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).