aka Milfoil, Achillea borealis. The common name is an old Scottish name after the parish of Yarrow. There are two varieties in the Park, var. alpicola which reaches 1′ (30 cm) and var. occidentalis which can grow to over 3′. Flower-heads are flat or round-topped clusters of small white or pinkish ray flowers. Leaves are fern-like. Usually found on dryish, well-drained sites, rocky slopes between 5,000′ to 7,000′ elevation.