Try this: Put on a pair of white socks—and a pair of shoes, of course. Go outside and find a roadside ditch or empty field. Walk through it. Then check your socks. You’ll probably find lots of plant “junk” stuck to your socks. Pick these little stickers off and take a careful look. You should find several seeds hitching a ride.
Seeds hitchhiking a ride on your socks is one way plants make sure—actually, the Creator makes sure—that they will spring up again next year. Even if the original plant doesn’t survive the winter, the seeds probably will. The more seeds each plant scatters, the more likely that kind of plant will survive.
But seedy hitchhikers don’t just depend on your socks for transportation. They have lots of cool ways to move around. Read on to find out some of their hitchhiking methods.
And here’s a challenge: Go back outside and count how many seedy hitchhikers you can find!
Hooks and Barbs
You know how hard it is to pick burrs off your pants or socks or your dog’s fur, right? Well, those sticky burrs are just certain kinds of grass seeds trying to plant themselves. They grab hold and won’t let go until you pull them off. Most people probably throw them into a wastebasket where they can’t grow. But animals don’t.
These burrs—and any kind of seed with hooks or barbs—usually hook themselves to animal fur. Eventually the animal pulls them off and drops them far away from the original plant.
Lots of plants that aren’t very noticeable grow hooked seeds. That makes sense—since no one’s going to pick them up on purpose, they have to grab a ride themselves.
Spit Those Pits . . . or Not
Do you like apples? How about watermelon, peaches, or pears? When you’re eating these fruits, you probably spit out the pits or throw them away in the garbage, right?
Animals like fruit too. Deer forage for apples; bears love blueberries; raccoons feast on berries. But unlike you, these animals don’t spit out the pits. They gobble up the whole fruit, pits and all. The pits go through the animal’s digestive system and come out, unharmed, in its droppings. Voilà! The fruit’s seed has traveled away from the original plant.
The seeds of some wild plants actually have to go through an animal’s digestive system before they can sprout. Usually the animal involved loves that kind of fruit. Can you think of why that might be? For sure it’s no accident!
Parachutes and Windsurfers
Some seeds spread by parachuting away from “home.” Milkweed, dandelion, and goatsbeard are just a few plants whose seeds are attached to designed parachutes. Some are made to close when the humidity is very high. That way the seed hits the ground right before a rainstorm. Often these seeds have little backward-pointing barbs designed to keep the seed in the soil after it lands.
Windsurfing seeds float lazily on air currents. A thistle seed called thistledown does this. So do some types of daisy seeds. If you notice a seed that has fluff without a definite design, it’s probably a windsurfer.
Here’s another challenge: Try to catch some of those parachutes and windsurfing seeds. It might be harder than you think! It almost seems as if some of them are designed to elude your grasp. If you do catch one, take a careful look at it and try to figure out whether it’s a parachute or a windsurfer.
Swimmers and Floaters
Have you ever floated down a river on an inner tube or water-skied behind a boat? That’s what seeds from waterside plants do. Some, such as watermint and foxglove, do this without a “tube” or “ski.” The bare seeds simply float on the water.
Others, such as weeping willow trees that grow along a riverside, produce fluffy seeds that float. It’s as if they have their very own “wetsuits” made of waterproof fluff.
Still other trees have “wetsuits” that are thick and insulated. Think of coconut trees growing on tropical beaches. Their seeds can float, protected, in salt water for months.
“Do-it-yourselfers” are plants created to shoot, pop, spit, or blow their seeds as far from the plant as possible. Each plant goes a little ballistic trying to send its seeds away from home—and each does that in its own way.
Lupines, for instance, make long, bean-like seedpods. When the seedpod dries, one side dries faster than the other. That makes the pod twist or bend and snap open, shooting out the seeds.
Wild geraniums fling their seeds out from the pods using a method that is very intricate and complicated.
Wood sorrel seeds are covered with an elastic-like coating. That coating dries out in the sunshine and then suddenly breaks like an old rubber band. The seeds shoot out as if someone had launched them with a slingshot.
Do-it-yourselfers aren’t really hitchhikers. But like the hitchhikers, they are a very cool part of the plant world.