Great St. John's wort is a native perennial of wet meadows and stream banks, found mainly in the Midwest with some populations in New England. Its size sets it apart from other St. John's worts: it grows up to 5 ft (1.5 m) tall, with golden yellow flowers about 2 in (5 cm) across. Its flowers make no nectar, but bumblebees come to gather their pollen.
Appearance
- Appearance
- A tall perennial, 2–5 ft (0.6–1.5 m), with stiff upright stems that are four-angled and branch mainly near the top.
- Leaves
- Opposite, smooth-edged, hairless leaves up to about 3 in (8 cm) long and 1 in (2.5 cm) wide, attached directly to the stem without a leaf stalk.
- Flowers
- Five bright to golden yellow petals around a mass of about 100 stamens. The green, pyramid-shaped center ends in five , which makes it easy to tell from most other St. John's worts.
- Flowering time
- July to August, with each plant blooming for about 2–3 weeks in midsummer.
- Fruit
- A pyramid-shaped capsule about 1 in (2.5 cm) long that dries brownish black and opens at the top, releasing tiny dark brown seeds.
Look-alikes
Kalm's St. John's wortHypericum kalmianum
Kalm's St. John's wort also has five styles, but it is a woody, shorter, bushier shrub with narrower leaves and smaller flowers.
Why they get mixed upBoth have yellow flowers with five styles, unlike most other large St. John's worts, which have one to three.
Where it lives
- Typical habitats
- wet meadows
- stream and river banks
- moist thickets
- fens
- woodland openings
- Range
- Native to North America and East Asia. In the US it grows mainly in the Midwest, with some populations in New England; in Illinois it is occasional in the north and west-central parts and rare elsewhere, near the southern edge of its range.
- Preferred conditions
- Full sun and moist soil; usually found in good-quality natural habitat.
- Flowering
Flowers Jul–Aug
Flowers Jul–Aug
Name and classification
- About the name
- North American plants belong to their own subspecies, H. ascyron subsp. pyramidatum. Some botanists treat them as a separate species, Hypericum pyramidatum, which is why older guides use that name.
Conservation
- IUCN Red List
- NENot EvaluatedNot yet assessed
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