Seedling trees were grown in complete nutrient solution and in one without added boron for a period of 5 years. Roots and shoots of boron‐deficient plants showed a variety of symptoms which were involved in the disruption of normal cellular differentiation. Abnormalities in structure, cell shape, wall conformation and rigidity are described for both primary and secondary tissues. The persistence of the trees in spite of the death of apical meristems and local or seasonal variations are discussed.

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