Alternate source for repeat bloom

[Karl_K]

“Musk rose” has long been applied to species other than Rosa moschata of Herrmann. The “musk rose” of Shakespeare is widely thought to have been R. arvensis; R. sempervirens was also associated, as Bauhin’s 1623 name of Rosa moschata sempervirens makes clear. The “dark and shining” leaf descriptions would likely refer to the latter species. And, when the R. moschata that we know was largely supplanted in England by R. brunonii, leading to the incorrect assumption that R. moschata was a once-blooming species, it took Graham Thomas’ careful sleuthing to rediscover the true species and then reintroduce it into cultivation there from a single plant. That was not quite the situation in the United States, although the rose had become rather obscure over time, probably being found more often in old southern cemeteries than in gardens until interest was somewhat reignited.
Stefan

The autumnal Musk rose of Herrmann had dark and shining leaves, hoary beneath. He also wrote, “Floret per totum autumnum usque in hyemem, flores autem primo statim die marcedscunt.” So, his Rosa moschata was very similar to what we now have, but not exactly the same.
http://bulbnrose.x10.mx/Roses/Ehret/Herrmann1762.html

[MidAtlas]

Maybe. You do have to allow a bit of license in such descriptions (and while the protologue is important, it’s not as important as the type specimen, if one exists); more critically, the Latin term used to describe the abaxial leaf surface doesn’t really translate as ‘hoary’ but rather ‘canescent’ (“canescentia”), and that of the adaxial surface translates not as ‘shining’ but rather ‘bright’/‘lustrous’ (“splendentia”). Those terms are not so clearly at odds with the clones that are currently widespread in cultivation. Also, it’s important to consider that even in recent times, Rosa moschata has often been regarded as primarily an autumnal-flowering rose in places like England. There simply isn’t enough spring and summer heat in cooler parts of Europe to start the flowering period as early in the year as happens in, say, the southern United States. Nevertheless, being a natural species, one always has to make certain allowances for infraspecific variation.

Stefan