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Hypericum ascyron (Great st. john's-wort)
Smith, R.W.

Hypericum ascyron

Hypericum ascyron L.

Great St. John's-wort, Giant St. John's-wort

Clusiaceae (Mangosteen Family)

Synonym(s): Hypericum pyramidatum

USDA Symbol: HYAS80

USDA Native Status: L48 (N), CAN (N)

A stout, erect, 2-6 ft. plant with large, elliptic leaves and 2 in., yellow, 5-petaled flowers with very bushy stamens.

The scattered distribution of this plant in Ontario is thought to match historical aboriginal encampments. (Ontario Native Plants 2002)


From the Image Gallery

2 photo(s) available in the Image Gallery

Plant Characteristics

Duration: Perennial
Habit: Herb
Fruit Type: Capsule
Size Notes: Up to about 6 feet tall.
Leaf: Green

Bloom Information

Bloom Color: Yellow
Bloom Time: Jun , Jul , Aug


USA: CT , DE , IA , IL , IN , KS , MA , MD , ME , MI , MN , MO , NE , NH , NJ , NY , OH , PA , VT , WI , WV
Canada: ON , QC
Native Distribution: Que. to MN, s. to NJ, PA, IN, s.w. IA & n.e. KS
Native Habitat: Moist places; stream banks; thickets; rich woods

Growing Conditions

Water Use: Medium
Light Requirement: Sun , Part Shade , Shade
Soil Moisture: Moist , Wet
CaCO3 Tolerance: Low
Soil Description: Moist soils


Conspicuous Flowers: yes

Value to Beneficial Insects

Special Value to Native Bees

This information was provided by the Pollinator Program at The Xerces Society for Invertebrate Conservation.


Seed Treatment: Cold stratify.
Commercially Avail: yes

National Wetland Indicator Status

This information is derived from the U.S. Army Corps of Engineers National Wetland Plant List, Version 3.1 (Lichvar, R.W. 2013. The National Wetland Plant List: 2013 wetland ratings. Phytoneuron 2013-49: 1-241). Click here for map of regions.

From the National Organizations Directory

According to the species list provided by Affiliate Organizations, this plant is on display at the following locations:

Mt. Cuba Center - Hockessin, DE

Web Reference

Webref 38 - Flora of North America (2019) Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA.
Webref 23 - Southwest Environmental Information Network (2009) SEINet - Arizona Chapter

Additional resources

USDA: Find Hypericum ascyron in USDA Plants
FNA: Find Hypericum ascyron in the Flora of North America (if available)
Google: Search Google for Hypericum ascyron


Record Modified: 2023-02-14
Research By: TWC Staff

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