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simple tissues

Simple tissues are composed of similar cell types that have a common origin and function. There are three main types: parenchyma, collenchyma, and sclerenchyma. Parenchyma tissue is made of living cells and performs functions like photosynthesis, storage, and gas exchange. Collenchyma cells provide support and flexibility to plant structures. Sclerenchyma cells are dead at maturity and provide strength and structure through thick lignified cell walls. Each tissue type has subcategories that differ in cell shape, arrangement, and specific functions.

Science◦
SIMPLE TISSUES
“ A simple tissue is made up of similar type of cells which have common origin and function”
Three types of simple tissues are 1. Parenchyma 2. Collenchyma 3. sclerenchyma
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
It occurs in  Pith  Mesophyll of leaf  Pulp of fruit  Endosperm of seed  Xylem and Phloem
 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
Arenchyma In aquatic plants large air cavities are present which give buoyancy to the plants and help them to float Chlorenchyma 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
 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
three types are 1.Angular 2.Lamellar 3.tubular
1. Angular In this type cells are irregularly arranged e.g ficus 2.Lamellar Cells are arranged in tagential rows(plate like arrangement) e.g sambucus 3. tubular Tube like arrangement, intercellular spaces are present
 It provides mechanical support and flexibility in plants.  Helps in photosynthesis
The sclerenchyma is a Greek word Sclerous means “hard” & enchyma means “infusion”
 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
 It provides strength to the plant parts.  it maintain the turgidity of plants
Two types are  Fibres  Sclereides
 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
Two types of fibres are  Xylem fibres  Extraxylary fibres
the fibres develop from the same maristematic tissues as the other xylem cells or The fibres which originated from xylem
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
 - 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.Brachysclereids 2.Macrosclereids 3.Osteosclereids
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
3.osteosclereids theses are bone shaped & found in the hypodermal layer of seeds & fruits 4.Asterosclereids these are star shaped found in intercellular spaces of the leaves & stem of hydrophytes