Morphology and architecture of
Growth in Cedar is rhythmic and all axes are built up of by succession of annual shoots. At the spring time, the current annuals shoots are often slanted and generally straighten up from the July beginning. The shoot growth rate decreases progressively from the main stem, which grows with a vertical direction, to the branches and the branchlets, which grow in a horizontal direction (mean cumulative length of currently-elongating shoots according to axis category over a growing season ).
In natural regeneration, the first annual shoots of the main stem have a small size. The following years, the apical meristem of the main stem normally forms successive annual shoots of increasing number of leaves and increased length . Vigorous annual shoots may develop lateral axes in the same year that their extension. These lateral axes correspond to a mixture of short and long shoots. In this case, branching of current year annual shoots is immediate and the most vigorous lateral shoots have a median position on the bearing shoot. The following year, bearing shoots develop shoots from dormant buds which are located in apical position on the bearing shoot and their lateral axes continue to grow. Like this, lateral axes show an acrotonic gradient of decreasing vigour from the top to the base of the bearing shoot . The branches with immediate development are characterised by the absence of scaly leaves associated with the absence of a protecting resting stage at their base.
After the expression of its architectural unit, the tree will continue to develop its trunk and to remain regularly branched . Oldest branches increase their volume by a process partially reiteration of the architectural unit. At the top of the branches, a sub-apical bud of the annual shoot develops to a vigorous shoot. This phenomenon give rise to fork formation. Thus, the repeating of this process allows the development of branches. During following years, this phenomenon of fork formation progressively invades the branches.
Female flowering affect brachyblasts borne by the most vigorous axes: the main stem, the branches and reitered branchlets. The first flowering is generally located on the upper part of the tree . During successive flowering, the floriferous zone spreads toward the tree periphery and progressively invades its crown . Male flowering is located on the brachyblasts corresponding to highest orders of branching. Male flowering is distributed at the periphery of female floriferous zone .
As the tree continues its development, new branches located in the upper part of trees develop in accordance with the architectural unit of these species. In the lower part of trees, the branches form more and more short annual shoots and finally die.
The comprehensive architecture of the old tree tends to bend and only some branched systems still grow up. In these complexes, axes are more or less bicyclic and then can be branched ; they allow the extension of tree crown.