Question

Is archegonia absent in cycas?

Answer 1

Cycas:

1. These are the gymnosperms in which the ovules are not covered by any ovary wall and remain open.
2. These have specialized root structures called coralloid roots are associated with N₂ - fixing cyanobacteria and unbranched stems. Also, pinnate leaves persist for a few years.

Reproductive features of cycas:

1. These are heterosporous that is they produce haploid microspores and megaspores.
2. These are produced on different trees. The microsporophylls and microsporangia bearing strobili are called microsporangia or male strobili.
3. Macrosporangiate or female strobili are the cones bearing megasporophylls with ovules or megasporangia.
4. The ovules are borne on megasporophylls which are grouped to form the female cones. The megaspore mother cell undergoes meiosis that forms four megaspores.
5. Female gametophyte develops from one of the megaspores enclosed within the megasporangium. It bears two or more archegonia that are female sex organs.
6. An archegonium has an egg, a ventral canal nucleus and 2 neck cells.
7. Fertilization takes place inside the archegonium and the egg develops in the sporophyte in it.