Teri Enigle, age 11, of Montoursville, Pennsylvania, for her question:
Do any plants hibernate?
There is a time to be busy and a time for rest, a time for waking and a time for sleeping. These rhythmical routines hold true for people and for all other living things that belong to the planet Earth. Sometimes words mislead us because we use different names to describe the same event. For example, certain animals are said to estivate or hibernate, some nap or sleep and all of them take rest periods. The plants also take long or short rests, and these are said to be dormant periods.
Right now, the woodchucks are hibernating and the tender leafed maples are dormant. Each in its own way is taking a long rest period through the cold winter months. This winter sleeping is very similar in both plants and animals. However, ours is a very precise language with words to express even very slight differences. This is why we say that though animals hibernate, the plants become dormant.
A walk through the wintry woods shows us which of the trees are taking a dormant rest period. Plants need green chlorophyll to use sunlight to manufacture the food that keeps their cells busy. Obviously the oaks and elms, the beeches and birches are not operating at maximum capacity for they have lost their green, food producing leaves. Actually they are dormant, operating at minimum capacity through the winter.
Dormancy is not limited to the trees that lose their green leaves in the fall. During the year, all plants take rest periods of some kind. Even for evergreens, winter is a lazy rest period during which no new growth is added. This semi dormancy ends with an outburst of new growth in the spring.
Our trees, of course, are used to the warm summers and cool winters of the temperate zone. But what of the trees that live in the winterless tropics? Many of them are evergreens with huge wide leaves, rather than narrow pine needles. Certainly the year round climate is suitable for year round growth. But year round growth, it seems, is not suitable for the plant world. From time to time, most tropical trees shed some of their leaves and take a rest before sprouting new growth.
The earth's smaller plants also take dormant rest periods. For example, many of the weeds are annual plants that complete their life cycles in a single year. They have a most ingenious system for getting through the winter. Come fall, the parent plants scatter their seeds and die d
own. The seeds lie sleeping in the soil until the warm weather wakes them up in the spring. These plants spend the winter dormant period as seeds.
Everywhere, the work and rest routines of the plant world are regulated by day and night and by the changing seasons. In the Arctic tundra, the low growing vegetation beds down with the first frosts and remains dormant through the long polar night. Come spring, their sleeping seeds and perennial roots awake from their dreams and burst into frantic acitivity. They must mature and produce seeds before the short Arctic summer ends and the cold winter night returns.