Horse tail is pre-historic and a great source of silica for those who need it. I never tried the sword fern but the children said it helped them? Haven't tried horsetail either though there is tons here. Avoidance and licking my wounds works for me.

One of the best uses of burdock is the exercise one gets digging it out!! It occurs to me, I could just get rid of my - boxes and boxes of - books and just google everything. Wean myself from books???