Complex tissues or vascular tissues or conducting tissues


Plant tissues are of two kinds.Thay are
(1)Simple tissues
(2)Complex tissues
The complex tissues help in transportation of substances in higher plants.In lower plants,transportation takes place by Diffusion,Osmosis and by active transport.
        But in higher plants,transportation is done by vascular tissues as substances have to travel long distances.This type of movement of substances by conducting tissues is called Translocation

Complex tissues

Complex tissues is also called as Vascular tissues or Secondary tissues or Conducting tissues.
Complex tissues are of two types.They are:
(1)xylem
(2)Phloem

  Xylem:

Xylem is a thick-walled,tubular,placed end to end like pipelines.It conducts water and minerals from roots to stems and leaves.It is uni-directional i.e.upward direction.It provides mechanical strength to the plant.It consists of :

Trachieds,Vessels,xylem fibres and xylem parenchyma.

Gymnosperms lack vessels.So presence of vessels is the characteristuc feature of angiosperms.
Xylem parenchyma stores food materials in the firm of starch.
Old xylem forms the wood and not participate in transport.

Phloem:

Phloem is tubular transports food materials by upward and downward movement.Unlike xylem it is bi-directional.Depending on the seasons the movement varies from upward to downward.In few seasons leaf forms food material and transports to roots in downward direction whereas in few seasons roots forms food material and transports to leaves in upward direction.
Phloem transports sucrose,sugars,harmones and amino acids.
Phloem consists of 

Sieve tube elements,Companion cells,Phloem parenchyma,phloem fibres,Albuminous cellsand Sieve cells

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