Shrub to 2 m tall Leaves: opposite, short-stalked, 3 - 6 cm long, 0.8 - 1.5 cm wide, linear to oblong or narrow elliptic with an abruptly tapered base, non-toothed. Smaller leaves are borne in the axils of larger leaves. Flowers: borne three to seven on a small widely branched terminal inflorescence (cyme) with smaller clusters (cymules) in the upper leaf axils. The 2 - 3 mm wide sepals are lance- to egg-shaped with a pointed tip, the five yellow petals are 7 - 10 mm long, the stamens are numerous, and the four styles are attached near the base. Fruit: a three-chambered capsule, 0.7 - 1.4 cm long, 3.5 mm wide, cone- to egg-shaped, beaked, with chambers partitioned but not joined at the center. The capsules persist throughout winter. Bark: gray and thin, shedding to reveal pale orange inner bark. Twigs: stiff, erect, reddish brown, becoming gray to light brown with age, highly branched, two-edged (sharper when young).
Similar species: Hypericum prolificum and Hypericum kalmianum are the only shrubby Hypericum species in the Chicago Region. Hypericum kalmianum reaches 1 m tall, has peeling papery white to multicolored bark, four-angled twigs, leaves less than 8 mm wide, flowers with 10 - 16 mm petals and five styles, and five-chambered capsules.
Flowering: June to September
Habitat and ecology: Local in partial shade along stream edges, brushy prairies, and railroads.
Occurence in the Chicago region: native
Notes: This species makes a nice native ornamental shrub. Bees collect nectar from the flowers.
Etymology: Hypericum is the Greek name for St. John's Wort, which blooms around St. John's Day (June 24). Prolificum means abundant, referring to the many stamens.
Diffusely branched shrub to 2 m, the twigs sharply 2-edged; lvs articulate at the base, linear to oblong or narrowly elliptic, 3-6 cm נ4-15 mm, usually abruptly narrowed to a short petiole; infl a small terminal cyme of mostly 3-7 fls, often with additional cymules from the upper axils; pet 7-10 mm; styles 3(4), connate at the base and forming a beak on the fr; fr mostly 7-14 mm, quasi- 3(4)- locular, the partitions meeting in the center but not joined; 2n=18. Many habitats, from swamp-margins to cliffs and woods; N.Y. to s. Mich. and Minn., s. to Ga. and La. July-Sept. (H. spathulatum)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.