devil's nettle

Compound of devil +‎ -'s +‎ nettle, perhaps for a stinging effect of the leaves, and/or for an association with the Devil or witches (see quotations below).

devil's nettle (plural devil's nettles)

1. Achillea millefolium or common yarrow, a flowering plant native to temperate regions of the Northern Hemisphere.
   • 1884, Hilderic Friend, Flowers and Flower Lore‎, volume 1, page 67:

     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.

   • 2007, Waruno Mahdi, Malay Words and Malay Things‎, page 114:

     Not to be confused with devil’s nettle, i.e. yarrow, Achillea millefolium L., allegedly considered the Devil’s favorite plant by witches in some places in Europe.

2. Dendrocnide sinuata (synonym: Laportea crenulata), a species of nettle in the family Urticaceae found in Australia and South Asia.
   • 1888, C.D.E. Black, “Review of Malabar by William Logan”, in The Academy, volume 33, page 253:

     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;