Preliminary Course
Botany. Architectural Analysis
Plant organization
Organization levels
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Several levels of organization in the plant structure can be observed, revealed and used for plant edification understanding,
modelling and simulation (Barthélémy, 1991, Godin and Caraglio, 1998).
- The lowest description level is the phytomer, to be considered as the basic element of the plant structure establishment.
- Then successive phytomers build a stem or an axis from a growth process. When growth is rhythmic, growth units appear consecutively.
- A succession of phytomers (continuous growth) or growth units (rhythmic growth) then give rise to an axis.
- In the axil of leaves, branches appear, building a branched structure. We will see further that when this branched system develops, various categories of axis appear, some may specialize (bearing the sexuality for instance). This third hierarchical level builds the architectural unit.
- When the plant matures, the reiteration process, allowing the development of a crown, is involved in defining the whole plant organization level.
From the most elementary, the three repetition phenomena, growth, branching and reiteration, build the plant and give rise to several levels of organization, as follow:
Organization levels of a plant (Drawings D. Barthélémy, CIRAD)
The phytomer defines the first level.
The axis defines the second one, resulting from the growth process.
(Axes are composed of growth units if growth is rhythmic.)
The architectural unit defines the third level, resulting from both growth and branching.
The whole plant level results from the occurrence of the reiteration processes.
Bibliography
Barthélémy, D., Edelin, C., Hallé, F. 1991. Canopy architecture, in: Raghavendra A.S. (Ed.), Physiology of trees, John Wiley and Sons, Chichester, 1991, pp. 1-20
Godin C., Caraglio Y. 1998. A multiscale model of plant topological structures. Journal of Theoretical Biology, 1998, n. 191, pp.1-46.
Definition
Architectural Unit
Botany. The architectural Unit of a given plant species is the specific expression of its architectural model. The architectural Unit of a plant can be seen as a hierarchical branched system in which the axes can be grouped into categories according to their morphological, anatomical or functional distinctive features (Barthélémy et Caraglio, 2007).See also: Architectural Model.