Species Native to Missouri
Common Name: great St. John's wort
Type: Herbaceous perennial
Family: Hypericaceae
Native Range: Eastern Canada, United States
Zone: 3 to 6
Height: 2.00 to 5.00 feet
Spread: 1.00 to 3.00 feet
Bloom Time: July to August
Bloom Description: Yellow
Sun: Full sun to part shade
Water: Medium to wet
Maintenance: Low
Suggested Use: Naturalize, Rain Garden
Flower: Showy, Good Cut, Good Dried
Attracts: Butterflies
Tolerate: Rabbit, Deer, Clay Soil, Wet Soil, Shallow-Rocky Soil
Culture
Easily grown in moist, well-drained soils in full sun to part shade. Adaptable to a range of soil types including clayey and rocky soils. May self-seed in ideal conditions. Propagate through cuttings or seed. The seed requires cold, moist stratification and light to break dormancy and germinate. Hardy in Zones 3-6.
Noteworthy Characteristics
Hypericum ascyron, commonly called great St. John’s wort or giant St. John's wort, is a herbaceous perennial native to meadows, streambanks and moist wooded slopes in eastern and central North America as well as eastern and central Asia. Mature clumps will reach 2-5’ tall and 1-3' wide. The upright stems are clad with sessile, elliptic leaves that reach 2-4" long and up to 1" wide. and features a showy display of yellow, 2" wide flowers that bloom in rounded to pyramidal cymes in mid to late summer. Each flower has 5 yellow petals, 5 styles (most hypericums have 3 styles) and a center boss of bushy yellow stamens. The flowers are attractive to bumblebees and other insect pollinators, and the caterpillars of several moth and butterfly species feed on the foliage.
Subspecies pyramidatum is the name applied to plants native to North America where it is found in woodland openings, roadside ditches, moist meadows, fens, and streambanks from Maine to Manitoba south to Maryland, Indiana and Kansas. The leaves of this subspecies tend to be somewhat wider than the species (reaching up to 1.5" wide) and the tips of the sepals tend to be acute rather than rounded, but these characteristic are variable.
Genus name comes from the Greek words hyper meaning "above" and eikon meaning "picture" in reference to the practice of hanging flowers from this genus above images, pictures or windows.
The specific epithet ascyron most likely comes from the Greek askyron which was a name used for St. John's wort.
The infrapecific epithet means "resembling a pyramid" in reference to the arrangement of the flowers.
Plants of the genus Hypericum (some species have been used since ancient times in the treatment of wounds) were apparently gathered and burned to ward off evil spirits on the eve of St. John’s Day, thus giving rise to the genus common name of St. John’s wort.
Problems
No serious insect or disease problems. Deer and rabbits tend to avoid this plant.
Uses
Treat as a specimen or allow to naturalize in borders, woodland margins, and rain gardens. The long, straight stems make this hypericum a good choice for fresh or dried flower arrangements.