in Thoreau’s Journal:
When I am opposite the end of the willow row, seeing the osiers of perhaps two years old, all in a mass, they are seen to be very distinctly yellowish beneath and scarlet above. They are fifty rods off.
Here is the same chemistry that colors the leaf or fruit, coloring the bark. It is generally, probably always, the upper part of the twig, the more recent growth, that is the higher colored, and more flower or fruit like. So leaves are more ethereal the higher up and further from the root. It the bark of the twigs, indeed, is the more permanent flower or fruit. The flower falls in the spring or summer, the fruit and leaves fall or wither in autumn, but the blushing twigs retain their color throughout the winter, and appear more brilliant than ever the succeeding spring. They are winter fruits. It adds greatly to the pleasure of late November, of winter, or of early spring walks to look into these mazes of twigs of different colors.