5: Tissues and Organs - How the Plant is Built

5.1: Tissues
Tissue is a union of cells which have common origin, function and similar morphology. Tissues belong to organs: organ is a union of different tissues which have common function(s) and origin. Plants have simple and complex tissues. The simple tissues (tissues with uniform cells) are composed of the same type of cells; complex tissues (tissues with more than one type of cells) are composed of more than one type of cell, these are unique to plants.
5.2: Organs and Organ Systems
5.3: The Leaf
5.4: The Stem
The stem is an axial organ of shoot. It has functions of support, transportation, photosynthesis, and storage. Stem has radial structure, no root hairs and grows continuously.
5.5: The Root
Root is a latest evolutionary innovation in the vegetative plant anatomy. Many “primitive” plants (all mosses and even some ferns like Psilotum) do not have roots; some flowering water plants like the> rootless duckweed (Wolffia) or the coontail (Ceratophyllum) have also reduced their roots. However, large homoiohydric plants need the constant supply of water and minerals, and this evolutionary challenge was responded with appearance of the root system.