9.2 - A - Phloem
In plants, organic compounds are transported through phloem tissues which are found throughout plant bodies. The structure of phloem consists of:
Phloem transports organic solutes throughout plants, which is referred to as translocation. It connects parts of plants that need organic compounds (sink) with those that have a surplus (source). Examples of each include the following:
Sometimes, plant sinks can turn into sources and vice versa. Because of this, phloem must be able to transport organic compounds in either direction. Fluid within the phloem flows inside the sieve tubes as a result of pressure gradients.
Since energy is needed to produce this pressure, translocation is an active process.
Xylem & Phloem Images
Xylem and phloem can be visualized using different types of microscopy. Phloem are typically smaller than xylem and are located towards the outside of vascular bundles in stems and roots.