Formation and function of compression wood in gymnosperms

Westing, Arthur H. (Middlebury Coll., Vt.). 1965.Formation and function of compression wood in gymnosperms. Bot. Rev. 31: 381–480 A review with ca. 575 references. The world literature pertaining to the biology of compression wood (Rotholz; reaction wood) is evaluated critically. Compression wood is a geotropic reaction to an inertial force and is peculiar to the Coniferales, Ginkgoales, and Taxales. It is formed by the cambium (or cambial derivatives) of the lower side of inclined stems and branches, where it expandsin situ thereby tending to right the former and maintain (or restore) the inherent angle of the latter. Compression wood is stimulated to form by applications of indoleacetic acid, but under natural conditions is interpreted to result from an increased sensitization of cells on the lower side to an insignificantly changed level of endogenous auxin. A theoretical model of the perception (susception) mechanism is advanced. The mechanics of righting is discussed and the forces involved are estimated. Frequent reference is made to other geotropic phenomena of the higher plants, particularly to tension wood, the analogue of compression wood in the arborescent Dicotyledoneae. Much pertaining to the perception, formation, and function of compression wood remains to be elucidated