Wikipedia explains: It is a species in the genus Achillea. It has loose clusters of white, button-like flowers that bloom from June to August. Its dark green leaves have finely-toothed margins. This is a hardy, drought-tolerant plant that prefers full sun and moist but well-drained soil. The name ptarmica comes from the Greek word ptairo (=sneeze) and means 'causes sneezing'. Like many other plants, the sneezewort's pattern of development displays the Fibonacci sequence.[1] Uses Leaves can be eaten raw or cooked. Leaves are Cardiac; Diaphoretic; Digestive; Emmenagogue; Odontalgic; Sternutatory; Styptic. The leaf is chewed to relieve toothache. The dried, powdered leaves are used as a sneezing powder. Yields an essential oil that is used medicinally. The leaves are used as an insect repellent. The plant is poisonous to cattle, sheep, and horses. Symptoms are generally slow to develop, and include fever, rapid pulse, difficulty breathing, weight loss, drooling, spasms and loss of muscular control, and convulsions.

So called because the roots were once ground for snuff; white flowers