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. The following tree illustrates how the successive stem groups 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. The following tree illustrates how the successive stem groups 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
The above tree illustrates the time of first appearance of each stem group (where known) and their phylogenetic relationships, or lines of descent from ancestors to descendants.
The above time tree also indicates that there is a long ghost lineage of around 130 million years on the angiosperm stem line. This represents a huge data gap that contributes to the difficulty of understanding the Origin of Angiosperms.
The above time tree indicates that more of the gymnosperm clades appeared during Jurassic and later time than in the Paleozoic (Permian and older). This relationship can be seen more clearly in the following plot, which shows the number of new clades (represented by stem group fossils) appearing in successive intervals of geological time:
The above time tree also indicates that there is a long ghost lineage of around 130 million years on the angiosperm stem line. This represents a huge data gap that contributes to the difficulty of understanding the Origin of Angiosperms.
The above time tree indicates that more of the gymnosperm clades appeared during Jurassic and later time than in the Paleozoic (Permian and older). This relationship can be seen more clearly in the following plot, which shows the number of new clades (represented by stem group fossils) appearing in successive intervals of geological time:
Figure 4. Appearance of gymnosperm clades over geological time
This plot demonstrates more than 60% of the gymnosperm clades appeared during and after Late Triassic time.
References
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.
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.