I have seen these little yellow flowers appearing all over my lawn during March. I finally found time to photograph them! These flowers are about an inch in diameter, about half the length of a honey bee.
Oxalis dillenii are perennials which means they come back every year. I love their tiny, bright yellow flowers. The day was slightly overcast when I took these pictures. When the sun isn’t shining brightly enough, these little guys fold their leaves.
One of the characters that identifies this species is the way its flower stems bend at both ends to position its seed capsule so it can eject its seeds far from the parent plant when it explodes! Little missile launchers in the lawn! You can see a flower in the bottom foreground that has set seed and shows the double bend. The maturing seed pod at the center of the image is what the foreground flower will look like eventually.
When the sun goes down, O. dillenii rolls up its flowers, and folds its leaves. Amazing!