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.
Nectria galligena canker â This maple bark disease will attack the tree while it is dormant and will kill healthy bark. In the spring, the maple tree will regrow a slightly thicker layer of bark over the fungus infected area and then, the following dormant season, the fungus will once again kill back the bark.