Transportation is a vital process in plants. Trees transport all the nutrients and water it needs for survival from its roots to the tips of the leaves.

In the case of transportation in plants, the biggest constraint is water as it ends up being a limiting factor in growth.  To overcome this problem, trees and other plants have the perfect system for the absorption and translocation of water.

Plants contain a vast network of conduits which consist of xylem and phloem. This is more like the circulatory system that transports blood throughout the human body. Similar to the circulatory system in humans, the xylem and phloem tissues extend throughout the plant. These conducting tissues originate from the roots and move up through the trunks of trees. Later they branch off into the branches and then branching even further into every leaf, like spider webs. 

Transportation occurs in three levels in the case of plants:

Transportation of substance from one cell to another.

Long-Distance transport of sap within phloem and xylem.

The release and uptake of solute and water by individual cells.

Let us have a detailed look at the process of absorption and transportation in plants.

Transport in plants

Xylem moves water from roots to the leaves, and phloem moves food from the leaves to the rest of the plant. During transpiration water evaporates from the leaves and draws water from the roots....

Xylem and phloem

Plants have tissues to transport water, nutrients and minerals.

Xylem transports water and mineral salts from the roots up to other parts of the plant, while phloem transports sucrose and amino acidsbetween the leaves and other parts of the plant.

Xylem and phloem in the centre of the plant root

This table explains what is transported by the xylem and phloem:

XylemWater and mineralsTranspiration streamPhloemSucrose and amino acidsTranslocationXylem

Mature xylem consists of elongated dead cells, arranged end to end to form continuous vessels(tubes).

Mature xylem vessels:

contain no cytoplasmare impermeable to waterhave tough walls containing a woody material called ligninPhloem

Phloem consists of living cells arranged end to end. Unlike xylem, phloem vessels contain cytoplasm, and this goes through holes from one cell to the next.

Phloem transports sucrose and amino acids up and down the plant. This is called translocation. In general, this happens between where these substances are made (the sources) and where they are used or stored (the sinks).

This means, for example, that sucrose is transported:

from sources in the root to sinks in the leaves in spring timefrom sources in the leaves to sinks in the root in the summer

Applied chemicals, such as pesticides, also move through the plant by translocation.