Mountain St. John's-wort
- Name also: Pale St. John’s-wort, Mountain St John’s-wort, Mountain St. Johnswort
- Family: St. John’s-wort Family – Hypericaceae
(formerly Clusiaceae (Guttiferae))
- Growing form: Perennial herb.
- Height: 20–80 cm (8–32 in.). Single-stemmed. Stem almost or completely unbranched, cylindrical, glabrous, woody at base.
- Flower: Regular, 1.5–2.5 cm (0.6–1 in.) wide. Petals 5, yellow, without glands, without spots, stripeless. Sepals 5, lanceolate, taper-tipped, with ciliate margins. Stamens many, fused at base into three bunches. Pistil of 3 fused carpels. Inflorescence a dense, short-branched cyme.
- Leaves: Opposite, stalkless. Blade ovate, cordate-based, with veined underside and rough-hairy along edges, margin often black-spotted, uppermost often with translucent dots.
- Fruit: 3-parted capsule.
- Habitat: Light forest margins and precipices. Calciphile.
- Flowering time: July–August.
- Endangerment: Critically endangered, protected in all of Finland.
Mountain St. John’s-wort is native to temperate areas of Europe and North Africa. The species north-easternmost stand is in Finland in Lohja, on the northern side of Lake Hormajärvi. This is where it was picked for the first time in 1888 for a museum collection, and the picking that has carried on from this same area has been so intense that it has possibly had a negative effect on the stand. Luckily any desire to map mountain St. John’s-wort in Finland has not led to it becoming extinct. Nowadays it is protected and so collection is no longer a threat, but on a very local level its fate is closely tied to holiday home construction. Over 90% of Finland’s small mountain St. John’s-wort grows in summer-cottage plots or by roadsides. Luckily local land-owners have a positive attitude towards it and in this respect its future looks bright. The best place to look for mountain St. John’s-wort is on open, even sunny south-facing dryish forest slopes and rocky crags – without disturbing any cottage-owners.
Another cylindrical-stemmed St. John’s-wort Family species that grows in Finland is hairy St. John’s-wort, which can be differentiated from mountain St. John’s-wort by its glabrous stem, cordate leaves and ragged-toothed sepals.