Limb development articles from across Nature Portfolio Limb development is the process by which a limb forms in the vertebrate embryo. Early in limb development, outgrowths called the limb buds ...

Steve Nix is a member of the Society of American Foresters and a former forest resources analyst for the state of Alabama. Leaf shapes play an important role in tree identification, providing key ...

Pine trees are one of the most common coniferous species in North America. Learn how to identify the types found in the United States and Canada.