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.
As the weather cools, the red fall leaves of red maple trees brighten your yard. Red maple tree (Acer rubrum) varieties have distinctive palmate-shaped, green foliage that turns brilliant shades of red in fall. These trees display showy red flowers in spring that give way to red winged-seeds in spring or summer.