The seed plants (Subphylum Spermatophytina, Phylum Tracheophyta) comprise seed-bearing vascular plants, of which more than 300,000 species of extant seed-bearing vascular plants are known (Encyclopaedia Britannica). They represent a clade which is known as the Spermatophyta and consists of the gymnosperms and the angiosperms.
Summaries of the phylogenies of the gymnosperm and angiosperm clades are shown below:
Summaries of the phylogenies of the gymnosperm and angiosperm clades are shown below:
Figure 1. Summarized phylogenetic tree of the gymnosperms
Figure 2. Summarized phylogenetic tree of the angiosperms
The following pages present (1) phylogenetic trees that illustrate the history of development of each stem group within the crown-gymnosperms, and (2) discussion of the origin of the angiosperms. In neither clade have stem-group fossils been documented with any degree of consensus.
Regarding the gymnosperms, if we summarize and combine these data, we can construct a phylogenetic time tree for the entire gymnosperm clade. All of the time trees presented in this website were created using the R packages "strap" (Bell and Lloyd, 2015) or "paleotree" (Bapst, 2012). The following tree, constructed using a minimum branch length of 2 million years in the paleotree package, illustrates how the successive stem groups of the internal nodes of the tree relate to one another through geological time. For simplicity, each stem group is represented by the oldest known member of that stem group:
Regarding the gymnosperms, if we summarize and combine these data, we can construct a phylogenetic time tree for the entire gymnosperm clade. All of the time trees presented in this website were created using the R packages "strap" (Bell and Lloyd, 2015) or "paleotree" (Bapst, 2012). The following tree, constructed using a minimum branch length of 2 million years in the paleotree package, illustrates how the successive stem groups of the internal nodes of the tree relate to one another through geological time. For simplicity, each stem group is represented by the oldest known member of that stem group:
Figure 3. Summarized phylogenetic time tree of the gymnosperms
An important point to realize about the above tree is that a sister relationship between gymnosperms and angiosperms (see Figure 1 above), implies a ghost lineage of around 140 million years on the stem line of the angiosperms, a length of time not recorded by any known stem-angiosperm fossils. Note also that some of the terminal nodes of the tree are represented by crown groups rather than stem groups. The reason for this is that no stem-group fossils are known for those nodes.
References
Bapst, D. W. (2012). paleotree: an R package for paleontological and phylogenetic analyses of evolution. Methods in Ecology and Evolution, 3(5), 803-807.
Bell, M. A., & Lloyd, G. T. (2015). strap: an R package for plotting phylogenies against stratigraphy and assessing their stratigraphic congruence. Palaeontology, Vol. 58, No. 2, pp. 379-389.
Li, H. T., Luo, Y., Gan, L., Ma, P. F., Gao, L. M., Yang, J. B., ... & Li, D. Z. (2021). Plastid phylogenomic insights into relationships of all flowering plant families. BMC biology, 19(1), 1-13.
Yang, Y., Ferguson, D. K., Liu, B., Mao, K. S., Gao, L. M., Zhang, S. Z., ... & Zhang, Z. X. (2022). Recent advances on phylogenomics of gymnosperms and an updated classification. Plant Diversity.
Bell, M. A., & Lloyd, G. T. (2015). strap: an R package for plotting phylogenies against stratigraphy and assessing their stratigraphic congruence. Palaeontology, Vol. 58, No. 2, pp. 379-389.
Li, H. T., Luo, Y., Gan, L., Ma, P. F., Gao, L. M., Yang, J. B., ... & Li, D. Z. (2021). Plastid phylogenomic insights into relationships of all flowering plant families. BMC biology, 19(1), 1-13.
Yang, Y., Ferguson, D. K., Liu, B., Mao, K. S., Gao, L. M., Zhang, S. Z., ... & Zhang, Z. X. (2022). Recent advances on phylogenomics of gymnosperms and an updated classification. Plant Diversity.