A Brief History of Plants by Luke Wallace

A Brief History of Plants by Luke Wallace Let us skip the first two and a half their success on land. Today, these plants new group, the seed-bearing gymnosperms, billion years of the Earth’s history from only survive in the groups known as the Club came to dominate. Placed in this group is when organic compounds in our early mosses, Whisk fern, Horsetails and, a group I Ginkophyta (Ginkgo biloba being the only Evidence shows that atmosphere made the transition to single am sure we are all familiar with, the Ferns. extant member of this group), Gnetophyta, during the Permian celled organisms via the creation of It is in a small number of Fern species that Cycads and, of course, the Conifers. For the nucleotides, RNA and DNA. For the sake of era a new group, we first see the production of separate male most part, gymnosperms did relatively well brevity, we will also have to gloss over the the seed-bearing sperm cells and female egg cells, the earliest throughout the Permian, Triassic and Jurassic adaptive radiation of early multicellular known plant lineage capable of this biological periods, exhibiting much more diversity and gymnosperms, organisms that would eventually lead phenomenon. This is thought to be crucial abundance than we see now. to the colonisation of the land 425 - 475 came to dominate. to the evolution of seed-bearing plants. million years ago. These stories could not However, during the Jurassic, another group of Placed in this group Simply put, up until this point plants produced be done justice here! plants were rapidly growing in dominance and identical sex cells and relied on water to by the Cretaceous this new plant superpower is Ginkophyta, Mosses, Liverworts and Hornworts (known bring these together. The separation of these was ready to supersede the gymnosperms. Gnetophyta, Cycads as Bryophytes) were the first terrestrial plants sex cells into larger, nourishing, protected They were of course, the angiosperms, or and, of course, to emerge, still very much reliant on water to female seeds and small, fertilising male ‘flowering plants’. Angiosperms could do complete their reproductive cycles. Whilst the pollen grains eliminated the need for water everything more effectively in temperate the Conifers. Bryophytes were expanding in abundance in reproduction. Male pollen grains could climates, including photosynthesis (because and diversity in this strange new land-based simply be blown, or transported via animals, they had bigger leaves), seed dispersal and world, lineages of algae evolving alongside to the female reproductive cells. Therefore, pollination. For example, the evolution of would give rise to the first vascular plants, i.e. they could thrive in environments deprived flowers attracted a variety of animals that plants with lignified tissues (ones that have of liquid water and radiate across the land could transport pollen with greater efficiency become woody) that are able to conduct the unlike their heavily water-reliant relatives. and effectiveness, driving much evolutionary transportation of water and carbohydrates. As with the earliest vascular plants and their change and achieving some astonishing These tissues also allowed for more rigid newly evolved advantages, the first seed- animal-plant relationships. structures, taller plants and defensive bearing plants would have been pioneers chemicals giving them a competitive edge in new environments. Evidence shows that Gymnosperm pollen, on the other hand, is going in to the Carboniferous period. However, during the Permian era (leading on from predominantly windborne which is relatively early vascular plants still required wet the Carboniferous), the number of seedless ineffective and wasteful of resources. That environments for reproduction which limited vascular plants diminished in species whilst a said, gymnosperms have retained some advantages over their flowering relatives. In general, they are still much better equipped to compete in cold climates and, given the chance, they can outreach, outweigh and outlive angiosperms. Additionally, conifer abundance has always outweighed that of angiosperms in the expanse that is the northern forests. Nevertheless, angiosperms went on to become the most prolific plant group ever, and by some distance too, with approximately 235,000 species having been described to date. The number of extant Ginkophyta gymnosperm species is only around 1,000, with conifers being the largest group at roughly 600 species. Trends on a geological timescale would suggest that conifers are heading towards an evolutionary dead-end; however, we as humans cannot practicably live by such a time scale. The fact is that, if a species still exists, it is winning its own battle for selection among an ocean of genetic variation and extreme competitiveness. Out of the four groups of gymnosperms, Bedgebury National Pinetum has three. Of course, conifers (Pinophyta) are the most abundant so constitute the majority of the specimens but several Ginkgos (Ginkophyta) can be found on the site, including in Dallimore Valley. You may also find the one member of Gnetophyta we have (Ephedraceae) behind the Visitor Centre. Ephedraceae Did you know… Some of the seed we collect on our expeditions across the world is stored at the Millennium Seed Bank at Wakehurst Place. However, some seeds can’t be stored there, such as the seeds of the Monkey Puzzle Araucaria araucana Bedgebury also provides a “living, so seed bank” for such species..

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