Tree fork

In arboriculture, junctions in the crown structure of trees are frequently categorised as either branch-to-stem attachments or co-dominant stems.

[3][4] There is actually no hard botanical division between these two forms of branch junction: they are topologically equivalent, and from their external appearance it is only a matter of the diameter ratio between the branches that are conjoined that separates a tree fork from being a branch-to-stem junction.

[5] To alleviate potential strain, it is recommended to identify and prune the codominant stem early in a tree's life, while in mature trees, a risk analysis should be conducted to decide whether to remove one stem, cable them together, or leave them intact.

[9] The complex interlocking wood grain patterns developed in axillary wood present a great opportunity for biomimicry (the mimicking of natural biological structures in man-made materials) in fibrous materials, where the production of a Y-shaped or T-shaped component is needed:[10] particularly in such components that may need to act as a conduit for liquids as well as being mechanically strong.

[15] The strength of a normally-formed tree fork can be assessed by its shape and the presence and location of axillary wood: those that are more U-shaped are typically considerably stronger than those that are V-shaped at their apex.

Typical wood grain pattern at a mature tree fork, Slater et al. 2014 [ 1 ]
A typical tree fork in a Norway maple ( Acer platanoides )
Fork at canopy level in a kapok tree ( Ceiba pentandra ), colonised by an epiphytic Tillandsia
Wood grain pattern of a fork of Fraxinus excelsior (Common ash), as found by stripping off the outer and inner bark layers