devil's nettle

noun devil's nettles

1. Achillea millefolium or common yarrow, a flowering plant native to temperate regions of the Northern Hemisphere. In some parts of England the general name for Ferns is Devil’s Brushes, while in Cheshire, where the children draw the Yarrow across their faces and experience a tingling sensation in consequence, that plant is called the Devil’s Nettle.
2. Dendrocnide sinuata (synonym: Laportea crenulata), a species of nettle in the family Urticaceae found in Australia and South Asia. But be careful what you are about, for overhead is the terrible Laportea crenulata, or devil’s nettle; the petioles of the leaves are hispid with poisonous hairs, the sting of which, once felt, will not be forgotten by you in a hurry;