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“ A simple tissue is made up of similar
type of cells which have common origin
and function”
DEFINITION OF SIMPLE TISSUES
Three types of simple tissues are 1. Parenchyma 2. Collenchyma3. sclerenchyma
TYPES OF SIMPLE TISSUES
Parenchyma is a Greek word Para means “beside”& en means “to pour”
parenchyma tissues is composed of living cells which are variable in their morphology & physiology
1. Parenchyma
It consists of unspecialized cells with
thin cell walls these are living, with a large central
vacuole intercellular spaces between them. Oval ,rounded & polygonal in shapes
Structure
Arenchyma
In aquatic plants large air cavities are present which give buoyancy to the plants and help them to float
Types of parenchyma tissuesChlorenchyma
It contains chlorophyll & performs photosynthesis.
1. It provides support to plants and also stores food in the form of starch grains fats & oils
2. Air spaces in parenchyma also facilitate exchange of gases
Functions
They are elongated living cells with small intercellular spaces. Their cell walls are made of cellulose and pectin.
It occur in the peripheral regions of stems and leaves.
It allows easy bending in various parts of a plant (leaf, stem) without breaking.
mature collenchyma are living & contain
protoplast
2.collenchyma( supporting tissues)
Types of collenchyma tissues on the basis of cell arrangement three types are 1.Angular 2.Lamellar3.tubular
1. AngularIn this type cells are irregularly arranged e.g ficus2.LamellarCells are arranged in tagential rows(plate like arrangement) e.g sambucus3. tubularTube like arrangement,intercellular spaces are present
It provides mechanical support and flexibility in plants.
Helps in photosynthesis
Function of collenchyma
Sclerenchyma are long, dead cells with a deposit of lignin in their cell wall.
They have no intercellular spaces. This tissue is present in stems, around
vascular bundles, in the veins of leaves and in the hard covering of seeds and nuts.
Thick walled cells Don’t possess living protoplast at
maturity
structure
elongated sclerenchyma cells,usually with pointed end
The wall of fibres are usually lignified Pits of fibres are always small,round,or
silt like At maturity the protoplast disappear &
permanent cells becomes dead or empty
It occurs in patches Average length of fibres is 1to 3mm
1.Fibres
the fibres develop from the same
maristematic tissues as the other xylem cells
orThe fibres which originated from xylem
Xylem fibres
These are related to phloem that form continous cylinder in monocotyledon stem arise in the ground tissue under the epidermis at variable distance
TYPES: 1.Phloem fibres (originating primary &
secondary phloem)2.Cortical fibres ( originating in the cortex)3.Perivascular fibres( originated in the
peripheral region of vascular cylinder
Extraxylary fibres
- Sclerenchymatous cells which are short and possess extremely thick, lamellated, lignified walls with long singular piths. They are called sclerides
Its is commonly found in cortex and pits of gymnosperms
Types:1.Brachysclereids2.Macrosclereids3.Osteosclereids
sclereids
4.Astrosclereids 1.brachysclereids stone cells are short & more or less isodiametric. These are commonly found in cortex ,phloem,& pulp of fruit 2.macrosclereids more or less rod like cells found in
xerophytic leaves