All cell junctions on the pennulum are called nodal structures. To be considered a node, the width of the nodal structure must be at least twice as thick as the adjacent internode. Nodes may have various shapes, i.e. triangular, oval (see photograph 'shape of nodes'). Nodes may be located along the entire length of the barbules, or only at its proximal or distal part. Nodes may be more or less pigmented. Pigmentation is due to the accumulation of melanin.

Alternative form for node : nodes.