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.
More about sugar maple trees. The sugar maple, acer saccharum, a native tree to North America, is the most common type of maple tree in the eastern United States. It is a hardwood tree with a moderate to slow growth rate. Maples trees can live to be 400 years old.At maturity, this type of maple will grow to be 20-35 meters (60-80 feet) tall.ore about sugar maple trees. The sugar maple, acer saccharum, a native tree to North America, is the most common type of maple tree in the eastern United States. It is a hardwood tree with a moderate to slow growth rate. Maples trees can live to be 400 years old.