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.
Silver Maple (Acer saccharinum): Silver maple seed matures in spring or early summer; collect immediately upon ripening. No stratification period required; sow seed at 0.25-1.00 inches in moist growing medium such as vermiculite, peat moss, or sand. Place germinants in larger planting media when necessary.