A microscope opens a door into a fascinating—and educational—world
Redwoods don’t actually have needles, they have leaves. We call their leaves needles because they’re thin and pointy, but they are indeed leaves, performing all the necessary leafly duties. As it turns out, redwoods even have two distinct kinds of leaves. One kind specializes in making the tree’s food through photosynthesis and the other focuses on absorbing water. It’s a botanically harmonious division of labor.
One of the researchers who figured this out is Dr. Alana Chin, an associate professor of plant physiology at Cal Poly Humboldt. Dr. Chin is part of the university’s Tree Function Lab, where she studies how nimble the redwoods and their pointy little leaves can be when adapting to a warmer, drier climate. (Save the Redwoods League helps fund the Tree Function Lab.)
For instance, redwoods along California’s rainy North Coast arrange their leaves so that the ones that absorb water grow low on their trunks, with the photosynthesizing leaves higher up near the tree’s crown, in order to better collect light from the sporadically shining sun. Redwoods further south, in sunnier, drier areas, do the opposite: Their water-absorbing leaves grow nice and high where they can more easily capture fog and rain.
As part of her work, Dr. Chin collects redwood leaves, bathes them in ultraviolet light, and looks at them under powerful microscopes. The resulting images can be stunning. Some look like little nebulae awash in neon colors produced by natural chemicals in the leaves that react to the UV light. Others show highways of brightly glowing stomata—the tiny pores on leaves that allow a plant to breathe.
Dr. Chin analyzes the colors and the arrangement of the stomata to better understand how redwoods absorb water from fog. Eventually, images like these may help researchers predict how redwoods will fare in drier conditions. They may also help inform restoration work by showing us which redwoods will grow healthy and strong in the future.
Plus, the photographs are just plain cool. In the hand, a redwood’s leaf is just a thin strip of green. But there’s an entire universe in that leaf.
