Introduced. Perennial. Propagates by seeds and by rootstocks. Time of bloom: July to September. Seed-time: August to October. Range: Newfoundland and New Brunswick to Michigan, southward to Massachusetts. Habitat: Moist soil; low meadows, and waste places.
The range of this weed has increased of recent years, chiefly by the agency of baled hay. Stem slender, one to two feet tall, rather rigid, smooth or only slightly hairy, sometimes branched at the top but usually simple. Leaves alternate, one to three inches long, narrow lance-shaped to linear, pointed, sharply and very finely toothed, sessile and partly clasping, often hairy on the veins beneath. Flowers in loose corymbose clusters, the heads on long, slender pedicels, about a half-inch broad, with six to fifteen white rays, notched at the tips; rays and disk-florets both fertile. Achenes compressed oblong, without pappus.
Fig. 339. - Sneeze-wort Yarrow (Achillea Ptarmica). X 1/4.
Means of control the same as for common Yarrow. (Fig. 339.)