A timeline chronicling the evolution of plant life; from the Silurian to the end of the Quaternary periods.  

Silurian 450 mya to 420 mya

The journey of the plants begins here, at the beginning of the Silurian period, and the lowering of carbon dioxide levels in the atmosphere led to global cooling.. Named the Ordovician-Silurian extinction event , the subsequent dropping of sea level and glaciation over the next 10 million years led to the extinction of approx with 100 marine families, and 49% of all fauna genera, or 60% of all life. However, following a rise in volcanic activity, most glaciers formed during the mass extinction melted, and life began to develop again. 

The melting of the glaciers led to one outstanding event, life on land, as the soil of the land became moist, and allowed for the migration and flourishing of complex plant life on land, now able to support themselves. This also led to the evolution of a different type of reproduction. 

During the past 200 million years, almost all plant species alive lived in the ocean, with a few exceptions to algae
778px-Marchantiales cf Conocephalum 20071111

A Marchantiales liverwort. Scientist speculate from fossils that this is what early land plants looked like.

like lifeforms living on beaches. The reproduction method of these plants was to disperse sperm and eggs into the surrounding water, and if the two joined, it would allow for the formation of a zygote. When plants migrated and evolved onto land, this method of reproduction became obsolete. Plants then evolved motile sperm (sperm that can move freely). Male plants would deposit this into the moist ground, where it would swim through a thin film of water to a female plant, and fertilize it.

This process became the most used process of reproduction for the early land plants, and it allowed them to diversify into more distinct plant groups (Zosterophylls).

Since the end of the Ordovician period, and the melting of the glaciers, the average surface temperature had been around 17°C [1] [2]. However near the end of the period, dramatic temperature rises and the the drying of the

The earliest vascular plant, the Cooksonia.

land led to the decline on plants that used the motile sperm method of reproducing, as the dry soil couldn't support the sperm.
This led to the proliferation of spore releasing or asexual means of reproduction in plants.

However, some vascular plant species that lived around the equator (Cooksonia) to develop a different method of reproduction, movement.

Devonian 420 mya to 360 mya

Vascular plants, at the beginning of the Devonian period, in an effort of gain more water and minerals from the now dry land to keep nourished, evolved larger and more far reaching  roots.

This had it's consequence though, as the plants had to develop a larger and better transport tissue (Xylem transporting water, and Phloem transporting minerals and other organic compounds). This allowed the plant, by 400 mya, to evolve a greater ability to manipulate turgor pressure, the pressure of water in plant cells that allow it to stand straight and firm.

Using this manipulation, plants could absorb water and minerals through it's roots, and using the transport tissue, it would quickly transport water throughout the entire structure, filling individual cells with water, and increasing turgidity, then suddenly draw water away to a small bulb at the base of the plant for storage, decreasing turgidity, and allowing the plant to move in accordance to the wind. A male would use this method of "movement" to fertilize nearby females, by allowing the wind to blow it's stems towards the general area of the female plants, and releasing sperm (now formed in small bulbs atop the males stems), which would fertilize a females outer reproductive organ (again atop the plants stems), and would eventually form proto-seed formation, and once fully grown, it would drop, and grow.

This method of reproduction allowed "motile" or "moving" plants to cover a large area of the continents, whilst individual stayed in relatively close proximity to other members of the species. Also, the sexual nature of the motile plants allowed it to adapt faster to the changing Devonian landscape, as asexual plants couldn't genetically diversify as well as plants using sexual reproduction. This method of reproduction gave motile plants advantages of asexual, non-motile plants in the coming years.

By the end of the Devonian, large, forests covered the Devonian landscape, blocking the suns rays from reaching smaller plants under the vast canopies. The motile plants, able to change to their environment faster and more effectivly, adapted to this by a new innovation, the ability to move with their roots.

Carboniferous 360 mya to 300 mya

As the life on Earth began to change to the newly developing world around it, a series of new mutations which had been utilised by the plants to move more effectively became more common in plant species around this time period; Renuse, or plant "muscles". The evolution of plants to adapt this new feature came at a cost however, as plants needed far more energy to use Renuse, and due to the large trees covering much of the terrain during the Carboniferous, many smaller motile plants could no longer receive the suns rays due to the dense canopies. The plants adapted by evolving more powerful methods of mobility using Renuse. After millions of years, plants began to move on their own, however, this did not yet mean they were intelligent. The plants used cells located on
Resuasia permova

Reusasia permova, the oldest fully mobile plant

primative "light sensors" (an ancestor to modern day leaves), to locate areas of land exposed to sunlight, and allow more energy to be used for mobility. The first (known) plant to utilise full plant mobility by Renuse was the Reusasia permova. Able to transport itself by use of it's powerful roots filled with Reuse cells, the plant could move, however, only incredibly slowly (20 meters a day). However, the aspect of moving was immense, as it allowed the plant to breed with other permova with genes unlike it's own, thus maximising genetic diversity. 

However, an event that would result in the destruction of much of the abundant forests of the Carboniferous was about to occur; the Carboniferous Rain forest Collapse (CRC). Occurring 305 mya, the CRC was brought on by the falling in global temperatures, resulting in a cooler, drier period. This closing period of the Carboniferous would result in the extinction of 40% of plant life, and as the polar ice caps expanded, many of the surviving, mobile plants "migrated" towards the equator and shore. The mobile plants ability to migrate and survive during this time period resulted in an expansion of the moving plants during the coming Permian period, despite the temperature of the continental Pangaea, which stood at 16 °C (2° above modern day temperature). It was the coming Permian that was to shape the future of all plant life on Earth, as the diversification and adaptation of plants would continue to the evolution of the first plant brain.

Permian 300 mya to 250 mya

Following the begining of the Permian 300 million years ago, and the fall of the Carboniferous forests, plant life began to diversify at a rate never seen before. The common ancestor to almost half of the motile plants on the period was the Reusasia permova, perhaps the most "advanced" of all plants up to that point in time. However, like every plant of the era, it based movement not on though process, but factors such as sunlight and fertile ground which simple cell receptors managed to pick up on. This was because no plant before the Permian had a brain, nor nerve cells, and the evolution of such cells during the first 30 million years of the era was a major leap forward. The need for brain cells to coordinate the plant, alongside other factors including the Carboniferous Rainforest Collapse, and the evolution of larger plant eating lifeforms, made a major impact on the plants evolution. The first plant to have nerve cells was believed to be Reusasia excogitatoris, a descendant of the permova. Like most plants during the early Permian, it was often found along the shoreline of Pangea, where this species flourished, and where the evolutionary origins of the plants brain originate. Mutations within the plant began to change the structure of Renuse cells across the plant, and by 270 million years ago, Reusasia excogitatoris was believed to be able to respond to a number of outward stimuli, such as touch. This early form of nervous system was not dissimilar from today's nerve nets, found within many marine based animals, such as the jellyfish.

Despite not being as complex as today's nervous systems in plants, the original nerve nets gave the motile plants one more step above the competition; it could now truly respond to predators in its environment and escape (. However, another "innovation" occured during the Permian, giving the plants one more step above competition; the evolution of light-detecting cells, or in other words, the first plant eyes.

Ever since the first cyanobacteria performed the first form of photosynthesis 3 billion years ago, plants had used sunlight to convert Carbohydrates into energy. This was true for billions of years, and by the Permian, mutations within the first leaves began to allow the plant to more easily identify areas where sunlight was most present. However, when the first nerve nets evolved, these cells slowly became more complex in design, despite being a far run from the eyes of today. These early eye-like light receptors were in many ways, similar to early animal eyes, as in the fact that they lacked the ability to perceive depth in their surroundings, but managed to perceive areas of differing light. Now having the sense of early sight, the plants could now more easily locate areas of sunlight, and as a result, the species of plant that evolved such an ability could develop more and more complex defence mechanisms.

Towards the end of the Permian, the plants nervous systems began to become more complex in the way that a central nervous system began to form towards the water bulge of the plant. With this, senses such as touch and sight became more acute. Eyes began to evolve and develop on small stalks growing towards the top of the plant, allowing it to spot danger from further distances, and further evolution of the Renuse cells allowed the plants to become far more motile than ever before, allowing it to move individual stems and leaves, without moving the rest of its body. However, these were only going to be short lived, as the plant, as well as the animal kingdom was going to have to rebuild following the most devastating mass extinction in Earth's history; the Great Dying.

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