The trout lily (also known as yellow dogtooth violet) is a perennial spring ephemeral flower native to North America. It grows in woodland habitats throughout eastern North America. The common name "trout lily" refers to the trout-like brown or gray mottling of its leaves.

Trout lilies do not flower until the plants are 4 to 7 years old. The young plants have just one leaf. When mature they may grow 2 paired leaves and produce a single flower. The flowers last for several days. They open on sunny mornings as the air warms the flowers and close at night. This time-lapse movie was filmed in Dunns Woods on the Indiana University campus over a three hour period starting at about 9:00 am.