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Ecophysiology of a fossil Carboniferous progymnosperm
Water stress commonly causes live xylem parenchyma to bulge into adjacent conducting cells. This forms tyloses that inhibit further water transport. Scheckler and Galtier (pp. 739-747) show that distribution of tyloses in Protopitys wood corresponds to recurring water stress-induced dormancy, heartwood vs. sapwood location, tracheary cell dimension, and geometry of ray parenchyma distribution.
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