Branching in plants

Almost all kinds of plants exhibit some form of branching, and particularly in smaller plants the branching is often extremely regular. In a plant as large as a typical tree—particularly one that grows slowly—different conditions associated with the growth of different branches may however destroy some of the regularity of branching. Among algae and more primitive plants such as whisk ferns, repeated splitting of a single branch into two is particularly common. Ferns and conifers both typically exhibit three-way branching. Among flowering plants so-called dicotyledons exhibit branching throughout the plant. Monocotyledons—of which palms and grasses are two examples—typically have only one primary site of growth, and thus do not exhibit repeated branching. (In grasses the growth site is at the bottom of the stem, and in bamboos there are multiple growth sites up the stem.)

The forms of branching in plants have been used as means of classification since antiquity. Alexander von Humboldt in 1808 identified 19 overall types of branching which have been used, with some modifications, by plant geographers and botanists ever since. Note that in the vast majority of cases, branches do not lie in a plane; often they are instead arranged in a spiral, as discussed on page 408. But when projected into two dimensions, the patterns obtained still look similar to those in the main text.