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Plants of the Eloise Butler Wildflower Garden

Common
Name

Scientific
Name

Plant
Family

Garden
Location

Prime
Season
Common St. Johnswort
Hypericum perforatum L.
Clusiaceae (Mangosteen)
Upland
Early Summer to Early Autumn
Other names and notes

(Kalmath Weed or Touch and Heal).There are a great number of St. Johnsworts in the genus Hypericum. The flowers are generally yellow and in terminal clusters. The Common St. Johnswort, is an introduced plant from Europe that is an erect perennial, growing to 3 feet high on a branching hairless stem. The larger stems have a pair of ridges at the base of the leaves. Leaves are very narrow, oblong, stalkless, that have numerous translucent dots, which are the oil producing cells. These dots which look like "perforations" are what caused Linnaeus to name the plant H. perforatum. Flowers: The inflorescence is a rounded branched cluster made up of numerous stems (a cyme). The five golden yellow flower petals have margins spotted with small back dots. Flowers are about one inch wide, with 3 styles, numerous stamens that are united at their bases into 3 sets; anthers are yellow and there are 5 green sepals which are much smaller than the petals. Seeds: The flower petals turn brown and remain with the developing seed pod which is a 3-celled capsule containing numerous brownish-black seeds.

Habitat: The plant has a taproot and a rhizomatous root system from which multiple stems can arise. It prefers full sun and adapts to dry conditions. It can spread rapidly and can be noxious in pasture areas and thus it is listed as a noxious weed by a number of states that have large grazing lands such as Colorado, Nevada, Wyoming and Montana among others. Nevertheless, it is an attractant to pollinators and very useful in restoring pollinator habitat. Some references will assign this plant to Hypericum pyramidatum Aiton. in the family Hypericaceae. The common name is a European reference to St. John's Day on June 24th - the day when the plant is usually blooming. Comparisons: Great St. Johnswort, Hypericum ascyron, is native and the leaves are different as is the flower structure.
St. Johnswort
Common St. Johnswort flower
Common St. Johnswort: Blooms begin in late June. Below left - one of the last blooms of late August, but depending on the year, may bloom even later. Near it are numerous developing seed capsules and note the brown twisted remains of the petals. Below right - the small leaves. Note the light colored translucid dots.
St. Jhnswort
St. Johnswort Leaf
Below: A pair of flowers of Common St. Johnswort. Note the 3 long styles spreading outward from the stigma and the numerous black dots on the margins of the petals. The numerous stamens are united at their bases into 3 sets.
Common St. Johnswort flowers
 
 

Notes: Common St. Johnswort - Eloise Butler's records show that she obtained plants of this species on April 4, 1912, on April 4, 1913, on April 28, 1916 and on April 2, 1925, all from Malden, Massachusetts. This was Eloise's hometown where her sister, Cora Butler Pease, lived and to where Eloise would return in the late Fall to spend the winter. She either collected these herself, or Cora did, and then had them shipped to her in Minneapolis. There are seven known species of St. Johnswort in Minnesota, the "Common" is not native, but introduced into the United States and to Minnesota, and is found most often in scattered counties in the eastern section of the state. There are very few states or lower Canadian Provinces where it is not found. In our western states, beginning from the rangeland of northern California near the Kalmath River, the plant spread widely over the rangelands of the western states, taking over from beneficial rangeland plants. This is how the alternative common name of Kalmath Weed became applied. The edible parts of the plant are toxic to cattle as they react to the chemical "hypericin" contained in the plant. In the mid 20th century, first in Canada, then in the west, beetle control was introduced from Europe in the form of three species of the Chrysolina beetle, which feeds only on the leaves of Common St. Johnswort. The most commonly used species is C. quadrigemina. These beetles greatly reduced the abundance and spread of the plant.

Lore: H. perforatum has a long history as a medicinal ingredient and is available as an over-the-counter herbal supplement today to help with numerous maladies. The medicinal parts are the plant tops and flowers. Edwin Way Teale (A Walk Through the Year) reported that "During medieval times it was gathered and hung in doors and windows to ward off evil spirits. Its name comes from an old belief in England that it begins to bloom on June 24, the day of St. John the Divine. " Less well known is that a small quantity added to bread flour is said to improve the quality of bread.

 
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References: Plant characteristics are generally from sources 15, 16, 30, 31, 33, W2 & W3. Distribution principally from W2 and also 31, 34 and W1. Planting history generally from 1, 4 & 4a. Other sources by specific reference. See Reference List for details.  
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