- Family: Heather Family – Ericaceae
(formerly Wintergreen Family – Pyrolaceae)
- Growing form: Perennia wintergreenl herb. With subterraneous runners.
- Height: 10–30 cm (4–12 in.). Stem glabrous, sometimes reddish.
- Flower: Corolla campanulate (bell-shaped)–regular (actinomorphic), white–greenish white–yellowish white, 8–12 mm (0.32–0.48 in.) long; petals 5. Calyx 5-lobed, lobes narrow. Stamens 10. Pistil a fused carpel, single-styled (stigma 5-lobed), body red–yellowish red, curved, protruding from flower. Inflorescence an erect, usually at least 10-flowered raceme, flowers nodding.
- Leaves: In a basal rosette, stalked, overwintering. Stalk wingless, shorter–longer than blade. Blade round–elongated–roundly ovate, with entire margin or small rounded teeth (crenulate), quite thick, glossy, leathery. Stem leaves alternate on base, small, sheath-like–scaly.
- Fruit: 5-valved, nodding capsule.
- Habitat: Young and broad-leaved forest heaths, broad-leaved forests, rich swampy forests, fens, mountain birch woodland and tundra. Ssp. norvegica is calciphile,
- Flowering time: June–August.
Like tens of other plants that grow in Finland, round-leaved wintergreen has its own northern form, and in this case it has been classed as a subspecies. It is not that the northern habitat has caused the change; rather the reasons can be found far in the past. When the continental ice place melted a good 10,000 years ago, Finland’s soil was initially plantless. Plants then began to spread to Finland along two main routes: from both sides of Lake Ladoga in the south-east and from the east from the direction of the White Sea. The virgin land was first populated by tundra plants, followed by steppe plants and finally forest plants. Northern Finland’s plants came directly from the east, while in the south the direction of flow was mainly from the south-east. Round-leaved wintergreen that overwintered in different places through the Ice Age was first divided by the broad steppe, which these forest plants were unable to cross. This split lasted for thousands of years, and the plants developed in slightly different directions and became different-looking. There was nothing to prevent these subspecies from cross-breeding. When the forest finally closed in on the open space, the wintergreens met and then began to cross-breed. There are many subspecies, especially in the southern part of Lapland and Kainuu. Round-leaved wintergreen’s flowers smell slightly like lily-of-the-valley and they lack nectar, so are mainly self-pollinating. The stands do not mix much even when they grow together. It has subterraneous runners, through which it also spreads efficiently.
Both (ssp. rotundifolia) in the south and (ssp. norvegica), which is more common in the north, are easy to recognise as round-leaved wintergreen from the curved and reddish body of the pistil protruding from the open flower. The leaves on ssp. norvegica are relatively small and short-stalked, the corolla is greenish white, and its flowers are relatively large.