Britannica
Sources used in this answer
How are tracheids different from vessel members?
Created from Britannica articles
using AI.
AI can make mistakes, so verify using Britannica articles.
wood
Temperate softwoods (left column) and hardwoods (right column), selected to highlight natural variations in colour and figure: (A) Douglas fir, (B) sugar pine, (C) redwood, (D) white oak, (E) American sycamore, and (F) black cherry. Each image shows (from left to right) transverse, radial, and tangential surfaces. Click on an individual image for an enlarged view.
Tracheids and vessel members are both specialized, hollow, and elongated cells that function as water-conducting elements within xylem tissue. However, they differ significantly in structure and efficiency:1
- Structural Differences: Tracheids are primitive, single cells with pointed ends that contain pitsāthinned areas of the cell wallābut lack perforations. In contrast, vessel members are thought to have evolved from tracheids through the loss of end walls, resulting in the formation of perforations that allow for more direct, unimpeded water flow.234
- Conductivity: Because water must pass through pit membranes when moving between tracheids, conduction is relatively slow. Vessel members are joined end-to-end to form vessels, which provide a more efficient system for water transport, though this increased efficiency makes them more susceptible to air bubbles and disruptions.13
- Distribution: Tracheids are the only water-conducting elements in most gymnosperms and ferns, whereas vessel members are the principal conducting cells in angiosperms.41