Publisher Summary This chapter discusses the growth and differentiation in endosperm cultures and reviews the effect of various physical and chemical factors on the growth of endosperm callus. It also describes the results of histological and cytological studies of endosperm cultures. Some of the physical and chemical factors affecting endosperm cultures include pH, light and temperature, sugars, and amino acids. As a carbon energy source, sucrose is commonly used in endosperm tissue cultures. With higher concentrations of sucrose there is generally a decrease in growth. In prolonged cultures, endosperm callus exhibits cells of different ploidy. The mature endosperm of some species fails to proliferate if cultured without the embryo. Perhaps, the embryo releases certain substances (embryo factor) for the activation of the endosperm. The chapter also discusses the applicability of endosperm cultures in various areas, including the raising of triploid plants in relation to plant improvement. The production of triploid plantlets from the endosperm of Citrus is a very significant advancement.