CONTRACTILE ROOTS OF NARCISSUS

All the tissues in the contracted region of the contractile root of Narcissus become adjusted to the shortening of the root, which is brought about by vertical contraction and radial expansion of the inner cortical cells. Consequently the outer cortex including the exodermis is lifted passively in large wrinkles over the surface, while the vertical walls of cells in the stele become undulated or indented as in the case of the vessels. These phenomena are primarily brought about by the mechanical process of lifting and pulling due to the shortening and radial expansion of the inner cortical tissue. The possible mechanism of contraction of this cortical tissue is discussed. © 1969 OXFORD UNIVERSITY PRESS.