Describe the structure of Megasporangium with a diagram.

The ovule is a small structure attached to the placenta by means of a stalk called funicle.

The body of the ovule fuses with funicle in the region called hilum. Thus hilum represents the junction between ovule and funicle.

Each ovule has one or two protective envelopes called integuments.

Integuments encircle the nucellus except at the tip where a small opening called the micropyle is organised.

A diagrammatic view of a typical

anatropous ovule

Opposite the micropylar end, is the chalaza representing the basal part of the ovule.

Enclosed within the integuments is a mass of cells called the nucellus. Cells of the nucellus have abundant reserve food materials.

Located in the nucellus is the embryo sac or female gametopyte. An ovule generally has a single embryo sac formed from a megaspore.

Megasporogenesis : The process of formation of megaspores from the megaspore mother cell is called megasporogenesis.