The species of the genus Cyrtorchis are epiphytic or lithophytic herbs,[3] which do not have pseudobulbs.[4] The white, fragrant, star-shaped flowers are distinctly spurred.[2]
Cytology
The diploid chromosome count of Cyrtorchis arcuata is 2n = 46.[5]
Physiology
Cyrtorchis is known to utilize the crassulacean acid metabolism,[5] which entails photosynthesis during the daytime, and gaseous exchange through open stomata during the night. This enables the plant to save water.[6]
Etymology
The generic name Cyrtorchis is composed of the Greek words "kirtos" meaning curved and "orchis" meaning testicles, which refers to orchids.[7]
The genus has been divided into the sections Cyrtorchis section Homocolleticon Summerh. and Cyrtorchis section Cyrtorchis based on differences in the shape of the viscidium.[2] Originally the section Cyrtorchis was published as section Heterocolleticon Summerh., but it is now known as Cyrtorchis section Cyrtorchis.[9][10] The section Homocolleticon is characterized by an uniformly textured viscidium,[11] in contrast to the viscidium of section Cyrtorchis, which consists of two distinct zones.[12]
The section Homocolleticon Summerh. was elevated to a genus by Szlach. & Olszewski in 2001, but Homocolleticon (Summerh.) Szlach. & Olszewski is now a synonym of Cyrtorchis Schltr.[1][9]
Species
As of December 2022, there are 19 currently accepted species:[1]
Cyrtorchis cufodontii Chiov. is now considered to be a synonym of Ypsilopus amaniensis (Kraenzl.) D'haijère & Stévart[13]
Cyrtorchis refracta (Kraenzl.) Schltr. is now considered to be a synonym of Ancistrorhynchus refractus (Kraenzl.) Summerh.[14]
Ecology
Habitat
It grows in dense forests and rainforests, as well as in plantations. It is found growing on tree trunks and branches, which receive high levels of sunlight.[15] In addition to epiphytic growth, it can also grow as a lithophyte attached to rocks.[3]
Pollination
Several hawk moth species of the genus Hippotion have been identified as likely pollinators of Cyrtorchis okuensis.[16]
The white flowers shift to an orange pollination[2][3] after pollination or senescence. Such post-pollination behaviour is not uncommon, and it may be explained by a reduced attractivity of flowers to pollinators,[7][17][18][19] if the flowers are no longer viable.
Young, viable Cyrtorchis arcuata inflorescence without discolouration
Older Cyrtorchis arcuata inflorescence exhibiting senescence and discolouration of older, non-viable flowers
^Foden, W. & Potter, L. 2005. Cyrtorchis arcuata (Lindl.) Schltr. subsp. arcuata. National Assessment: Red List of South African Plants version 2020.1. Accessed on 2022/12/26
^Rokni, S., Matimele, H.A., Alves, M.T., Chelene, I., Darbyshire, I., Datizua, C., De Sousa, C., Langa, C., Massingue, A.O., Mucaleque, P.A., Odorico, D., Osborne, J., Rulkens, A.J.H., Timberlake, J. & Viegas, A. 2018. Cyrtorchis glaucifolia. The IUCN Red List of Threatened Species 2018: e.T120961124A120980358. https://dx.doi.org/10.2305/IUCN.UK.2018-2.RLTS.T120961124A120980358.en. Accessed on 26 December 2022.