Asteraceae : Tanacetum vulgare
Tanacetum vulgare is a perennial herb with erect, usually smooth stems arising from a branched rhizome, singly or in clusters growing 50–150 cm tall and branching near the top. The plant is strongly scented and has numerous, alternate, twice pinnately divided, fern-like green leaves. The inflorescence consist of numerous (up to 200) heads in a corymbiform cyme. The heads are disk shaped, hemispheric at maturity, 5-10 mm in diameter and surrounded by an involucre of overlapping bracts. The outer yellow disc flowers are tubular and 3-toothed and the inner corollas are 5-toothed. The achenes are 5-sided with a short crown-like pappus. Tansy blooms in July and August in waste places stream banks and flood plains in the eastern and western edges of South Dakota.