Definition of "yarrow"

Yarrow is one of the aboriginal English plants, and from time immemorial it has been used in incantations and by witches. Country folk still regard it as one of our most valuable herbs, especially for rheumatism.

1922, Eleanour Sinclair Rohde, The Old English Herbals‎, Longmans, Green and Co.

The Yarrow, where-with-all he stops the wound-made gore:

1612, Michael Drayton, Poly-Olbion, song 13 p. 218

“Oh, yarrow! This is it,” she said, extracting a single long stemmed ferny grass with clusters of small white flowers from the bouquet in her hand.

1979, Victor Kaplan, The Woman who Gathered Yarrow; The Box; Miss Vesey's Other Leg, page 11