View photos of the medicinal plant Achillea millefolium (Yarrow), profiled in Medicinal Plants of the Western Mountain States.

A passage from Medicinal Plants of the Western Mountain States:

Effectively combining elements of an astringent, stimulant, and antiinflammatory, Yarrow serves as a multi–faceted application for an array of problems.
The plant’s best overall use is as a tonic in conditions where there is tissue laxity due to low regional vitality. In whatever area (urinary, reproductive, or gastrointestinal) this tendency of deficiency that Yarrow best addresses often results in unchecked, yet minor, hemorrhage or discharge.