Xylem and Phloem Differentiation in Perspective

Abstract

The discovery of the microscope made possible an examination of the internal structure of multicellular plants, and the first publication on vascular plant anatomy involved the xylem tissue of the walnut tree (Henshaw 1661, cited in Preston 1981). Early publications on the tissues of higher plants by Grew (1682) and Malpighi (1675) also described mainly the xylem, since xylem forms the major supporting tissue of all the spermatophytes and pteridophytes. In spite of innumerable publications since those early days, Preston (1981) 300 years later commented that “more needs to be known about the differentiation of wood, anatomically, physically, and biochemically...