Across the cosmos lie many various flora, one such plant is Enroachus Mathematicus.
The seeds from this very rare plant float on solar winds across space until encountering a world with the right chemical makeup to support her seed, ( I use the term “her” because there are some findings that indicate this shrub/tree may be a sentient life form ).
The worlds it picks seem to be both arid and barren of life and in the orbit of a gas giant, just one seedling takes root, grows to about 11 meters, then using self-propagation sends forth seedlings that cover the planet with a grass like growth.
This goes on for about 2200 Earth years, at which time billions of spores shoot into space and continue their journey of colonization.
The worlds are usable to every species once this release happens, the why of it will remain just one of those strange mysteries of the cosmos.
This is a sculptured fractal, using Artmatic and Photoshop CS6, the render took about 4 hours on my Mac.