The red, orange and gold leaves are gone, turned to crumpled brown paper. Now, in the dark days of winter, the evergreen trees come into their own. They’ve been there all along, of course, hidden by autumn’s lavish foliage. Their green shines brightly amid the bare branches.
The spruces create a geometric shape, a tall, narrow triangle against the skyline. Pines are ragged, unsymmetrical, awkward in a lovable way. On the Woodland Trail, graceful hemlocks shade the hillside. Sometimes the trees are frosted by snow. Sometimes they sing in the wind. But the main thing about evergreens is that they’re, well, green: ever green.
Not really. Nothing lasts forever, of course. The tree itself can endure for centuries, but the leaves have a much shorter lifespan. (They’re shaped like needles, but structurally they’re considered leaves.) An individual pine needle, for example, lives three years or so, then turns a sickly yellow and falls off the branch. But evergreen trees keep at least some of their leaves green all winter, retaining the chemical chlorophyll in their tissues. The plants are making food — actively photosynthesizing, going through the processes of life, even in the “dead” of winter. This is an incredibly important adaptation for plants that live where sunlight is scarce, the cold fierce, and the snow deep.
Nothing looks quieter and more serene than an evergreen tree in a winter landscape. But even while standing motionless under an overcoat of snow, a spruce or fir or pine or cedar is busily working, capturing any stray gleam of sunshine to use in photosynthesis. Sunlight, even a pale winter ray, is the start to this process, the key that turns the engine. Only a small trickle of light penetrating the snow is enough to trigger the light-sensitive cells and begin the long chain of chemical reactions, turning air and water into sugars that nourish the plant.
Since water must be available for photosynthesis to happen, the needle shape of the leaves allows them to conserve water. Cold, dry winds blowing across a surface rob it of moisture (as we can feel on our chapped hands and lips.) Thin narrow leaves help a tree hoard water. A waxy coating on the needles also helps keep moisture from evaporating — botanical chapstick, so to speak.
As you walk under the evergreen boughs on Arboretum trails, remember you’re not the only living thing in the stark winter landscape. Those quiet trees are churning with life.