Thank you Lynn for your recollection and insight regarding misheard lyrics. The identify of the lyrics however, is up for grabs. I have recently been trying to trace the words to Wildwood Flower. This modification of lyrics and titles has long been a by product of the folk process. Amanita is a mushroom like fungus which is indeed pale.
Slip comes from sylppe, the word describing such leavings.
My problem with this is that both flowers are yellow. I have been unable to locate a flower called islip. I believe the word must describe a flower in order to carry out the internal logic of the couplet. I should be interested to know if anyone can shed any light on this mystery. Our family has several hymn mondegreens.