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They must swim, unaided, across an ephemeral film of water coating the nooks and crannies of mosses in search of an egg concealed within a protective structure called an archegonium.

In germination they develop a minute prothallus which bears archegonia to be fertilized by antherozoids developed from the microspores.

The structure of the seed, the presence of two neck-cells in the archegonia, the late development of the embryo, the partially-fused cotyledons and certain anatomical characters, are features common to Ginkgo and the cycads.

By dissecting the young buds, archegonia in all stages of growth may be found.

Their general similarity to the mature antheridia and archegonia of liverworts and the main difference in their development have been referred to.