The Oncidium Section Excavata

A Section containing nine species boothianum, buchtienii, excavatum, graciliforme, iricolor, klotzschianum, lepidum, obryzatum and platychilum. These plants are all distinguished by their conspicuous leaf bearing pseudobulbs. The sepals and petals are spreading, noticeably clawed or constricted at their bases. The lateral sepals are free to their bases, and are shorter than the lip. The petals are distinctly wider and more conspicuous than the sepals. 2 The disc of the lip bears an uneven number of tubercules. The rostellum is short.

Onc. obryzatum is a showy species of neat compact habit, and growing freely in the cool house. Its flowers are produced in great abundance in branched panicles, and are bright yellow barred with brown, yielding a delicious perfume.7 Mostly spring flowering, it is native of Costa Rica, Panama Colombia, Ecuador,. and Peru. Stevens, in his article on Colombian Oncidiums, 32 notes this species is easy to grow and flowers regularly. He reports this species in Colombia comes from the subtropic zone, and grows in wet forests, so it needs warm moist conditions all the year round, but drier in June, July and August. The sub-tropic habitat lies between 900 to 1,900 metres above sea level, with a mean temperature of 19 to 24 oC. This information does appear to be in conflict with some other temperature recommendations, perhaps confirming the considerable natural adaptability of many of the oncidium species.

The Section type species is excavatum, this plant having compressed pseudobulbs 75 to 125 mm long. The usually solitary leaf is about 600 mm tall, Handsomely paniculate in the form of a pyramid, many flowered. Each flower is about 35 mm in diameter, with very undulate. sepals, yellow with 2-3 red-brown bars on the basal half, the petals very undulate, longer than the sepals, entirely yellow or with 1-2 red-brown spots neat the base. The lip is a vivid canary yellow with red-brown small lateral lobes. Spring-early summer flowering, it is native of Ecuador and Peru.1 Williams7 indicates it is a robust growing species, appreciating cool growing conditions. It can bear over 1,000 flowers per spike, and has been cultivated since 1840.6 There are also a number of forms listed.

Oncidium excavatum

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