During a road trip to Maine (the summer of 2002), I noticed rugosa roses all along the coastal areas of New England. I also noticed quite a few roses, which I suspected were intermediates between rugosa and another rose. In some of the park areas (for example Acadia - in the Thunder Hole area), there were what appeared to be whole hybrid swarms involving rugosa and a low growing native type. Parental types and almost any type in between could be observed. I know that rugosa is well known to have naturalized itself in this area, but has anyone ever studied or has anyone else observed this large-scale hybridization phenomenon?
I haven’t noticed wide-scale hybridization with rugosas and North American natives, but have found some fertile intermediates in Northern Wisconsin among some stands of R. blanda. The rugosa parent was probably the rugosas growing up by the home on the property.
Is it possible that the low-growing native might be R. nitida? This is also common in New England.
If I had to hazard a guess – I would guess that they were Rosa blanda. They didn’t resemble the R. nitida clone that I grow, which is quite bristly and has very shiny leaves. The plants bore some resemblance to the R. arkansana clones that I have, but I don’t know if arkansana grows in that region.