Wednesday, March 18, 2015

Exciting Leaf Scars!

I don't think very many people get excited about leaf scars.  I didn't know what they were much less have any interest in them until I took a class called Nature Study when I was finishing my undergrad art degree.  The class was a botany class I think;  all I remember from it was that we had to make moss gardens in large jars, that we went out into the winter woods and dug sassafras root and made sassafras tea by boiling the bark of the roots, and that I made a dichotomous key for identifying trees in winter using their leaf scars as the identifying feature.

So in the failing light after dinner on this somewhat gloomy day I went out to the little woods behind our house and clipped some twigs.  I haven't looked at a leaf scar for so many years, but there they were, perfectly shield-shaped and dotted with little circles where veins entered the leaves from the twig.  The leaf scar is a dehiscent (weak) area between the leaf stem and the twig where the leaf detaches when it's time to do that.  As you can see from this collection, each kind of tree has its own characteristic leaf scar.  Some are as small as the head of a pin;  others, such as the walnuts, are 1/4' across or bigger.  Fruit trees have nice pronounced leaf scars, but we don't have any in our yard.  Some scars are narrow and wrap around the branch more;  others look like paint palettes.  In spring the new buds grow directly above leaf scars.  The best time to spot the scars is on a leafless tree in winter.

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