The Oncidium Section HETERANTHA
24 species are included in this Section, which contains plants characterised by their conspicuous leaf bearing clustered or close together pseudobulbs. The sepals and petals are spreading, rarely bent back. The column is smooth, cuned like an "S" with an elongate proboscis-like rostellum. Normally developed flowers, which are produced in succession, are intermixed with aborted, star-shaped ones, consisting only of the linear segments.2
The species -are abortivum, acinaccum, brevilabrum, bryocladium, calanthum, cuencanum, cultratum, cycnicolle, dactylopterum, formosissimum, heteranthum, ionopterum, jamiesoni, lepturum, lucasianum, orbatum, ornithocephalum, orthotis, pentadactylon, retusum, rostrans, semele, virgulatum and weddellii.2
Williams describes7 acinaccum as being distinct and elegant, producing 25 mm flowers having white sepals, large violet petals with a white border, the lip of the same colour, shaded carmine. Spikes are 300 to 600 mm long. Calanthum has light yellow sepals and petals and a lip broad and coloured deep yellow, the crest and column stained red. The spike is long and many flowered. This is described as pretty and free flowering. Onc. rostrans is brightly coloured with flowers in dense clusters. Oncidium heteranthum is interesting as the illustration indicates, with aborted and entire flowers intermixed on the same spike, on small plants.6
The habitats are listed as Colombia, Peru, Venezuela, Ecuador and Brazil. Cool to intermediate conditions are indicated. The descriptions available indicate that there could be some interesting plants from this Section. Little specific information is available on these plants.
Remember, growing orchids is all
about enjoying your plants
Good luck and good growing.
Site established 9th May 1998
Oncidium series first uploaded 20 October 1999