Plant Life Through the Ages

Plant Life Through the Ages consists of eight panels depicting great moments in plant evolution. It is a significant body of work because while there are numerous depictions of animal evolution, there had been no mural devoted to the evolution of plants until this work.The paintings were created by muralist Robert Evans. With a specialty in natural history, ethnography and history, his work can be found at the Smithsonian, Mount Vernon, and numerous museums, zoos, and aquaria.

Along with the works of art are informational panels that touch on plant fossils, plant evolution and plant extinction. All of the panels are installed along the corridor to Palm House.

Panel 1: Age of Stromatolites

Late Archaean Eon — 3,500-1,250 million years ago

Earth was a very lonely and desolate place, essentially a planet of bacteria. The only visible sign of life was an endless stretch of cyanobacterial mats and their fossilized remains called stromatolites. Here photosynthesis began, the first step towards plant evolution, and oxygen was introduced into the atmosphere.

Panel 2: Rhynie Chert Flora

Early Devonian Period — About 400 million years ago

Primitive vascular plants (those with water and food-conducting tissue) were beginning to evolve on land. However, they were small and inconspicuous. This mural reconstructs what we know of the flora from the fossil collection near the present day Scottish village of Rhynie. Plants from that time and place are now all extinct.

Pictured: 1.Steroxylon mackei 2.Aglaophyton major 3.Nothia aphylla 4.Horneophyton lignieri 5.Rhynia Gwynne - vaughanii

Panel 3: Rise of a Land Flora

Early and Middle Devonian Period — 416–385 million years ago

An upsurge in land plant evolution — the Devonian Explosion — resulted in plants becoming more complex, evolving roots, leaves, and more complex reproductive structures. The Earth became covered with a wide-ranging land flora. As Earth’s landscape changes drastically, new habitats are created, presenting more opportunities for evolving organisms.

Pictured: 1.Cladoxyon scoparium 2.Cooksonia 3.Wattieza 4.Pertica 5.Drepanophycus 6.Pseudosporochnus 7.Psilophyton dawsonii 8.Zosterophyllum 9.Sawdonia 10.Renalia

Panel 4: First Forests

Late Devonian Period — 385-360 million years ago

Major innovations were occurring in land plant morphology—more advanced vascular systems and refined reproductive structures. The development of secondary growth (woody tissue) enabled plants to get much bigger. The first forests appeared, composed of progymnosperms, non-seed, spore-bearing plants, which later gave rise to the first seed-plants, the gymnosperms, about 360 Ma.

Pictured: 1.Archaeosigillaria 2.Aneurophyton 3.Archaeopteris 4.Protolepidodendron 5.Rhacophyton 6.Acanthostega

Panel 5: Carboniferous Coal Swamp Forests

Late Carboniferous Period — 323-300 million years ago

These tropical wetland forests were dominated by non-seed-bearing vascular plants, such as giant tree lycopods (club mosses) and tree horsetails. Without seasonal temperature changes, plant growth continued year-round. As plants died, there was a massive buildup of dead plant matter, which would over time be transformed into coal.

Pictured: 1.Medullosa 2.Sigillaria 3.Lepidodendron 4.Lyginopteris 5.Chaloneria 6.Calamites 7.Cordiates 8.Psaronius 9.Giant dragonfly 10.Edaphosaurus 11.Sphenophyllum 12.Callistophyton

Panel 6: Age of Gymnosperms

Triassic Period through early Early Cretaceous Period — 250–130 million years ago

Plant life on Earth was now dominated by gymnosperms, seed-producing plants such as conifers, cycads, and ginkgos. While many conifer and cycad species exist today, the living ginkgo is the sole surviving species of a primitive gymnosperm group that reached the height of diversity in the Jurassic Period. Today’s representatives of gymnosperms include pine, spruce, and hemlock.

Pictured: 1.Sphenobaiera 2.Archaeopteryx 3.Tempskya 4.Araucaria 5.Nathorstiana 6.Brachiosaurus 7.Morganucodon 8.Stegosaurus 9.Glossopteris 10.Pleuromeia 11.Allosaurus 12.Williamsonia 13.Leptocycas

Panel 7: Rise of the Flowering Plants

Late Early Cretaceous Period through Cretaceous Period —130–65 million years ago

As flowering plants (angiosperms) evolved and diversified, many established relationships with animal pollinators. Spreading over the globe, they came to dominate terrestrial ecosystems, as they still do today, with 250,000‒400,000 living species compared to fewer than 1,000 living gymnosperm species.

Pictured: 1.Drimys 2.Metasequoia 3.Nymphaea 4.Cycadeoidea 5.Amborella 6.Eomaia 7.Magnolia 8.Archaefructus 9.Triceratops 10.Archaeanthus 11.Ginkgo 12.Ascarina 13.Liriodendron

Panel 8: Plants and Human Affairs

The Holocene Epoch — The last 11,500 years

The rise of human civilization impacts the composition of the world’s flora through the domestication and breeding of plants, the rise of agriculture, and the movement of species (intentional and unintentional) around the globe. Overpopulation, industrialization, and other human activities are destroying habitats and changing climate, endangering species, and causing extinctions.