More Spring Thoughts

We spent the weekend in northern Vermont and New Hampshire and so had a second chance at observing processes of spring. Up there in the forests you see the greening process in a whole new light. Each individual tree is putting out its leaves. But the whole forest is transforming. What is at the heart of this transformation?

The photosynthetic "machinery" inside each leaf is becoming established for the season. That machinery resides in the chloroplasts, bodies that are descended from once free-living bacteria that live in every photosynthetic plant cell. The cells of plants were invaded by these bacteria eons ago, but in a sense they re-infect the plant (and the forest) with the beginning of each photosynthetic season.

So in a way when we observe a mountainside with its steadily greening trees we are seeing a wave of bacteria (beneficial ones) spreading across the population. Photosynthesis is a partnership between the leaf and the chloroplasts, between the host plant and its endosymbiotic bacteria. It's the spread of these bacteria, the chloroplasts, as they invade in a wave over the weeks of greening, that transform a northern mountainside into a shimmering green solar collector.