Plant morphology leaf-converted

It discuss about the total morphology of a leaf. It explains leaf characters, size, types, shape, Base of Sessile Leaves, kinds, functions, leaf modifications types, Phyllotaxis types, leaf margin, apex, lamina and leaf structure in detail.

1. PLANT MORPHOLOGY -LEAF
DR. C. BEULAH JAYARANI
M.Sc., M.A, M.Ed, M.Phil(Edn), M.Phil(ZOO), NET, Ph.D
ASST. PROFESSOR,
LOYOLA COLLEGE OF EDUCATION, CHENNAI -34

2. SIMPLE LEAF
The Leaf (Latin: Folium) a thin leaf
or plate.
•a lateral outgrowth or an appendage
on the stem.
•possesses neither nodes nor
internodes and buds or lateral
branches arise in its axil.
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3. Characters OF LEAF
➢-flattened form
➢-thin texture
➢-presence of chlorophyll
➢-presence of veins
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4. Leaf Morphology
➢Leaf lamina
➢Stipule
➢Petiole
➢Node
➢Internode
➢Axillary bud
➢Stem Axil
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5. •Leaves have two main parts: The
leaf blade and the Stalk or the
petiole.
•The leaf blade:It is also called the
lamina. It's generally broad and flat.
•The petiole:It is the stalk-like
structure which connects the leaf
blade to the stem. The petiole has
tiny tubes, that connect the veins
on the leaf blade to the stem.
•Petiolate:The leaf blade is situated
on the petiole, e.g., Hibiscus, Ficus
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6. •Sessile:Without a petiole or
stalk, e.g., Ixora.
•Sub-Sessile: Having a short
stalk, e.g., Polygonum.
•Stipules:either of a pair of
small, usually leaflike
appendages borne at the
base of the petiolein many
plants.
•Stipulate: The leaf with
stipules, e.g., rose, Ixora,
•Exstipulate:
•The leaves having no
stipules, e.g., Ipomoea.
Stipulate
Exstipulate
SessileSub-SessilePetiolate leaf
Petiolate leaf
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7. SIZE OF THE LEAF
❑The length from the base to the apex and
the broadest width
❑It varies from tiny leaves (few millimeters)
as Savinto a very considerable size as
banana
❑In leaves used in medicine the doesn’t
exceed about 30 cm long as Digitalis
❑Leaves vary in size on the same plant being
bigger at the base and becoming smaller as
getting near the apex
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8. Leaf Base of Sessile Leaves
•Connate:Two sessile opposite
leaves meeting each other across
the stem and fusing together, e.g.,
Lomiceraflava.
•Auriculate:Leaf with expanded
bases surrounding stem, e.g.,
Calotropis.
•Perfoliate:A leaf with basal lobes so
united as to appear as if stem ran
through it, e.g., Aloe perfoliata.
Perfoliate
Auriculate
Connate
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9. •Decurrent:Having leaf base prolonged
down stem as a winged expansion or rib,
e.g., Laggerapterodonta
•Amplexicaul: Clasping or surrounding the
stem, as base of leaf, e.g., Sonchus.
Amplexicaul
Decurrent
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10. kinds of leaves
•Two major kinds of leaves are seen. They aresimple leaves and compound leaves. A
simple leaf has a single blade on its stalk and the stalk is attached to the plant
body.A compound leaf is a leaf stalk that has more than one leaf blade on it, and
the multiple leaf blades are called leaflets
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11. FUNCTIONS OF A LEAF
•Manufacture of food-Photosynthesis is the
process by which green plants make their
food from carbon dioxide and water in the
presence of sunlight.
•Transpiration-interchange of gases
between the atmosphere and the plant
body and evaporation of water.
•Guttation -isthe exudation of drops of xylem
sap on the tips or edges of leaves of some
vascular plants,
•Storage
•Défense
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12. types of leaf
modification
•Tendrils
•Leaf-spines
•Thorns
•Bracts
•Storage Leaves
•Adhesive Disc
•Reproductive leaf
•Phyllode
•Insect Catching Leaves
•Leaf Roots
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13. TENDRILS
STORAGE
LEAVES
THORNS
BRACTS
SPINES ADHESIVE DISC
REPRODUCTIVE
LEAF
PHYLLODE
INSECT
CATCHING
LEAVES
ROOTS
TYPES OF
LEAF
MODIFICATION
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14. •Tendrils: The leaves of a pea plant are modified
into tendrils that help the plant in climbing.
•Spines: The leaves in cactus are modified into
sharp spines that act as an organ of defense
•Phyllode:The leaves of some Australian acacia
are short-lived and soon replaced by flattened,
green structures called as phyllodes that arise
from the petiole of the leaves.
•Pitcher:The leaves of the pitcher plant are
modified into pitcher-like structures, which
contain digestive juices and help in trapping and
digesting insects. In insectivorous plants, the
leaves are especially adapted to catch and digest
insects to fulfil their nitrogen requirement.
Spines
Pitcher
Phyllode
Tendrils
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15. •Storage Leaves:Some plants of xerophytic
habitats and members of the family
Crassulaceae generally have highly thickened
and succulent leaves with water storage
tissue. These leaves have large
parenchymatous cells with big central vacuole
filled with hydrophilic colloid.
•Scale-leaves:Typically these are thin, dry,
stalkless, membranous structures, usually
brownish in colour or sometimes colourless.
Their function is to protect the axillary bud
that they bear in their axil. Sometimes scale-
leaves are thick and fleshy, as in/onion; then
their function is to store up water and food.
Storage leaves
Scale leaves11/19/2021 Dr. C. Beulah Jayarani 15

16. •Leaflet Hooks:In Bignonia unguiscati
the three terminal leaflets of leaf get
modified into claw like hooks which help
in climbing (Fig. 4.29).
•Leaf Roots: In case of Salvinia three
leaves are present at one node. Out of
these two leaves are normal and third
gets modified into adventitious roots
which help in floating over the surface of
water
•Adhesive Disc:are found on the stem
of the plant. These discshelp to climb
up on the support. Example Ficus
repens
Leaf roots
Leaflet hooks
Adhesive Disc
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17. •Reproductive Leaf: A special type of
reproduction occurs wherein theleaves
are modified to formreproductive
leaves. These leaves have the ability to
form a whole new individual. This kind of
leaves usually forms a tiny plant at the
ends or edges of the leaves.
•Bracts: When a flower arises in the axil
of a leaf-like structure, this structure is
known as a bract. Because bracts are
large and brightly coloured structures,
they are often mistaken for petals.
Thishelps to attract insects for
pollination.
Reproductive leaf
Bracts
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18. PHYLLOTAXIS
✓It is the disposition of the leaves
on the stem.
✓The leaves being arranged on the
stem in a definite manner
characteristic for each species of
plants.
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19. Phyllotaxis
•Alternate:A single leaf arises at each
node in an alternate manner.
Examples: China rose, Sun flower.
•Spiral:leaves are arranged in a spiral
along the stem.
•Opposite:A pair of leaves arise at
each node and lie opposite to each
other. Examples: Calotropis, Guava.
•Whorled: More than two leaves
arranged in a circle round an axis,
e.g., Spergula, Alstonia.
•Phyllotaxis, the regular arrangement of
leaves or flowers around a plant stem,
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20. Compound leaf
Forms of Compound leaves
✓There are three types of compound
leaves:
✓Palmately compound leaf
✓Pinnately, 2-pinnate, 3-pinnate,
bipinnate, tripinnate, odd-pinnate, and
even-pinnate
✓Double pinnatelycompound leaf
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21. A. Palmately compound Leaf
(i) Unifoliate:Having one leaflet only, e.g., Citrus.
(ii) Bifoliate:Palmate compound leaf with two leaflets,
e.g., Prinsepia, Balanites.
(iii) Trifoliate:Such palmate compound leaf having
three leaflets growing from same point, e.g., Oxalis,
Vigna, Trifolium, Melilotus, etc.
(iv) Quadrifoliate: Compound palmate leaf with four
leaflets arising at a common point, e.g., Marsilea (a
pteridophyte).
(v) Multifoliate:Compound palmate leaf with five or
more leaflets arising at a common point, e.g.,
Gynandropsispentaphylla, Bombax ceiba.
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22. B. Pinnately Compound Leaf
(a) Pinnate:A compound leaf having
leaflets on each side on an axis or midrib.
(b) Unipinnate:Having leaflets on each
side of an axis, e.g., Cassia.
(c) Bipinnate: The central axis produces
secondary axis which bears the leaflets,
e.g., Acacia.
(d) Tripinnate: The secondary axes
produce the tertiary axis which bear the
leaflets, e.g., Moringa.
(e) Decompound:More than thrice pinnate,
e.g., old leaves of coriander.
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(f) Paripinnate (Even
Pinnate):Pinnately compound
without a terminal leaflet, e.g.,
Cassia.
(g) Imparipinnate (Odd
Pinnate):Pinnately compound
leaf with an odd terminal
leaflet, e.g., pea.

25. Margin of Lamina
•Entire:With continuous margin, e.g., Psidium,
mango, madar
•Serrate:With serrate edges themselves toothed,
e.g., China rose, nim
•Lobed:Leaf margin divided into many lobes, e.g.,
Ranunculus
•Undulate:The margin is wavy, e.g., Polyalthia
•Dentate:With large saw like teeth on the margin,
e.g., Nympluiea, watermelon
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26. •Lacerate:Having margin or
apex deeply cut into irregular
lobes, e.g., many members of
Ranunculaceae.
•Crenate:With obtusely toothed
margin, e.g., Bryophyllum,
Centella
•Convolute:Rolled together
•Laciniate:Irregularly incise,
fringed.
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27. •Laciniolate:Minutely
incised or fringed.
•Ciliate:Bearing fine hairs
on the margin, e.g., Cleome
viscosa.
•Crispate:Curled or
extremely undulate margin.
•Spinous:Bearing many
spines, e.g., Argemone.
•Pectinate:Comb like
margin.
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28. APEX OF THE LEAF TYPES
The outer end or apex ofa leaf lamina that is opposite the petiole. Leaves apexes
vary greatly from plant to plant and are useful in classification and identification.
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29. Leaf Apex
•Acute:Ending in a sharp point forming an acute
angle, e.g., mango.
•Acuminate:Drawn out into long point; tapering;
pointed, e.g., Ficiisreligiosa.
•Obtuse:With blunt or rounded end, e.g.,
Banyan.
•Emarginate:Having a notch at apex, e.g.,
Bauhinia.
•Truncate: Terminating abruptly, as if tapering
end were cut off, e.g., Caryotamens,
•Mucronate:Abruptly terminated by a sharp
spine, e.g., apex of leaflet of Cassia obtusifolia.
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30. •Cuspidate:Terminating in a
point.
•Aristate:Provided with awns or
with a well developed bristle.
•Retuse:Obtuse with a broad
shallow notch in middle, e.g.,
Oxalis.
•Cirrhose:Leaf with prolongation
or mid-rib forming a tendril, e.g.,
Gloriosa.
•Apiculate:Forming abruptly to a
small tip, e.g., Dalbergia.
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31. Parallel Vein Reticulate
LEAF
VENATION
Unicostate -longitudinalMulticostate -parallel
Palmately
Pinnately netted
Dentate netted
Leaf Venation
•System or disposition of
veins in the leaves.
•They are of several types:
•Reticulate: Like net work,
e.g., in most of dicots.
•Parallel:Parallel veined,
e.g., most of monocots.
•(a)Unicostate reticulate:
Having only one principal
vein, e.g., mango, banyan,
etc.
•(b)Multicostate
reticulate:Having many
principal veins, e.g., castor,
cucumber, etc.
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33. Shape of Leaf Lamina
•Linear:Long and narrow leaf, e.g., many
grasses.
•Lanceolate:Lance-shaped leaf, e.g.,
bamboo, Nerium, etc.
•Round or orbicular:Leaf with a circular
leaf blade, e.g., lotus, garden nasturtium,
etc
•Elliptical:An ellipse-shaped leaf, e.g.,
guava, jack, etc.
•Ovate:Leaf with an egg-shaped leaf
lamina, i.e., slightly broader at the base
than at the apex, e.g., banyan, China rose,
etc.
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34. •Spathulate:Spatula-shaped leaf, i.e., broad
and round at the top and narrower towards
the base, e.g., Calendula and Drosera.
•Oblique:Leaf with two unequal halves, e.g.,
Begonia.
•Oblong:Leaf with wide and long leaf lamina.
Here the two margins run more or less
straight up, e.g., banana.
•Reniform:Kidney-shaped leaf, e.g., Indian
pennywort.
•Cordate:Leaf with heart shaped leaf
lamina, e.g., betel.
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35. •Obcordate:Inversely heart-shaped leaf blade,
e.g., wood-sorrel.
•Sagittate:Leaf with an arrow shaped leaf blade,
e.g., arrow-head and some aroids.
•Hastate: Sagittate leaf with its two lobes
directed outside, e.g., water bindweed and
Typhonium.
•Lyrate:Lyre-shaped leaf lamina, i.e., with a large
terminal lobe and some smaller lateral lobes,
e.g., radish, mustard, etc.
•Acicular:Long, narrow and cylindrical leaf, i.e.,
needle-shaped, e.g., pine (a gymnosperm).
•Cuneate:Wedge shaped leaf, e.g., water lettuce.
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36. Structure of the leaf
Cuticle–the outermost layer of both the upper and
lower surfaces of the leaf. It is clear and waxy to
prevent against water loss.
Epidermis:
✓a layer of cells one cell thick that provides
protection for the inner tissues. These cells are
clear to allow light to reach the photosynthetic
tissues. It occurs on the surface of plants and it
is a complex tissue consisting of epidermal
cells, trichomes (hairs) and stomata
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37. Structure of the leaf
Epidermal cells:
➢It consists of a single layer of cells, but in some
cases it may become many layered as a result of
division
➢many layered epidermis often acts as water storage
tissue and the inner layer is often described as
hypodermis
➢tubular or lenticular with complete absence of
intercellular spaces except where the stomata occur
Mesophyll–between the epidermal layers. It contains
palisade cellsthat are tall,tightly packed, and filled
with chloroplasts for photosynthesis.
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38. Structures of the Leaf
Stomates–openings in the surface of
the leaf and stems for gas exchange.
The lower surface of a leaf usually has
more. Water vapor also passes out
through these holes.
Veins–contain the vascular tissue that
is continuous with that in the stem.
Xylemcarries water and minerals
upward.
Phloemcarries dissolved food
throughout the plant.
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39. Stomatal control
•When water is abundant: Temporal regulation of
stomata is used:
•OPENduring the day
•CLOSEDat night
•At night there is no photosynthesis, so no
demand for CO2 inside the leaf. Stomata
closed to prevent water loss. Sunny day -
demand for CO2 in leaf is high –stomata wide
open. As there is plenty of water, plant trades
water loss for photosynthesis products
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40. REFERENCES
“SCIENCE READER”
➢Tamil Nadu text books
➢NCERT Books
➢Google Images
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