Friday, February 24, 2012

Native Plant of the Week: Great St. John's Wort ~ Hypericum ascyron

Great St. John's Wort ~ Hypericum ascyron (pyramidatum)


Great St. John's Wort is the showiest Hypericum species in the midwest. The large bright yellow, 5 parted flowers are over 2" in width.

A native of partly shaded, moist sites in woodlands, woodland edges as well as along riparian areas.

The single flowers open in early July above the tall branched stems. Great St. John's Wort forms a nice large cluster, reaching heights of 3 to 5 feet and 2 to 3 feet in width, taking a form more like a shrub than a herbaceous perennial.

The flowers last into August and are a favorite of bumble bees, syrphid flies and smaller native bees. They love to bury themselves in the many stamens.

The central ovary is quite dominant in the center of the flower and as the petals fall it is equally showy as it dries, browns and matures. The seed capsule gets quite hard and inside are 5 chambers containing many small seeds.



The seeds are easy to collect, and can be collected as late as early November. I break open the capsules and bang the seeds out into a white container. This makes it easier to see and sort the seed.

The leaves are large, oppositely arranged and clasp to the leaf stem. Their size and form are a nice balance with the size and arrangement of the flowers.

Great St. John's Wort is native to northeastern North America. See map below for range.
Kartesz, J.T., The Biota of North America Program (BONAP).
2011. 
North American Plant Atlas. Chapel Hill, N.C.