Morphology of Flowering Plants - The Fruit and Seed
The Fruit
It is a ripened ovary developed after fertilisation.
It is a characteristic feature of the flowering plants.
A fruit formed without fertilisation of the ovary is called parthenocarpic fruit.
In mango & coconut, fruit is called a drupe. They are one seeded and develop from monocarpellary superior ovaries.
A fruit consists of:
Pericarp (fruit wall): It may be dry or fleshy. Thick and fleshy pericarp is differentiated into outer epicarp, middle mesocarp and inner endocarp.
Seeds
In mango, the pericarp is well differentiated into thin epicarp, fleshy edible mesocarp and stony hard endocarp.
In coconut, the mesocarp is fibrous.
The Seed
It is the mature ovule developed after fertilisation.
A seed is made up of a seed coat and an embryo.
Embryo is made up of a radicle, an embryonal axis and one (e.g. wheat, maize) or two cotyledons (e.g. gram & pea).
Structure of a Dicotyledonous Seed
The outermost covering of a seed is the seed coat.
Seed coat has 2 layers: outer testa and inner tegmen.
On the seed coat, there is a scar called hilum through which the developing seeds are attached to the fruit.
Above the hilum is a small pore called the micropyle.
Within the seed coat is the embryo, consisting of an embryonal axis and two cotyledons.
The cotyledons are often fleshy and full of reserve food materials. At the two ends of the embryonal axis, the radicle and plumule are present.
In some seeds such as castor, the endosperm is formed due to double fertilisation. It is a food storing tissue.
In plants such as bean, gram and pea, the seeds are non-endospermous (endosperm is not seen in mature seeds).
Structure of Monocotyledonous Seed
Generally, monocot seeds are endospermic but some are non-endospermic (e.g. orchids).
In cereals such as maize, the seed coat is membranous and generally fused with the fruit wall.
The endosperm is bulky and stores food.
The outer covering of endosperm separates the embryo by a protein layer called aleurone layer.
The embryo is small and situated in a groove at one end of the endosperm. It consists of one large and shield shaped cotyledon known as scutellum and a short axis with a plumule and a radicle.
The plumule is protected in a sheath called coleoptile and radicle is protected in a sheath called coleorhiza.
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wow thanks for this notes,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
ReplyDeleteit is really helpfull for exams
thank again
by gaurav s.k
hi
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