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Morphology:
branch of botany that deals with
external features of plants.
Anatomy: also known as
Micromorphology of plants and plant
or vegetable histology; is concerned
with the microscopic structure of the
tissues, cells and organs of plants.
Taxonomy: the classification and naming
of plants.
PLANT MORPHOLOGY
Phyllotaxis (arrangement of cauline leaves):
Alternate (spiral or acyclic): one
leaf arises at each node and
the leaves are not shaded
each other.
Opposite: they may be;
Opposite decussate: one pair of
leaves is perpendicular to the
other.
Opposite superposed: each pair of
leaves is parallel to the other.
Whorled: more than two leaves
arise at each node e.g.
Nerium.
Parts of leaves: The leaf consists of
leaf base, stipules, stalk or petiole and
blade or lamina.
1- Leaf base:
* It is the part of the leaf directly
attached to the stem.
* It protects the lateral bud and
facilitates the movement of petiole
2- Stipules: they are appendages at the
leaf base, when they are absent the
leaf is exstipulate. e.g. tendrillar,
spiny, hairy,….
3- Petiole: it is the part of the leaf
between the blade and the base, it has
vascular tissue. When it is absent the
leaf is sessile.
4- Leaf blade or lamina:
It is the green flattened part of the leaf used for
photosynthesis, it may be:
Simple: when the blade is continuous.
Lobed: when the blade divides into number of
lobes connected by undivided center.
Compound: when the blade is divided into
independent leaflets.
A- Forms of simple leaves or leaflets
B- Forms of lobed leaves
1- Pinnately lobed:
divisions directed towards the midrib;
a- Pinnatifid: the cutting is less than half distance between
margin and midrib.
b- Pinnatipartite: the cutting is more than half the distance
between margin and midrib.
c- Pinnatisect: the cuttings reach the midrib.
2- Palmately lobed:
divisions directed
towards the base;
a- Palmatifid: the
cutting is less than half
distance between
margin and base.
b- Palmatipartite:
the cutting is more
than half the distance
between margin and
base.
c- Pamatisect: the
cuttings reach the
base.
C- Forms of compound leaves
a-Compound pinnate:
the leaflets are arranged
in two rows on leaf
stalk.
i- Paripinnate:
ends by two leaflets.
ii- Imparipinnate:
ends by one leaflet.
b- Compound palmate:
more than two leaflets
are radiated from the
tip of petiole.
Leaf margin
Entire: the margin has no processes.
Serrate: with small teeth directed forwards.
Serrulate: minutely serrate.
Dentate: teeth directed outwards.
Crenate: teeth rounded.
Spiny: margin with spiny processes.
Leaf apex
Acute: tip forming acute angle.
Acuminate: tip is narrow and prolonged.
Obtuse: rounded tip.
Truncate: tip is flat.
Emarginate: deeply notched.
Mucronate: tip with short horny point.
Leaf surface
Glabrous: smooth surface.
Hairy: with coarse hairs.
Rough.
Waxy.
Wrinkled.
Base of lamina
1- Symmetric: the two halves of the lamina are
identical.
2- Asymmetric: the two halves of the lamina are
not identical.
3- Decurrent.
Venation
1- Reticulate: the veins forms network;
a- Reticulate pinnate: with single midrib from which
branches are given.
b- Reticulate palmate: with several veins.
2- Parallel: the veins are parallel and of same size.
Comparison between compound leaf and
branch
Compound leaf
Branch
1- It arises directly at the
1- It is axillary to the leaf.
node of stem and not
subtended from outside by
any structure.
2- The rachis bearing the
leaflets is not divided to
nodes or internodes.
2- The branch divides to
nodes and internodes and
bearing leaves at the
nodes.
3- There is no axillary buds
in the axil of leaflets and
no terminal bud at the end
of rachis
3- A branch bears axillary
buds in the axils of leaves
and terminal bud at its
apex.
4- The stipules are borne
at base of compound leaf,
no stipules in base of
leaflets.
4- The leaves of branch
bear stipules at their
bases.
5- The leaflets of
compound leaf fall off
simultaneously.
5- The leaves of branch fall
off at different times.
The Flower
The flower is a modified fertile shoot, carrying
modified leaves, highly specialized for
performance of reproductive function and
adapted to produce fruits and seeds, i.e. for the
propagation of the individual.
A typical flower is usually formed of four sets of
floral leaves arranged on a shortened axis
(flower stalk or pedicel), the swollen or
expanded apex of which is called receptacle.
The floral leaves are in the following sequence
from the periphery to the center
The calyx: composed of sepals.
The corolla: composed of petals.
The petals and sepals when all alike
called perianth.
The andrœcium (male organ):
composed of stamens; each stamen
composed of anther and filament).
The gynæcium (pistil, female organ):
composed of carpels; each carpel
composed of ovary, style and
stigma.
Parts of a Flower
Stigma
Stamen
Anther
Style
Filament
Pistil
Ovary
Ovule
Petals
Sepals
Pedicel
Courtesy of McGraw Hill Publishers
Swollen base
where are parts
attach
Receptacle
The ovary may be inserted on the
receptacle on a level above all
the other parts; so the ovary is
known as superior and the
flower is hypogenous.
The ovary may be inserted on the
receptacle on a level below all
the other parts; so the ovary is
known as inferior and the
flower is epigenous.
The flower may be accompanied by accessory leafy
structures:
Bract: is leafy structure from its arises a flower.
Bracteole: is a scale-like leaf found on the floral stalk.
Involucre: is a group of bracts arranged in one or more
whorls just below the flower e.g. Nigella or group of
flowers e.g. Compositae.
Kinds of Flowers
1- According to the number of whorls
i- Tetracyclic: showing four whorls
e.g.Iridaceae.
ii- Pentacyclic: with five whorls.
2- According to the number of
segments in each whorl
i- Bimerous: with two segments e.g.
Cruciferae.
ii- Trimerous: with three segments in each
whorl as in Monocots.
iii- Pentamerous: with five segments as in
Dicots.
3- According to the presence of all
floral parts
i- Complete: the flower
has all the usual parts.
ii- Incomplete: if lacking
one or some of the
regular parts.
4- According to the symmetry of all floral leaves
i- Regular or actinomorphic
(Ө): when the segments in
each whorl are all alike,
regularly arranged and
the flower can be divided
by a number of radial
longitudinal cuts into
equal halves e.g. Clove.
ii- Irregular: when the
members of one or more
whorls are not all alike. In
such case the flower may
be:
Zygomorphic (%): when it
can be divided only in one
plane into equal halves as
in Papilionoideae.
5- According to presence or absence of
sexual organs
i- Hermaphrodite, bisexual or perfect: when both male and
female organs are present e.g. Rosa.
ii- Sterile or neutral: when both male and female organs are
absent or not functioning e.g. the marginal florets of Sunflower.
iii- Unisexual or imperfect: when only one of the sexual organs
is present and functioning. These flowers are either:
Staminate (♂): which possess only the male organs.
Pistillate (♀) which possess only the female organs.