Plant Parts, plant tissues, microscopy and morphology

1. 3. Introduction to parts of plants
A. Cell and its organelles
B. Cell inclusion
C. Plant tissues
D. Microscopy and morphology of plants
1. Leaves
2. Root
3. Stem
4. Flower
5. Fruits
6. Seed
7. Bark
8. Rhizome

2. A. Cell and its organelles
• Plant cells are the basic unit of life in organisms of the
Plant kingdom. They are eukaryotic cells, which have a
true nucleus along with specialized structures called
organelles that carry out different functions.
• Animals, fungi, and protists also have eukaryotic cells.
• Bacteria and archaea have simpler prokaryotic cells.
• Plant cells are differentiated from the other cells by
their cell walls, chloroplasts, and central vacuole.

4. Cell organelles
The plant cell has many different parts. Each
part of the cell has a specialized function.
These structures are called organelles.
1. Cell wall 7. Golgi bodies
2. Vacuole 8. Ribosomes
3. Plastids 9. Endoplasmic Reticulum
4. Cytoplasm 10. Microtubules
5. Nucleus 11. Peroxisomes
6. Mitochondria

5. 1. Cell wall: Cell wall is the outermost layer of the plant cell that
protects the cell and gives shape to the cell. It is composed
of cellulose, hemicellulose and pectin. It plays important role
in intercellular communication. Plants have two types of cell
walls, primary and secondary. Plasmodesmata are the pores
in the cell wall through which cell communicates.
2. Vacuole: Vacuole is a cell organelle that helps in storage and
maintaing turgor pressure of cell against cell wall. It occupies
more than 30% of volume in a plant cell which may increase
upto 90% in some cells. It is covered by a membrane called
tonoplast. It also helps in detoxification, protection, and
growth of cell. When a plant cell matures, it typically contains
one large liquid-filled vacuole.

6. 3. Plastids: Plant plastids are a group of membrane
bound organelles that functions in photosynthesis, storage of
starch, synthesis of cellular building block materials, etc .
Plastids in plants include chloroplasts, chromoplasts,
leucoplasts, amyloplast, elaioplast and
proteinoplast/aleuronoplast depending on the function they
play. The main types of plastids and their functions are:
• Chloroplasts are the organelle of photosynthesis. They capture
light energy from the sun and use it with water and carbon
dioxide to make food (sugar) for the plant.
• Chromoplasts are the organelle that provide color to the plant.
They make and store pigments that give petals and fruit their
orange and yellow colors.
• Leucoplasts are the organelles that are specialized for bulk
storage of starch, lipid, or protein. They do not contain pigments
and are located in roots and non-photosynthetic tissues of
plants.

7. 4. Cytoplasm is the gel-like matrix inside the cell
membrane which contains all other cell organelles.
It controls cell metabolism and cell signal.
5. Nucleus is the control center of the cell. It is a
membrane bound structure which contains the
hereditary material of the cell - the DNA.
6. Mitochondria carries out cellular respiration and
provides energy to the cells. They convert glucose to
energy molecules (ATP). They possess their own
hereditary material which help in self duplication
and multiplication.

8. 7. The Golgi bodies are known as the golgi apparatus or golgi
complex which are made of flattened sac-like organelle
(cisternae) located near the nucleus. The golgi body packages
proteins and carbohydrates into membrane-bound vesicles for
"export" from the cell.
8. Ribosomes are smallest and the most abundant cell organelle.
It consists of RNA and protein. Ribosomes are sites for protein
synthesis. They are found in all cells because protein are
necessary for the survival of the cell. The ribososomes are known
as the protein factories of the cell.
9. Endoplasmic reticulum is a membrane bound compartment,
which look like flattened sacs lined side by side. It is a large
network of interconnecting membrane tunnels. It is composed of
both rough endoplasmic reticulum and smooth endoplasmic
reticulum. They are responsible for protein translation, and
protein transport to be used in the cell membrane.

9. 10. Microtubules: Microtubules are composed of polymers
of the globular protein ‘tubulin’ that maintains the
structure of the cell and chromosome movement
in mitosis and meiosis. Together with microfilaments
they form the cytoskeleton.
11. Peroxisomes: Peroxisomes are the organelles that
contain enzymes which produce hydrogen peroxide as a
by-product. These structures are involved processes such
as photorespiration.

10. B. 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.
• The cell inclusions belong to three categories:-
1. Reserve materials
2. Metabolic and secretory materials
3. Minerals

11. 1. Reserve food:
• Starch: Starch is the insoluble carbohydrate
containing amylose and amylopectin.
• Cellulose: Cellulose is a solid carbohydrate that occurs
in endoplasm of some seeds.
• Glycogen: Glycogen are the carbohydrate that are
stored as reserve foods.
• Fat droplets: Fat droplets are fatty acid and glycerol
present in cytoplasm as small globules. They posses
more caloric value than protein and sugars.
• Aleurone: Aleurone are insoluble storage proteins
present inside special leucoplasts called aleuroplasts.
They occur in the outer endosperm cells of cereals
such as wheat, rice & maize.

12. 2. Metabolites and secretory products:
• Essential oils: These are volatile oils produced by special glands and
cells. Aromatic flowers, leaves and bark are due to essential oils.
• Alkaloids: These are nitrogenous compounds, made up of carbon,
hydrogen, oxygen and nitrogen. They are found in storage organs
of plants such as seeds, bark and leaves. They are insoluble in
water but soluble in alcohol. They have sour taste and some are
poisonous. However, a large number of alkaloids, such as quinine,
reserpine, nicotine, caffeine, strychnine, morphine, atropine, are
used as medicines.
• Resins: These are produced by the oxidation of essential oils. These
are found in some special glands either alone or in combination
with essential oils. These are insoluble in water but soluble in ether
and alcohol. These are used in the manufacture of paints and
varnishes.

13. • Gums: Produced by the disintegration of cellulose cell wall.
They are soluble in water. Used for sticking purposes, and
also as medicine,
• Tannins: They are sour in taste and related to glycosides.
They occur in vacuolar sap, cell wall, bark and leaves of some
plants. They are found mostly in unripe fruits. They are used
on a large scale for hardening of leather, a process called
tanning of leather.
• Latex: It is a milky substance secreted by latex glands. Robber
secreted by the rubber tree Hevea brasiliensis is an important
example.
• Nectar: Nectar is secreted by nectaries in plants that attracts
insects for pollination because it is sweet and contains
sucrose, glucose and fructose.

14. 3. Minerals:
Minerals may occur in crystals as:
• Calcium oxalate
• Silicon salts
• Calcium carbonate
e.g: Leaves of Ficus species have cystoliths in
their epidermal cells.

15. C. Plant Tissues
Ground Tissue Vascular Tissue
•Epidermis
•Periderm
•Guard cell
Dermal Tissue

16. Meristematic Tissues
• Tissues where cells are constantly dividing are called
meristems or meristematic tissues.
• They are the mass of young and undifferentiated cells having
the power to divide.
• These regions produce new cells. These new cells are
generally small, isodiametric structures with a number of tiny
vacuoles and a large nucleus, by comparison. As the cells
mature the vacuoles will grow to many different shapes and
sizes, depending on the needs of the cell.
• There are three types of meristems:
• Apical Meristems
• Lateral Meristems
• Intercalary Meristems

17. • Apical meristems are located at or near the tips of roots and shoots. As
new cells form in the meristems, the roots and shoots will increase in
length. This vertical growth is also known as primary growth. A good
example would be the growth of a tree in height. Each apical meristem
will produce embryo leaves and buds as well as three types of primary
meristems: protoderm, ground meristems, and procambium. These
primary meristems will produce the cells that will form the primary
tissues.
• Intercalary meristems are found in grasses and related plants that do not
have a vascular cambium or a cork cambium, as they do not increase in
girth. These plants do have apical meristems and in areas of leaf
attachment, called nodes, they have the third type of meristematic
tissue. This meristem will also actively produce new cells and is
responsibly for increases in length. The intercalary meristem is
responsible for the regrowth of cut grass.
• Lateral meristems account for secondary growth in plants. Secondary
growth is generally horizontal growth. A good example would be the
growth of a tree trunk in girth. There are two types of lateral meristems
in the plants; vascular cambium and the cork cambium.

19. Permanent Tissue
Simple Permanent Tissue
• Parenchyma Tissue: Parenchyma cells form parenchyma tissue. Parenchyma cells are
the most abundant of cell types and are found in almost all major parts of higher
plants. These cells are basically sphere shaped when they are first made. However,
these cells have thin walls, which flatten at the points of contact when many cells are
packed together. These cells have large vacuoles and may contain various secretions
including starch, oils, tannins, and crystals. Parenchyma cells can divide if they are
mature, and this is vital in repairing damage to plant tissues. Parenchyma cells and
tissues comprise most of the edible portions of fruit.
• Some parenchyma cells have many chloroplasts and form the tissues found in leaves.
This type of tissue is called chlorenchyma. The chief function of this type of tissue is
photosynthesis, while parenchyma tissues without chloroplasts are generally used for
food or water storage.
• Additionally, some groups of cells are loosely packed together with connected air
spaces, such as in water lilies, this tissue is called aerenchyma tissue. These type of
cells can also develop irregular extensions of the inner wall which increases overall
surface area of the plasma membrane and facilitates transferring of dissolved
substances between adjacent cells.
• Functions: Synthesis, Storage, Conduction of water and food, photosynthesis
(chlorenchyma), buoyancy (aerenchyma)

21. • Sclerenchyma Tissue: Sclerenchyma cells form sclerenchyma tissue. These cells have
thick, tough secondary walls that are imbedded with lignin. At maturity, most
sclerenchyma cells are dead and function in structure and support. Sclerenchyma cells
can occur in two forms:
• Sclereids are sclerenchyma cells that are randomly distributed throughout other
tissues. Sometimes they are grouped within other tissues in specific zones or regions.
They are generally as long as they are wide. An example, would be the gritty texture in
some types of pears. The grittiness is due to groups of sclereid cells. Sclereids are
sometimes called stone cells.
• Fibers are found in a wide variety of tissues in roots, stems, leaves and fruits. Usually
fiber cells are much longer than they are wide and have a very tiny cavity in the center
of the cell. Currently, fibers from over 40 different plant families are used in the
manufacture of textiles, ropes, string and canvas goods to name a few.
• Collenchyma Tissue: Collenchyma cells form collenchyma tissue. They are mechanical
tissue with cell wall thickened by cellulose and pectin. These cells have a living
protoplasm, like parenchyma cells, and may also stay alive for a long period of time.
Their main distinguishing difference from parenchyma cells is the increased thickness
of their walls.
• Collenchyma cells are found just beneath the epidermis and generally they are
elongated and their walls are pliable and strong. As a plant grows these cells and the
tissues they form, provide flexible support for organs such as leaves and flower parts.
Good examples of collenchyma plant cells are the ‘strings’ from celery that get stuck in
our teeth.

22. Complex Permanent Tissue
• Xylem: Xylem is permanent tissue that conducts water along with minerals
from root to leaf. They are composed of tracheids, vessels, xylem fibers
and xylem parenchyma.
• Tracheids are the elongated, spindle shaped, thick lignified walled cells
which are dead at maturity.
• Vessels are multicellular elongated tubes formed by chain of elongated
cells.
• Pits are the areas of primary wall of tracheids and vessels through which
diffusion of fluid takes place from cell to cell.
• Xylem fibres are the sclerenchyma fibres associated with xylem.
• Xylem parenchyma are the parenchymatous cell of xylem that are living
elements in xylem.

23. • Phloem: Phloem is permanent tissue that conducts dissolved food from
leaves to storage organs and to growing regions. It occurs along with
xylem. This conduction system is composed of sieve elements, companion
cells, phloem fibres and phloem parenchyma.
• Sieve elements are composed of sieve cells and sieve tubes. Sieve cells
are living, elongated and slender that help for conduction. Sieve tubes are
combined to form sieve plate that consists of numerous perforating.
• Sieve-tube members that are alive contain a polymer called callose.
Callose stays in solution as long at the cell contents are under pressure. As
a repair mechanism, if an insect injures a cell and the pressure drops, the
callose will precipitate. However, the callose and a phloem protein will be
moved through the nearest sieve plate where they will form a plug.
• This prevents further leakage of sieve tube contents and the injury is not
necessarily fatal to overall plant turgor pressure.
• Companion cells are living, have dense granular cytoplasm and a
prominent nucleus.
• Phloem fibres are the sclerenchyma associated with phloem that are
lignified and having small and rounded simple pits.
• Phloem Parenchyma are the parenchymatous cell of phloem present in
dicots.

24. D. Microscopy and morphology of a plant
1. Leaves
2. Flower
3. Fruit
4. Seed
5. Stem
6. Bark
7. Root
8. Rhizome

25. 1. Leaves
• Leaves are flat, thin, green appendages to the stem
that have important role in support and functions of
plant.
• Leaf includes leaf and leaflets.
• Medicinal leaves are collected during flowering season
of the plants, when plants reach maturity and they are
photosynthetically most active.
• Leaves containing volatile oils are collected when the
plant is rich in volatile oils.
• The weather and time of collection is important in
procurement of the leaves.
• Discolouration of leaves is considered as substandard.

26. Characterstics of leaf
1. Stomata: Stomata are minute epidermal openings in the
leaves of plant for gaseous exchange and transpiration.
Stomata consists of two kidney shaped cells and a minute
opening in between.
According to type and arrangement of cells the stomata are of 4
types:
a. Moss type
b. Gymnospermous type
c. Gramineous type
d. Dicotyledonous type

27. • Dicotyledonous stomata are further classified as:
• Paracytic or parallel celled stomata: It comprises of two guard
cells covered by two subsidiary cells, the long axes of which are
parallel to that of stoma.
• Diacytic or cross celled stomata: The guard cells are covered by
two subsidiary cells, the arrangement of subsidiary cells on guard
cells is at right angle to that of stoma.
• Anisocytic or unequal celled stomata: Two guard cells are
covered by three subsidiary cells of unequal size.
• Anomocytic or irregular celled stomata: Stomata is sorrounded
by varying number of subsidiary cells.
• Actinocytic or radiate celled stomata: Two guard cells are
sorrounded by a circle of radiating subsidiary cells.

28. Stomatal number: The average number of
stomata per square mm of the epidermis is
known as stomatal number.
Stomatal Index: The percentage proportion of
the number of stomata to the number of
epidermal cells of a leaf is known as stomatal
index.
Stomatal Index = S × 100
E+S
S= No. of stomata per unit area
E= No. of epidermal cells in the same area

29. 2. Leaf constants:
a. Vein-islet number is defined as the number of vein islets per
sq. mm of the leaf surface between midrib and the margin.
b. Vein termination number is defined as the number of veinlet
terminations per sq. mm of the leaf surface between midrib
and margin.
c. Palisade ratio is defined as the average number of palisade
cells beneath each epidermal cell.
3. Water pores: Water pores are present on the teeth of the
margin and are similar in structure and function with stomata.

30. 4. Trichomes: Trichomes are the tubular elongated or glandular
outgrowth of the epidermal cells. They are also called plant
hairs that have secretory functions. Trichomes are classified
as:
a. Glandular trichomes: Presence of glandular cells at top of
trichome. It may be unicellular or multicellular.
b. Covering or non-glandular trichomes: It may be unicellular or
multicellular.
c. Hydathodes: Trichomes for absorption or secretion of water
developed in certain plants.

31. 2.
Flowers
• The flower is the modified shoot meant for
the production of the seeds.
• A flower is built upon stem or pedicel with
the enlarged end known as thalamus or
receptacle.
• e.g: clove, saffron, etc

32. • A flower consists of four different circles (whorls) arranged in a
definite manner.
• Calyx: Outermost whorl of the flower usually green in color.
Individual calyx are called sepals.
• Corolla: Second whorl of the flower usually bright coloured.
Individual corolla are petals.
• Androcium: Male part of the flower which lies inside second
whorl. Individual component is called stamen which consists of
filament, anther and connective.
• Gynocium: Female part of the flower which lies in inner part of
the flower. Individual component is called carpel or pistil which
consists of stigma, style and ovary.

33. 3. Fruits
• The ovules of the flower convert into seeds after fertilization
and the ovary wall develops into protective covering of seeds
known as fruit.
• Fruits may or may not have seeds. If the ovules do not
fertilize, the seedless fruits are formed.
• Fruit layer or pericarp is composed of 3 layers:
a. Epicarp: Outermost coating of pericarp that may be thin, thick
or woody.
b. Mesocarp: Middle layer between epicarp and endocarp that
may be pulpy or made up of spongy parenchymatous tissue.
c. Endocarp: Innermost layer of the pericarp that may be thin,
thick or woody.

34. Depending upon the number of carpels present in the
flower, fruits are classified as:
a. Simple fruits: Simple fruits are formed from single carpel or
from syncarpous gynaecium. It may be dry or fleshy fruit.
e.g: dry fruits: pea, gram, rice, nut, etc
fleshy fruits: apple, mango, pear, orange, grape, etc
b. Aggregate fruits: Aggregate fruits are formed from many
carpels or apocarpous gynaecium.
e.g: rasp-berry, star-anise, etc
c. Compound fruits: Compound fruits are formed from many
flowers that come together and become fruits.
e.g: long pepper, pineapple, mulberry
• Pseudocarp or false fruits: Fruits that grows from parts
other than the ovary like thalamus, receptacle or calyx are
known as pseudocarp. E.g: strawberry, cashewnut, etc

35. 4. Seeds
• The seed is a fertilized ovule that represents a condensed form
of life.
• It is a characteristic of phanerogams which contains embryo,
endosperm and seed coat.
• Seeds are classified as:
• Endospermic or albuminous seeds: Seeds containing
endosperm and part of the endosperm remains until
germination. e.g: colchicum, linseed, nux-vomica, etc
• Non-endospermic or exalbuminous seeds: Endosperm is
absorbed during development and not present in seeds. e.g:
sunflower, cotton, etc
• Perispermic seeds: Seeds in which nucleus develops to form
storage tissue and seeds contain embryo, endosperm,
perisperm and seed coat. e.g: pepper, cardamom, nutmeg, etc

36. Characteristics of seeds
• Hilum: It is the point of attachment of seed to stalk.
• Micropyle: It is the minute opening of the tubular structure,
whereform water is provided for the germination of the
seeds.
• Raphe: It is the longitudional marking of adherent stalk of
anatropous ovule.

37. Special features of seed:
a. Aril: Aril is the succulent growth from hilum covering the entire
seed. e.g: nutmeg
b. Arillode: It is the outgrowth originating from micropyle and
covering the seed. e.g: cardamom
c. Arista: It is the stiff bristle like appendage with many flowering
glumes of grasses. e.g: strophanthus
d. Cranucle: It is the warthy outgrowth from micropyle. e.g: castor
e. Strophiole: It is an enlarged funicle. e.g: Datura fastuosa
f. Hairs: It is hairy outgrowth. e.g: Gossypium

38. 5. Stems
• Stem is the ascending axis of the plant developed from the
plumule.
• It consists of nodes, internodes and buds and it gives rises to
branches, leaves and flowers.
• The stem may be aerial, sub aerial and underground. Depending
upon the presence of mechanical tissues the stem may be weak
herbaceous or woody.
• Weak stems: These are thin, long and unable to stand erect.
a. Creepers or prostate stems
b. Climbers
c. Twinners
• Herbaceous or woody stems: These are soft, hard or woody
stems.
• e.g: sugarcane, sunflower, ephedra, etc.

39. 6. Barks
• Barks are the secondary external tissues lying
outside the cambium in stem or root of
dicotyledonous plants. e.g: Cinchona bark
• Botanically, bark is known as periderm.
• Periderm consists of three layers:
a.Cork (phellem)
b.Cork cambium (phellogen)
c. Secondary cortex (phelloderm)

40. • Shapes in barks : flat, curved, channeled, quill
• Fractures in bark: short fracture, splintery fracture, fibrous
fracture & laminated fracture
• Methods of collecting barks
a. Felling method: The tree is cut at base and bark is peeled out.
b. Uprooting method: Roots of plants are dug out of soil and
bark is stripped off from roots and branches.
c. Coppicing method: Plant is cut off at specific distance from
soil and the stumps are allowed to send shoots that develop
into aerial parts. These parts are cut and bark is collected
from shoots.

41. 7. Roots
• Roots are the underground parts of the plant
for anchorage and water/nutrient absorption.
• On the basis of origin roots may be primary,
secondary or adventitious types.
• e.g: radish, carrot, turnip, sweet potato, etc

42. 8. Rhizomes
• Rhizomes are the underground modification
of stem with nodes and internodes that are
thick & fleshy. They may also possess bud and
adventitious roots.
• Rhizomes may be branched and serve as
storage organ.
• e.g: ginger, turmeric, rhubarb, etc