In polygounm ,

Options

A. ovule is orthotropic with an endosporic embryo sac derived from a single chalazal megaspore
B. ovule is orthotropic with an endosporic embryo sac derived from a single micropylar megaspore
C. ovule is anatropous with an endosporic embryo sac derived from a single chalazal megaspore
D. ovule is anatropous with an endosporic embryo sac derived from a single micropylar megaspore

Answer

### Step-by-Step Text Solution:

1. **Understanding Polygonum**: Polygonum refers to a type of plant that has a specific structure of its embryo sac. In this context, it is important to know that the embryo sac is formed through a process of meiosis.

2. **Formation of Megaspores**: In Polygonum, the diploid megaspore mother cell undergoes meiosis to produce four haploid megaspores. This is a crucial step in the formation of the female gametophyte.

3. **Degeneration of Megaspores**: Out of the four haploid megaspores formed, three degenerate, leaving only one functional megaspore. This surviving megaspore will develop into the embryo sac.

4. **Structure of the Embryo Sac**: The embryo sac consists of several cells:
- One egg cell located at the micropilar end.
- Three antipodal cells located at the chalazal end, which eventually degenerate.

5. **Orthotropic Ovule**: The ovule in Polygonum is described as orthotropic, meaning that the arrangement of cells is parallel, with the egg cell at the micropilar end and the antipodal cells at the chalazal end.

6. **Chalazal Megaspore**: The ovule is derived from a single chalazal megaspore, confirming that the structure is formed from one megaspore, which is consistent with the definition of orthotropic.

7. **Antropos Ovule**: The term "antropos" refers to a different arrangement of ovules, which is not applicable in this case, as the ovule in Polygonum does not exhibit this arrangement.

8. **Conclusion**: Based on the analysis, the correct statement regarding Polygonum is that it has an orthotropic ovule derived from a single chalazal megaspore, with the egg cell at the micropilar end.