61. Diplandrorchis S. C. Chen, Acta Phytotax. Sin. 17(1): 2. 1979.
双蕊兰属 shuang rui lan shu
Authors: Xinqi Chen, Phillip J. Cribb & Stephan W. Gale
Herbs, small, heteromycotrophic, with stout, short rhizomes and tufted fleshy roots, without green leaves. Inflorescence erect, terminal, racemose; peduncle with several sheaths; sheaths tubular in lower half of peduncle, becoming bractlike above; rachis densely many flowered; floral bracts membranous. Flowers erect, not resupinate, actinomorphic; pedicel rather long, slender, not twisted; ovary ellipsoid, not twisted. Perianth composed of 3 similar sepals and 3 similar petals, without a modified lip. Column erect, cylindric, with 2 fertile stamens at apex; stamens similar, erect, borne opposite dorsal sepal and central petal (lip) respectively; anthers 2-locular, each with an extremely short filament; pollinia 2, granular-farinaceous, without caudicle; stigma terminal, oblate; rostellum absent.
● One species: China.
For a detailed discussion on this genus and the allied Holopogon, see Chen and Tsi (Acta Phytotax. Sin. 25: 329-339. 1987).
Two of us (Cribb and Gale) consider Diplandrorchis to be a peloric form of Neottia. Our understanding of the genetic control of organ development in orchids can be used to explain how zygomorphic flowers may become "regular" (i.e., actinomorphic) and how floral organs can take on different forms, as when the lip becomes petaloid or a staminode develops as an anther. For further discussion on the occurrence of actinomorphy in the Orchidaceae and other monocot groups with zygomorphic flowers, see Rudall and Bateman (New Phytol. 162: 25-44. 2004).