Synonyms: Achillea millefolium var. occidentalis | A. millefolium var. lanulosa A perennial with leaves finely divided with gray woolly hairs; flowers are white, in dense, flat-topped cluster; plants are aromatic. Quite drought tolerant. Blooms from June through July. Native from Quebec to Yukon, south to OK, CA and Mexico on dry, open rocky places. Prefers full sun; well-draining soils. Very drought tolerant; will be aggressive in moister soils, spreads by rhizomes.