Terraphyta

Terraphyta, meaning "land plant," are one of the oldest groups of Rixarn life. They are the primary photosynthesizers and producers in Rixarn ecology, but unlike Plantae on Earth, they are often motile, and frequently predatory, using their long tendrils to move around.

Evolutionary History
All Terraphyta are obviously derived from a single basal form; this basal form is one of the most commonly fossilized soft tissued organisms from the Cupruzoic, and was a disc of plant matter with tendrils branching of it that it used for steering. Similar organisms can be found today on Rix, and are considered living fossils. These relic forms are referred to as Eoterraphytes, or "dawn land plants."

Eoterraphytes were the first organism on land, besides microscopic bacteria-analogues. Due to this they had a leg up in exploiting niches, and since Eoterraphytes were already motile, the evolution of forms that used their tendrils to drag themselves forward took fairly little time; the species also adapted to be able to detect relative levels of light using the degree to which its chloroplasts were active. This adaptation allowed it to move to better sources of light, which was crucial in the often overcast environment of Rix.

C-Q Boundary
Tendril forms exploded in diversity shortly after Xenoserpentes arrived on land. This radiation was only in part due to Xenoserpentes, however. Terraphytes had reached a point in their evolution where they were beginning to run out of niches that didn’t require much in the way alterations from their base form. There was no ecological pressure to diversify.

Changes at the end of the Cupruzoic and the beginning of the Qualxicarin touched off an explosion in tendril shapes, sizes, functions, and special features. Entire lineages that still thrive were started from relatively humble beginnings in the Qualxicarin Explosion—Spinavinea, for example, currently makes up approximately 30% of Terraphyte diversity, not including the subclades of Suspendata, and Adfligadosa. By Earth standards, many of the forms that emerged in the Qualxicarin Explosion would be megafauna. For instance, Chromoflora, a genus in Spinvinea, can grow up to three meters in diameter, and bludgeons prey to death against convenient nearby objects, such as boulders, trees, cliff faces, the ground, and other parts of the prey item’s body that have already been torn off.

At around the same time, some Eoterraphytes became sessile, and developed a fractal body plan. Each pad had three tendrils branching off at 120° from each other, and each tendril had a smaller pad at the end. As the plant grew, not only would the pads and tendrils grow larger, but more layers of complexity would be added—this maximized the area available for photosynthesis, while retaining a very simple body plan and allowing the plant to easily reproduce by budding. Several genera of Fractafolidae grow on water, similar to lilypads, and they are often used as nurseries, since they have long, feathery tendrils reaching down into the deep water that collect nutrients.

As Xenoserpentes began to prey on Terraphytes, and evolve counters to Terraphyte defenses ranging from wrapping their tendrils taut around objects to suspend themselves in the air, to toxins, some Terraphytes developed the ability to use their predators for their own benefit by containing spores, resistant to digestive processes, in the most appetizing parts of their flesh. Before long, Terraphyte species were developing more and more appetizing flesh when they had reached sexual maturity. Being partially eaten was an excellent strategy for distribution; while Terraphytes could move, Xenoserpentes were far more mobile.

Rewtian Period
This relationship was fruitful for some time. But when Geotergum arrived on land during the Rewtian Period 15 million years later, Xenoserpentes was no longer the only thing eating Terraphyte flesh. Geotergum were ravenous eaters of Terraphytes, and would consume the spores and then not move any significant difference—the disadvantage of having spores distributed by glorified slugs. For a time, it looked like biologically-distributed spores would entirely vanish, and they did heavily decline in favor of wind-blown seeds (which helped lead to the formation of aeroplankton, and air coral reefs). However, Xenoserpentes quickly became extremely territorial over "their" Terraphytes, and adopted Geotergum as another source of food. The result was that biologically-distributed spores and seeds were able to hold on, albeit barely.