- Name also: Long-leaved Helleborine, Sword-leaved Helleborine
- Family: Orchid Family – Orchidaceae
- Growing form: Perennial herb. Rootstock short, horizontal.
- Height: 25–50 cm (10–20 in.). Stem glabrous.
- Flower: Perianth irregular (zygomorphic), campanulate (bell-shaped), often only half-open, white, 10–16 mm (0.4–0.64 in.) long. Tepals 6, in 2 whorls, almost same size, 1 elaborated into labellum. Labellum under perianth, spurless, tepals shorter, constricted in middle, blunt-tipped, tip with yellow blotch. Androecium and gynoecium fused into a column, stamens 1, stigmas 2. Inflorescence a lax, 5–20-flowered spike, flowers ascending oblique.
- Leaves: Alternate, almost in 2 rows, stalkless, 6–10. Blade lanceolate–almost linear, parallel-veined, with entire margin.
- Fruit: Erect capsule, seeds tiny, like dust.
- Habitat: Broad-leaved forests, forest margins. Calciphile.
- Flowering time: May–June.
- Endangerment: Near threatened, protected on the Åland Islands.
Narrow-leaved helleborine is a central European species which grows in Finland in the calciferous soils of the Åland Islands at the northernmost reach of its habitat. It thrives best in light-filled broad-leaf forests, coppices and pasture land, and it is nowadays threatened by overgrowth and expanding fir forests. Previously when forests were used as pasture and food was collected for cattle in coppices, narrow-leaved helleborine was common and abundant. An increase in the deer population also taxes the species: a lot of stems with the heads bitten off can be found in areas with a lot of deer. Despite being protected, picking and transplanting it to gardens casts a shadow over its future. There are still quite a lot of plants in certain areas, and these can serve as examples of what a landscape adorned with thousands of blooming flowers used to look like.
Narrow-leaved helleborine’s beautiful flowers don’t reward pollinators with any nectar. It is visited by small bees, especially burrowing bees, which collect the yellow powder that imitates pollen from the labellum and take it back to their nest. It is actually just the plant’s surface tissue however, and it has no nutritional value. Narrow-leaved helleborine’s pollen is in two pollinia, which stick to the back of a bee that is bustling around. Pollen production varies greatly, probably according to the amount of burrowing bees in the area, but it is usually poor. Apart from narrow-leaved helleborine, red helleborine (C. rubra) also grows in Finland. It is critically endangered and protected. Its flowers are pink and it only grows in mainland Finland.