Plant Anatomy Also known as Micromprphology of plants and plant- or vegetable-histology, is concerned with the microscopic structure of the tissues, cells and organs of plants.

Plant tissues A tissue is a group of coherent cells having similar form and function and have common origin. Tissues are classified according to stage of development to: Meristematic tissue: the cells have the ability of division. Mature (permanent): the cells lost the power of division.

Meristematic tissue They characterized by: 1- Thin walled. 2- Isodiametric. 3- With dense cytoplasm. 4- With large nucleus. 5- Have proplastides. 6- No intercellular spaces. 7- No vacuole or presence of minute ones. 8- No reserve food materials.

Classification of meristems Apical meristems: located at the growing points of stems and roots e.g. those present in stem and root apices. Intercalary meristems: present between two permanent zone, present at base of internodes e.g. sugarcane and maize. Lateral meristems: present laterally and cause increase in diameter of plant.

Different types of mature tissues 1- Parenchyma 2- Collenchyma 3- Sclerenchyma 4- Epidermis 5- Endodermis 6- Pericycle 7- Cork (phellem) 8- Laticiferous tissue 9- Sieve tissue 10- Tracheary tissue 11- Vascular tissue 12- Secretory structures 13-Nectaries

1- Parenchyma Characters: 1- Simple living cells. 2- Have primary cellulosic thin wall with simple pits. 3- Have intercellular spaces. 4- They may be elongated, isodiametric or lobed.

Occurrence: 1- In cortex and pith of stems and roots. 2- Associated with xylem and phloem. 3- In leaves and fruits. Function: 1- In aeration. 2- In photosynthesis. 3- Storage of water, protein, minerals, etc.. 4- May become meristematic and divide.

2- Collenchyma Characters: 1- Simple living tissue. 2- Have primary cellulosic thick wall with simple pits. 3- May have intercellular spaces. 4- They are elongated cells.

Types: Lamellar: thickening on tangential walls. Angular: thickening on angles between the cells. Lacunar: thickening on walls facing the intercellular spaces.

Occurrence: 1- Under epidermis of stems. 2- Cortical tissue and pericycle of leaves. Function: They are plastic tissue used for mechanical support of soft plants.

3- Sclerenchyma They are dead cells when mature with thick secondary walls, they are elastic tissue used for mechanical support. Sclerenchyma has two types; fibres and sclereids.

A- Fibres They are dead cells have pitted walled with narrow Lumina and pointed apices, xylary fibres are lignified while extraxylary fibres may be lignified or non-lignified.

B- Sclereids They are dead cells short, isodiametric, elongated or branched thick walled, pitted, lignified with branched lumina.