With a neat, labelled diagram, describe the parts of a typical angiosperm ovule.
With a neat, labelled diagram, describe the parts of a typical angiosperm ovule.
Ovule is an integumented megasporangium.Ovules are enclosed within the ovary in angiosperms.
An ovule consists of a female gametophyte (embryo sac), nutrient rich tissue (nucellus) and a jacket of cell layers (integuments). On fertilisation , the ovule ripens into a seed and the integuments form the seed coat.
Description
An ovule has following parts
(i) Attachment points:
Funicle is the stalk that attaches the ovule to placenta.
Hilum is the point where funicle is attached to the ovule body.
Raphe is a ridge-like structure formed, where funicle fuses with the body of ovule.
(ii) Integuments:
Integuments are the covering layer that protects the developing embryo.
(iii) Nucellus:
A mass of cells that lies enclosed within the integuments is called the nucellus. Cells of nucellus have abundant reserves of food material.
(iv) Embryo sac/ female gametophyte:
Female gametophyte covered by a thin membrane is called embryo sac. It is located in the nucellus. An ovule generally has a single embryo sac formed from the megaspore through reduction division(meiosis).
Ovule is an integumented megasporangium.Ovules are enclosed within the ovary in angiosperms.
An ovule consists of a female gametophyte (embryo sac), nutrient rich tissue (nucellus) and a jacket of cell layers (integuments). On fertilisation , the ovule ripens into a seed and the integuments form the seed coat.
Description
An ovule has following parts
(i) Attachment points:
Funicle is the stalk that attaches the ovule to placenta.
Hilum is the point where funicle is attached to the ovule body.
Raphe is a ridge-like structure formed, where funicle fuses with the body of ovule.
(ii) Integuments:
Integuments are the covering layer that protects the developing embryo.
(iii) Nucellus:
A mass of cells that lies enclosed within the integuments is called the nucellus. Cells of nucellus have abundant reserves of food material.
(iv) Embryo sac/ female gametophyte:
Female gametophyte covered by a thin membrane is called embryo sac. It is located in the nucellus. An ovule generally has a single embryo sac formed from the megaspore through reduction division(meiosis).
