The phloem in vascular plants is basically the living vascular tissue that is responsible for carrying photosynthate, (organic nutrients, particularly glucose (sugar)) to different parts of the plant.

 It is the bark’s innermost layers in trees, therefore getting its name from the Greek word “phloos”, which  means bark. Phloem is only responsible in transporting soluble organic materials that were produced during the process of photosynthesis, which is termed as translocation.

Phloem is one of the two types of vascular tissues found in plants. Xylem and phloem are the two main components of the plants’ transport system. Although these two parts are separated completely within the transport system. both of them are located at all parts of the plant; they transport different substance from one another, throughout the plant. Xylem is responsible in carrying water and nutrients while phloem carries dissolved substance, sap and sugar throughout the plant.

The sugars, produced during photosynthesis are being transported to the other parts of the plant through the phloem tissue, and will be used for storage, growth or cell functions. Phloem consists mainly of still-living cells that are responsible in transporting sap, unlike xylem that is normally composed of dead cells.

Difference between the transport systems of plants and animals

The transport system of mammals differs from plants in two different ways: the latter do not need the substances as fast as mammals do simply because they are not as active. Dissolved substances as well as water move through the plant by means of osmosis and diffusion, and not through the pumping of a certain organ, the mammals’ heart.

Another distinguishing characteristic is in what is being carried and where it is about to be carried by the transport system. Different substances aside from water are carried in all directions, to and from, up and down the leaves via the vascular tissue; unlike in mammals where the blood is carried by the arteries away from the heart while the veins carry it back.

©2005-2015 Plant Biology Advice - Dean Ravenscroft