Megasporangium is equivalent to ovule. Ovule is also called integumented magasporangium. It is present inside the ovary that is attached to the cushion called placenta. It has a single embryo sac that is formed from a megaspore through reduction division.

Megasporangium, also known as the nucellus, is the main reproductive structure found in the ovule of a flowering plant. It plays a crucial role in the formation of the female gametophyte, or embryo sac, which is essential for sexual reproduction in plants.

An ovule is a structure found within the ovary of a flower and contains the potential to develop into a seed after fertilization occurs. The ovule consists of several parts, including the integument, micropyle, megasporangium, and female gametophyte.

The megasporangium, or nucellus, is a part of the ovule that contains the megaspore mother cell. This cell undergoes meiosis to produce four megaspores, out of which only one survives and develops into the female gametophyte. The megasporangium provides nourishment and protection to the developing megaspore and later to the female gametophyte.

The female gametophyte, or embryo sac, is the matured megagametophyte that contains the egg cell and other cells necessary for fertilization. It is formed within the megasporangium and is surrounded by the integument.

The megasporangium, or nucellus, is equivalent to the ovule because it is the part of the ovule that undergoes development and produces the female gametophyte. The ovule itself is the structure that contains the megasporangium and other components necessary for sexual reproduction in plants.

To summarize:
- The megasporangium, also known as the nucellus, is the reproductive structure within the ovule of a flowering plant.
- It contains the megaspore mother cell, which undergoes meiosis to produce the megaspore.
- The megasporangium provides nourishment and protection to the developing megaspore and later to the female gametophyte.
- The female gametophyte, or embryo sac, is formed within the megasporangium and contains the egg cell and other cells necessary for fertilization.
- The megasporangium is equivalent to the ovule because it is the part of the ovule that undergoes development and produces the female gametophyte.