Growth and Bifurcation of Tree Branches
How a branch thickens and its fork rises as the limbs expand
This folio studies how a tree branch forks and thickens as it grows. A series of diagrams labeled n and m follows a single bifurcation from an early stage, with the fork or 'groin' about mid-height, to an advanced state in which the swelling girth of the limbs has driven the groin upward (points a and b). A companion note observes that at each origin of a smaller branch the limb makes a turn as it gives birth to the branch, so that the fork lies between two unequal angles, the larger falling on the side of the larger branch.
On this page
Three stages in the growth of a fork (n, m)
Three superposed views follow one bifurcation as it matures: an early fork with the groin near mid-height, the same fork advanced, and a further-grown state labeled m. As plant n thickens toward the girth of m, the whole junction ab fills out on the inside and the outside of the limbs, and the groin is driven upward.
Why a fork sits between two unequal angles
At each point where a smaller branch is born, the limb makes a turn and begins to bifurcate. The fork lies between two angles, and the larger of the two falls on the side of the larger branch, in due proportion, unless some accident distorts it.