The Friends of the Wild Flower Garden, Inc.

Plants of the Eloise Butler Wildflower Garden

The oldest public wildflower garden in the United States

Great St. Johnswort

Common Name
Great St. Johnswort (Giant St. Johnswort)


Scientific Name
Hypericum pyramidatum Aiton


Plant Family
St. Johnswort (Hypericaceae)

Garden Location


Prime Season
Early Summer Flowering



There are a great number of St. Johnsworts in the genus Hypericum. The flowers are generally yellow and in terminal clusters. Great St. Johnswort is an erect native perennial plant that can reach to 5 feet in height with flowering branches near the top, unbranched below. Stems are multiple from the base, smooth and often reddish. See Eloise Butler's notes at the page bottom.

Leaves are opposite, large - lanceolate - and either stalkless or slightly clasping. The upper surface is a shiny green, margins are smooth.

The inflorescence is composed of mostly single flowers at the tops of many short terminal stems, and also rising from the upper leaf axils. Flowers are sometimes in a small cluster.

Flowers: Each flower is stout stemmed, the calyx with 5 green sepals that are smooth, with pointed tips and ovate bases and much shorter than the 5 yellow petals which have more rounded tips. These petals are often floppy looking or with contorted tips. Petals turn brown after pollination and remain in a twisted spiral instead of dropping. There are numerous stamens, united at their bases into 5 sets, each stamen with a yellow anther. The pistil is a yellow-green color, has 5 united carpels and 5 united styles which only separate at their tips. The styles persist onto the seed capsules. Flowers can be from 1.5 to 2.3 inches wide when open.

Seeds: The sepals remain, (along with the remains of the brown twisted petals) turning brown as the seed pod develops into an ovoid 5-celled capsule which contains several hundred small oblong brown seeds. Seeds require 60 days of cold stratification and then light for germination, so they should be surface sown.


Habitat: Great St. Johnswort grows from a rhizomatous root system, preferring full sun and wet-mesic to mesic moisture conditions. It tolerates some shade and will adapt to most soil types. Bumblebees are the primary pollinators. If forms clumps from the rhizomes rather than spreading colonies, and also re-seeds readily.

Names: Some references assign this plant as Hypericum ascyron in the family Clusiaceae. Neither that species name or that family is currently accepted by most authorities including the U of M Herbarium on their Checklist of the Vascular Flora of Minnesota (Ref.#28C) The genus Hypericum is from the Greek hyperikon, meaning 'above picture' or 'above an apparition' and refers to the old practice of placing a sprig of a Hypericum above images or in the house to ward off evil at such times as the during the old festival of Walpurgisnacht and especially on midsummer eve, the night before St. John's Day. (see next paragraph). The species pyramidatum means 'pyramid shaped' which is the shape of the flower buds and the seed capsules of this species. The author name for the plant classification, ‘Aiton,’ is for William Aiton (1731-1793), Scottish botanist, succeeded Philip Miller as superintendent of the Chelsea Physic Garden and then became director of Kew Gardens, where he published Hortus Kewensis, the Garden’s catalogue of plants.

The common name of 'St. Johnswort' is a European reference to St. John's Day, a church feast date on June 24th when the plant would usually be in flower; the 'wort' portion referring to the plants healing properties. These properties refer to the European species Hypericum perforatum which was brought to the New World and now widely spread. The eve of St. John's Day (San Giovanni in Italy), midsummer eve, June 23rd, is considered a night for spirits and witches. It is several days after the actual Summer solstice date but is a remnant of the old Julian calendar.

Comparisons: Common St. Johnswort, Hypericum perforatum, is not native and the leaves are different as is the flower structure.

See bottom of page for notes on the Garden's planting history, distribution in Minnesota and North America, lore and other references.

Great St. Johnswort stem Great St. Johnswort seed capsules

Above: 1st photo - Flowers are usually singles on long stout stalks from the upper leaf axils. Note the stigmas of 5 styles have separated at their tips as the stamens fade away. 2nd photo - Great St. Johnswort as flowering ends and seed capsules form. Note the twisted brown remains of the petals and the styles persisting at the top of each capsule.

Below: The petals have a slight twist and rolled edges. The stamens are numerous but united at their bases into five distinct sets.

Great St. Johnswort flower Great St. Johnswort flower center

Below: 1st photo - The 5 green sepals that are smooth, with pointed tips and ovate bases and much shorter than the 5 yellow petals which have more rounded tips. 2nd photo - The root system of a young plant is composed on many long thin rhizomes and many fibrous root. 3rd photo the root of a mature plant; they run hortizontally just sub-surface.

calyx root Mature Root

Below: 1st photo - The leaves are opposite and sessile and sometimes a little clasping. 2nd photo - The seed capsule with its 5 cells opening at maturity. The sepals persist at the base of the capsule.

Great St. Johnswort leaf Great St. Johnswort seed capsule

Below: 1st photo - Plants are erect and about 5 feet high. 2nd & 3rd photos - The seed capsules mature in Autumn and each contains several hundred small brown oblong seeds.

plant Seed capsules seeds

Below: Two images of a single plant- multiple stems from the root.

full plant Full plant


Notes: Great St. Johnswort is native and found in the eastern section of Minnesota, particularly counties of the SE Quadrant. In North America it is found in the NE quadrant, from Minnesota eastward to the coast and south as far as Missouri and West Virginia. In a great number of these states it is either threatened or endangered and believed extirpated in Maine and Maryland. In Canada it is found from Ontario eastward.

Eloise Butler's records show that she planted this species in 1907, '08, '09, '19 and '28 - obtained from Minnesota sources. She used the old name Hypericum ascyron. Martha Crone reported planting it in 1933, '34, and '50'. It was listed on her Garden Census of 1951 and presumably has been in the Garden for all these years.

Eloise Butler wrote of Great St. Johnswort: "One of our finest native, yellow flowered plants is the Great St. Johnswort, Hypericum ascyron. It may be seen in rich lowland about Minnehaha. It is tall and sturdy, a profuse bloomer and interesting in bud and in fruit. The multiplicity of the stamens gives a light-some grace to the flowers of this family. The flower of this species is large, measuring some three inches across. The petals, when aging, roll up lengthwise, forming a spidery appearance, which adds variety to the inflorescence, together with the striking buds and seedpods. We can but wonder that with all its merits this plant has not been seized upon for cultivation. In the wild garden in Glenwood Park, it is well established in two colonies." Published July 23, 1911 Minneapolis Sunday Tribune.

References and site links

References: Plant characteristics are generally from sources 1A, 32, W2, W3, W7 & W8 plus others as specifically applied. Distribution principally from W1, W2 and 28C. Planting history generally from 1, 4 & 4a. Other sources by specific reference. See Reference List for details.

graphicIdentification booklet for most of the flowering forbs and small flowering shrubs of the Eloise Butler Wildflower Garden. Details Here.