The Artful Forest Family
Creativity and color in nutrient-poor places
What happens when a forest is encouraged to diversify? The Douglas-fir plantations we have all too often inherited are known for their tight spacing and lack of diversity, hence lack of habitat and scarce wildlife. But what about lack of color?
Those stands are dark. As I tramp through one of our diverse local forests, in scattered patches of sunlight I find all sorts of color. The sunset orange of madrona bark, peeling to reveal the tree’s chartreuse skin. A continuum from pinot gris to malbec in clusters of salal berries. I even find the freakish white of ghost pipe, a parasitic plant without chlorophyll.
Say, what do these three plants—Pacific madrona, salal, ghost pipe—have in common?
They are cousins. They are all in the same plant family, the Ericaceae, sometimes called the heath or heather family, along with rhododendrons, blueberries, and quite a few other cool plants.
To me, it is the family of creative types. Why? They thrive in oligotrophic places—soils that are nutrient-poor and often acidic. Think of the classic image of a Salish Sea madrona, twisting from a seaside bluff with hardly a pocket of soil for its roots. Or blueberries, which cannot survive without regular acidifying inputs to their soil.
It is a family that is stress-tolerant, creative with its use of limited nutrients, and somehow still showy and verdant. One of its powers is a deep linkage with mycorrhizal fungi. Mycorrhizae are underground fungal filaments that bond with plant roots for the benefit of both. A plant sends sugars and lipids created by photosynthesis to the fungus, while the fungus hunts for water and mineral nutrients and shares them with the plant. Plants in the Ericaceae work with special fungi, called ericoid mycorrhizae, that send microscopic coils into the very cells of the plants’ root hairs. These fungi are also able to predigest nutrients, allowing them to draw on forest litter that has not yet fully decomposed.
Our forests tend to grow on young, fast-draining, nutrient-poor soils. Red alder, one of our few native trees that thrives on bare mineral soil, right after a big disturbance, has a similar cheat code in its root-nodule partnership with a bacteria that turns atmospheric nitrogen into a form of nitrogen plants can use.
Some in the Ericaceae truly cheat, like ghost pipe and its mountain cousins, candystick and pinesap. These plants, which look almost like weird mushrooms, have no chlorophyll, hence are not green. They get the products of photosynthesis from nearby plants via mycorrhizae. Their leaves, like the wings of flightless birds, are reduced to rudimentary flaps.
Wintergreens in the genus Pyrola, with round leaves that lie flat on the ground and thin flowering stalks, have it both ways. They are mixotrophs, stealing food from the mycorrhizal network while also producing their own. Look for them on mossy forest floors.
Plants in the Ericaceae remind me of the third hexagram in the I Ching, the ancient Chinese book of changes. The symbol is Chun. It is translated as “difficulty at the beginning.” It follows on the heels of the first two hexagrams, Ch’ien (“the creative”) and K’un (“the receptive”), which are tied to sun and soil, light and shadow, and together form the powerful synergy behind all growth. But their meeting is beset by rockiness, thunder, chaos—the confusion of tender sprouts vying for space in a world that can turn hostile in a moment.
The I Ching’s advice for such a situation? “It furthers one to appoint helpers.” Well, the Ericaceae has nailed that, with its fungal partners.
My translation includes this commentary: “Just as one sorts out silk threads from a knotted tangle and binds them into a skein, in order to find one’s place in the infinity of being, one must be able both to separate and to unite.”
Which makes me think of the famous last paragraph of “The Origin of Species,” where Darwin contemplates “an entangled bank, clothed with plants of many kinds, with birds singing on the bushes, with various insects flitting about,” and asks how this diversity of forms has arisen. You need the knotted tangle, the difficulty at the beginning, to live in a world in which the strands have separated into the variety that is the spice of life.
The Ericaceae family is global. The Andes Mountains have dozens of species of blueberries. Some are epiphytes, living in trees. The Himalayas are full of many kinds of rhododendrons. Mountainous regions, having lots of habitats crammed together, are the perfect grounds for a radiation of species. So are challenging, nutrient-poor microhabitats.
Around here, evergreen huckleberry sprouts from its roots after fires. Hairy manzanita is right there beside it. Both are part of the berry-rich ecosystem that grows after big landscape disturbances. Salal too. All are in the Ericaceae. Early Key Peninsula homesteaders got creative to take advantage of the abundance of wild food. They built and perfected huckleberry-cleaning machines that used chutes and drums and fans to separate berries from leaves and spiders.
For the first few centuries of European settlement in northeastern America, it was understood that blueberries could not be cultivated. Many farmer tried, and every transplant from the wild soon died. In 1910, USDA plant scientist Frederick Colville made a breakthrough, discerning blueberry’s need for acidic, nutrient-poor, and moist-but-not-wet soil. Farmer Elizabeth White provided land and the determination to find, breed, grow, and market the first domesticated blueberries. White was prepared for such a task because her farm was already devoted to another member of the Ericaceae, cranberries, which themselves had been domesticated only 100 years before by a Revolutionary War veteran on Cape Cod, who noticed that the best cranberries grow in places regularly blanketed with shifting dune sand.
Some Ericaceae family members, like rhododendrons, are notoriously easy to transplant and cultivate. Others, like madrona and manzanita, are maddening. Western azalea, native to the Oregon coast, is popular in local gardens while Cascade azalea, native to the mountains, is thus far impossible to grow.
This family, popping with color, its creative plants mixing and remixing habitats with their hidden helpers, like art is impossible to put in a box.
Endnotes
Their fruits are creative too. Salal’s fruit is not a berry but a “fleshy calyx,” meaning that instead of the flower’s ovary swelling to become a fruit, the flower’s sepals swell to surround the seeds. Sepals are the often-leaflike structures that initially enclose the petals and peel back to reveal the flower.
My thanks go to a local reader, who saw in the newspaper version of this essay (the “unextended cut”) that I had mistakenly written that the huckleberry-cleaning contraptions separated stems from the berries. In fact, a short length of stem likes to cling to each evergreen huckleberry you beat from the bushes, and it is beyond tedious to pick them all off. Homesteaders simply baked the stems into their pies along with the berries. More fiber.
Ericoid mycorrhizae are actually only one group of mycorrhizae that have coevolved with the Ericaceae. There are also arbutoid mycorrhizae, which work with wintergreens as well as madrona and manzanita, and monotropoid mycorrhizae, which work with the nonphotosynthetic oddballs. Each has a different structure for its invasion of the plant’s root hairs, a different socket if you will.
Lastly, let me geek out on leaves for a second. Botanists have a measurement called specific leaf area (SLA), which is the ratio of a leaf’s area to its dry weight. A leaf with a low SLA, like those of salal, will be thicker and denser, more tightly packed with cells: the plant is loading its hard-won investment of growth into fewer leaves that will presumably last longer. This is typical of oligotrophic plants. Such leaves allow these plants to keep growing even in non-optimal times (i.e. winter), since the plants are already built for non-optimal sites.
It is Pacific madrona that takes the cake for creative use of leaves. Madrona leaves last 1.25 years. If you have a madrona in your yard, you have to get out the leaf rake in midsummer. The tree never has to go naked, but it also gets to renew its leaves. (Leaf renewal has a number of benefits, including the prevention of self-shading by new growth, continued high photosynthetic efficiency, and the shedding of the many foliar diseases that make madronas blotchy.) The shed leaves are a delight to crumple in your hand. They do not bend but snap like super thin porcelain.
Thanks for reading Infinite Peninsula. Subscribe to receive every ramble and adventure, become a paid subscriber to keep me going, and share with anyone who would dig a spy’s-eye view of the world we share with Cascadia critters. Hopefully half as creative and tasty as salal.
Wintergreen is a new plant for me. I'll be on the lookout for it!
Outstanding newsletter. Love the idea of the creative family of plants.