Preliminary Course
Botany. Architectural Analysis
Branching typology.
In rhythmic growth, the distribution shape of the branching process within the growth units is a characteristic feature.
Branching position
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Acrotony or basitony are frequently considered as two fundamental phenomena underlying, respectively, the
arborescent or bushy growth habit (Troll, 1937; Rauh, 1939; Champagnat, 1947; Barnola and Crabbe, 1991).
Nevertheless these authors refer mainly to the acrotonic branching of growth units or annual shoots in the arborescent case whereas they consider the proximal branching at the base of the whole individual when considering bushy plants.
In architectural botany, acrotony and basitony terms are used at the growth unit or annual shoot levels.
The branching patterns within those growth units may be different on various axis orders, within the same species. It is however understood that, along a stem, a similar branching pattern appears in consecutive growth units.
More precisely:
Acrotony is the prevalent development of lateral axes in the upper (distal) part of the parent growth unit or annual shoot.
Mesotony is the term used to name privileged development of ramifications from the median part of a growth unit or annual shoot.
Basitony is the privileged development of lateral axes in the lower (proximal) part of the parent growth unit or annual shoot.
Branching position (Photos and drawings D. Barthélémy, CIRAD)
Left: Acrotony (Fraxinus excelsior)
Middle: Mesotony (Cedrus atlantica)
Right: Basitony (Stenocereus thurberi)
Note:
Acrotony, mesotony, and basitony can be seen as various states of a single branching gradient within the shoot.
They can be symbolized by a simple geometrical drawing:
∇ for acrotony, ◊ for mesotony, and Δ for basitony.
Definition
Hypopodium
Botany. Botanical entity defined on a branch by the portion of stem below the first leaf on a shoot, between the shoot base and the first node.Definition
Syllepsis - Immediate or Sylleptic branches
Botany. Syllepsis is the continuous development of a lateral from a terminal meristem, to establish a branch without an evident intervening period of rest of the lateral meristem. Immediate (or sylleptic) branches lack basal bud-scales and have an extended basal internode (hypopodium) generally below the first leaf or pair of leaves. See also ProllepsisDefinition
Prolepsis, Delayed or Proleptic branches
Botany. Prolepsis is the discontinuous development of a lateral meristem to establish a branch, with some intervening period of rest of the lateral meristem. Delayed (or proleptic) branches have one or more basal bud-scales (often arranged in pairs) and usually with a series of transitional forms (transitional in both size and shape) towards the adult leaf. See also SyllepsisDefinition