I guess I should know the answer to this, but I don’t. People exposed to sunlight or UV for long periods are candidates for cancer. Plants spend all their time in the sun. Why don’t they get cancer too? The germnatve cells in plants are exposed to UV and continual mitosis offers ample oppertunity for mutations. Why don’t plants get cancer? Or do they and nobody talks about it?
Primarily because they do not have a circulatory system to allow cancer to metastasize. They can get tumorlike growths, though.
As always, the Master has adressed it better than I can
Hmmmm. Ok, but what about UV induced cancer-like growths? Does that ever occur in plants?
Many insects cause galls to form on plants. Two of the most common are the Oak Apple and the Goldenrod Knot. In central PA, almost any field of goldenrod will have dozens of these galls (it is easy to observe them in the fall when the plants dry up.) These are caused by a tiny fly. The mom-to-be deposits its eggs in the goldenrod stem with its needle-loke ovipositer. The developing larva releases hormones that altter the local growth of the stem. Oak apple are common around here on the leaves of White Oaks, and are caused by a family of tiny wasps (Cynipidae, among others). They resemble green or red apples, up to golf-ball size. Pretty much the same deal as the Goldenrod fly. One side effect of the Oak Apples’ growth is it causes the parasitized leaf to manufacture toxic levels of tannins to discourage predation. In the days of yore, these were harvested in quantity as these tannins are useful in leather processing. But Cecil is right; the lack of a centralized nervous system keeps the growths in check.
Sorry.
Centralized cardiovascular system, I meant to say.
Though if trees had a central nervous system, they might be able to outrun those pesky wasps…
