Written by OLC Board Member Jim Nardi
As the spring ephemeral flowers finish blooming on the forest floor, the trees overhead are unfurling their tender young leaves. I had often wondered why red oaks and white oaks received their names. At this time of year, the reason for assigning these names is clear:
The first leaves of red oaks are bright red; the first leaves of white oaks are a pale, ghostly green.
First leaves of red oak.
First leaves of white oak.
On some of the white oaks, you will notice white, woolly balls dappled with red spots. These are known as wool-sower galls that have a remarkable story to tell. In a couple of weeks about 200 tiny gall wasps will emerge from each woolly ball. The mother of these wasps emerged several weeks earlier from the leaf litter and deposited her eggs on a bud of the white oak. The act of egg laying induced the white oak cells to form this elaborate and ornate gall that the oak would never have formed during its normal development. The little wasp manipulates the hormones and genes of the white oak to awaken the oak’s latent creative abilities.
Wool-sower gall of the gall wasp, Callirhytis seminator on a white oak twig.
The female gall wasp (left) and the male gall wasp (right) that emerge from the wool-sower gall in late May.
All photographs taken on Liriodendron Loop trail at Atherton Island Natural Area.