The windbulb split from its ancestor, the tundra grass. It has spread to both continents because of the South Tundra now being connected. It spread when certain strains of the tundra grass began using larger seeds to catch the wind, thus spreading easier, and having it be able to reprodue via budding of the roots.
The windbulb is also different in the fact that it will, during the summer, lose all of its leaves, leaving only the seeds clinging onto the inside of it. These will be blown off to be spread across the land. During all other times of the year, they will only reproduce using budding.