Root Capillary Action
Plant roots have the capacity to draw up water and oxygen through their cells and store internally produced nutrients in the form of plant sugars. The vascular system of the plant disperses the water and oxygen molecules via turgor pressure to fuel the plant's metabolic processes including the main life process of photosynthesis.
The process of photosynthesis allows the plant to manufacture its own food using sunlight to drive the process. Carbon dioxide taken in by the stomata mixes with water in the plant and is bombarded by light in the foliage cells to produce the simple sugar glucose and oxygen.
Vascular Transport of Sap
The vascular tissues of the plant, called xylem, move water and minerals from the plant roots to the foliage. Phloem tissues move simple and complex sugar molecules, plant hormones and acids up and down the plant foliage. Sap is the mixture of elements in the xylem and phloem. Veins in the plant are a key part of this vascular system, akin to nutritional highways in the leaves where the majority of photosynthesis occurs.