By George Ellison with illustration by Elizabeth Ellison
Winter simplifies, scaling life down to the bare essentials. Solitude is surer then. The muted browns and grays of the soil and stones display a somber intensity. There are no curtains of leaves to obstruct vision. And winter outings provide an opportunity to observe evergreen plants more closely.
The word “evergreen” is, for me, one of the most highly evocative botanical terms. An evergreen can be defined as a plant that "holds green leaves, either broadleaf or needle-shaped, over winter." But a fuller understanding of why some plants remain evergreen will enable us to appreciate them more fully.
All plants in the southern mountains and similar upland or northern environments face the double-edged dilemma of a lack of moisture in winter and a short growing season in summer. Most species hunker down in cold weather and then really hustle during the growing season to do their thing and produce seeds. Evergreens have "chosen" the other, less traveled path. Instead of shedding leaves (as do the broadleaved deciduous trees and various shrubs and vines) or dying completely back in above-ground forms, evergreens opt to tough it out so as to get a head-start on the growing season.
For this category of plants, photosynthesis can continue longer in the fall and begin earlier in spring, while energy that would otherwise be channeled into leaf reproduction is saved for direct reproductive efforts.
Various strategies like needle-shaped leaves that expose less surface, botanical "antifreeze" in the form of resinous chemicals, increased sugar content in cells to lower freezing points, or conical shapes that minimize buildups of snow and ice allow evergreens to survive the drying winds and freezing temperatures of winter.
Individual evergreen species often have their own distinctive over-wintering strategies. Everyone has observed how the leaves of rosebay rhododendron curl and droop in extreme cold. This temporarily shields and closes off the air-circulation pores (stomata) on the underside of the leaves.
Aside from the always-apparent conifers and other obvious evergreen plants such as rattlesnake plantain, American holly, rhododendron, laurel, dog-hobble, and mistletoe, there are a number of small woodland evergreens like trailing arbutus, galax, teaberry, striped pipsissewa, and the dainty little partridgeberry vine that are always a delight to encounter nestled down among the leaf-litter while out on a winter walk. They lift our spirits on a gloomy, slushy day.
George Ellison is an award-winning naturalist and writer. His wife is the noted artist and paper-maker, Elizabeth Ellison, who has a gallery-studio in Bryson City, NC. Contact them at firstname.lastname@example.org or email@example.com.