Saturday, March 13, 2010

Falling Samaras

I've been watching two trees that hold their fruits all winter - the ash (Fraxinus) and boxelder (Acer negundo).

Their fruits are similar - both are "winged achenes" known as "samaras,"  distinguished by flattened wings of paper-like tissue that develops from the wall of the ovary.

Botanists describe these fruits as "simple" (the ripened ovary of a flower with a single pistil), "dry" (not fleshy like an apple) and "indehiscent" (they don't open to expel seeds - like a milkweed pod)

When I was a kid we called them helicopters and whirlybirds.   Their winged design helps the wind fly them away from the parent trees.

When do these trees "let go" and drop their seeds?

I could look it up, but it's more fun to wait and see.  I've been waiting and I've been watching all winter.

The dropping of the samaras started last week...

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