For those of us who walk in the woods on a regular basis, a little sadness haunts the air. As spring wanes, so do the perky blooms on many of our native woodland wildflowers. The seasonal show of sweet but subtle blooms is about over. But another is just beginning. To take in of this current production, though, you’ll need sharp eyes, a little patience and maybe a hand lens…
Think back to your high-school biology class. (Or, if you happen to know a first grader who’s attended a St. Charles Park District Seeds-and-Cycles program, ask them.) What do flowers produce? Seeds! And what is the purpose of seeds? To make new plants!
But here’s where the plot thickens. Plants, with very few exceptions, are stationery. Yet they need their seeds to be mobile. If all seeds grew right next to their parents, none would survive. So, over the years, plants have set about developing many innovative ways to spread around their offspring.
As it turns out, almost anything goes. Dandelions and cottonwoods, for example, use wind to disperse their seeds; burdock sends its seeds (a.k.a. burs) hitchhiking on animal fur, pant legs and shoelaces. Meanwhile, oaks depend on the kindness (okay, appetites) of squirrels and blue jays.
Then there are the plants that rely on ants. That’s right, ants. Several of our native woodland wildflowers, such as bloodroot, hepatica, twinleaf, spring beauty, trout lily, trillium, violets and wild ginger, send their seeds packing in the jaws of those tiny but mighty insects.
Folklore has taught us that ants are industrious and hardworking, and that such toil often reaps rewards. Indeed, the whole process of myrmecochory—the $10 word for “seed dispersal by ants”—hinges on ants receiving their just deserts.
The above-mentioned wildflowers are examples of plants that produce seeds with a small, fleshy appendage called an elaiosome (ka-ching–$10 more!). This structure is rich in carbohydrates, fats and proteins—a sort of Happy Meal for ants.
Worker ants haul these seeds back to their home colony to feed the growing larvae. Nursery ants chew off the elaiosome and mash it into a Gerber-like pulp, just right for feeding the tiny white youngsters. Once all of the elaiosome has been removed, the unharmed seed is toted to the ants’ waste pile.
Like people, ants produce a lot of trash. Food remains, assorted debris, dead bodies and frass (only $5 for this one; it’s the scientific word for insect poop) make up these Lilliputian landfills. Rich in nutrients, well aerated and moist, they offer the sort of environment in which seedlings flourish.
A seed minus its elaiosome will grow just fine. The structure really is produced for the ants, and the ants alone. Some elaiosomes are shaped like handles, and may facilitate carrying. Some are sheaths, some look like hats, and some bear a distinct resemblance to the swirl on top of a Dairy Queen cone. Talk about just desserts!
The next time you head out for a walk in the woods, or your own backyard if you’re a native plant gardener, take a closer look at what’s happening beneath your feet. Keep your fingers crossed—if you’re lucky, you may find you have ants in your plants!
Pam Otto works for the St. Charles Park District and can be reached at potto@stcparks.org or 630-513-4346.