In many species the pith of branchlets bears a row of rounded oil glands. These are usually light to dark brown and easily seen with the naked eye. In some species they can be quite pale and harder to see. If the species possesses this character, the glands will always be seen at the nodes, but in many species the glands are a continuous row in the internode pith.
The character is best seen by examining a second year branchlet at a node where a subsidiary branchlet leaves the main axis and pulling apart to expose the pith. In many bloodwood (Corymbia) species there are more elongated oil bodies or ducts running longitudinally at the edge of the pith.
