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 prune selectively, almost anytime is the right time to prune a Japanese maple. With that said, these maples are most easily pruned in winter or summer. With the leaves out of the way in winter, it is easy to see the branch structure and, in turn, make the right cuts.In summer, however, you can judge the right amount of thinning needed to see the treeâs bones.ith that said, these maples are most easily pruned in winter or summer. With the leaves out of the way in winter, it is easy to see the branch structure and, in turn, make the right cuts. In summer, however, you can judge the right amount of thinning needed to see the treeâs bones.