How did the dog rose get its name?
The name dog rose, or Rosa canina, can be traced as far back as ancient Greece. The Greek physician Hippocrates, and later the Roman naturalist Pliny, believed that a cure for the bite of a rabid dog could be made from the roots. There are alternate theories but their histories cannot reach back as far. Some say the name is from ‘dag’ rather than dog, and that it refers to the dagger-sharp thorns. But this seems implausible, given how many fiercely thorny rose species there are. Some also claim that is it a pejorative name, as in ‘a dog of a rose,’ an inferior flower. Again, there is no history backing this theory.
According to Elsevier’s Dictionary of Plant Lore (edited by D. C. Watt, Academic Press, 2007), the medicinal property of the the rose’s roots came from a mother’s dream about her soldier son who had been bitten by a mad dog. In the dream, a voice told her to make a decoction of a wild rose’s roots, “which they call Cynorrhodon,” and she followed this advice, healing her son of his ailment.