This document discusses the functions and structures of plant stems. It describes stems as structures that support plants, conduct water and food, and store products like water, starch, and sugars. Stems are made up of nodes and internodes and contain buds. The document contrasts characteristics of herbaceous versus woody stems. It outlines secondary functions of stems including protection, photosynthesis, support, storage, and reproduction. Various specialized structures are defined, such as rhizomes, tubers, bulbs, corms, runners, stolons, offsets, suckers, tendrils, thorns, cladophylls, and phylloclades.