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 and phloem are the two types of vascular tissues that are present in plants. They are responsible for transporting water, minerals, food and other organic materials between the roots, stems and leaves of the plant.ylem cells are hard walled cells, which are stacked on top of each other and are mainly found in the center of the stem. Hence, xylem has another function, which is to provide mechanical support to the plant. Xylem is surrounded by the phloem. Phloem is the other type of transport tissue in vascular plants.