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.
Mature Height/Spread: Red maple grows 40 to 60 feet tall, 25 to 35 feet wide. They occasionally grow 100 to 120 feet in the wild. Growth Rate: This tree grows at a medium to fast rate (10 to 12 feet in five to seven years). It has a moderate life span in urban areas; it is longer-lived in wet areas.