Shizhenia

Shizhenia grows from a ovoid shaped tuber. It has a single stem leaf, situated near the base of the stem. The inflorescence consists of a single relatively large flower, rose-red to purple in colour, with a three-lobed lip (labellum). The upper sepal and the lateral petals are grouped to form a hood. The flower has a conical spur, longer than the lip. There are two stigmas that extend under the short rostellum.[2]

The species was first described in 1878 as Gymnadenia pinguicula. It was later transferred again to Habenaria and then Amitostigma.[1] A molecular phylogenetic study in 2014, found that species of Amitostigma, Neottianthe and Ponerorchis were mixed together in a single clade, making none of the three genera monophyletic as then circumscribed. Amitostigma and Neottianthe were subsumed into Ponerorchis, with Amitostigma pinguicula becoming Ponerorchis pinguicula.[3] Later studies suggested that Ponerorchis pinguicula lay outside the main clade consisting of Hemipilia, Ponerorchis, Sirindhornia, and Tsaiorchis, and a new genus, Shizhenia, was created for it.[2][4] After some adjustment of the generic boundaries, the five genera were related as shown in the following cladogram. All are placed in subtribe Orchidinae, tribe Orchideae, subfamily Orchidoideae.[4]