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Pistil
● Gynoecium- The female reproductive part of the flower.
● Monocarpellary - Single pistil
● Multicarpellary - Have more than one pistil
● Syncarpous- Fused pistils
● Apocarpous - Free pistil
Parts of Pistil
Parts of Pistil
● Stigma: The stigma serves as a landing
platform for pollen grains.
● Style: The style is the elongated
slender part beneath the stigma.
● Ovary: The basal bulged part of the
pistil is the ovary. Inside the ovary is
the ovarian cavity (locule)
Megasporangium
Anatropous
Megasporangium
● Ovule is considered to be an integumented
megasporangium.
● Stalk of ovule is called funicle.
● The point of attachment of funicle with the
body is called hilum.
● The body of the ovule shows two ends: the
basal end, (chalazal end) and the upper end
(micropylar end).
● The main body of the ovule is covered with
one or two envelopes called integuments.
Megasporangium
● Micropyle is the opening of the ovule.
● The integuments enclose a large
parenchymatous tissue known as
nucellus.
● Nucellus store abundant reserve food
materials.
● Embryo sac or female gametophyte is
located in the nucellus
Monosporic type (Polygonum)
Megasporogenesis
● The process of formation of
megaspores from the megaspore
mother cell is called megasporogenesis.
● Ovules generally differentiate a single
megaspore mother cell (MMC)
● The MMC undergoes meiotic division
producing four megaspores.
● Female gametophyte (embryo sac)
develops from one functional
megaspores
Monosporic type (Polygonum)
● Monosporic type (Polygonum) : The
functional haploid megaspore enlarges in
size and by means of three successive
mitotic divisions, gives rise to an
8-nucleate embryo sac.
● Four nuclei occur at micropylar end and
the other four at the chalazal end.
● Three nuclei at the micropylar end form
egg apparatus and the fourth migrates
from the both pole to the centre and form
polar nucleus.
Embryo sac
● Embryo sac consist of seven cells and eight
nuclei.
● Egg apparatus : This is a group of 3 cells situated
at the micropylar end. The centrally located cell is
called egg cell.
● Egg cell has a large vacuole at its upper end and a
prominent nucleus near its lower end.
● On its sides are present two synergids.
● Synergids show a filiform apparatus attached to
their upper wall. It is known to attract and guide
the pollen tube.
Embryo sac
● Polar nuclei : These are situated
in the centre of the embryo sac
representing a large binucleate
central cell.
● Antipodals : The three cells
situated at the chalazal end are
called antipodals.
● These cells generally degenerate
soon after fertilization.
Kinds of ovules
● Orthotropous or Atropus : The micropyle, Orthotropous or Atropus
chalaza and funicle are in straight line. e.g., Betel,
Piper, Polygonum.
● Anatropous: The body of the ovule is completely
inverted (turn at 180o angle ) so that micropyle and
hilum come to lie very close to each other. e.g.,
82% of angiosperm families.
● Hemianatropous : Ovule turns at 90o angle upon
the funicle or body of ovule is at right angle to the
funicle e.g., Ranunculus. Hemianatropous Anatropous
Kinds of ovules
● Campylotropous : Ovule is circled more or less at right angle to funicle. Micropylar end is
bent down slightly. e.g., in members of Leguminosae and Cruciferae.
● Amphitropous : Curvature of ovule is more and embryo sac becomes curved like horse
shoe e.g. Lemna, Poppy, Alisma.
Campylotropous Amphitropous
