Brassia is a genus of orchids classified in the Oncidiinae subtribe. Its abbreviation in the horticultural trade is Brs.
This epiphytic genus occurs in South Florida USA, the West-Indies and tropical America, in wet forests from sea level to altitudes under 1500 m, with the Peruvian Andes as its center. Occurrence is mostly restricted to a certain area, but Brassia caudata can be found over the whole geographic area.
Brassia species and its popular hybrids are common in cultivation, and are notable for the characteristic long and spreading tepals (in some clones longer than 50 cm), which lend them the common name "spider orchid".
They have large elliptic-oblong pseudobulbs with one or two leaves at the apex, lateral, unbranched many-flowered inflorescences with small floral bracts. The lip is not attached to the column. The pollinarium shows a narrow stipe. There are two distichous, foliaceous sheaths around the base, from which the inflorescence emerges.
Brassia has a very specific method for pollination : it uses entomophily : pollination by insects and in this case specifically by female spider-hunter wasps of the genera Pepsis and Campsomeris. Mistaken by the mimicry of Brassia, the wasp stings the lip, while trying to grasp its prey without any success. By these movements the wasp comes into contact with the pollinarium, that then sticks to its head. By flying to another Brassia flower, this flower gets pollinated.
Grow in cool conditions with moderate light. Water the plant right before the potting mix starts to dry. Plants should be potted in a well drain medium such as medium fir bark.
The genus was named after William Brass, a British botanist and illustrator, who collected plants in Africa under the supervision of Sir Joseph Banks.
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