It’s entirely possible, actually. Generally speaking, regional variants are much less documented than the “standard” forms (which are often far more common), but they do indeed exist. In this case, budew does indeed have a regional variation native to very specific regions of the Netherlands, where they find it much more useful to blend in with tulip fields than wild roses. These budew are often well cared for and are thus both pure grass and taller than standard. (Care for them is roughly the same, though.) Finally, they’re not that common as breeding stock outside of their home region because, bizarrely enough, they’re more fragile, but consequently, they’re well sought-after by truly avid grass-type collectors. In short, your uncle may be quite lucky!