when the poet said his love was like a red, red rose, the flower he had in mind was not the kind of roses you commonly see in florists, and which most people today think of as roses. those red flowers that go to make up gaudy valentine bouquets are actually a very late class of roses called hybrid tea roses, and the first was grown only in 1867, nearly a century after robert burns's poem. when you see roses referred to in literature it is almost certainly never what you're picturing - old world roses were large, full-petalled, intensely fragrant, complex - shakespeare's damask roses probably came to europe from persia in the 14th century: see an example here, and even after the introduction of the modern hybrid rose the victorian roses par exemplar remained bourbon roses, a damask hybrid. (now would those have been the kind that grew at helstone?)