Anticlinal Divisions and Cell Length in Conifer Cambium

A contradiction seems to exist with respect to the relationship between cell length and tree growth. Comparisons of species, varieties, and ecotypes have shown that cells were longer in the faster growing trees. Some work on the influence of height growth on tracheid length in seedlings as evidence of a positive relationship. Uncertainty exists as to whether greater early length of cell is maintained through the succeeding growth sheaths. The effect of leader growth on cell length in the cambium lower in the bole of mature trees remains to be determined. Investigations of fluctuation within the tree have firmly established the existence of a negative relationship between rate of radial growth and cell length in the cambium. The inverse relationship between cell length and ring width does not hold throughout the entire growth range. It is operative only when ring width exceeds 1.5 mm. At a ring width of about 1 mm, cell length tends to maximize. Contraction in ring width to less than 0.5 mm is accompanied by reduction in cell size. Often an inverse relationship between frequency of anticlinal division and cell length in the cambium is manifest. This interrelation is exhibited in the sequential changes outward from the pith, in the local fluctuations which occur in the middle to late growth of mature trees, and in tree to tree, and to a lesser degree in species to species, comparisons. The prevalence of this relationship might be interpreted as indicating that rate of anticlinal division is a major determiner of cell length. Considerable evidence has been presented for genetic control over tracheid length. Much of the fluctuation in cell length is attributable to the action of elements in the internal and external environment which govern rate of radial growth. Intrinisic sequential changes in cell size take place, which are part of the transition from juvenility to maturity in the development of the individual tree. Cell size is largely determined by the interplay of genetic, environmental, and ontogenetic factors. Anticlinal division in the cambium may be regarded as a part of the mechanism by which cell divisions are regulated.

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