Using a key is like following the branches of a tree-- each additional branch gets smaller and smaller until you reach a single branch tip. All the species described in a tree are represented by the trunk, while each branch tip represents a single species of tree.

To identify a tree, first decide whether it is a conifer or broadleaf...

• Conifers have needlelike or scale-like leaves and usually bear seeds inside woody cones;
  
• Broadleaves usually have wide, flat leaves and bear their seeds inside of soft fruits.