The Yellow Wood Sorrel’s technical name is Oxalis Corniculata. This native perennial plant is usually about 6″ tall, but sometimes reaches 1′ or a little more. There is a central stem that branches occasionally, creating a bushy effect on mature plants. It is often covered with scattered white hairs. The alternate trifoliate leaves have fairly long petioles, and are about ¾” across when fully open. Depending on environmental conditions, they are light green, green, or reddish green, and fold up at night. Occasionally, they fold up in response to intense sunlight during midday. A nice closeup taken by Kira.