Final answer:
Primary xylem cells, which include tracheids and vessel elements, conduct water throughout the plant and are dead at maturity, which means that the proposition that these cells are matured when they are open is False.
Step-by-step explanation:
Primary xylem cells are the cells that make up the xylem tissue responsible for the transportation of water and minerals throughout a plant. These cells are categorized into different types, including xylem parenchyma, tracheids, and vessel elements. It's important to note that out of these, tracheids and vessel elements are the ones that primarily conduct water, and they are functional when they are mature, which in fact means they are dead. Now, let's focus on the formations within the xylem that help us to understand its function and development.
The activity of the vascular cambium, a type of meristematic tissue, is crucial for the growth of xylem. This activity leads to the formation of annual rings, which are visible in the cross-section of a tree trunk and represent a record of the tree's age and the environmental conditions in which it grew.
During different seasons, the nature of xylem cells formed varies. For instance, in the spring, cells in the secondary xylem have larger internal diameters and thinner primary cell walls, known as early wood. In contrast, the late wood, formed in the fall, exhibits thickened cell walls, making it denser. This pattern of early and late wood formation is what gives rise to the visible annual growth rings in trees. Additionally, the xylem transport occurs as a thermodynamic response to water loss from leaves or water entry into growing cells, illustrating the interconnectivity within plant systems.
In summary, primary xylem cells are not open when they are mature. Instead, they are functional when they are no longer alive. This contradicts the proposition in the question, thus the correct statement is that primary xylem cells are matured when they are open, is False.