| Because the egg is retained and fertilized within the archegonium, the early stages of the developing sporophyte are protected and nourished by the gametophytic tissue. |
| The young sporogonium is protected by a thick calyptra derived from the tissue of the thallus around the archegonium. |
| Although more than one archegonium may be fertilized, only one gives rise to a viable embryo. |
| The fertilized nucleus or germ-cell of the archegonium in Cryptogams, from which the new plant is directly developed. |
| The axis of the embryo is inclined to that of the archegonium and may be almost at right angles. |
| The neck of the archegonium is quite long, but does not project above the surface of the prothallium. |
