The Grass tree is a species of plant located within the Great Plateau 100 million years in the future. As a descendent of modern bamboo, it is actually a giant species of grass.
Outward appearances show that they are most likely hollow, having to hold water which would be a hard to receive in the high mountains. Alongside this, they are rigid and tough, with woody stems latched into the hard ground allowing them to withstand the high winds of mountains. Finally, the plant is perceived to be short, or shorter than the average bamboo plant, as a tall structure would not be able to withstand the high winds of plateau.
As a descendent of bamboo, much like other true grasses, the plant itself uses wind to its advantage; launching its seeds into the wind. The seeds of the grass tree however have evolved a parachute, similar to those of dandilions. This event occurs for a few weeks every summer, however, the seeds are often caught in the large webs of the Silver spider, which uses the aforementioned seeds to feed Poggles, which are later eaten by the spiders themselves.