In cress roots (Lepidium sativum L.), abscisic acid prevents the development of the central cap cells into statocytes.

If seeds of Lepidium sativum are soaked in a 10(-4)M solution of abscisic acid (ABA) for 30 min, the structural development of the central cap cells (C.C.) deviates strongly from the norm. ABA inhibits the elongation of the C.C., the sedimentation of the amyloplasts which may be caused by a higher viscosity of the cytoplasm, the formation of the stacked ER-cisternae at the distal cell pole, and the polar arrangement of the cell organelles along the gravity vector. The statistical distribution of the organelles and the arrangement of lipid droplets near the plasmalemma indicate that ABA prevents the normal development of the C.C. into statocytes.