The requirement of light for photosynthesis is a fact of life for plants. Dominance in the competitive plant world belongs to the plant that can reach the highest. Great height solves the light problem but creates major logistical problems. Once water and minerals are acquired, the logistical problems are far from over. The mechanism for movement of materials from roots to the uppermost shoots baffled scientists for ages. What forces would transport materials higher than a pump will pump water from a well? Food produced in the lighted leaves must be distributed throughout the immense structure. It was no less difficult to explain the movement of sugar from the site of photosynthesis to the site of need or storage. These mysteries are explained in this chapter.