Progesterone. Print | Email article to a friend | Last updated: January 14, 2015. Progesterone is a hormone released by the corpus luteum in the ovary. It plays important roles in the menstrual cycle and in maintaining the early stages of pregnancy. It may also be involved in the growth of certain cancers.
Maple helicopters fall before the leaves drop from the trees. Maple trees (Acer spp.) produce winged seeds called double samaras, which twirl to the ground in late summer or early fall. They resemble helicopters in motion, earning them the common name of helicopters or whirligigs.
On maple trees, it causes brown or purplish-brown spots and stripes near the veins on the leaves, and the tree may lose its leaves prematurely. If the disease cycle repeats year after year, the tree may become stunted or deformed because it cannot keep its leaves long enough to grow.