Vitamins in lettuce are plentiful. Its fresh leaves are an excellent source of several Vitamin-A and Î²-carotenes. Just 100 g of fresh, raw-lettuce provides 247% of daily vitamin A, and 4443 Âµg of Î²-carotene (Carotenes convert into vitamin-A in the body; 2 Âµg of carotene is considered equivalent to 1 IU of vitamin-A).
Xylem is one of the two types of transport tissue in vascular plants, phloem being the other.he most distinctive xylem cells are the long tracheary elements that transport water. Tracheids and vessel elements are distinguished by their shape; vessel elements are shorter, and are connected together into long tubes that are called vessels. Xylem also contains two other cell types: parenchyma and fibers.
Xylem is a tubular structure which is responsible for water transport from the roots towards all of the parts of the plant. Phloem is also a tubular structure but is responsible for the transportation of food and other nutrients needed by plant. Xylem imports water and minerals while Phloem transports water and food. Xylem consists of tracheids, vessels, xylem parenchyma and xylem fibres. 2  Also ray parenchyma Also the xylem of softwoods (Gymnospermae) do NOT contain vessels. 3  It is a living complex permanent tissue. 4  Inner phloem is alive.