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.
All maples produce samaras, but red, silver and Norway maples often produce the largest quantities. Over the next few weeks, these seeds will rain down on lawns, decks, roofs and gutters in many locations. These can become a nuisance, especially if they clog gutters and down-spouts or germinate in garden beds.