Last winter while visiting a natural history museum in Colorado, I learned some remarkable facts about the aspen tree. An entire grove of slender, white-trunked aspens can grow from a single seed and share the same root system. These root systems can exist for thousands of years whether or not they produce trees. They sleep underground, waiting for fire, flood, or avalanche to clear a space for them in the shady forest. After a natural disaster has cleared the land, aspen roots can sense the sun at last. The roots send up saplings, which become trees.

For aspens, new growth is…