| An archegonium consists of neck cells and a large egg cell. |
| In the club mosses the zygote divides in a plane at right angles to the axis of the archegonium. |
| The young sporogonium is protected by a thick calyptra derived from the tissue of the thallus around the archegonium. |
| Spermatozoids are formed in the antheridium, and these enter the archegonium and fertilize the germ cell. |
| When the sporophyte has developed all three regions, the seta elongates, pushing its way out of the archegonium and rupturing it. |
| In all the Archegoniate fertilization and the first critical phases of embryogeny occur within the shelter provided by the archegonium and the adjacent gametophytic tissue. |
