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.
If you just want to shape your maple trees then choose a time with more stable temperatures, but still cool in the 30âs. You can also start pruning apple, European pear, quince, elderberries, mulberries, and medlar. Other types of plants are best pruned later in the season, for various reasons.