One of two main parts of the transport system in the roots
and stems of plants, the other being
the xylem. Phloem consists of vascular tissue
that conducts synthesized foods, including sugars, proteins, and some mineral
ions, through the plant. It is characterized by the presence of sieve-tubes
and, in some plants, companion cells, fibers, and parenchyma
cells. Phloem is of two kinds: primary, formed by differentiation from procambium,
and secondary, additional phloem produced by activity of cambium.
| Comparison of xylem and phloem.