Morphology of Flower

Dr. Suprabuddha
POOJA SINGHKundu
 Angiosperm
• Morphology of the
Angiosperm plants
• These are
characterised by
presence of roots,
stems, leaves,
flowers and fruits.
 THE INFLORESCENCE
• When a shoot tip transforms into a flower, it is
always solitary
• The arrangement of flowers on the floral axis
is termed as inflorescence
• Depending on whether the apex gets
developed into a flower or continues to grow,
two major types of inflorescences are defined
– racemose and cymose.
• In racemose type of inflorescences the main
axis continues to grow, the flowers are borne
laterally in an acropetal succession
• In cymose type of inflorescence the main axis
terminates in a flower, hence is limited in
growth. The flowers are borne in a basipetal
order
 THE FLOWER
• The flower is the reproductive unit in the
angiosperms
• A typical flower has four different kinds of
whorls arranged successively on thalamus or
receptacle
• calyx, corolla, androecium and gynoecium
• Calyx and corolla are accessory organs, while
androecium and gynoecium are reproductive
organs.
• In some flowers like lily, the calyx and corolla
are not distinct and are termed as perianth.
• When a flower has both androecium and
gynoecium, it is bisexual.
• A flower having either only stamens or only
carpels is unisexual.
• In symmetry, the flower may be
actinomorphic (radial symmetry) or
• zygomorphic (bilateral symmetry)
• A flower is asymmetric (irregular) if it cannot
be divided into two similar halves by any
vertical plane
• A flower may be trimerous, tetramerous or
pentamerous when the floral appendages are
in multiple of 3, 4 or 5, respectively
• Flowers with bracts-reduced leaf found at the
base of the pedicel - are called bracteate and
those without bracts, ebracteate
• Based on the position of calyx, corolla and
androecium in respect of the ovary on
thalamus, the flowers are described as
hypogynous, perigynous and epigynous
 Parts of a Flower
• Calyx
• The calyx is the outermost whorl of the flower and
the members are called sepals.
• Generally, sepals are green, leaf like and protect the
flower in the bud stage. The calyx may be
gamosepalous (sepals united) or polysepalous
(sepals free)
• Corolla
• Corolla is composed of petals. Petals are usually
brightly coloured to attract insects for pollination.
Like calyx, corolla may also be gamopetalous (petals
united) or polypetalous (petals free)
 Aestivation
• The mode of arrangement of sepals or petals in
floral bud with respect to the other members of
the same whorl is known as aestivation
• The main types of aestivation are
 valvate,
 twisted,
 imbricate
 vexillary
• When sepals or petals in a whorl just touch
one another at the margin, without
overlapping, it is said to be valvate.
• If one margin of the appendage overlaps that
of the next one and so on, it is called twisted.
(lady’s finger )
• If the margins of sepals or petals overlap one
another but not in any particular direction,
the aestivation is called imbricate. (Cassia and
gulmohur)
• In pea and bean flowers, there are five petals,
the largest overlaps the two lateral petals
which in turn overlap the two smallest
anterior petals ; this type of aestivation is
known as vexillary
 Androecium
• Androecium is composed of stamens.
• Each stamen which represents the male
reproductive organ consists of a filament and
an anther.
• Each anther is usually bilobed and each lobe
has two chambers, the pollen-sacs.
• The pollen grains are produced in pollen-sacs.
A sterile stamen is called staminode.
• When stamens are attached to the petals,
they are epipetalous (brinjal), or epiphyllous
when attached to the perianth (lily).
• The stamens may be united into one bundle
(monoadelphous) as in china rose, or two
bundles (diadelphous) as in pea, or into more
than two bundles (polyadelphous) as in citrus
 Gynoecium
• Gynoecium is the female reproductive part of
the flower and is made up of one or more
carpels. A carpel consists of three parts
namely
stigma
style
ovary
• Each ovary bears one or more ovules attached
to a flattened, cushion-like placenta
• When more than one carpel is present, they
may be free and are called apocarpous
• when carpels are fused, they are termed as
syncarpous
• After fertilisation
the ovules develop into seeds
the ovary matures into a fruit
 Placentation
• The arrangement of ovules within the ovary is
known as placentation
marginal
axile
parietal
basal
central
free central
• In marginal placentation the placenta forms a
ridge along the ventral suture of the ovary and
the ovules are borne on this ridge forming two
rows, as in pea
• When the placenta is axial and the ovules are
attached to it in a multilocular ovary, the
placentaion is said to be axile, tomato and
lemon.
• In parietal placentation, the ovules develop
on the inner wall of the ovary or on peripheral
part. Ovary is one-chambered but it becomes
twochambered due to the formation of the
false septum, e.g., mustard
• When the ovules are borne on central axis and
septa are absent, as in Dianthus and Primrose
the placentation is called free central
• In basal placentation, the placenta develops
at the base of ovary and a single ovule is
attached to it, as in sunflower, marigold.
 DESCRIPTION OF ONE IMPORTANT
FAMILY
• Solanaceae- tomato, brinjal, potato, chilli,
ashwagandha, tobacco
• commonly called as the ‘potato family’
• Stem: herbaceous rarely woody, aerial; erect,
cylindrical, branched, solid, hairy or glabrous,
underground stem in potato (Solanum
tuberosum)
• Leaves
 alternate,
 simple,
 rarely pinnately
compound,
 exstipulate
 venation reticulate
• Inflorescence : Solitary, cymose
• Flower: bisexual, actinomorphic
• Calyx: sepals five, united, persistent, valvate
aestivation
• Corolla: petals five, united; valvate aestivation
• Androecium: stamens five, epipetalous
• Gynoecium: bicarpellary obligately placed,
syncarpous; ovary superior, bilocular, placenta
swollen with many ovules, axile
• Fruits: berry or capsule
• Actinomorphic
• Bisexual

• Calyx K
• Corolla C
• Androecium A
• Gynoecium G