Classification of Orchid Genera 5
This is part five a compilation of five instalments that first appeared in the Nambour Orchid Society newsletter between June and October 2021.
Still within the tribe Epidendreae, we have the subtribe Pleurothallidinae, a very large group with 35 genera and 4571 species, few of which are represented in the collections of our members. Genera are distributed across Neotropical America but the centre of diversity is the Andean regions of Colombia, Ecuador and Peru. I shall limit commentary to genera and species seen in local collections as many of the high altitude species are not amenable to cultivation in our subtropical lowland environment.
Masdevallia amabilis
(photo by C. McMonagle)
Masdevallia, with 589 species is one of the more popular genera. A characteristic is that sepals generally dominate with petals almost insignificant. It is not uncommon for sepals to be fused. Masdevallia amabilis, left, is an example.
Dracula with 127 species is closely related to Masdevallia and occurs in similar areas.
There are 1085 species of Lepanthes distributed across Central and the northern parts of South America, often inhabiting cloud forests. Lepanthes generally have tiny flowers which don’t appeal to hobby growers but Lepantes tsubotae, below, is an exception.
Stelis is another large and varied genus (879 species) within this subtribe. Characterised by large numbers of small flowers, specimen plants are quite attractive. Stelis papaquerensis, below right, received AOC culture and quality awards in 2019.
Lepantes tsubotae Stelis papaquerensis
(photo by C. McMonagle) (photo by C. McMonagle)
Pleurothallis is another large genus with 551 species and probably a lot more yet to be described. They are distributed across Neotropical America from lowlands to high altitude cloud forests. Most species have tiny flowers, perhaps a reason why they are not often cultivated, except some of the species growers have focussed on them in recent years. Pleurothallis gargantua, below, is one of the larger flowered species.
Restrepia (53 species) is a related genus, found mainly in the Andean cloud forests of Bolivia and Ecuador. Most species have small flowers but Restrepia brachypus, below, is popular with species growers.
Octomeria, Platystele, Specklinia and Zootrophion are other genera that we occasionally see on the show bench.
Pleurothallis gargantua Restrepia brachypus Mediocalcar decoratum Phaius tankerviliieae
(photo by C. McMonagle) (photo by C. McMonagle) (photo by W. Harris) (photo by C. McMonagle)
The tribe Collabieae (no subtribes) contains 20 genera and 552 species that are usually regarded as terrestrial. Calanthe, Phaius and Spathoglottis are common in cultivation. They are distributed across S.E. Asia and into Australia. Calanthe is the most diverse with 216 species. Phaius tankerviliieae, left, is one of 6 accepted varieties of this species.
Broomheadia pulchra
(photo by W. Harris)
Podochileae is another relatively small tribe (no subtribes) containing 27 genera and 1292 species. Appendicula (146 species, one of which occurs in NE Queensland), Eria (237 species), Mediocalcar (17 species), Podochilus (62 species) and Pseuderia (20 species) are the most popular genera in cultivation. Mediocalcar decoratum, above, is an example.
Polystachya galeata
(photo by W. Harris)
The final tribe in the subfamily Epidendroideae is Vandeae. There are 4 subtribes, Adrorhizinae, Polystachyinae, Aeridinae and Angraecinae. The first two are quite small having 3 and 2 genera respectively. The dominant genus in Adrorhizinae is Broomheadia with 30 species, one of which, Broomheadia pulchra, right, occurs in north Queensland.
In the subtribe Polystachyinae, the genus Polystachya dominates with 234 species, distributed primarily across Africa and Madagascar, with a few species in Neotropical America and South-east Asia. Polystachya galeata, left, is one of the more popular species in cultivation.
Sarcochilus fitzgeraldii
(photo by W. Harris)
The subtribe Aeridinae comprises 83 genera and 1314 species, distributed across Asia, Malesia and Australia, with a few species in South-east Africa and Madagascar. The major change to this subtribe in GO Vol 6 was the transfer of the genus Ascocentrum into Vanda. Around 30 of the 83 genera are cultivated. Taeniophyllum (185 sp.) and Thrixspermum (161 sp.) are the largest genera numerically but are not popular, due no doubt to the small flowers. Cleisostoma comes next, followed by Vanda with 73 Species and Phalaenopsis with 70. Phalaenopsis dominate the world potted flower market with annual sales of 120 million through Holland alone. Sarcochilus (25 species) is the principal Australian native in this subtribe. Sarcochilus fitzgeraldii, right, has been widely used in hybridising.
Other genera in cultivation include Acampe (8sp.), Aerides (25 sp.), Amesiella (3 sp.), Arachnis (14 sp.), Gastrochilus (56 sp.), Holcoglossum (14 sp.), Luisia (39 sp.), Micropera (21 sp.) Papilionanthe (11 sp.), Paraphalaenopsis (4 sp.), Pelatantheria (8 sp.), Plectorrhiza (3 sp.), Renanthera (20 sp.) Rhinerrhiza (1 sp.), Rhynchostylis (3 sp.), Robiquetia (45 sp.) Saccolabium (5 sp.), Schoenorchis (25 sp.), Seidenfadenia (1 sp.), Trichoglottis (69 sp.) and Vandopsis (4 sp.). Micropera rostrata, below, received quality and culture awards last year. While, Pelatantheria insectifera, below right, is an example of the small but colourful flowers to be found in this subtribe.
Micropera rostrata Aerangis biloba. Angraecum leonis. Podangis dactyloceras
(photo by C. McMonagle) (photo by C. McMonagle) (photo by W. Harris) (photo by W. Harris)
The subtribe Angraecinae contains 47 genera and 753 species. Most genera are distributed across sub-Saharan Africa and Madagascar but two genera, Camplyocentrum and Dendrophylax, are found in Neotropical America. Flowers on most species are characterised by elongated spurs on the labellum.
Pelatantheria insectifera
(photo by C. McMonagle)
Angraecum with 221 species, grouped into 19 Sections, is the largest genus. Angraecum leonis, above, is illustrated.
Aerangis (58 sp.) is another popular genus having generally smaller flowers than Angraecums, usually on pendulous inflorescences. Aerangis biloba, below, is a locally grown plant. Aeranthes (43 sp.), Jumellea (59 sp.) and Podangis (1 sp.) are also seen in local collections. Flowers on the Podangis dactyloceras, above, are almost transparent.
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