Is Phloem Alive?
Yes, phloem is alive. Unlike xylem, which primarily transports water and is composed of dead cells at maturity, phloem is a living tissue crucial for transporting sugars and other organic compounds throughout the plant.
Phloem's living nature is essential to its function. The cells within phloem, particularly sieve tube elements, are specialized for transport. While they lack nuclei at maturity, they remain alive and are supported by companion cells that provide metabolic support. This allows for active transport of sugars and other nutrients, requiring energy and living cellular processes.
Several sources confirm this:
-
Multiple scientific articles and educational resources explicitly state that phloem consists of living cells. (BBC Bitesize, Wikipedia, Journal of Experimental Botany) These sources highlight the importance of the living state for the active transport processes within the phloem.
-
The role of companion cells is emphasized, illustrating the collaborative nature of the living tissue. These cells support the sieve tube elements, providing the necessary energy and metabolic functions essential for the transport of nutrients. (Wikipedia)
-
The active transport mechanism within phloem requires living cells and energy expenditure to move sugars against concentration gradients, unlike the passive transport in xylem. (homework.study.com)
In contrast to the outer layers of a tree trunk, which are living, the inner layers are composed of dead cells (xylem) (Colorado State Forest Service). However, the phloem, a distinct tissue within the tree trunk, remains vital and alive.
