Hypericum swinkianum

Hypericum swinkianum, known as Swink's St. John's wort, is a shrub in the St. John's wort family. It was named after Chicago Region botanist Floyd Swink.

Description

Swink's St. John's wort is a many-branched shrub up to high. It has exfoliating bark. The leathery, oblong leaves reach in width and in length, with weakly revolute edges. The flowers are produced in terminal flowerheads known as dichasia. Each dichasium produces 7-31 bright yellow flowers, each with 5 petals and numerous yellow stamens. The capsules are 5-parted. In the Chicago Region, it blooms between July and August.
Hypericum swinkianum differs from the closely related Hypericum kalmianum by its notably larger vegetative features, flowerheads each averaging more than 7 flowers, and an affinity toward acidic rather than calcareous habitats.

Distribution and habitat

Swink's St. Johns wort is known to occur in sand flatwoods and acidic wet to wet-mesic sand prairies in the western Great Lakes region in the United States, including Illinois, Indiana, and Michigan. It is a highly conservative species with a coefficient of conservatism of 10 in the Chicago Region and in Michigan.