The Dandy Lion
I may be in a small minority here, but I have gone for years without knowing the etymology of Dandylion, I thought (mistakenly) that it must have been something to do with the bold flower, a dandy indeed. I knew the French for dandelion - pissenlit - and that it was called such because of the diuretic properties of the roots. But I hadn't realised that there was another French word - Dent de Lion, or tooth of the lion seeing the shape of the leaves. The penny finally dropped. This is a London dandylion, though.