The Oncidium Section Rostrata

This Section contains some 27 species.2 Most are unknown in local collections, although two, cheirophorum and ornithorhynchum, are frequently seen. Both these plants are compact growers and put on an attractive and colourful display. The plants are distinguished by their conspicuous pseudobulbs, which may be either close together or clustered. The flowers have their sepals and petals generally spreading, only rarely bent back. The column is smooth, curved in an "S" shape, bearing an elongate proboscis like rostellum. The type species for this Section is the popular ornithorhynchum.2 Because of their compact size and generally free flowering characteristics, the available forms make ideal additions to any collection.

THE SPECIES

Garay and Stacy 2 include the following species in this Section: alcicorne, angustisepalum, braunii, cheirophorum, chrysornis, cristatellum, dactyliferum, deltoideum, elephantotis, examinans, hapalotyle, hartwegii, hebraicum, lancifolium, luteum, magdalenae, melanops, miserrimum, ornithorhynchum, ototmeton, pictum, pyramidale, scalerophyllum, tipuloides, trulliferum, xanthocentron and xanthornis.

They are natives of Central and South America (Colombia, Peru and Ecuador).6

The two species locally familiar are:-


One. cheirophorum is a pretty dwarf growing plant producing flowers, which though not of large size, should secure its admission to any collection because of its free blooming properties and its delightful fragrance. 7 It has tightly clustered pseudobulbs, oval in shape, compressed, to 35 mm long, 25 mm wide, becoming wrinkled with age. There is usually a solitary leaf which is rather thin textured 50 to 150 mm long. There are usually 1 - 2 inflorescences per growth, which may be erect or arching, slender in nature. It is usually densely branched, to 300 mm long. There are numerous vivid yellow fragrant flowers, each usually less than 40 mm in diameter. Mostly autumn to winter flowering, it is native of Nicaragua, Costa Rica, Panama and Colombia, coming mostly from the highlands in those countries.1 It has been cultivated since 1848. 6


One. ornithorhynchum has been in European cultivation since 1826.6 It is a pretty and free flowering species,7 having clustered rather pale greyish green pseudobulbs, oval, slightly compressed, to 125 mm long, usually smaller. The plant roots very copiously There are two rather thin textured leaves, to 300 mm long, almost 50 mm broad. There are often more than two inflorescences per growth, which are arching or pendulous, forming a densely many flowered panicle to 600 mm long. Each flower is some 20 mm long, highly fragrant, long lived rose-ae in colour. It is mostly autumn-winter flowering, and is native of Mexico, Guatemala, El Salvador, and Costa Rica.1 This is said to be a useful plant for cut flowers.7


One. ornithorhynchum

CULTURE

The species are listed6 as requiring either cool or intermediate conditions. Williams 7 for cheirophorum, advises odontoglossum conditions. As many come from the higher habitats, subjected to misty rains, a constant supply of water is required although the roots of the plants must never be subjected to stale media conditions. Stevens 32 advises that cheirophorum grows in the lower montane regions in wet forest areas; this confirming a moist growing environment, and that perhaps it may appreciate some heat, although Adnam 33 states that in his experience "some heat may be required, although we have always grown the plant cool". This author also advises ornithorhynchum is a plant easy to grow.

Like most oncidiums, reasonably good light must be provided, especially for cheirophorum, although ornithorhynchum with its "softer" pseudobulbs may appreciate more shade.

The opportunity to acquire members of this Section, and especially the two species described, should not be passed up. They provide an attractive and long lasting display, and have the advantage of not taking up too much space where this is at a premium.

Remember, growing orchids is all about enjoying your plants
and sharing your growing success with friends and family.

Good luck and good growing.

   
   


 


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 Site established 9th May 1998
Oncidium series first uploaded 20 October 1999