Great St. John’s Wort (Hypericum pyramidatum)

A.k.a. Giant St. John’s Wort. An adaptable, easy to grow St. John’s Wort with large yellow summer flowers. Spreads moderately by rhizome. Like other herbaceous St. John’s worts, it’s mildly poisonous sap means it is avoided by mammalian herbivores, but contact with skin may cause irritation.

Light: Full Sun, Part Sun/Shade

Soil Moisture: Wet Mesic, Mesic

Soil Type: Adaptable

Height: 3’-5’

Bloom Color: Yellow

Bloom Time: Jul-Aug

Root Type: Rhizomatus

Notable Wildlife Interactions: Flowers attract a variety of bees, including bumble bees, and smaller pollinators like flies. Hosts the gray hairstreak butterfly, a number of moths including the wavy-lined emerald, and a couple of leaf beetles and smaller insects. Mildly toxic sap means it is generally avoided by mammalian herbivores.

Notes: Hypericum ascyron ssp. pyramidatum is a common synonym.