you've got "a different goatsbeard," certainly, but it is still a goatsbeard, the same way a Great Dane is a different dog from a chihuahua and yet both are dogs.
And in the same way that a human is a different primate than a chimp or a macaque.
That's pretty amazing that goatsbeard is that recently introduced. The dang things made up about 20% of my back yard's vegetation when I lived in Oklahoma.