The Transport System In Plant

The vascular tissues are concerned with transport and are functionally equivalent to the circulatory system of mammals. The two types of vascular tissues are called xylem and phloem.

The main function of the xylem is to transport water and minerals salt from the roots to the stem an leaves. Xylem forms wood in shrubs and trees. Therefore, xylem provides support to the plants. Xylem consists mainly of vessels, which are elongated tubes with thick walls. The walls are strengthened with a substance called lignin. Xylem vessels are dead structures without protoplasmic contents and transverse walls.

Source : http://cnx.org/content/m44708/latest/Figure_30_05_04.png

Phloem transport synthesised food substances from one part of the plant to another. Phloem consists mainly of sieve tubes. Sieve tubes are living cells without nucleus. The walls of sieve tubes are composed largely of cellulose. The transverse walls of sieve tubes are perforated by pores and are called sieve plates. Each sieve tube cell has a companion cell beside it.

Source : http://leavingbio.net/FLOWERING%20PLANTS_files/image048.jpg