Hypericum pyramidatum, commonly called great St. John’s wort, is an upright perennial that typically grows 2-5’ tall and features a showy display of yellow flowers (2” across) that bloom in pyramidal cymes in July-August. Each flower has 5 yellow petals, 5 styles (most hypericums have 3 styles) and a center boss of bushy yellow stamens. Stem-clasping, elliptic leaves to 5” long. Hypericum pyramidatum (considered by many to be synonymous with Hypericum ascyron) is native to streambanks and moist wooded slopes from Maine to Manitoba south to Maryland, Indiana and Kansas. It is found in wooded slopes and thickets. This plant is also native to central and eastern Asia.
(Info from Missouri Botanic Garden)