Rhyme - shmyme - some songs need it - in others it would just be cheese on a stick - Never mind Wee Kate MacRusby - the most of us have been singing it that way for years - since it was written in fact - it doesn't need to rhyme - in fact if you force it to rhyme thats what it sounds - forced!
Now forcing may be all very weel for yer rhubarb but hands off my bloomin' heather thank ye kindly!!