Sexual reproduction in flowering plants

REPRODUCTION IN PLANTS
SEXUAL
REPRODUCTION IN
FLOWERING PLANTS

Development of endosperm and embryo, maturation of ovules
into seeds and ovary into fruit are collectively termed as post-
fertilization events.

Endosperm
 This is a product of triple fusion and develops from central cell of
embryo sac.
 The cells of this tissue are filled with reserve food materials.
 They are used for the nutrition of the
developing embryo.
It is generally a
triploid tissue.

 It is absent in families such as Orchidaceae, Podostemaceae and
Trapaceae.

Hemicellulosic
Cellulosic
Oily
Proteinaceous (Aleurone layer)
Starchy
Date palm
Ivory palm
Castor, Coconut
Cereals (e.g. Maize)
Cereals (e.g. Rice, Wheat)
Plant Nature of Endosperm

 The stony endosperm is present in betel nut (Areca nut) and date
palm(Phoenix dactylifera).
 Diploid endosperm is found in Oenothera.

Non endospermic or exalbuminous seeds :
 In seeds like gram, pea, groundnut the endosperm is completely
consumed by developing embryo, thus the seeds are called non-
endospermic or exalbuminous.
• Mature seeds are of two types :

Endospermic or albuminous seeds:
 In monocots and castor, bean (dicots) embryo does not consume all
the endosperm. So, it persists in the mature seed.
 Such seeds are called endospermic or albuminous seeds. In these
seeds, food is stored in endosperm.
e.g. Wheat, Maize, Barley, Sunflower, Coconut.
Wheat Maize

Sunflower Barley
Coconut

Embryo
 The development of an embryo from a zygote is called Embryogeny.
 Embryo develops at the micropylar end of the embryo sac where
the zygote is situated.
 Most zygotes divide only after certain amount of endosperm is
formed.

 This is an adaptation to provide assured nutrition to the
developing embryo.
 It means endosperm development precedes embryo development.
Early stages of
embryogeny are
similar in both
monocotyledons and
dicotyledons.

Stages in embryo development in a dicot

 A typical dicot embryo consists of an embryonal axis (Tigellum) and
two cotyledons.
 The portion of embryonal axis above the level of cotyledons is the
epicotyl, which terminates with the plumule or stem tip(first apical
bud of shoot).
 The cylindrical portion below the level of cotyledons is hypocotyl that
terminates at its lower end in the radicle or root tip.
The root tip is
covered with a
root cap.
Dicot embryo

A typical dicot embryo

 Embryos of monocotyledons possess only one cotyledon.
 In the grass family, the cotyledon is called scutellum that is situated
towards one side (lateral) of the embryonal axis.
 At its lower end, the embryonal axis has the radical and root cap is
enclosed in an undifferentiated sheath called coleorhiza.
 The portion of the embryonal axis above the level of attachment of
scutellum is the epicotyl.
Monocot embryo

 Epicotyl has a shoot apex and a few leaf primordia enclosed in a
hollow foliar structure, the coleoptile.
 The outer covering of the endosperm separates the embryo by a
proteinaceous layer called aleurone layer.

L.S of an embryo of grass
(Monocot)

 Mostly nucellus is consumed after fertilization due to absorption of
food by the endosperm and embryo.
 But in some seeds remnants of nucellus are of persistant nature. This
residual, persistent nucellus is called perisperm.
Perisperm

 Such seeds are called perispermic seeds.
e.g. Black pepper (Piper nigrum), Beet.
Black pepper Beet

1.The cells of the endosperm are filled with reserve food materials and
are used for the nutrition of developing embryo is generally a --- in
angiosperms.
2) Diploid tissue
3) Haploid tissue
4) Hexaploid tissue
1) Triploid tissue

2.The portion of the embryonal axis above the level of cotyledons is…
2) Epicotyl
3) Coleorhiza
4) Radicle
1) Hypocotyl

3. PEN develops into….
1) Thalamus
2) Embryo
3) Endosperm
4) Periderm

4. Perisperm is found in the seeds of….
2) Barley
3) Beans
4) Groundnut
1) Piper

5. In gram, pea and groundnut plants….
2) Embryo development precedes endosperm development
3) Mature seeds lack endosperm
4) Non- albuminous seeds are formed due to absence of triple fusion
1) Endosperm is not formed in life cycle

6.Remnant of nucellus seen in the seed is….
2) Perisperm
3) Embryo
4) Endosperm
1) Periderm

Thank you…

Sexual reproduction in flowering plants

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