Briefly explain four functions of stems. Solution Function of Stems: 1. It helps store water , as in cacti, and the products of photosynthesis, as in the trunk of sago palm (Metroxylon sagu) and sweet palm (Argenga pinnata) which store large stock of starch 2. Young green stem also performs a minor role in the production of food through the process of photosynthesis, but in some species (e.g. cactus) the stem is the chief photosynthesizing organ 3. It supports the leaves, flowers and fruits and connect them with roots. In trees and shrubs the main stem or trunk provides a strong columnar structure from which branches are attached raising the leaves upward to be expressed more fully to the sun 4. The plant stem serves as a means of asexual reproduction in many species..