Vascular tissues are complex tissues found in plants which is used to conduction, transport and support. The primary components of vascular tissues are the xylem and the phloem.
Xylem conducts water and some minerals form the roots upward throughout the entire plant. Xylem can be found in vascular bundles which are present in non-woody parts of the plant, in secondary xylem or as part of stellar arrangement which are not divided into bundles.
Phloem transport food which includes large organic molecules such as glucose to any location in the plant where it is needed. Phloem is also concerned in the delivery of nutrients and molecules needed for photosynthesis. Phloem tissue consists of parenchyma cells (albuminous and unspecialized cells), supportive cells and conducting cells
The vascular tissues include xylem, which conducts water and minerals from the roots upward and throughout the plant, and phloem, which transports dissolved foods in all directions within the plant.
The main conducting vessels of xylem are the tracheids and the vessels. Tracheids are long, thin tubes found in most vascular plants, while vessels are large tubes found predominantly in angiosperms. The tracheids and vessels form pipelines that have pores and perforated ends, which allow water and minerals to be conducted from one tube to the next and out to the surrounding tissues. Tracheids and vessels also help support the plant body.
The main conducting cells of phloem are sieve cells and sieve tube members. Both cell types have numerous pores through which substances are exchanged with adjacent cells. Sieve tube members occur in angiosperms, while sieve cells are found in other vascular plants. In angiosperms, small cells called companion cells assist the sieve tube members in their functions.