Fig. 9.1-1. Transverse section of magnolia leaf (Magnolia). This leaf has individual cells that produce and store oils. This is an extremely simple secretory system: the accumulation space is the vacuole and the isolation mechanism is the vacuole membrane (the tonoplast). The cells are not aggregated together as a complex or duct or chamber, they are just individual cells that differ from the other cells around them (that is, they are idioblasts).