The wind has stripped most of the leaves from the trees, and the only bit of color left is the brilliance of fall-flowering chrysanthemums set against the backdrop of ever-fading grass. It’s nature’s last hurrah before it slips us under a blanket of winter.

My thermometer has dipped down to 34 degrees, but I think it has been trying to keep my spirits up; several mornings I’ve been greeted with an icy sheet on the windshield of my truck. As the coats I don become progressively heavier, I find myself feeling more and more sorry for the trees which, being stripped of their leaf cover, seem to shudder with me in the cool air.

Why is it that the parsley in my husband’s herb garden is still going full-bore, untouched by the chill of fall, while trees slip quietly into dormancy? The trees are still living; they’re just a bit more quiet about it.

Only a few plants are able to function fully when the mercury falls toward the freezing point. Dormancy is an escape route for plants that must survive for months below the freezing point. The state of dormancy allows plants to reduce their metabolic activity to a point that uses very little of the energy they’ve put into storage throughout the summer and fall.

It’s most obvious to us that the tissues and buds of deciduous trees in our midst have slipped into quiet rest. Other plants have as well. The herbaceous plants in our gardens that have died back to the ground already have put a lot of energy from this growing season into their roots and as storage. Although they are deceptive with their green needles, evergreens show reduced activity in the winter, too.

It may be most obvious that temperature signals plants to pass into dormancy, but light plays a role as well.

Simply put, plants rely on light to survive. Specifically, they need light to photosynthesize. They use water from the soil and carbon dioxide from the air, combine them with energy from the sun and, presto! They’ve made sugars which they use for maintenance and growth. Well, the process is a bit more complex than that, but those are the essential points.

When plants sense a reduction in the amount of light they’re exposed to every day, they slip into dormancy — the same state you wish you could slip into when it starts getting dark around 6 o’clock.

Mature plants aren’t the only ones that use dormancy to escape the more harsh side of nature. Seeds of all plants which need to survive the elements are dormant or quiescent during the winter months. Quiescence is the condition of a seed when it is not able to germinate because the environmental or external conditions required for growth aren’t present. Dormancy is the condition of a seed when it fails to germinate because of limiting internal conditions, even if environmental conditions (moisture, temperature, light and gases) are suitable.

During the winter, the buds and seeds of plants wait for just the right moment to signal them to emerge from dormancy. Growth in the spring is dependent on the prolonged exposure of the resting buds and seeds to low temperatures. The buds and seeds have internal clocks and calculators which sense the periods of exposure to cold. In doing this, plants measure the length of the winter and anticipate the arrival of spring, knowing exactly when it is safe to emerge from the dormancy of winter.

And, of course, at that point, we’re all eager to follow their lead.

Diana George Chapin is the NEWS garden columnist. Send horticulture questions to Gardening Questions, c/o MaineWeekend, Bangor Daily News, P.O. Box 1329, Bangor 04402-1329. Selected questions will be answered in future columns. Include name, address and telephone number.