Ergastic Substances

it contains appropriate content about almost all ergastic substances

1. Ergastic Substances &
Sclerenchyma Cells

2. Ergastic Substances or
Cell Inclusions
Cell Inclusions are non-living substances present
in the cells.
They are also called ergastic substances or
ergastic bodies. They may be present in
soluble or insoluble state and can be organic
or inorganic in nature.These are present in
components or sub-components of cell. They
are raw materials or products of
metabolism.THEY may be exported or
expelled from the cell.

3. The cell inclusions belong to three
categories:-
Reserve food
Excretory or secretory products
Mineral matter

4.  Reserve food: They are of four main types-
•Starch
•Glycogen
•Fat droplets
•Aleurone grains
Starch grains occur in plant cells. The grains
are found in chloroplasts and amyloplasts. As
such they are insoluble. The grains may occur
singly when they are called simple. They are
called compound starch grains when two or
more of them occur in amyloplasts.

5. Here SIMPLE STARCH grains of potato and
wheat repectively

6. COMPOUND STARCH grains
in avena and potato

7. Each starch grain has a central proteinaceous
area called HILUM. Starch is deposited
around it in the form of layers. Depending
upon the position of hilum,a starch grain may
be concentric or eccentric.
FAT DROPLETS: Fat droplets or globules occur
abundantly inside the seeds either in
endosperm(e.g., Castor,Coconut) or
cotyledons(e.g., Groundnut,Mustard

8. ALEURONE GRAINS
They represent the storage proteins which are
generally insoluble and occur inside special
leucoplasts called aleuroplasts. Depending upon
their internal structure,aleurone grains are of
four types:
•Amorphouus
•Protein matrix containing a crytalloid
e.g., outer layer of endosperm in
wheat,maize,barley,grains.
•Protein matrix with globoid
•Protein matrix having both crytalloid and globoid

9. inclusion, e.g, endosperm cells of castor seeds.
CRYSTALLOID is crystal like protein-carbohydrate
body while glboid contains lipid and phytin

10. EXCRETORY OR
SECRETORY PRODUCTS:
They are of several types like:
•Essential oils
•Alkaloids
•Resins
•Gums
•Tannins
•Waxes
•Latex etc.

11. Tanniferous bodies are widely distributed in
different parts of the plant body and they
are particularly abundant in leaves,vascular
tissues,periderm,unripe fruits,seed coat. They
are small granular or rounded
particles,yellow,red or brown in color.These
phenolic compounds are commercially useful in
tanning industry.
Other soid and semi-solid substances,such as
oils,fats and waxes also occur frequently. Oils
and fats are common reserve materials of
seeds,while waxes occur usually as protective
covering on the epidermis.

12. MINERAL MATTER(CRYSTALS)
Crystals of different composition,which are byproducts
of the metabolic processes of the cells,occur in
different parts of the plant.
Calcium oxalate crystals are most common in plants.
Their shape varies considerably and may be
elongated,needle-
like,rectangular,rhomboidal,sphaeroidal or prismatic.

13. •The elongated crystals when occurring solitary
are known as styloids and when in bundles they
are called raphides. Crystals of inorganic
compounds, such as silica and gypsum although
uncommon are also present in some plants.
•In moneyplant,
Needle-shaped
Raphides appear as
Scratches on slide.
•In Opuntia,arranged
In the form of spheres-
“Sphaeroraphides”

14. •Silicon salts are often deposited in the
cell walls of grasses. Cystoliths, which are
internal outgrowth of cell wall occur in
many plants.
e.g., Ficus
Calcium carbonate
Crystals present in
Sacs
-appear like bunch of
Grapes,”CYSTOLITH”

15. Sclerenchyma cells
Mature sclerenchyma
cells are dead and have secondary cell walls
thickened with cellulose and
usually impregnated with lignin. In contrast
to collenchyma, which is pliable(able to
fold), sclerenchyma is elastic.Unlike the
collenchyma, mature sclerenchyma is
composed of dead cells. with extremely
thick cell walls (secondary walls) that make up
to 90% of the whole cell volume.  It is the
hard, thick walls that make sclerenchyma cells
important strengthening and supporting
elements in plant parts that have ceased
elongation

16. TYPES
•There are two types of sclerenchyma
cells, namely sclereids and fibres.
Fibres: The cells are needle-shaped with
pointed tips, thick walls and rather
small lumen. Secondary cell walls,
impregnated with, are formed. Simple
pits are also present. Fibres are
abundant in the vascular tissue of
angiosperms, i.e. flowering plants.
.

18. •Contrasting are hard fibres that are mostly
found in monocots. Typical examples are the
fibres of many grasses, agaves. Their cell walls
contain, besides cellulose, a high proportion
of lignin. Starting at the centre of the fibre are
the thickening layers of the secondary wall
deposited one after the other. Growth at both
tips of the cell leads to simultaneous elongation.
. During development ,the layers of secondary
material seem like tubes, of which the outer one
is always longer and older than the next. After
completion of growth the missing parts are
supplemented, so that the wall is evenly thickened
up to the tips of the fibres.

19. ECONOMIC FIBRES
•The phloem fibres of dicotyledons represent bast
fibres and these are classofied as soft fibres
because lignified or not,they are relatively soft and
flexible. Some of the well-nown sources and usages of
bst fibres are hemp(Cannabis sativa),jute(Corchorus
capsularis),flaax(Linum usitatissimum),textiles(e.g.,
linen).
•Phloem fibres of some dicotyledons are used for
making paper.
The fibres of monocotyledons-usually called leaf fibres
because they are obtained from leaves-are classified
as hard fibres. Examples of sources and uses of leaf
fibres are Manila hemp(Musa textilis),Pineapple
fibre(Ananas comosus) and Sisal(Agave sisalana).
Leaf fibres of monocotyledons(together with the xylem)
serve as raw material for making paper.

20. •Sclereids: The cells are irregular in shape.
The cell walls are thick, hard and lignified
which makes the lumen very small. Simple pits
(canals) are found in the thickened cell walls
and link adjacent cells. Sclereids are
commonly found in fruit and seeds. These
have a shape of a star.
•They are small bundles of sclerenchyma tissue
in plants that form durable layers, such as the
cores of apples. They can be grouped into
bundles, can form complete tubes located at
the periphery or can occur as single cells or
small groups of cells
within parenchymatissues. But compared with
most fibres, sclereids are relatively short

21. On the basis of their shape and thickness of
walls sclereds have been variously classified:
Astrosclereids: They are star-
shaped(stellate) cells found in the leaves of
Nymphaea and stems and leaves of Thea

22. Brachysclereids or Stone cells: They are
short roughly isodiametric sclereids,occurring
in the cortex,pith and phloem of
stems(Cinnamomum),pulp of fruits(Pyrus)
Macrosclereids: They
are elongated columnar
Sclereids distributed in
Seeds and fruits in the
Form of a layer
(leguminous seeds)

23. Macrosclereids
Osteosclereids: They are bone or
barrel shaped and dilated at ends.
They occur in the leaves and seed coat of
many cot many monocotyledons.

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