The Mycad, a species of small, tropical woodlouse-grass, originated 1.5 million years ago as a strange palm-grass offshoot and the sole member of its genus. While still somewhat restricted in its range and diversity, there are now a handful of Mycodendron species spread around the remnant Loxodian jungles. Far from the tropics, though, a small, far-flung population grows in the temperate rain-pseudoforests that have recently cropped up just off the Ailuropian coast. This long, narrow island first began to peek above the waves about 400,000 years ago, running parallel to the mainland. Here, not far from the swamps where the original palm-grasses first evolved, is the home of M. palustris, the largest and strangest of all mycads. Brought here a few hundred millennia ago by a migrating pod of seawis, a few seeds that happened to be unusually resilient to temperate conditions sprouted and flourished in this land, one equally new to them as it was to every other pioneering species that initially colonized the island.

Like all members of its subfamily, this species grows in bursts. The first few warm days of spring signal the growth of a long, smooth internode that can increase the plant's height by up to 25 centimeters in less than a week. A whorl of frond-like leaves soon follows, spreading from the end of the stalk just as the previous year's blades drop to the ground. Even after this, however, their sheathes stay attached to the stem, where they may persist for up to three more years until rotting away, at which point only a ring of dead bark-like scar tissue is left behind. These circular leaf scars wrap around the entire culm, and there may be up to fifteen of them packed in close layers, one for each leaf in the old whorl. For most mycads and other palm-grasses, this is no issue, for xylem and phloem can easily be routed through the living inner layers of the hollow culm. Only for the Tree Mycad (Mycodendron palustris) does this quirk of Pseudodendroid anatomy pose a serious limitation on growth.

After going through all the regular phases of the palm-grass life cycle, tree mycads employ their resident Poamyces fungi to take their growth to further extremes. In particular, the Trunkshroom (P. dendrifex) has a close relationship with this woodlouse-grass, with its hyphae spreading throughout the plant's roots and stems. It even releases spores at the same time as its host flowers, ensuring the next generation will never have to live without its lifelong companion. Like its Middle Muricene ancestors, P. dendrifex can synthesize an enzyme called Dendrase that mimics certain growth factors in mycad tissues that come in contact with it, catalyzing local cell division wherever it's secreted. In millennia past, this only took place when the fungus detected that its home had been damaged, but since the trunkshroom diverged a quarter million years ago, it has mutated to overproduce the substance, spreading it constantly in a thin layer across the outer surface of the mycad's trunk. The tree mycad gets its name from the inevitable result of this process: slowly, year after year, its stem widens, adding another thin ring with each passing summer.

In short, this is Apterra's first genuine tree. Unlike the thousands of species of pseudotrees ubiquitous across the planet, its trunk undergoes true secondary growth, aided by its fungal symbiote. It can grow to tremendous sizes as a result, climbing up to twenty meters tall and reaching a maximum diameter of about a meter. This is a gradual process; trunkshroom mycelium is slow-growing, and M. palustris often don't appear noticeably different from other palm-grasses until their third or fourth year, with their leaves and stems progressing through all the phases mentioned earlier. By five years old, though, various trunkshroom-induced changes are obvious. The smooth segments of the mycad's culm widen in an even and predictable fashion, increasing in width by about a centimeter per year under good conditions. The process is much more disorganized around the old leaf scars, where the hardened, dead blemishes cannot engage in this growth. After a few more years, when the core-filling stem layers start to gradually die and solidify into wood, only the thin gaps between the old blades remain for moisture, sugar, nitrogen, and other trace nutrients to pass through. As the number of segments increases, the sap is forced to take truly labyrinthine paths. The non-widening scar regions are also unable to become stronger with time, resulting in weak points at regular intervals. Consequently, while tree mycads live longer than any other palm-grass (potentially almost a century), their maximum age is still constrained by the weakness of these nodes.

The tree mycad is one of the most unique ever to evolve on Apterra so far. If times were good, they'd be poised to spread across the globe over the next million years or so, a perfect example of the increasing complexity and derivity among all the planet's flora. Unfortunately, the current state of the world means that M. palustris will have no easy time finding its place among the few destined to survive. As a species that emerged from the tropics so recently and is still quite sensitive to extreme cold, the odds are poor for the tree mycad.