Ever wondered how water and minerals reach every part of a plant, including its tip? How do you think the food, synthesised by plant leaves via photosynthesis, is transported to the other parts, including the roots?
Plants transport food, water, minerals, organic nutrients and plant regulators across longer distances via a vascular system that comprises of xylem and phloem. This phenomenon of transporting substances is called translocation.
The transfer of water and minerals through the xylem is usually unidirectional, that is, from the roots to the other parts of the plant.
It is the organic and mineral nutrients that are transported in multiple directions. The leaves synthesise carbohydrates that need to be transported to all the parts of the plant, including the storage organs. The storage organs, in turn, further export the mineral nutrients to all the growing parts. Likewise, if a part of a plant ages or decays, nutrients are usually withdrawn from that region and transported to the other parts.
Substances move across the short distances either by diffusion or by cytoplasmic streaming, which is supported by active transport. Therefore, in a flowering plant, translocation of a variety of substances takes place, with each organ giving out some substances while receiving others.