considered as one of the biggest orchid genera and some authors indicated
750 species and some situated it at about 600. Due to the studies realized,
part of sections of the genus has been elevated to generic rank under
different nomenclature, so nowadays, the number of species has decreased.
Senghas informs (in a revision of Die Orchideen by Rudolf Sclechter, which
was published in Schlecher, Die Orchideen, 3rd. edition, l997)
that until now, 910 species have been described under the name Oncidium.
He could certified, by his revision, the existence of 315 species, around
them turn nothing less than 222 synonyms and the rest of 373 names are,
nowadays, located in independent genera.
However Brazil, with aproximately 100 species, is still considered as
the center of geographic distribution.
publication are very important to understand this genus and the new genera
of Subtribus Oncidiniae:
1) "Orchidaceae Brasiliensis (vol. II)", by Pabst and Dungs,
2) "Synopsis of the Genus Oncidium", by Leslie A. Garay
and John E. Stacy, published in Brazil, in Bradea, vol I, nº40, l974
3) the recent studies by Karlheinz Senghas, above.
genus occurs in central and tropical America, from Florida to Argentina,
however the most past of species occurs in Brazil, Colombia (Andes region),
Ecuador and Peru. The species occur from the sea level to high altitudes
(4.000m elevation). Some species require a dry climate and some others
which come from Atlantic Forrest need a humid environment.
grows on the tree, rocks or as terrestrial but there are epiphytic species
found growing as terrestrial or rupiculous and vice-versa. It is very
difficult to separate rupiculous and terrestrial species.
inflorescence arises every year from a new shoot and produces from one
to more than hundreds flowers depending on the species. It appears from
the base of the pseudobulbs or from the axils of the leaves.