Oncidium Sw.
Tribe: Cymbidieae
Subtribe: Oncidiniiae
Etymology: From Greek = Onkos.
Olof Swartz, in 1800, gave this name due to the small callus situated at the base of the lip which seams to be a wart, tumor, swelling, in Greek, Onkos.

  It characteristic is the main callosity in the disc of the lip which has the shape of a corn (from rhinoceros). This section has three species and Brazil has O. macronyx and O. longicornu which are very similar and, as result, they are not easy to be separated. However, a more detailed investigation of the taxonomical aspects allows its differentiation. O. longicornu did a right angle between the lobes of the lip and the corn is long with a very sharp tip. O. macronyx does an acute angle between the lobes of the lip, the corn is round with obtuse tip. The third one is O. rhinoceros which does not occur in Brazil.

  O. enderianum appeared in a show in 19 century and "The Gardener's Chronicles" which besides to publish descriptions of species, did the chronicles of those show, recorded the event.
In general, each species is described by a botanist whose name is put just after the identification. For example, O. varicosum Lindley, O. warmingii Reichenbach and there are some which, instead of having the name of the botanist, it is written hort. from horticulture.
Some times, a botanist, when he has material to be pressed and do type, he can get one of those plants "hort" and describe as a species. In "The Gardner's Chronicle" is written O. enderianum hort. By this time, it was admitted that it could be a natural hybrid between O. curtum and O. crispum. That is all we know about it. It has not been described, there is no herbarium material, there are just three drawings where some pieces of the flower are missing. The species which is currently known as O. enderianum, is completely in disaccord with those drawings where the callus is divided into two parts.
The species of the section Crispa have been subdivided, by Pabst & Dungs, into two sub-sections (or alliances) according to the shape of the main callus. This division is very well done, I do not know if someone had done it before, I do not think so.
In some species, there is just one main callus, in O. crispum, in so called O. gravesianum, O. praetextum, O. marshallianum. There is another group in what the callosity is divided into two calli, there would be O. forbesii, O. enderianum, O. gardneri, O. curtum, O. imperatoris-maximiliani, O. zappii, O. pectorale.
Although he believes that O. enderianum really exists, Carlos Eduardo has never seen it, however he found O. rivierianum, and he used to think that it did not exist.

  O. pohlianum is a species that he most looked for and felt very disappointed. He never found it and never got it even from Baron Ghilany who apparently had.
  Examining O. pohlianum, in Brussels herbarium, described by Cogniaux, he could concluded based in what he saw, it is, in reality, O. harrisonianum, although the drawing in Orchidaceae Brasilienses is something completely different from this species. O. harrisonianum - Photo/Foto: Sergio Araujo

  O. praetextum. Foto/Photo: Sergio Araujo It is reported in Orchidaceae Brasilienses from the state of Rio Grande do Sul until Northeast.
According to the drawing of the description, in "The Gardener's Chronicle" that Carlos Eduardo had the occasion to examine, O. gravesianum has the petals turn down and this is the only one different characteristic.
Although he has many plants from different habitats, including coming from Pernambuco, he never found a flower with this petal. He imagine it could be a certain plant with a genetical imperfection. To corroborate with his theory, the callus is exactly the same of the species known as O. enderianum that he thinks is, in fact, O. praetextum. So, he believes that the three could be the same thing: O. praetextum, O. gravesianum and what is called O. enderianum.

  Besides O. mantini, there are other species considered as synonyms of O. pectorale, such as O. larkinianum and O. duveeni, described by Fowlie.
The observation of the material in Kew Gardens herbarium and the comparison with alive flowers of O. duveeni made Carlos Eduardo admits the identity between this species and O. mantini.
To him, two species are valid: O. mantini and O. pectorale.
. larkinianum and O. duveeni would by synonyms.


O. varicosun - Arquivo/Archive - Carlos Eduardo

O. varicosum - desenho de Hoenner

O. euxanthinum - Arquivo/Archive - Carlos Eduardo

O. varicosum Lindl.
O. varicosum var. rogersii
O. euxanthinum Rhcb. f.
  The descriptions found in Flora Braziliensis by Martius evidence some so relevant differences that provoked in him a suspicion that there were two different species. Researching in Kew herbariums and the Natural History Museum of Vienna, he had the occasion of clarifying this doubt.
The plant which is the type of A O. varicosum, described by Lindley has been collected in Serra de Mar (maybe it occurred by this time) and is the same species which occurs in Goiás, in Chapada dos Veadeiros.
It has been described in l842, it means it should be collected before it.
Times later Reichenbach f. described O. euxanthinum which is, in fact, the species which every body calls O. varicosum var. rogersii. It grows in the interior of São Paulo, in the south of Minas and occurred in Carandaí, Barbacena.
This species has the callus and the lateral lobes different from O. varicosum described by Lindley.
. varicosum var. rogersii, also called O. rogersii appeared in a show, in l868, and is hort. it has never been described, there is no herbarium's material. It has been referred to in "The Gardner's Chronicles". In Reichenbach's herbarium, there are separated exsiccataes of O. varicosum and O. euxanthinum although there are many other exsiccataes, besides the type. In Kew, in the general herbarium (not Lindley's which is separated), the material concerning O. varicosum and O. euxanthinum is mixed but in Flora Braziliensis, in 1906, there are two species.
To him, O. varicosum var. rogersii is O. euxanthinum, it means, we would have two different species. O. varicosum with small and rounded lateral lobes of the lip and the callus composing by two series of three teeth surrounded by small warts.
To see better the

difference between

them, see a drawing

of the details by

Cristina Miranda.
  By the rules of nomenclature, the first name prevailed over others, so theoretically O. rogersii should prevail over O. euxanthinum but there is no description, no material pressed, so O. euxanthinum should be considered as the valid name, not O. rogersii.
In principle, the habitat do O. varicosum would be Chapada dos Veadeiros but no one can affirm that there is not any plant in Serra do Mar, in São Paulo, where the plant-type has been collected.
. euxanthinum would be from São Paulo and Minas Gerais.

  Pabst & Dungs considered O. ottonis as synonym of O. concolor, some researchers considered as two different species. Hoehne in the "Iconografia de Orquidáceas brasileiras" said that the flowers of O. ottonis would be bigger and more numerous and its petals and sepals would have longitudinal veins. Karlheinz Senghas has also considered it in the same way.
  Carlos Eduardo considered that although they have the same vegetative habit, similar flower and the same habitat, there are some substantive differences between them the shape of the flowers, the presence of red brownish veins in the petals and sepals and the existence of an accessory callus situated alongside of every two keels of the disc of the lip.
Independently of the color, this difference would be enough to consider them as two independent species. The callus of the O. concolor is like two veins, in O. ottonis there two bars alongside.
In general, the skilled people who work in the nurseries, say that the outside part of the sepals in O. ottonis has red spots.
Carlos Eduardo does not consider the difference of color so determinant but, to him, the species is valid because of the difference of the callosity, which is very characteristic.
The differentiation of many species is done by the difference in the callosity.

O. barbatum - Arquivo/Archive - Carlos Eduardo
O. ciliatum - Arquivo/Archive - Carlos Eduardo
They are completely different however the biggest difference is in the lobes.
O. barbatum
has bigger lateral lobes and the terminal lobe is very small.
. ciliatum has the lobes with the same size.