→ Anatomically, a plant is made up of different kinds of tissues. Tissue is broadly classified into meristematic (apical, lateral, and intercalary) and permanent (simple and complex) tissues.

→ Tissues perform various functions such as assimilation, mechanical support, storage, and transportation of materials such as water, minerals, and photosynthates.

→ There are three types of tissue systems viz. epidermal ground and vascular.

→ The ground tissue system may be divided into three zones-cortex, pericycle, and pith.

→ The vascular or conducting tissue system includes the xylem and phloem.

→ Dicotyledonous and monocotyledons plants show marked variation in internal structures. They differ in the type, number, and location of vascular bundles.

→ Secondary growth occurs in most of the dicotyledonous roots and stems and it increases the diameter of the plant.

→ The wood is actually secondary xylem, which is formed during one growth session. There are different types of wood on the basis of their composition.

→ Meristems: Growth in plants is largely restricted to specialized regions of active cell division called meristems.

→ Apical meristems: The meristem which occurs at the tips of roots and shoots and produces primary tissues are called apical meristems.

→ Intercalary meristems: The meristem which occurs between mature tissues is known as the intercalary meristem

→ Primary meristem: Both apical meristems and intercalary meristem are also called the primary meristem.

→ Lateral meristem: The meristem that occurs in the mature regions of shoots and roots of many plants, particularly those that produce a woody axis and appear later than primary meristem is called the lateral meristem

→ Protoxylem: Primary xylem is of two types. The first formed xylem elements are called protoxylem.

→ Metaxylem: The later formed xylem is called metaxylem.

→ Endarch: In stems, the protoxylem lies towards the centre (pith) and the metaxylem lies towards the periphery of the organ, called Endarch.

→ Cuticle: The outside of the epidermis is often covered with a waxy thick layer which is called the cuticle.

→ Guard cells: Each stoma is composed of two bean-shaped cells known as the guard cells.

→ Subsidiary cells: Sometimes, a few epidermal cells, in the vicinity of the guard cells become specialized in their shape and size, known as subsidiary cells.

→ Stomatal apparatus: The stomatal aperture, guard cells, and the surrounding subsidiary accessory cells are together called stomatal apparatus.

→ Trichomes: The cells of the epidermis bear a number of hairs known as trichomes.

→ Mesophyll: In leaves, the ground tissues consists of thin-walled chlorenchyma and is called mesophyll.

→ Open vascular bundles: The xylem and phloem together constitute vascular bundles. Such vascular bundles are called open vascular bundles.

→ Radial: When xylem and phloem within a vascular bundle are arranged in an alternate manner on different radii as in the roots are called radial as in the roots.

→ Epidermis: The outermost layer is the epidermis.

→ Endodermis: The innermost layer of the cortex is called the endodermis.

→ Conjunctive tissue: The parenchymatous cells which lie between the xylem and phloem are called conjunctive tissue.

→ Mesophyll: The tissue between the upper and the lower epidermis is called the mesophyll

→ Bulliform cells: In grasses, certain adaxial epidermal cells along the veins modify themselves into large, empty, colourless cells, which are called bulliform cells.

→ Secondary growth: Apart from primary growth most dicotyledonous plants exhibit an increase in girth. This increase is called secondary growth.

→ Springwood or earlywood: The wood formed during this season is called springwood pr earlywood.

→ Autumn wood or latewood: In winter, the cambium is less active and forms xylary elements. These have narrow vessels, and this wood is called autumn wood or latewood.

→ Annual ring: The two kinds of woods appear as alternate concentric rings, constituting an annual ring.

→ Cork cambium: Sooner or later, another meristematic tissue called cork cambium or phellogen.

→ Periderm: Phellogen, phellem, and phelloderm are collectively known as periderm.