Plant veins consist of two distinct types of tissues. The xylem is responsible for transporting water and minerals from the roots of the plant to other areas of the plant. On the other hand, phloem is responsible for carrying nutrients and sugars away from the leaf to where the plant is growing or to storage areas within the plant. The stoma, which are typically located on the bottom of the leaf, is used to allow gases involved in photosynthesis (carbon dioxide and oxygen) to enter and leave the leaf. The guard cells, which surround each stoma, are used to open and close the stoma.