Abstract

Structural changes accompanying the reversal of spirality in interlocked grain were studied in Anacardium occidentale. The reversal of spirality sometimes occurs within a narrow zone comprising a few cell layers of the growth increment. This zone is distinguishable by numerous small vessels occurring in groups and clusters, shorter and thin-walled fibres, abundant parenchyma and wider rays densely filled with extractives. The course of vessels is irregular and their anastomosis is frequent in this zone, while adjacent to it, a tendency towards left or right spirality is evident. This tendency is more pronounced in the vessels