This might sound a bit nitpicky, but my baby name book says that as a name, it is actually from the COLOR of a fox-glove. In medieval poetry, the word is used to describe the color of a beautiful girl's cheeks. So by extension, it is describing the owner as being as pretty as someone in an old poem, with cheeks as rosy as fox-gloves.
Ffion is NOT a Welsh version of Fiona. Many people 'presume' this but they couldn't be more wrong. In fact, it is FOXGLOVE in Welsh. It's pronounced fee-on and is surprisingly easy to say. The two F's tend to confuse people. In the Welsh alphabet 1 F makes a 'V' sound whereas the 'FF' makes a 'F' sound. Simple! [noted -ed]
I'm called Ffion and apparently it's the Welsh version of Foxglove! One thing I can't understand is why English people can pronounce Fiona but not Ffion!