All plant stems, from the soft herbaceous stems of a tomato to the mighty wood of a mature oak are built out of nodes linked by internodes. Whatever your plant, it is important to understand how to identify its nodes and cut around them while you are pruning or grafting.
Nodes are the points on a stem where the buds, leaves, and branching twigs originate. They are crucial spots on the plant where important healing, structural support, and biological processes take place.
In winter, the leaves of many plants will lack leaves, and some nodes will never grow stems, but still, in these cases, you can usually find buds at a node on living wood. Sometimes, however, the buds will have died and fallen off at that node. Sometimes buds are there but might be minuscule and easy to miss (such as in sourwood) or buried in the wood and invisible.
The base of a bud, leaf, twig, or branch is always attached to a node, so this is one easy way to find them.
Even without visible buds or leaves, you can tell where the node of a twig is by some signs that you will only see at a node:
- a scar in the wood where a leaf has fallen away
- a knob-like, slight fattening of the wood (think of a bamboo cane)
- in plants with hollow stems such as forsythia, smooth hydrangea, and bamboos, the nodes are solid
By contrast, internodes are the sections of stem between nodes. If the nodes are the crucial “organs” of the plant, the internodes are the blood vessels carrying water, hormones, and food from node to node.
Usually, internodes seem long and provide spacing between nodes of many inches. However, some plants are notable for how close together their leaves, and thus their nodes, always are. Dwarf conifers have closely-spaced nodes. Yews and boxwoods, with their very dense leaves, also always have short internodes. This fact is why they can be sheared or pruned into any shape, including the special form of topiaries.
Nodes in Pruning
When you make a pruning cut, you are always trying to cut the branch or twig back to a node. Usually, you are trying to make a good cut through the part of the internode located just above a node. You never want to cut through the node itself because this would likely kill that important spot where healing and regrowth are supposed to start.
Most of the time, you won’t want to cut back to just any node. Only some nodes have strong buds or branches. It is to these you try to cut back since they will best heal the wound and continue healthy growth.
Nodes in Grafting
In contrast to pruning, often you want to make cuts for grafting not near nodes, but right through the center of an internode. In the whip and tongue graft, for example, careful cuts need to be made along the grain of the wood. If you were to make these cuts through the thick, knobby nodes, they would not be straight and the graft union would fail.
Since nodes are where most of the plant’s best healing and growing tissue live, the scions are always chosen to have at least one healthy node with one or more strong buds.