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.
Plant lettuce seed right out in the garden as soon as the ground is no longer frozen. Seeds will germinate when the soil temperature is as low as 45Â° F. Seedlings purchased from the garden center or grown indoors can go in the ground a week or so before the last expected spring frost in your area.