white flower with green leaves

A redwood sorrel plant in Muir Woods, also known as Oxalis oregana. These are native to the coastal redwood and Douglas fir forests of the Pacific Northwest region of North America. The Oxalis are so accustomed to the low light of the forest floor that, when struck by direct sunlight, the leaves fold downward. When shade returns, they reopen. The movement is quick enough to be observable by the human eye.