Notions
January 31, 2014 / Little Stories of Seed Travel
Say you’re a plant. You’ve germinated, grown, made your flowers, got them pollinated—and now your pollinated ovaries have ripened into seeds. Your final task this year is to send the seeds off somehow so they can start their own lives (kind of like being a parent). You want to be sure they have a good chance in their new life, so you don’t want them right next to you, competing for your place. How to do this?
It turns out that plants have a lot of strategies for getting their seeds to travel away from home.
There are the Shooters. Violets are shooters: their seeds form in three-parted capsules, which as they dry, shrink and squash the seeds, and suddenly the whole thing explodes open and there go the seeds. A plant called Jewelweed is a shooter, too, a famous one. Its seed capsule is held in a line by a couple of straps under tension, and when it’s touched ZAP! the little straps curl up and the brilliant turquoise-colored seeds are shot as much as four feet.
You already know some Sailers and Flyers. Such as Dandelions, right? After all the flowers on a dandelion head have bloomed (each “petal” is actually a complete flower, and makes a seed), the head closes up for a few days to let the seeds mature, and the stem gets longer to make a higher launch pad. Then it opens up and all those little parachutes, each with a seed at the end, fly off. Milkweed is kind of like that, too, except that it lets its downy seeds go just a few at a time, so as not to go in a heavy, non-waftable clump. “Away they all flew like the down on a thistle” indeed—maybe as much as a mile away from Mom.
How about Floaters? Well, there are coconuts, which if they fall into the water can go for hundreds if not thousands of miles before reaching land and finally germinating. Bye, Mom! Send you a postcard when I get there! Yellow Waterliles that you see on ponds have got a complicated plan. After the waterlily is pollinated, its flower stalk coils up, pulling the developing seed-head under water. Hundreds of seeds mature there, under the water, inside a kind of bag. Eventually the bag thing (called an aril) breaks off, floats to the surface, lets the seeds go, and they sink down to the bottom of the pond, where they hang out and germinate the following year. Kind of boring but they are patient.
A plant called a Campion uses the Shake ‘n’ Drop method. Its little bitty seeds just sit in a pretty brown scalloped open cup where the flower used to be. An animal walking by, or the wind, twitches the cup and the seeds spill out. Columbine has a little more complex method of shake ‘n’ drop: its flower points down until it’s pollinated, when it turns up. The seeds develop in a little set of five tubes. When the tubes dry, they open up and the seeds fall out. Not too far from Mom.
Of course, there is the Stick 'n' Ride method. If you have a dog you know this one. Queen Anne’s Lace and a bunch of others use this technique. They have artfully-crafted seeds with grabbers on them, which will hitch a ride on you, your dog, a mouse, a bird, or anything else that happens to brush up against them, and off they go to their new home.
You probably also know the Twirl ‘n’ Drill technique. If you have a yard, and a maple tree near it, you may go around in the spring pulling up the seedlings planted by this method. The seeds are what we used to call helicopters when we were kids: a little sail at one end, and the heavier seed at the other end. When they fall, they twirl around prettily because of the seed-end’s weight. The seed hits the ground first, and although it may be far-fetched to call it “drilling,” who has not seen one of these helicopters seed-end down in the grass?
Then there is the delightfully-named Eat ‘n’ Poop. If you make a nice fruit around your seeds, as you do if you are a cherry or a rose or a blueberry or sumac or—there are lots and lots of you—you are counting on hungry mammals or birds to eat this fruit and pass its seeds through their digestive loops, with the end result, as it were, of pooping out the seeds. Lots of you eat ‘n’ poop plants actually need to have your seeds go through animal guts, so as to remove the seeds’ outer coating. See, you really want your seeds to be carried far away from you, giving them a better chance to thrive, so you want to be sure they travel a while within their living carrier. Neat, isn’t it? You eat ‘n’ poopers are so clever!
There are classy plants which use the Grab ‘n’ Carry method. Bleeding Heart is one of them. Attached to its seeds is a tasty, oily packet called an eliaosome. Ants love eliaosomes! They are attracted to the seeds by the reward of this bit of food; they grab the seed, carry it back to their nest, eat the treat or feed it to their young, and “plant” the seed by simply ignoring it.
How about Do It Yourself? A water-dwelling plant called Arrow-Arum forms seeds at the tip of a thing called a spathe. Sometimes the seeds drop off from here, but if they don’t, no worries, the spathe turns downward, drills into the mud, and plants its own seeds. Thus taking matters into its own—whatever.
Finally, of course, there is what I like to call Anthroforming. Anthroforming is when a plant is so alluring to humans that they will nurture and cultivate it. I bet you have tended at least one anthroforming plant—all the things in those pretty catalogs that come in the spring. But most astonishing are all those plants we eat and feed to our food animals. All of them—corn, wheat, rice, oats and all the others—they have given over their seed travel arrangements to us. That’s why we call them “domesticated.”
Plants: The Other Wildlife.