A node is a position on a plant stem where a leaf, or a group of leaves, is attached. The segment between successive node positions is an internode. An axillary bud commonly occurs in the angle between a leaf and the plant stem.[ref]
The distinction is useful when taking a plant cutting: a short piece of bare internode and a piece carrying a node need not contain the same developmental structures. Counting attachment positions at each node also separates the production of new leaves from elongation of existing internodes. Two equally tall shoots can therefore differ in both developmental age and spacing of their leaves.
New to topics? Read the docs here!