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Common St. John's Wort

Hypericum prolificum (hy-PER-ih-kum pro-LIF-ih-kum)

Family: Hypericaceae Native Shrub (3-15 ft)

Shrubby St. John's Wort is a herbaceous, perennial, deciduous or evergreen flowering shrub with a compact, dense habit, dark green leaves, and yellow flowers. It is one of around 400 species of Hypericum, which include herbs, shrubs, and trees, with different bloom times and cultural requirements. In nature, it is often found in open woods, bogs, hedge banks and grassland, dry sunny places, and usually on calcareous soils. The 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 means many or prolific in reference to the many stamens. Shrubby St. John's Wort will grow in a range of soils from sandy to clay and, while it prefers to stay moist, it will tolerate dry soils. The plant will grow in full sun or partial shade, but full sun will maximize blooms. It is a slow grower and will tolerate drought. It can spread, the root pattern is rhizomatous with underground stems sending roots and shoots along their length, but can be kept under control with spring pruning. This plant can be used in a ran garden. Diseases, Insect Pests, and Other Plant Problems : No known diseases or insect pests. However, root rot and wilt can be significant problems in hot and humid climates.

Source: NC State Extension Gardener Plant Toolbox ↗ NC State Extension Gardener Plant Toolbox, 67 attributes.

How it fits the guild

Guild layer 3 - Shrub (3-15 ft) Optimal soil pH Acid (<6.0); Alkaline (>8.0); Neutral (6.0-8.0)
See companions & conflicts ↓

Companions & Conflicts

Curated pairwise relationships between this plant and others in the library — who feeds whom, who competes, who confuses the pests. Green reads as a good pairing, red as one to avoid.

No curated interactions recorded for this species yet.

Also noted by NC State

Related species the NC State Plant Toolbox flags for this plant — look-alikes to tell apart, and plants that play a similar role in a planting. Ones we carry in the library are linked.

Often confused with Hypericum kalmianum

Full plant profile

Growing Conditions
Plant type
Native Plant; Perennial; Shrub; Wildflower
Life cycle
Perennial
USDA zones
3a, 3b, 4a, 4b, 5a, 5b, 6a, 6b, 7a, 7b, 8a, 8b
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 | Occasionally Dry
NC region
Coastal; Mountains; Piedmont
Mature size
Height: 1 ft. 0 in. - 5 ft. 0 in. | Width: 1 ft. 0 in. - 4 ft. 0 in.
Growth rate
Slow
Maintenance
Low
Canopy layer
3 - Shrub (3-15 ft)
Form & Appearance
Habit / form
Dense; Erect; Mounding; Multi-stemmed; Rounded
Texture
Medium
Foliage
Deciduous
Leaf color
Green
Leaf type
Simple
Leaf arrangement
Opposite; Whorled
Leaf shape
Elliptical; Linear; Oblong
Leaf margin
Entire
Leaf size
1-3 inches long, < 1 inch wide
Hairs present
No
Leaf detail
Dark green 3 inch leaves with no appreciable fall color. Opposite or whorled, decussate, simple, entire; sessile or petiole short.
Flower color
Gold/Yellow
Flower value
Long Bloom Season; Showy
Flower form
Cyme
Flower size
< 1 inch
Flower detail
Bright yellow flowers in summer on current season's growth; dry capsules persist all winter. Solitary or cymose, terminal or axillary. Yellow (usually) 5-petaled (rarely 4), 5 sepals (rarely 4); stamens numerous, in bundles or in showy boss. Blooms from June to October. 5-petaled flowers with numerous stamens. The upper stems terminate in small clusters of 3-7 flowers; additional clusters of flowers may appear along the 2 upper pairs of opposite leaves. Each flower is ¾ to 1 inch across. The petals are much larger than the sepals.
Bloom time
Summer
Fruit color
Brown/Copper
Fruit type
Capsule
Fruit size
< 1 inch long, < 1 inch wide
Fruit detail
A (2)3-5 celled ovoid 1/2 inch capsule, sometimes fleshy. Displays from July to November.
Bark color
Light Brown
Bark detail
Older bark is exfoliating.
Stem color
Brown/Copper; Green
Stem detail
Contains 2 to 4(up to 6) ridges on newer growth, smooth and rounded on older growth. The lower stems are woody with shredded gray-brown bark, while the upper stems are green and slightly winged on opposite sides.
Wildlife & Ecology
Native status
Native
Origin
Central and Eastern North America
Wildlife value
Fruits attract birds.
Attracts
Butterflies; Pollinators; Small Mammals; Songbirds
Food & Medicine
Harvest time
Fall
Fruit type
Capsule

Edibility

Ingesting St John's wort can reduce the effectiveness of some prescription medicines.

Landscape Use
Landscape location
Meadow; Naturalized Area; Woodland
Landscape theme
Butterfly Garden; Native Garden; Pollinator Garden; Rain Garden
Design feature
Accent; Border
Garden tags
#deciduous #drought tolerant #mounding #yellow flowers #fantz #bird friendly #Piedmont Mountains FACU #food source herbage #food source hard mast fruit #food source nectar #food source pollen #mammals #Coastal FAC #food source fall #pollinator plant #Audubon #bee friendly #wildlife friendly #NC native #NC Native Pollinator Plant #rain garden
Problems & Resistance
Resistant to
Drought; Dry Soil; Erosion
Particularly resistant to
Heat, drought, and soil compaction tolerant.
Propagation
Division; Seed
Poison severity
Medium
Poison parts
Leaves; Sap/Juice
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.
Toxic principle
Unidentified, possibly a glycoside
Contact dermatitis
Yes
Toxicity summary
Medium severity poison; parts: Leaves; Sap/Juice; contact dermatitis

Planted at Hunnicutt

Nobody’s planted this one yet.