Branching in Plants

Abstract

Branching in botany has been much studied for a long time; as a consequence plants, and especially trees, play an important part in the knowledge we have of branching. Depending on which plant species is considered, branching may be nihil, apical or lateral, exogenous (case of stems) or endogenous (case of roots), continuous or rhythmic, immediate (tropical plants) or delayed (plants of temperate climate), spontaneous or traumatic. Trees can be unitarian or, through a special mechanism of branching called reiteration, they can become colonies. A few architectural models — which are basically branching models — shall be presented. The many roles of branching will be discussed: space occupation, increase of energy catching, rapid increase of surface in still a small volume. Comparison with another group of sessile (= fixed) living beings, the corals, shows that branching is not restricted to plants, but that it is a characteristic of sessile life; mobility and branching are mutually exclusive. No plant, either fossil or extant, is completely devoid of branching (= ramification) and this is the reason why the term “branching” in itself evokes the plant kingdom. As a matter of fact, botany is the scientific field in which branches and branching can best be studied. There is a long history of interest in plant form — especially in plant branching, as a plant’s overall form is defined by its branching. The first scholar to become fascinated by the subject was, as far as I know, the Greek philosopher Theophrastus (circa 400 BC).