Halfway up the mountain, along a trace of a road long gone back to woods, there was a village that is no longer there. More than a century ago, some two dozen rough-hewn homesteads were nestled into this boulder-strewn glade. Nobody ever tried to plow fields here. Wild-harvested and small garden foodstuffs were gathered and stored by season, and animals were hunted or raised for all their gifts, including food, companionship, and hard labor. Common to these hardscrabble farms were orchards containing apples, serviceberry, hawthorn, and elderberry. Today, engulfed in the tangled wild, all that remains are stone foundations and the crumbling skeletons of old apple trees, starved for lack of light. In a few places where patches of sunlight prevail, there’s the curious presence of younger fruit trees and shrubs. The homesteaders are long gone, so how did the fruit trees get here in such concentrations? Forget Johnny Appleseed. Those that sowed the seeds of these plants were birds and bears, fishers and foxes.
A seed’s purpose in life is to disperse, settle down, and germinate. With persistence and luck, a seed will sprout, reach for the sun, and live long enough to flower and make more seeds. That’s the plan. A seed’s journey – whether it is encased in an apple, embossed on a strawberry, or set aloft to ride the wind as the downy tuft from a dandelion – benefits from an amazing suite of strategies and design. And animals, including insects, birds, mammals, and even fish and reptiles, are all too willing to lend a hand. Indeed, over 100 genera of North American plants depend upon coevolved, mutually beneficial partnerships with animal seed dispersers.
In the evolutionary scheme of things, seeds are tough, enduring, and remarkably adapted to seize upon special opportunities. In Carolyn Fry’s impressive book Seeds: A Natural History, we learn that “in ecosystems where wildfires occur regularly the presence of smoke can act as a trigger for germination; this signals to the seed that the vegetation above has been cleared and competition removed.”
Woody seedpods of Arctic lupine are capable of incredible longevity. Seeds discovered in fossilized lemming burrows, frozen and buried beneath as much as 18 feet of Pleistocene glacial sediments, can still sprout and grow today. Closer to home, our native pin-cherry seeds may lie dormant in the soil for decades before increased sunlight and changes in soil temperature induce them to grow. Foxes, coyotes, martens, black bears, ruffed grouse, and hermit thrushes eagerly consume the tree’s shiny red drupes and then wander off to plant more seeds with their moist and nourishing excrement. Deer mice, chipmunks, and red squirrels may collect the seeds from the feces and store them. Not all these stored seeds are eaten, however, and so the life cycle goes on.
Wind and water provide other ways for a seed to get away from a parent plant. We can all appreciate the utility of a coconut floating in an ocean to land upon some distant island. Here at home, I have observed a similar phenomenon. Following a dump of some six inches of rain, I was examining conditions along a tributary of Mill Brook as it raged with floodwater, when I noticed numerous speckled-alder fruits rafting down the brook’s turbulent flow. Over several minutes, hundreds passed by. The fruits’ conical structure, with air spaces between scales supporting nutlet seeds, enabled them to be fully buoyant, carrying the wetland trees’ precious cargo to some promised land.
Worldwide there are many marvelous winged seeds, including our own region’s familiar elm seeds, which have a papery circle of wing tissue. Ashes and maples bear single- or double-winged samaras. Even minute birch seeds are surrounded by wings that enable them to flutter to the ground and dash across a hard snowpack with help from the winter wind.
Tiny, densely packed flowers on willows and poplars are perfectly set up for wind pollination. Thousands of these late-summer seeds, suspended in air by tufts of white, silk-like hairs, look like snow and remind us northerners that winter is near.
Some wind-blown seeds become attached to animal fur, though they may only ride for a short distance before being brushed, groomed, or blown away. On the previous page, notice the goldenrod seed on the face of the handsome “silver fox,” which is a black furred color phase of the more common red fox.
An unusual dispersal method employed by some plants has been described as “ballistic expulsion.” Squeeze the ripe fruit of jewelweed, also aptly known as “touch-me-not,” and the five-chambered seedcase will explosively eject seeds in your face! Witch hazel also catapults its seeds away from the seed capsule – as far as 20 to 30 feet.
Some plants employ the strategy of self-propelling their seeds. The noxious nonnative weed of the American west, the tumbleweed, dies – pulls up stakes, as it were – and detaches from its roots. It’s now free to roll with the wind, scattering its seeds along the way. Wherever it comes to rest, still more seeds are released.
Other plants are designed to have their seed dispersal units, called diaspores, attach to an animal. Hooks, barbs, burrs – even a sticky, adhesive surface or gluelike substance – gets the job done. Sticking to an animal, bracts hold tenaciously to fur. When pulled apart or simply broken apart over time, the seeds are released. The wood bison of Manitoba has a woolly coat that’s a perfect attachment surface for the burdock’s hooks, and a vast habitat through which he may travel and sow the seeds. It’s no surprise, then, that in tallgrass prairie ecosystems, the bison is a species that profoundly shapes the biodiversity of the land. Dozens of ingested forage plant seeds are dispersed in bison droppings, and as many as 76 species of seed stowaways have been documented in hair samples. Humans are good dispersers, too, as we know from the seed hitchhikers found clinging to our boot laces and wool trousers whenever we go afield.
Birds, of course, have famously mutualistic relationships with seeds. It’s believed that bright red and purple fruits especially attract bird frugivores because they stand out like signal flags directing the birds through a sea of foliage to the foods they seek. While color is the “dinner is served” attractant for avian seed consumers, mammals key in on aromas wafting from ripe fruit. Here in our woods, the omnivores – including raccoon, striped skunk, opossum, fisher, American marten, red and gray fox, coyote and black bear – are quick to indulge.
Black bears have particularly catholic tastes. When analyzing the contents of their scat nationwide, I’ve identified 56 plant species, and I’m certain that’s not all. It’s no coincidence that so many fruits ripen when bears gorge in preparation for hibernation, and birds for migrations. For a short trip, the best option for seeds is to book a flight with a bird; for a longer journey, the mammals, especially the black bear, are the best travel agents in town.
Last fall, I was scouting a friend’s property to look for animal sign in an extensive wild orchard, which we’ve been restoring for several years by releasing crown space for hundreds of apples and hawthorns. Our work has really yielded results – healthy, leafy branches and tons of fruit for wildlife.
I have a soft spot for hawthorns, though their nasty spines occasionally remind me of just how soft I am. How can a bear, or any critter, possibly access the fruits from these trees? I no sooner wrapped my mind around the absolute impossibility of getting by the hawthorn’s fortress of spines when, voila, I saw a big pile of fresh bear poop full of brightly colored hawthorn seeds.
Susan C. Morse is founder and program director of Keeping Track in Huntington, Vermont.