How do xylem and phloem move different materials through a plant?

In vascular plants, xylem and phloem serve as specialized tissues for long-distance transport, functioning similarly to a circulatory system.1

Xylem: Water and Mineral Transport

Xylem, which constitutes the wood of a tree, is responsible for the upward movement of water and dissolved mineral nutrients from the roots to the rest of the plant. This process is primarily driven by transpiration, where water evaporates from the leaves, creating a pressure gradient that pulls water upward through the xylem’s tiny, rigid, lignified tubes. This movement is passive and occurs in one direction: from the roots to the above-ground parts of the plant.1234

Phloem: Nutrient Transport

Phloem, often found in the inner bark, transports the products of photosynthesis—primarily sugars—from the leaves to other parts of the plant, such as roots, fruits, and growing tissues. Unlike xylem, phloem transport is under metabolic control and can move materials in various directions depending on the plant's needs. Sugars are actively loaded into and removed from the phloem by companion cells, facilitating a pressure-driven flow from source regions (where sugars are produced) to sink regions (where they are used or stored).145