Common St. John's-wort Hypericum perforatum
Other Common Name(s):
- Phonetic Spelling
- hy-PER-ih-kum per-fuh-RAY-tum
- This plant has medium severity poison characteristics.
- See below
- Description
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St. John's Wort is a herbaceous, perennial, deciduous or evergreen shrub growing to 3 feet high by 2 feet wide. H. perforatum is one of about 400 species of Hypericum, which include herbs, shrubs and trees, with different bloom times and cultural requirements. In nature, St. John's Wort is often found in open woods, roadsides and waste places, hedge banks and grassland, and in dry sunny places, usually on calcareous soils. Introduced from Europe, it is now found throughout the United States. St. John's Wort is in flower from May to August, and the seeds ripen from July to September. This species is usually in bloom during the summer solstice (dedicated to St. John), hence the common name. The plant is self-fertile and can rapidly spread to the point where it is potentially invasive. The root pattern is rhizomatous with underground stems sending roots and shoots along their length. A single plant may produce up to 100,000 seeds per year and seeds buried in soil may last for 10 years.
St. John's Wort tolerates most soil types, including sandy, loamy, and clay soils, but prefers well-drained, moist soil. It can grow in semi-shade (light woodland) or no shade, but full sun is best for maximum blooms. It can also tolerate drought.
Diseases, Insect Pests, and Other Plant Problems: No serious insect or disease problems. Invasive spread can displace native species.
- See this plant in the following landscape:
- Entryway Garden, Cabarrus County Extension Office
- Cultivars / Varieties:
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- Tags:
- Cultivars / Varieties:
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- Tags:
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Attributes:
- Genus:
- Hypericum
- Species:
- perforatum
- Family:
- Hypericaceae
- Uses (Ethnobotany):
- Native Americans have been known to use this plant for medicinal purposes. Flowers can be used as a yellow dye plant.
- Life Cycle:
- Perennial
- Recommended Propagation Strategy:
- Division
- Seed
- Country Or Region Of Origin:
- Europe, North Africa, Western Asia
- Distribution:
- Throughout the United States and Canada
- Play Value:
- Attracts Pollinators
- Wildlife Food Source
- Edibility:
- Ingestion of St John's wort can reduce the effectiveness of prescription medicine.
- Dimensions:
- Height: 1 ft. 0 in. - 3 ft. 0 in.
- Width: 0 ft. 9 in. - 2 ft. 0 in.
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Whole Plant Traits:
- Plant Type:
- Ground Cover
- Perennial
- Wildflower
- Woody Plant Leaf Characteristics:
- Deciduous
- Habit/Form:
- Dense
- Mounding
- Multi-stemmed
- Spreading
- Growth Rate:
- Medium
- Maintenance:
- Low
- Texture:
- Medium
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Cultural Conditions:
- Light:
- Full sun (6 or more hours of direct sunlight a day)
- Partial Shade (Direct sunlight only part of the day, 2-6 hours)
- Soil Texture:
- Clay
- Loam (Silt)
- Sand
- Soil pH:
- Acid (<6.0)
- Alkaline (>8.0)
- Neutral (6.0-8.0)
- Soil Drainage:
- Good Drainage
- Moist
- NC Region:
- Coastal
- Mountains
- Piedmont
- USDA Plant Hardiness Zone:
- 3a, 3b, 4a, 4b, 5a, 5b, 6a, 6b, 7a, 7b, 8a, 8b
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Fruit:
- Fruit Color:
- Brown/Copper
- Display/Harvest Time:
- Fall
- Fruit Type:
- Capsule
- Fruit Description:
- Each 3-celled seed capsule is well-rounded at the base, becoming conical at its apex. Each cell of the seed capsule contain numerous seeds, which are oblong, flattened, and black. The surface of each seed is somewhat roughened by numerous small pits, rather than smooth.
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Flowers:
- Flower Color:
- Gold/Yellow
- Flower Inflorescence:
- Cyme
- Flower Value To Gardener:
- Long Bloom Season
- Showy
- Flower Bloom Time:
- Spring
- Summer
- Flower Petals:
- 4-5 petals/rays
- Flower Size:
- 1-3 inches
- Flower Description:
- Yellow petals with black dots on margins; bushy stamens. Solitary or cymose, terminal or axillary. Yellow (usually) 5-petaled (rarely 4), 5 sepals (rarely 4); stamens numerous, in bundles or in showy boss. The upper stems terminate in flat-headed clusters of several flowers. Each flower is about ¾ of an inch across. There are scattered black dots along the margins of the petals.
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Leaves:
- Woody Plant Leaf Characteristics:
- Deciduous
- Leaf Color:
- Green
- Leaf Type:
- Simple
- Leaf Arrangement:
- Opposite
- Whorled
- Leaf Shape:
- Oblong
- Leaf Margin:
- Entire
- Hairs Present:
- No
- Leaf Length:
- < 1 inch
- Leaf Width:
- < 1 inch
- Leaf Description:
- Leaves are about 1 inch long and 1/3 of an inch across. They are oblong, hairless, and sessile. The surface of these leaves is perforated by numerous translucid dots, and there are often scattered black dots along the margin of the lower surface.
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Stem:
- Stem Color:
- Green
- Stem Is Aromatic:
- No
- Stem Cross Section:
- Round
- Stem Surface:
- Smooth (glabrous)
- Stem Description:
- Contains 2 to 4 (up to 6) ridges on newer growth, smooth and rounded on older growth.
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Landscape:
- Landscape Location:
- Recreational Play Area
- Slope/Bank
- Woodland
- Landscape Theme:
- Children's Garden
- Pollinator Garden
- Design Feature:
- Barrier
- Mass Planting
- Attracts:
- Bees
- Pollinators
- Resistance To Challenges:
- Deer
- Drought
- Poor Soil
- Problems:
- Problem for Cats
- Problem for Dogs
- Problem for Horses
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Poisonous to Humans:
- Poison Severity:
- Medium
- Poison Symptoms:
- Skin contact with the sap, or ingestion of the plant, can cause photosensitivity in some people. Common side-effects are gastointestinal disturbances, allergic reactions and fatigue, ulcerative and exudative dermatitis.
- Poison Toxic Principle:
- Hypericin
- Causes Contact Dermatitis:
- Yes
- Poison Part:
- Leaves
- Sap/Juice
