The roles of cell division and cell expansion in the growth of alfalfa leaf mesophyll

Abstract

Leaf mesophyll of Medicago sativa (L.) was investigated to determine the roles of cell division and cell expansion in tissue growth. Samples of leaf tissue were macerated, stained, and squashed. The slides were studied under a phase microscope to determine the percentage of recently divided cells and the average cell diameter for leaflets of varying lengths. Cell division was greatest in young leaflets and virtually ceased as a leaf length of 12 mm was attained. For leaflets less than 12 mm in length, the rate of increase in cell size appeared to be inversely associated to the degree of cell division. For alfalfa leaflets greater than 12 mm in length, the mean cell size increased in proportion to leaf length since cell division had virtually ceased. © 1973 OXFORD UNIVERSITY PRESS.