Hypericum calycinum - St. John's wort

Hypericum calycinum, also known as Large-flowered St. John's Wort or Rose of Sharon, is one of the best ground covers for a temperate climate. Prolific, even invasive, this perennial or subshrub resists everything, grows absolutely everywhere, and spreads through creeping stoloniferous stems. The large, bright yellow flowers, open and adorned with a tuft of long central stamens, bloom all summer long, carried by slender stems above evergreen dark-green foliage. This very hardy plant is a boon for difficult slopes, wild or neglected areas, on the outskirts of a large garden.

 This plant, belonging to the Clusiaceae family (sometimes classified by certain authors in the Hypericaceae family), is native to Turkey. It is a deciduous perennial with a woody stump and creeping suckers, cousin to the shrubby St. John's wort so commonly planted in our gardens. The plant quickly forms a tuft 20 to 40 cm (7.9 to 15.7 in) high, which expands through stoloniferous stems that root upon contact with the soil. After a few years, the resulting carpet can reach impressive dimensions. Its rectangular leaves of a dark green shade are dotted with small translucent spots that contain numerous resinous glands. They measure about 4.5 cm (1.8 in) in length. The abundant flowering takes place from June to September, earlier or later depending on the climate. The solitary flowers are gathered in terminal cymes. They are composed of 5 bright yellow and shiny petals surrounding a crown of long protruding yellow stamens. This St. John's wort is almost indestructible, suffocating weeds with great efficiency.

Hypericum calycinum is an excellent plant for difficult, rocky, and dry areas or under trees where nothing grows. It is best suited for large spaces that allow it to fully play its role without interfering with other plants. Its preferred locations will be a large sunny slope, dry and shaded undergrowth, or the base of a hedge bordering the surrounding countryside.