The genus Monophyllis are often put in the genus Malaxis consisting of about 300 species.
In Great Britain is One-leaved bog orchid defined as Malaxis monophyllos – One-leaved bog orchid.
In Norway the species belong to the genus Microstylis which has only one species: Microstylis monophyllos.

Knottblom - microstylis monophyllus

Microstylis monophyllos –  One-leaved bog orchid

Microstylis monophyllos found scattered in Eurasia and North America, but lacking in the western parts of the Alps. It is found in Norway only in the south-eastern areas of Østfold to Vestfold and North to Stor-Elvdal, Dovre and Søndre Land. It has become a rare plant due marsh trenching because it requires calcareous marsh and swamp forests and therefore sets completely different requirements for habitat than Bog Orchid – Hammarbya paludosa. .

At last year’s pseudobulb growing growth season a rhizome and plant develops at the end of the rhizome. The Latin species epithet monophyllos tells us that it has only one blade, but it can also have two knives. Leaf can be be up to 10 cm long with a width of 5 cm. Plant height is 10-25 cm, stem hairless and has many tiny, greenish-yellow flowers that sits on a narrow inflorescence. Flower lip facing up as Bog Orchid.

The species is protected under the Nature Diversity Act and considered critically endangered on the Norwegian Red List.