Wednesday, November 4, 2015

What color do oaks turn in fall?

Bit of a trick question--even if you keep the question to just one species! 

 Oddly, most oaks around here have color names.  But--except in the case of scarlet oak--it isn't fall colors that seem to be meant.  (Our one neighborhood scarlet oak hasn't turned yet, but I'm waiting!)  I've seen oak leaves turn everything from basic brown, to rust, to yellow to deep, deep scarlet--my favorite.  Of course, like most leaves, their color evolves over time.  

Weather also plays an important role, since the red color (anthocyanin) is generated by continuing photosynthesis in the dying leaf.  This is favored by bright sun and cool temperatures, and can be defeated by rain, which washes the soluble color away.

 A black oak (Quercus velutina) coloring up high; close-up below.

Black oak.

 Why is this called White Oak?  Beats me!  Maybe because the undersides of leaves (above)
are noticeably lighter than the tops--especially when green.

 White oaks (Quercus alba).  A flowering dogwood (Cornus florida) in the foreground above.

White oaks.
Going its own way.

Black oaks.  Why are the veins in the leaves below still green?

Swamp white oak (Quercus bicolor).

Black oak.

White oak.

Black oak.

All photos taken between 10/24 and 10/29

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