Classification of Orchid Genera 3

This is part three of a compilation of five instalments that first appeared in the Nambour Orchid Society newsletter between June and October 2021.

Acriopsis emerginata
(photo by J. Varigos)

There are 10 subtribes in Tribe Cymbidieae, eight of them containing multiple genera of horticultural interest. A feature  common to many species in this tribe is that they have pseudobulbs which stand above the strata on which they grow.  The Australian native Cymbidium suave is an exception in which the pseudobulb is elongated to a thin stem.  

Subtribe Cymbidiinae contains the genera Acriopsis (ni species),  Cymbidium (71 species) and Grammatophyllum (12 species). Acriopsis occurs through India, South East Asia and south west Pacific Islands. The species Acriopsis emerginata, right, is endemic to Cape York. 

Subtribe Eulophiinae contains Ansellia (1 species), Dipodium (25 species), Eulophia (200 species) and Geodorum (12 species). Ansellia africana, pictured left, the single species in the genus, is popular in cultivation. Native to Africa, as the name suggests, it  can grow into large specimens, some reported to weigh over a tonne.  

Ansellia africana
(photo by W. Harris)

Cym. canaliculatum fma.sparkesii
(photo by W. Harris)

The genus Cymbidium is widely distributed across tropical and sub-tropical Asia, Malesia and extending into Australia where there are three endemic species, canaliculatum, suave and madidum. Plants have been cultivated horticulturally for 2200 years and the flowers of the more showy hybrids have been popular in the Florist trade for the past century. The exhibition types grow better in cooler climates so they do better in the southern states where they have been the most popular orchids in cultivation. Cym. canaliculatum fma.sparkesii is illustrated left. 

Grammatophyllums also grow into very large plants, arguably the largest in the family Orchidaceae, and the flowers are long lasting, up to nine months. They occur in SE Asia through Malesia to the SW Pacific Islands.

The subtribe Catasetinae contains the popular genera Catasetum (176 species), Clowesia (7 species), Cycnoches (34 species) and Mormodes (80 species), all of which have been extensively interbred in cultivation. Cycnodes Taiwan Gold, pictured below, is an example of an intergeneric hybrid.  

Galeandra (38 species) is another genus in this subtribe. All genera are endemic to Neotropical  America. The subtribe Cyrtopodiinae contains only one genus, Cyrtopodium, with 47 species, native to North, Central and South America. Cyrtopodium punctatum, below, (Wayne Harris photo), is one of the more popular species in cultivation. 

The subtribe Coeliopsidinae contains 3 genera, one of which is Peristeria with 13 species, and  one of these is popular in cultivation. It is Peristeria elata, the national flower of Panama, known locally as flor del Espiritu Santo because of its dove-shaped flower, pictured below, (photo by Wayne Harris). 'The subtribe Maxillariinae contains 12 genera, 4 of which are common in hobby collections.  They are Anguloa (9 species), Bifrenaria (21 species), Lycaste (32 species) and Maxillaria (658 species). Lycaste virginalis, below, (photo by author), often labelled as its synonym Lycaste skinneri, is the most popular species, featuring in the parentage of 871 hybrids. Maxillaria is a large and complex genus which posed many difficulties for taxonomists working on the GO project. It is possible that there will be some changes to species as scientists make progress on resolving these. 

Lycaste virginalis Peristeria elata Cyrtopodium punctatum Cycnodes Taiwan Gold
(photo by C. McMonagle) (photo by W. Harris) (photo by W. Harris) (photo by W. Harris)

Oncidium alexandrae
(photo by C. McMonagle)

The subtribe Oncidiinae is very large, containing 69 genera and 1596 species. The big change in the new classification was the elimination of Odontoglossum, its species being distributed across 16 genera but most going into Oncidium or Rhynchostele. Eleven years after publication of Volume 5 of Genera Orchidacearum, there is still a number of botanists, aided and abetted by disgruntled growers, arguing for the reinstatement of Odontoglossum as a genus. There were many other transfers of species between genera, including a number of popular Oncidiums which moved to Gomesa. In some cases, species names had to change because of names already used in existing genera. An example is Odontoglossum crispum which became Oncidium alexandrae, pictured right.

Brassia verrucosa Telipogon hausmannianum
(photo by C. McMonagle) (photo by C. McMonagle)

Miltoniopsis Breathless

The genus Oncidium, with 520 species, is the largest in the subtribe, occurring across Neotropical America with centres of diversity in Mexico and the Andes. The transferred Odontoglossums are amongst the most popular species. The genus Telipogon is the next most numerous with 205 species but I am yet to see one locally. Some species are quite striking with Telipogon hausmannianum, left) one of the most attractive. The genus Brassia (64 species) is popular in cultivation. Noted for its spidery flowers, it is widely used as a parent in hybrids and intergeneric hybrids. Brassia verrucosa, above left, can be grown into a striking specimen. Other genera in this subtribe include Aspasia (7 species), Comparettia (78 sp.), Cuitlauzina (7 sp.), Gomesa (19 sp.), Ionopsis (6 sp.), Leochilus (12 sp.), Lochartia (28 sp.) Miltonia (12 sp.), Miltoniopsis (5 sp.), Otoglossum (13 sp.), Psychopsis (4 sp.), Rhynchostele (17 sp.), Rodriguezia 48 sp.), Rossioglossum (9 sp.), Tolumnia (27 sp.), Trichocentrum (70 sp.) and Zelenkoa (1 sp.). Miltoniopsis, which occurs in Central and parts of South America (but not Brazil), was transferred out of Miltonia in GO Vol 5. Known as Pansy Orchids, they are very showy, Miltoniopsis Breathless, right, being one of the most popular hybrids.

Stanhopea tigrina
(photo by C. McMonagle)

The subtribe Stanhopeinae contains 20 genera but only two, Stanhopea (61 sp.) and Gongora (74 sp.) are generally found in hobby collections. Stanhopea are popular for their showy flowers which are carried on an inflorescence which usually emerges from the bottom of the pot but they rarely last more than three days. Stanhopea tigrina, left, is an example.

The subtribe Zygopetalinae contains 36 genera and 437 species but few are cultivated. RBG Kew lists 165 described names for species of Zygopetalum but only 14 of these are accepted, the remainder being synonyms. Zygopetalum maculatum, often labelled mackayi, is pictured below. Aganisia (4 species), Galeottia (12 species) and Huntleya (14 species) are other genera of this subtribe that are cultivated by species enthusiasts. Huntleya meleagris, also below, was tabled at a Nambour OS Species Group meeting in January 2021.

Explanatory notes: The term Malesia  defines a botanical region comprising the Malayan Peninsula, The Philippines, Indonesia, New Guinea and South-west Pacific Islands. While the term Neotropical America covers Central and South America, including Caribbean Islands but excluding Argentina and southern Chile.

Literature cited

Chase M. W., Cameron K. M., Freudenstein J. V., Pridgeon A. M., Salazar G., Van Den Berg C. and Schuiteman A., An updated classification of Orchidaceae, Botanical Journal of the Linnean Society, 177, 2015 151-174.

Pridgeon A. M., Cribb P. J., Chase M. W. and Rasmussen, F. N., Genera Orchidacearum, Vol 1 1999, Vol 2 2001, Vol 3 2003, Vol 4 2006, Vol 5 2010, Vol 6 2014, Oxford University Press.

Author: Charlie