Nodes and Buds

A ‘bud’, in botany, is a compact, undeveloped shoot which may develop into a twig/branch, leaf, or flower. The region in which buds are located is called a node, and the area between nodes is called an internode. Nodes are the points of attachment for branches, leaves and flowers. (Buds not arising from nodes, ie arising from unusual places, are called adventitious buds.)

Let’s revisit our Ta-Jan blogging tree for 2020, and mark the location of nodes (and internodes) along its trunk:

The nodes in some species are very distinct — bamboo nodes, for example, are the thickened rings between the stem segments. The nodes in other species can be harder to find if leaves or branches aren’t present.

Jujube nodes on dormant trees are visible as single, slightly raised bumps which alternate (change sides) along a trunk and branches. This alternating pattern is behind the distinctive zigzag growth of secondary branches, where the direction of growth changes at each node. This can be seen in the photo below of a Redlands secondary branch:

(We’ll be revisiting the structures and characteristics of the four branch types unique to jujubes in future posts if all this is new to you. But if you’d like to get up to speed now, or refresh your memory, please read Photo Journal: Growth and Branch Development 1 and Photo Journal: Growth and Branch Development 2.)

Nodes on leafy jujube trees are of course very easy to spot with all the green growth sprouting from them! But even these trees may still have less visible nodes barely noticeable as bumps, especially on older wood. On really old wood the nodes tend to blend into the thickening branches until they are hardly visible at all:

Jujube trees are unique, in that each node contains two distinct bud types: a main bud, and a secondary bud. Let’s look further!

Jujube Tree Buds

The main and secondary buds are easier to see when dormant, but the Ta-Jan blogging tree was too fast for me by the time I thought of this post! Every single one of its nodes had an active bud, so I had to make do with older tree substitutes. These have more established branches and are more likely to have at least some nodes with slower-to-wake buds. Below is a Shanxi-Li node on a secondary branch from last year’s growth:

And here are a main and secondary bud within a young fruiting mother branch on a Chico:

But not only do these trees have two types of bud, each bud may be of strong or weak vigour, and whichever one they are determines what they develop into.

Main Buds on Permanent Branches

Permanent branches are the ones that extend each year and which make up the shape of the tree.

Strong main buds on the ends of permanent branches (ie strong terminal main buds) produce the extension growth that make up the shape of the tree.
Weak main buds on the ends of permanent branches (ie weak terminal main buds) produce fruiting mother branches (which look more and more like pine cones the older they become).
Strong main buds along permanent branches (ie lateral main buds) are dormant, but the top-most one will break dormancy to produce a new permanent branch when the terminal strong main bud loses vigour.
Weak main buds along permanent branches (ie lateral main buds) produce fruiting mother branches.

Main Buds on Secondary Branches

Secondary banches develop from permanent branches and have a distinctive zigzag shape.

Main buds along secondary branches are dormant in the first year but produce fruiting mother branches from their second year on.

Main Buds on Fruiting Mother Branches

Fruiting mother branches are comprised of highly compressed bundles of shoots. These shoots do not have leaves, but contain many main and secondary buds. As a fruiting branch grows a little each year, this cluster of shoots also grows in size, and with each passing year resembles more and more a pine cone.

Fruiting mother branches are not to be confused with fruiting branchlets, the only branch type which produces fruit.

Very strong main buds on fruiting mother branches can break dormancy to produce a new permanent branch.
Strong main buds extend the fruiting mother branch by a millimetre or so each year.

Secondary Buds on Permanent Branches

Strong secondary buds on permanent branches produce secondary branches (the ones with the distinct zigzag shape).
Weak secondary buds on permanent branches produce fruiting branchlets (not to be confused with fruiting mother branches — the branchlets are the ones on which fruit grows).

Secondary Buds on Secondary Branches

All secondary buds on secondary branches produce fruiting branchlets (not to be confused with fruiting mother branches) the first year. The main buds then take over this role from the second year on.

Secondary Buds on Fruiting Mother Branches

All secondary buds on fruiting mother branches produce fruiting branchlets.

The photo below shows the four branch types and indicates the location of the bud type each developed from. This is an incredibly complicated structure to grasp the first time, so by all means ask any questions in the comments if you need anything clarified.

Back on the 24th September 2020 I finally potted up the Ta-Jan blogging tree for 2020 which had been soil-less since July — it was still going strong but it had been long enough! — and that alone will be the subject of a future post.

But next week we’ll go back to the first photo of this post and zoom in on each of the nodes on that tree trunk to see which buds are growing, and attempt to predict which branch types will develop!