Flower:

Flowers are from 2 to 2½ inches across with 5 bright to golden yellow petals and many long yellow stamens with orange tips. In the center is a green pyramid shaped ovary with 4 or 5 red-tipped styles that are fused at the base. A flowers is at the end of a stem that arises from a leaf axil in the upper part of the plant.

Leaves and stem:

Leaves are up to 3 inches long and 1 inch wide, toothless and hairless, rounded at the base and slightly tapering to a point at the tip, with no leaf stem. There are glandular dots or streaks scattered on the surface. Attachment is opposite. The main stem is 4-angled on young plants, becoming 4-lined with maturity.

Fruit:

Fruit is a pyramid-shaped capsule with 5 chambers, about 1 inch long. It dries to brownish black and opens at the top when the seed is ripe.

Seed is cylindrical, dark brown, about 1 millimeter long, and resembles a tiny ear of corn.

Notes:

While the general shape of this flower resembles other St. John's-wort species, the size of the flower sets it apart from the rest. Great St. John's-wort also goes by Latin name Hypericum ascyron, but the accepted name in Minnesota is Hypericum pyramidatum. All Hypericum species have switched from the Clusiaceae family to Hypericaceae.