No orchid-spotting trip is complete without finding one Disperis, writes Gerrit van Ede.
Close-ups of D. cardiophora (top) and D. renibractea (bottom) (Photographs: Gerrit van Ede)
There is one genus that looks so different from a traditional orchid that most people will not recognise it as an orchid: genus Disperis. For those of us that love the different orchid species this genus is a fascinating group of plants. To me an orchid spotting trip is not complete without finding at least one Disperis.
The name Disperis is derived from the spurs or pouches on the lateral sepals; derived from the Latin dis or double and pera or pouch. Spurs or nectar tubes are common in orchids and a single spur normally forms part of the labellum or lip. In some cases, a double spur occurs as it does in the genus Satyrium; sometimes the spur occurs on the dorsal sepal—in most cases then called a hood—as in the genus Disa. The Disperis species may have a spur on the dorsal or median sepal (hood), but all of them have a spur or pouch on the lateral sepals.
One of the characteristics of Disperis that always prompts a lot of discussion is the small size of the leaves in relation to the number and size of the flowers. This may be an indication that these species rely heavily on their symbiotic relationship with root fungi (mycorrhiza).
At Verloren Valei we have recorded seven species so far. They all tend to be fairly difficult to find. My two favourites, D. cardiophora and D. renibractea, each have their preferred locations but do look very similar. Both have a small single basal leaf, with that of D. renibractea normally a bit larger and oval or egg shaped, while D. cardiophora more round. Both have flowers that are normally arranged facing in one direction (one-sided) on a flowering stem that can be up to 230mm high. Colour in both cases is variable.
There are several ways to tell these two species of Disperis apart. D. renibractea can be identified by its kidney-shaped flower bracts (reni derives from the Latin for kidney, as in renal). But the easiest way to distinguish between these two is to look at the flowers: D. cardiophora has a “closed flower”, meaning that the petals obscure the inside of the hood, while D. renibractea has an “open” flower, allowing the inside of the hood to be seen. The photos clearly illustrate this closed and open aspect of the species.
In addition, D. renibractea also has larger flowers than D. cardiophora.
Other characteristics
D. renibractea normally grows in damper grassland than D. cardiophora. One would therefore find this species near streams and moist areas, with two or three plants often found in the same small area. By contrast, D. cardiophora prefers open grassland, frequently making small colonies—one colony numbered 30 plants.
Hubert Kurzweil and John C. Manning produced a synopsis of the Disperis genus in 2004[1]. At that stage, they recognised 74 species in the genus. Currently, the genus consists of 78 species with 77 occurring in Africa and Madagascar and one species in Asia. In South Africa 26 species occur. The synopsis indicate that the genus can be divided in two sub-genera, Dryorkis and Disperis. The species in the Dryorkis sub-genus have lip appendages that are deeply divided in two (bilobed lip appendage) while the lip appendage in the Disperis subgenus is entire. The species in the sub-genus Dryorkis number about 44 and occur mainly in the tropical and subtropical areas of Africa and the islands, with a few occurring in South Africa. The Disperis sub-genus occurs mainly in Southern Africa and compromises about 30 species.
[1] Hubert Kurzweil and John C. Manning, “A synopsis of the genus Disperis Sw. (Orchidaceae)”, Adansonia 3 (2005) 27 (2) : 155-207, available at http://sciencepress.mnhn.fr/sites/default/files/articles/pdf/a2005n2a2.pdf.
