruit! First, bear with me for just a bit of terminology. A seed is a single plant embryo. Seeds are often encased in a fruit, a structure that holds a few to many seeds. Some fruits, those those we commonly think of, are delicious, sweet, juicy things that people and animals enjoy eating. Later, we disperse the seeds when we pass them through our digestive system.
Other fruits are not tasty at all, but instead are structures like a burr, that holds the seeds inside a spiky shell that can get stuck to your fur or socks, and be transported to a new location. Technically, both are fruit. And, whatever the shape, fruit often aid the plant is dispersing the seeds. Which leads us to another fun science game: figuring out what type of travel different seeds are designed to do.
If you follow the Micheal Pollan school of thought, in the Botany of Desire, he argues that some plants have even evolved to be so useful or delicious that they convinced us to do their reproduction for them. We provide the pollinators, sow the seeds, reap the harvest, and repeat. The common wisdom is that we are winning. But, from the perspective of the plants, they’ve succeeded by using our agriculture as their dispersal. Think about that a little too long, and it might blow your mind.
Coming soon, more reasons to love plants. But, in the meantime, help my sister out. Why do you think plants are cool?