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Imperforate St. John's-Wort
Hypericum maculatum
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Alien species
Imperforate St. John's-Wort is an upright, long-lived wildflower with bright yellow, star-like blooms. It is widespread in much of Europe and is often seen on meadows, field margins and roadsides. In late summer its airy clusters of yellow flowers stand above the green foliage.
Did you know?
- The stem has four sharp ridges, giving it a square look.
- Often confused with common St. John's-Wort; counting the stem ridges helps tell them apart.
About the species
Identification
Upright perennial, usually a single smooth, hollow stem 40–70 cm tall with four sharp edges; few side-branches near the top. Leaves grow in pairs on the stem, with no stalks, broad oval and smooth-edged; held to the light they show tiny clear dots and some dark specks, often along the edge. Flowers in a loose cluster: five bright yellow petals often dotted or streaked with black; many long yellow stamens make a bushy centre. Dry seed pods split into three. Key clue: the stem looks and feels square with four ridges; common St. John's-Wort usually shows only two. Warning: the sap can burn the skin in sunlight. Flowers in Finland from July to August.
Plant group
Herbaceous plants
Habitat
meadow
Toxicity
Its sap can burn the skin in sunlight – do not touch it with bare hands. Source: HUS Poison Information Centre (Finland), tel. 0800 147 111.
Flowering
Jul–Aug
About the habitat
Open, sunny to lightly shaded grassland and disturbed ground: meadows, pastures, field margins, woodland edges and road verges, on generally well-drained soils. Common in southern and central Finland, scarce around the Oulu region, absent in Lapland.
Sources
Text: Pinkka: Laaja maatalouslajintuntemus 4 op - Koppisiemeniset, CC BY 4.0 https://laji.fi/taxon/MX.38301
Text: Wikipedia (Finnish), CC BY-SA 4.0 https://fi.wikipedia.org/wiki/S%C3%A4rm%C3%A4kuisma
