1. Megaspore tetrad is linear. The chalazal megaspore develops into an embryo sac of Polygonum type.

2. The chalazal megaspore of a linear tetrad develops into a polygonum type sac.

3. So it defined as crassinucellate. The megaspore mother cell divides transversally to form a linear megaspore tetrad. The megaspore at the chalazal end develops into the embryo sac mother cell.

4. Function megaspore is in the chalaza and the monosporic embryo sac is chenopodiad type.

5. The functional megaspore in the linear tetrad is the one endsac is the polygonum type.

6. The megaspore archesporium splits circumference, it circumferential edge cell and a sporogenous cell.

6.

7. Development of megaspore and formation of embryo sac:The ovule has a layer of parietal cells at the sporogenous stage.

8. In dandelion ( Taraxacum ), for example, the chromosomes of the megaspore mother cell remain in one cell after the first meiotic division, forming a restitution nucleus.

9. A single archesporium differentiates immediately below the nucellar epidermis, it functions directly as the megaspore mother cell.

10. No callose fluorescence shows in the wall of mononuclear embryo sac after its formation, while thick callose deposits in the wall of the degenerative megaspore.

11. The polysaccharides in the cells of micropylar and chalazal end increases with the formation of functional megaspore.

12. The gametophyte is derived from the product of a reduction division in the megaspore mother cell.

13. As development goes on, callose fluorescence disappears in the chalazal wall of diplosporous functional megaspore.

14. A single archesporium differentiates immediately below the nucellar epidermis, it functions directly the megaspore mother cell.

15. The archesporial cell below nucellus epiderm functions directly as the megaspore mother cell.