Hairy St. John's-wort
- Written also: Hairy St. Johnswort, Hairy St John’s wort
- Family: St. John’s-wort Family – Hypericaceae
(formerly Clusiaceae (Guttiferae))
- Growing form: Perennial herb.
- Height: 40–80 cm (16–32 in.). Often with many stems. Stem sparsely branched, cylindrical, upper part branched, densely haired, woody at base.
- Flower: Regular, up to 3.5 cm (1.4 in.) wide. Petals 5, pale yellow, dark-glandular tip, stripeless. Sepals 5, taper-tipped, glandular-serrate. Stamens many, fused at base into 3 bunches. Pistil of 3 fused carpels. Inflorescence a broad, dense, many-branched cyme.
- Leaves: Opposite, stalkless or sometimes short-stalked. Blade elliptic–obovate, with tapered base, clearly veined, abundantly hairy, with translucent dots, no black dots.
- Fruit: 3-parted capsule.
- Habitat: Juniper groves, woods, forest margins, banks.
- Flowering time: July–September.
Hairy St. John’s-wort is a central European plant that thrives in the temperate zone. Its spread in Finland is limited to the south-west archipelago. Perhaps because of this its Finnish habitats are to a large extent unusual for the species – sunny and bushy moraine hummocks rather than the more typical shady, damp hardwood forests. Hairy St. John’s-wort also favours calciferous soils, but it bucks this trend in Finland. In the future it might be found on the westernmost parts of Finland, on the largest of the Åland Islands. There is also a certified stand in southern Lohja, but other than that the mainland does not seem to be a happy hunting ground for the species. Its stem and leaves are hairy, and its identification can be confirmed by its cylindrical stem, glandular-toothed calyx and taper-based leaves.