Definition - What does Phloem mean?
The phloem is part of the vascular system of the vine that is responsible for transporting the food and sugars that are created from the photosynthetic process. Along with the xylem, the phloem tissues have many different types of cells that are each responsible for different jobs (transport, support, protection). The phloem also contains a sieve tube and ray cells which helps the movement of nutrients through the plant and the storage of reserves.
WineFrog explains Phloem
Located under the bark of the vine, the phloem creates a channel of movement through which nutrients are transported to all parts of the plant. Sugars are moved from the source cells to sink areas where they are sorted and then used. The sieve tube is the most important conductive part of the phloem and must remain functioning to allow the plant to survive. The plasma membranes of the sieve tubes have specialized cells called companion cells that allow nutrients to pass in/out of the sieve and be distributed in other parts of the plant. When there are excess nutrients in the sieve tubes, the ray cells help them relocate to sink areas for storage. There are fibers within the phloem that structurally support the vine and P-proteins that protect the plant by “clotting” near injured areas preventing fluid loss.
The phloem along with the xylem are the main parts of the grapevine’s vascular system and are responsible for moving nutrients from photosynthesis and the roots to the other parts of the vine.