Round-Leaved St John'S-Wort

hypericum nummularium

The Round-Leaved St John's-Wort is a charming perennial wildflower native to the rocky, limestone-rich slopes of southwestern Europe, particularly the Pyrenees and the western Alps. Unlike its upright, tall cousins, this species boasts a low-growing, prostrate habit. It drapes itself gracefully over sheer rock faces and crevices, forming cushions of rounded, bluish-green foliage that resemble tiny coins scattered across the stone. During the summer, these mountain gems come alive with bright yellow flowers, adding a splash of vibrant color to the stark alpine landscape.

Habitat: Found in damp limestone rock crevices, mountain scree slopes, and shaded alpine cliffs.

Appearance

This creeping perennial typically reaches heights of only 5 to 20 cm, spreading horizontally over rocky surfaces. Its small, opposite, almost perfectly circular leaves are glaucous or bluish-green, with tiny translucent glands visible under close inspection. The star-like flowers are bright golden-yellow, measuring 1.5 to 2.5 cm across, with five distinct petals that may show tiny black dots along the margins. The center of each flower is crowded with a dense, brush-like cluster of numerous long, protruding stamens.

KingdomPlantaePhylumTracheophytaClassMagnoliopsidaOrderMalpighialesFamilyHypericaceaeGenusHypericum

Round-Leaved St John'S-Wort

Interesting facts

It is a specialist of karst landscapes, perfectly adapted to survive in areas with soluble rocks where surface water quickly disappears underground.

The species name 'nummularium' is derived from the Latin word for coin ('nummulus'), referencing the beautifully round, coin-like shape of its leaves.

Unlike common St John's-wort, which grows tall and weed-like, this species behaves like a delicate mountain groundcover.

Special abilities

It possesses highly specialized, deep-reaching root systems that can wedge into tight limestone fissures to secure moisture and anchoring.

Its creeping, low-lying growth pattern helps it survive freezing alpine temperatures and high-velocity mountain winds.

The foliage contains hypericin and other secondary metabolites that act as natural deterrents against insects and mammalian grazers.

Measurements & details

Length: 5-20 cm
Lifespan: 3-10 years

Diet & Feeding

As a photosynthetic plant, it produces its own energy using sunlight, carbon dioxide, and water while absorbing essential minerals from limestone soils.

Primary Foods

Sunlight
Carbon Dioxide
Water
Limestone Minerals

Ecological connections

mutualism

Bilberry Bumblebee

Bombus monticola

Visits the bright yellow blossoms for nectar and pollen, acting as an alpine pollinator.

eaten by

Pyrenean Chamois

Rupicapra pyrenaica

Feeds occasionally on the subalpine vegetation of the Pyrenees, including wild St John's-worts.

competitor

Earleaf Bellflower

Campanula cochleariifolia

Competes for precious space and moisture in narrow rock fissures on alpine cliffs.

Traits

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Also known as

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Safety

Danger

1/5 · Very low

No special safety notes yet.

Frequently Asked Questions

How to identify Round-Leaved St John'S-Wort?

The easiest way to identify Round-Leaved St John'S-Wort is to use the Snappit nature identifier app.

How long is Round-Leaved St John'S-Wort?

5-20 cm

How long does Round-Leaved St John'S-Wort live?

3-10 years

What does Round-Leaved St John'S-Wort eat?

As a photosynthetic plant, it produces its own energy using sunlight, carbon dioxide, and water while absorbing essential minerals from limestone soils.

Where is Round-Leaved St John'S-Wort usually found?

Found in damp limestone rock crevices, mountain scree slopes, and shaded alpine cliffs.