Monday, November 26, 2007

Maple leaves: beauty in function

Seasons come and go and with them the ebb and flow of warmth and waters in Ohio. Our Autumn colors signal the time for the rains and rising waters of winter.

October maples ablaze in southern Ohio

The beautiful reds and yellows of maple tree leaves demand our attention every Autumn and paint glossy calendar and magazine pages year-round. These are brilliant colors for sure, but do we overlook the beauty of function in their exquisite leaf-shapes? When leaves are down and brown and gray trees pierce the cold blue sky of winter, do the leaves serve the resting trees?

Look at one great example, the silver maple (Acer saccharinum). This maple species is adapted to unconsolidated Recent alluvium (fancy geo-lingo for rocky-sandy-muddy stream deposits of Recent Era vintage) where its sprawling muscular roots reach shallow groundwater while grasping great globs of stream side silt to secure its foundation against flood. It grows fast and branchy along moist bottoms of our meandering stream ways. Its fast growth and broad shadow entices developers selling cheap landscaping for new homes, but plagues future homeowners with shed branches and massive leaf-falls.

It's the massive leaf-falls that suggest function in the shape of silver maple leaves; a function unrelated to photosynthesis. Look closely: The deep sinuses between leaf-lobes and coarse teeth identify the leaf as silver maple and suggest an adaptive function when you see them laying piled on the ground. The toothy sinuses interlock with each other forming a thick layer of slowly decaying leaves that resist wind and water.

The silver maple dominates vast stretches of Midwestern streams and I'm sure this results from the beautiful function of interlocking leaves blanketing silty stream banks and smothering seedlings of competing tree species. Frequently shed branches pile up under silver maples and slow flood waters assisting silty deposition while less adapted tree species are undermined by erosion.

Beauty is often beyond the eye of the beholder.

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