We have constructed a phylogenic tree for land plants by comparing the 5S rRNA sequences. The tree suggests that the Bryophyta and the Pteridophyta separated from each other after the emergence of the Spermatophyta. In the Pteridophyta,
Psilotum (whisk fern) firstly separated, and a little after
Lycopodium (clubmoss) separated from the ancestor common to
Equisetum (horsetail) and
Dryopteris (fern). During the Spermatophyta evolution, the gymnosperms (
Cycas and
Ginkgo have been studied here) and the angiosperms (flowering plants) separated, followed by the separation of
Cycas (cycad) and
Ginkgo (maidenhair tree) on one branch, and various flowering plants on the other.
Nitella (stonewort) separated at about the same time of the Spermatophyta and the Pteridophyta/Bryophyta separation.
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