Long distance transport of water
- Water, minerals and food are generally moved by a mass or bulk flow system.
- Mass flow is the movement of substances in bulk from one point to another as a result of pressure differences between the two points.
- In mass flow, the substances are swept along at the same pace.
- Bulk flow can be achieved either through a positive hydrostatic pressure gradient or a negative hydrostatic pressure gradient.
- The bulk movement of substances through the conducting or vascular tissues of plants is called translocation.
- The higher plants have highly specialised vascular tissues called xylem and phloem.
- Xylem is associated with translocation of mainly water, mineral salts, some organic nitrogen and hormones, from roots to the aerial parts of the plants.
- The phloem translocates a variety of organic and inorganic solutes from the leaves to other parts of the plants.
Fig. Long distance transport of water and minerals