Anatomy of Flowering Plants

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6. Anatomy of Flowering Plants
Tissue
 It is a group of cells that are similar in structure and are organised together to perform a specific function.
 It is of two types: Meristematic tissues and Permanent tissues  Meristematic tissue
 It consists of actively dividing cells that are found in those regions of the plant body that show growth.
 The examples include root tip, shoot tip, and base of the leaves.  It is classified into three types:
i. Apical meristem: They are present in the growing tips of stems and roots. Function – helps in increasing the length of the stem and root ii. Intercalary meristem: They lie at the base of leaves or internodes. Function – helps in the longitudinal growth of plants

iii. Lateral meristem: They lie on the lateral sides of the stem and root. Function – helps in increasing the thickness of stem and root  Apical meristem and intercalary meristem help in the formation of the primary plant body. Therefore, they are called primary meristems.

Lateral meristem is formed in the mature regions of roots and shoots of plants. Hence, they are known as secondary meristem.
 Permanent tissues
 They are formed from meristematic tissues through the process of cell differentiation.  They are of two types: Simple tissues and complex tissues  Simple tissues: These consist of only one type of cells that are more or less similar in structure and functions.

 Sclerenchyma is further divided into two types – fibres and sclereids.  Complex tissues: They are made up of more than one type of cells. All these cells work in coordinated manner to perform one common function.

o Xylem:
 It conducts water and minerals from roots to different parts of the plant.  Tracheids and vessels are long tube-like structures with thick walls and tapering ends. Presence of vessels is the characteristic feature of angiosperms. Function: to transport water and minerals vertically

 Xylem fibre is made up of dead cells.
Function: support to the cell
 Xylem parenchyma is made up of living cells.
Function: Storage of food and helps in sideways conduction of water o Phloem:
 It transports food material from leaves to different parts of the plant.  Sieve tubes are tubular cells with perforated walls.
Function: to transport food material
 Companion cells are specialised parenchymatous cells, closely associated with sieve tube elements. These are characteristic features of angiosperms. Function: to maintain the pressure gradient in sieve tubes

 Phloem parenchyma is composed of living cells that help in storage of food.  Phloem fibres, also called bast fibres, provide mechanical support to the cells. Tissue System
 Epidermal tissue system:
 It comprises of epidermal cells, stomata, trichomes, and hairs.  Epidermis is protective in function. Cuticle is the waxy layer present outside the epidermis.
 Cuticle prevents the loss of water. It is absent in roots.  Stomata help in gaseous exchange and transpiration.
 Root hair helps in absorption of water and mineral from soil.  Trichome prevents water loss due to transpiration.
 Ground tissue system

 It comprises of all tissues except epidermis and vascular bundles.  Vascular tissue system
 It mainly comprises of complex permanent tissues - xylem and phloem. Cambium may or may not be present.
 Open vascular bundle: It contains cambium between xylem and phloem. Cambium has the ability to form secondary tissues. It is the characteristic feature of dicotyledonous stem.
 Closed vascular bundle: It lacks cambium between xylem and phloem. Since cambium is absent, it lacks the ability to form secondary tissues. Closed vascular bundle is the characteristic feature of monocotyledonous stems.

 Radial vascular bundle: Xylem and phloem are arranged alternately on different radii. Such types of vascular bundles are present in roots.
 Conjoint vascular bundle: Xylem and phloem are arranged at the same radius of vascular bundle. Such types of...
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