Neottia ovata (eggleaf twayblade<ref>Template:PLANTS</ref> or Common Twayblade) is a terrestrial orchid widespread across much of Europe, including the British Isles, as well as Siberia, Central Asia, Southwest Asia and the Himalayas.<ref name=WCSP/> It has been introduced into Ontario, Canada, where it has been called the Eggleaf Twayblade.<ref name=USDA>Template:Citation (as Listera ovata)</ref> It was formerly placed in the genus Listera, but molecular phylogenetic studies have shown that Neottia nidus-avis, the Bird's-nest Orchid, evolved within the same group,<ref name=Stac10>Template:Citation, p. 864</ref> and the two genera have been combined.
Neottia ovata grows in a variety of habitats: woods, meadows, dune-slacks and moorland. The flowering stems are typically Template:Convert tall, occasionally up to Template:Convert. There are two large opposite basal leaves (hence the common name), Template:Convert long. A variable number of flowers is borne on the stems, usually more than 15 but less than 100. The flowers are small and yellowish-green in colour. The sepals and the two side petals form a fairly open hood, 5–6 mm (0.2 in) long; the labellum or lip (the central petal) is Template:Convert long and is divided at the end into two lobes.<ref name=Stac10/>
The flower of Neottia ovata is well accessible for a wide range of insects. It is above all pollinated by parasitic wasps, sawflies and beetles. The pollinia lie free on top of the gutter-shaped rostellum, an organ that is filled with viscid fluid. When an insect touches the sensitive tip of the rostellum, the viscid fluid is ejected and glues the pollinia to the visitor's body. Fruit set is quite high.
Over 60 species of mycorrhizal fungi have been indicated to form associations with N. ovata.<ref>Molecular Ecology - Mycorrhizal diversity, seed germination and long-term changes in population size across nine populations of the terrestrial orchid Neottia ovata</ref>
Neottia ovata is one of the most common European orchid species, and this is partially explained by it being less species-selective both in terms of pollinators and mycorrhizal partners. It is also an inconspicuous species, blending in to vegetation, which saves it from being picked by humans, a fate endangering many of the showier orchid species. Despite its success, there is evidence that populations are declining.<ref>Molecular Ecology - Mycorrhizal diversity, seed germination and long-term changes in population size across nine populations of the terrestrial orchid Neottia ovata</ref>
- CLAESSENS, J. & J. KLEYNEN : The flower of the European Orchid – Form and function, 2011, Template:ISBN.