Which type of xylem is characterized by being dead at maturity and having thick secondary cell walls?

The type of xylem that is characterized by being dead at maturity and having thick secondary cell walls is vessels. Vessels are specialized tubular structures that facilitate the efficient transport of water and minerals from the roots to the rest of the plant. The thick secondary cell walls provide structural support to withstand the negative pressure created during water transport, allowing the plant to maintain its integrity while conducting essential functions.

While tracheids also serve a similar purpose in water transport and are dead at maturity, vessels are generally more efficient in conducting water due to their larger diameter and multiple perforations at the ends, allowing for a faster flow compared to the narrower tracheids. Fibers, although they also have thick secondary cell walls and are dead at maturity, primarily provide structural support rather than playing a significant role in water transport. Rays, on the other hand, are involved in the lateral transport of nutrients and do not function primarily as conduits for water.