Gymnadenia

Gymnadenia is a genus in the orchid family (Orchidaceae) containing 22 terrestrial species.

Gymnadenia
Gymnadenia densiflora
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Monocots
Order:	Asparagales
Family:	Orchidaceae
Subfamily:	Orchidoideae
Tribe:	Orchideae
Subtribe:	Orchidinae
Genus:	Gymnadenia R.Br.
Synonyms[1]
Nigritella Rich.

They can be found in damp meadows, fens and marshes, and on chalk or limestone, often in alpine regions of Europe and Asia from Portugal to Kamchatka, including China, Japan, Mongolia, Siberia, the Himalayas, Iran, Ukraine, Germany, Scandinavia, Great Britain, etc.[1][2][3] The fragrant orchid (Gymnadenia conopsea) has been introduced into the USA and is reportedly naturalized in Connecticut.[4]

These hardy terrestrial orchids are deciduous. They survive the winter through their corms, two deep-cut tubers (more like tuberous roots). Long lanceolate green leaves grow at the bottom of the stem. There are some small leaves at the stop of the stem.

They flower during the summer. The inflorescence is a dense cylindrical spike between 5 and 30 cm long. It can consists of up to 150 small pleasant-smelling flowers. It is recently discovered that eugenol and isoeugenol, floral volatile scent compounds, are catalyzed by single type of enzyme in Gymnadenia species and gene encoding for this enzyme is first functionally characterized gene in this species so far.[5] Their color can vary from pale purple to pink and white. The lip is wide with three lobes. The marginal petals are horizontal. There is a long, thin, threadlike spur.

Several species were formerly classified under Nigritella. The nothogeneric name ×Gymnigritella was used for hybrids between these two groups.