Flower:

Flattish clusters of 3 to 7 flowers at the ends of branching stems. Flowers are ½ to 1 inch across, yellow, with 5 oval petals often crinkly at the tip end, and dozens of yellow stamens exploding from the center. Sitting at the base of the petals are 5 styles, joined into a pyramid shaped projection. Behind the flower are 5 green sepals, pointed at the tip and about half as long as the petals.

Leaves and stems:

Leaves are ¾ to 1½ inches long, up to 1/3 inch wide, toothless, hairless, typically blunt at the tip, linear to narrowly oblong but often narrowing at the base end, and little or no stalk. There are often smaller leaves clustered in the axils. Stems are woody, angular, leafy, and branching freely.

Fruit:

Fruit is a 5-chambered capsule about ¼ inch long, tear-drop to pyramidal in shape with the remains of the style persisting at the top, the capsule turning dark red as it matures.

Notes:

The only known locations of Kalm's St Johns-wort in Minnesota are along an access road to the Boundary Waters Canoe Area in Lake County. We were up there looking for Spiranthes lacera and came upon this instead. Kalm's St. Johns-wort is primarily found around Great Lakes Michigan and Huron, in Michigan and Wisconsin. Herbarium records indicate it is not likely native to Minnesota and unknown how it got here, but was probably transported by someone visiting the BWCA. It is, however, available from some native plant nurseries.