In vascular plants, phloem is the living tissue made up of small tubes which carry watery sap containing sugar and other organic nutrients to all parts of the plant where the nutrients are used for growth, or stored until needed. The sugar is made by photosynthesis. In trees, the phloem is the innermost layer of the bark, therefore the name, that comes from the Greek word φλοιος ("phloios") for "bark". 