Plant Transport Systems
How everything moves around inside plants
The inside of a plant is much like a multi-lane highway, in that nutrients move from one organ to another - between roots, leaves, flowers and fruits, and along the stem. Water, carbohydrates, and other nutrients move from one organ to another in one of two ways: either short distance transport or long distance transport.
Think of short distance transport as you would think of driving around your block: it is the movement of a nutrient from one cell to another cell that needs that nutrient.
Long distance transport is similar to a road trip on an interstate, as some plants need to be able to transport water and nutrients over long distances; xylem and phloem do this. Xylem is the portion of a plant's vascular tissues that transports water and minerals, and phloem transports sugars and other compounds.
Transport occurs by various mechanisms:
Diffusion is simply the movement of a material in an area of high concentration to an area of low concentration.
Osmosis is diffusion across a membrane (such as a cell wall).
Active transport is the process of a molecular pump (a very, very tiny pump) which moves molecules across a membrane by using the plant's energy.