Why Native Plants?
Robin Schachat
Why Straight Species Trees, not Cultivars? What is the Homegrown National Park?
Many ladies of the club have asked me these questions since we settled on the plan for a Shaker Lakes Garden Club Tree Grove to commemorate our club’s first hundred years of membership in the Garden Club of America. I cannot imagine a better way to answer than to discuss a recent webinar I attended led by one of my heroes, Doug Tallamy.
A bit of obligatory background: Doug Tallamy is a Garden Club of America honorary member. He has addressed GCA conservation and annual meetings, and was the prime speaker at a Zone X Meeting almost 10 years ago in Akron. He is a professor of Entomology and Wildlife Ecology at the University of Delaware, and author of many important books, three of which (soon to be four) are important reading for U.S. gardeners in our current age. He has lectured at the Cleveland Pollinator and Native Plant Symposium series founded by our own Ann Cicarella and now partnered by Holden Forests and Gardens, among many other such conferences nationwide. He and his wife garden on 10 acres near Wilmington.
Doug’s breakthrough popular book for gardeners is Bringing Nature Home, and that is precisely what it is about: returning a thriving network of life to our home gardens. When we were children, our gardens were teeming with fireflies as we waited for the fireworks to begin on the Fourth of July. Not anymore. We woke in summer to the sound of the Dawn Chorus, families of baby birds in nests clamoring for breakfast; and just before the sun went down we would hear the songbirds singing away to each other about their activities that day. Not any more. If our parents took us out for ice cream on summer evenings, the car windshields were plastered with moths. Not any more. The everyday fauna of our childhoods included groundhogs and porcupines, mink and beavers, red and gray foxes, moles and shrews, opossums and skunks, Luna moths and Monarch butterflies, wild turkeys and little brown bats…. Now? Deer and rabbits, if we are lucky. What has happened?
The network of our Food Web has broken down. The animals that evolved in our part of the world evolved simultaneously with the insects they eat. The insects evolved in step with the plants around them. The plants did not want to be eaten into extinction, so over millenia they developed protection: their leaves or bark became noxious or downright poisonous. We do not go into the garden and eat milkweed or pokeberries – we would die if we did. But a brave few insects developed “work arounds” to match those plants step for step.
The classic example we have all learned about is the Monarch butterfly, the larvae of which can eat members of the milkweed clan (Asclepias) and come to no harm. But Monarchs are so specialized that milkweeds are the only foods Monarch larvae can eat, so in order to support a colony of Monarchs in the garden we must grow a colony of milkweed plants, enough to support growing broods of butterfly larvae. One plant will not make enough food for more than one or two larvae. It takes, as we have all heard, a village.
You and I don’t eat milkweed larvae, however, so what’s the problem here? So what if we don’t have Monarch butterflies anymore? It would be a shame not to see them, but that’s life, right? We don’t need them. Wrong.
Did you know that more than half of a black bear’s diet is made up of insects? Did you know that a fox’s diet is over 90% insects? Did you know that bats eat ten times their weight every day in mosquitos? Did you know that in spring baby birds require a diet of pure protein? No seeds, just protein. Every single baby bird must eat thousands, even tens of thousands, of caterpillars before it is fledged and able to live on its own. And later, when it is feeding its own babies the next spring, what does it need? Protein. Caterpillars. Larvae. Seeds are all very well and good for high summer, but baby birds and mamas will starve if fed only seeds. Proven fact.
If we want to see even a single nest of birds in our gardens, we need to support them with tens of thousands of caterpillars. If we want Monarch butterflies, we must grow a colony of milkweed plants. If we want Luna moths, we must grow walnut trees or hickory trees or sumacs. And we must grow enough of those plants and trees to feed many more caterpillars than we plan to have butterflies or moths, because we must feed caterpillars to all of those birds and animals and still have caterpillars left over. And there’s one more trick: the protein sources of food for our birds and animals have to be protein sources that are not poisonous to them. Just as Monarchs can only get nutrition from milkweed, some of the next animals up the food chain are only nourished, or are best nourished, by the insects with which they in turn have co-evolved. An American songbird does not eat as well on Australian insects as an Australian songbird does; in fact, those Aussie insects might just be poisonous to a Baltimore oriole.
But the oriole sits further up the food chain from the larval butterfly, and has adapted to eat a number of different foods. If, one year, all of your milkweed plants died, you wouldn’t have Monarchs, but you might still have orioles. Diversity stabilizes the Food Web. Orioles can eat lots of different insects, and in some seasons can survive happily on fruit and seeds and grasshoppers; it doesn’t have to be caterpillars all year. We all know bears like fruit and fish and even, when they are very hungry, other animals. Diversity of food sources keeps us alive.
Necessary food to all vertebrate animals, however, are the essential carotenoids. These can be found only in plants; our bodies cannot create them. No plants, no food, no vertebrate life. It’s pretty simple. And those carotenoids carry right up the chain: if a caterpillar eats a plant leaf, and a chickadee eats the caterpillar, and a snake eats the chickadee, and a coyote eats the snake, the coyote gets its essential carotenoids. We can eat the plants directly, or we can eat the turkeys that ate the katydids that ate the plant leaves – either way, we get our carotenoids. We survive. So do the turkeys and the katydids.
So there it is, in a nutshell. We must grow plants that support the Food Web, and that means the Food Web with which our own food sources and the sources relied upon by the animals we need or want to see thrive have themselves co-evolved.
Monarch butterflies and Baltimore orioles and Groundhogs and Bald Eagles and Bison and Black Bears and anything else native to our Ohio ecosystem (yes, these are all native to Ohio) rely on the plants with which they co-evolved for life. If those plants disappear, the interrelated Food Web fails. And THAT is Why We Plant Native Trees. Their foliage, more important than even nectar and fruits, support our Food Web.
Why straight species? This gets a tad trickier. Sometimes you don’t need to grow the original, unadulterated species of a plant for the plant to provide the same food value to those who would eat it. For example, we get about the same food value from red lettuces as from green ones. Granny Smith apples or Red Delicious? We get similar food value from purple heirloom tomatoes as from orange cherry tomatoes, although we may prefer one or the other. But we are pretty far up the food chain – we can thrive on a wide variety of assorted foods. What about those specialists like the butterfly larvae?
When we breed new varieties of plants, we do so for all sorts of reasons. Perhaps we are breeding fruits to become sweeter, for example. Just as when we breed new types of dogs (think of labradoodles), we are making substantial changes in their DNA. The labradoodles are often non-allergenic; that’s a major change from a yellow lab! Similarly, when we cross mandarin oranges with “regular” oranges (which are themselves actually a cross of mandarins and pomelos), we get clementines, much smaller and sweeter and beloved of Moms who fill school lunchboxes. But the pollinators who specialize in carrying pollen from one mandarin orange tree to another don’t all recognize the blooms on a clementine tree; they are looking for the blossoms of the mandarin with which they evolved instead. Why? The blossom is a slightly different shape; it has a different scent. It’s not a huge problem, but it makes a difference to the insect pollinating the trees.
Here’s a more obvious example I can speak to from my own garden. I grow lots of Asclepias of different varieties, including A. tuberosa, common name Butterfly Weed. Its bloom is a loud orange. A new cultivar came out about 20 years ago, A. tuberosa ‘Hello Yellow’; I like the light, buttery color much, much better. This cultivar can still support Monarch butterfly larvae, but when the adult female butterflies come to lay eggs, they are looking for the Asclepias varieties they are familiar with. They don’t lay eggs on ‘Hello Yellow’ the way they do on the straight species. That color change is confusing. And if the leaf color were different? Probably the larvae could not even eat those leaves.
Here’s an even subtler example. On one side of my kitchen wing, I planted a row of beautyberries the year after we moved here. I couldn’t find the natives, so I planted the Asian variety that is common in the trade, Callicarpa dichotoma. It’s glorious; it thrives there. Twelve years later I found a local source for Callicarpa americana, and planted one on the other side of the kitchen wing, just below the window at the sink. To the basic observer, they look the same, cascading with shiny purple berries in late summer and fall. But my C. americana, although much younger, has already begun to throw baby plants. It is abuzz with pollinators in the summer. The berries disappear at least six weeks before the berries are eaten from the C. dichotoma shrubs; early migrating birds create a mad whirl of color and sound on the native, and only the late stragglers eat what is left over, the non-native berries. They look the same to me, but the local birds know the difference. And migrating birds need fats in their diets – fats from native berries.
Tony Avent, the brilliant plantsman who founded Plant Delights Nursery, coined a phrase many years ago: “native plant Nazis.” Tony is not devoted to people who insist everyone should plant only native plants, and only straight species; I guess you can tell I am not a “native plant Nazi.” You will have to wrest my ‘Delaware Valley White’ azaleas from my dead hands if you want to take them from me. But now you know why I like to make sure I have a fair number of straight native species in my garden. The pollinators rely on them. The caterpillars rely on them. The Food Web relies on them. And THAT is Why We Plant Straight Species.
On to the final question. This is Doug’s answer to our needs, The Homegrown National Park. And it is brilliant.
In the United States, over 40 million acres are planted in lawn grass. Lawn grasses are not native to North America. Those acres could be defined as “dead space,” just like concrete. In fact, worse than concrete: most of us use fresh water, an important commodity, to drench our lawns. We may treat them with chemicals that are dangerous to our children, our pets, the birds and insects we rely upon for life. We spend energy – usually fossil fuel energy – mowing that dead space every week.
Doug Tallamy is not a “native plant Nazi” either. He doesn’t want us all to rip up our lawns. Kids need someplace to play ball; dogs need someplace to run. He wants us to rip up HALF of our lawns, and to plant that space intensively with plants that will support our Food Web. We can put in ‘Delaware Valley White’ and daffodils and gooseberries if we want to, so long as we plant native azaleas and native spring bulbs and native shrubs as well. We need a continuity of native bloom throughout the growing seasons to support the pollinator life we require in our gardens. We need native vegetation to nourish thousands of caterpillars in spring. We need fatty native berries to help our birds survive the winter.
If HALF of the “dead space” currently devoted to lawns in the United States were converted to diverse native-heavy plantings to support life, that would amount to over 20 million acres, more than almost all of our national parks combined. It would create near contiguous supporting landscapes across the entire country, allowing wildlife corridors to flourish and wildlife to have sufficient hunting/gathering biomass to support life. After all, those black bears need more food than my backyard alone can provide! Those bison need a lot of prairies! Those turkeys may want to roost in your yard this month, but they will split into separate nests in nearby backyards in season.
So THAT, dear friends of the Garden Club, is the answer to the final question. THAT is the Homegrown National Park that can save our nation’s ecosystems. And it’s a “feel good” thing we can all do, with great ease. In fact most of us are on our way already. Visit homegrownnationalpark.org for more information on a pleasant, joyous way to save our world, and to sign up as a park steward. We are all in it together!