As you travel about Montana’s fall and winter landscape, you’re bound to see the brown and gray patchwork of roadside weeds. We tend to classify weeds as those nuisance plants that grow where they are not wanted. It’s a rather subjective definition. Often the “weedness” of a plant rests in the eyes of the beholder. One person’s weed may be another person’s wildflower. To me these remnants of summer look like survivors the morning after a great party.
Many weedy plants, like cheatgrass and thistle, are not native to this area. So how did these uninvited guests get here? You might discover the answer if you get out to gather some dried plants for a winter bouquet. Your wool mittens will soon be bristling with “hitchhiking” burrs and seeds.
Weeds exhibit a hardiness characteristic of plants that grow where they are not wanted. A weed is a pioneer species, an aggressive opportunist that takes advantage of land disturbed by human or natural activity. It is advantageous for weedy plants to colonize quickly. So they grow rapidly, have a huge seed output and have adapted for efficient seed dispersal. Lasting into winter is important to these plants to give them extra time to scatter their seeds.
Weed seeds are particularly well adapted for traveling. Otherwise, they would fall directly under the parent plant and overcrowding would soon prevent most seedlings from growing. Many plants have evolved ingenious methods to ensure that their seeds reach places where seedlings can grow successfully. Plants such as dandelions, thistles and milkweed produce downy seed parachutes that drift with air currents. The seeds of wild oats wiggle and jump along the ground as they get alternately wet and dry. The hitchhiking seeds of houndstongue have hooks that catch on to animals, giving their seeds a free ride. Another means of hitchhiking is used by plants with seeds that develop in a fruit eaten by a bird or mammal which then pass through the animal’s digestive tract and are deposited some distance away.
Weed seeds are quite hardy and can outlast the rigors of winter until conditions are favorable for germination and growth. As Ralph Waldo Emerson said, “A weed is a plant whose virtues have not yet been discovered.” Despite their bad reputation, weeds provide food for birds and homes for wintering insects. If you look closely, you may even discover a rugged beauty in their ability to withstand winter to ensure their seeds’ dispersal.
"Field Notes" is produced by the Montana Natural History Center.