There are two additional species that are normally classified as Bifrenaria, but which molecular analysis indicate to belong to different orchid groups entirely.

[6] Bifrenaria flowers are strongly scented, they have sepals slightly larger than the petals, with the lateral ones basally united to the column foot forming a calcar with truncated extremity.

Flowers show two elongated stipes, hardy ever one, at least twice longer than wide, with salient viscidium, visible caudicles and retinacle[check spelling] in inverted positions.

[7] Fruits are green, erect or pendulous; they take about eight months to ripe and hold hundreds of thousand yellowish or brownish elongated seeds up to 0.35 mm long.

Apparently the only existing records report the presence of some large species' pollinia observed on the back of male Eufriesea violacea bees (Euglossinae),[10] and of Bombus brasiliensis (Bombini).

[11] Although there are no reports of flower pollination being directly observed, a paper published in 2006 studied the micromorphology of the labellum in Bifrenaria species, looking for substances useful to insects as food.

[12] The absence of such substances on the densely pubescent surface of most Bifrenaria labelli seems to indicate possible pollination by large bees as the major mean.

[17] The name Bifrenaria comes from bi, two, and freno, brake, a reference to the shape of the two pairs of pollinia hold by separated caudicles presented by its flowers.

[20] Two species similar to Bifrenaria, but that showed a highly salient claw at the base of the labellum and lateral lobes abruptly divided were then classified under this genus.

In 1914, Rudolf Schlechter suggested they should be classified under the genus Lindleyella, with Lindley's Bifrenaria aurantiaca (which presented the mentioned differences) as the type.

[21] Just thirty years later, in 1944, Frederico Carlos Hoehne, working on the first revision of genus Bifrenaria, corrected the suggestion of Schlechter.

[22] Finally a genus with an available name in homage to Schlechter was erected in the very next issue of the journal, Rudolfiella, by which time the number of species had increased to seven.

On this revision, besides Rudolfiella, Hoehne divided Bifrenaria into two genera, accepting Lindley's Stenocoryne but calling attention to the existence of Rafinesque's Adipe, which should have nomenclatural priority, while also raising doubts about the identity of several described species.

[20][24] Making the picture even more complex, in 1994, Karheinz Senghas, based on several characteristics shared only by B. tetragona and B. wittigii, described the genus Cydoniorchis to accommodate them.

The results did not allow for the acceptance of Adipe as a separate genus and, although they confirmed the monophyly of Cydoniorchis (B. tetragona and B. wittigii), they dissuade its recognition because six other genera would then be required to accommodate the remaining species.

Bifrenaria is formed by about twenty species[15] divided in two main groups of plants, large and small, with some visible morphological subdivisions highly confirmed by phylogeny.

They present four sided pseudobulbs, with relatively short and erect inflorescence bearing up to ten fleshy large flowers but generally less.

They present smaller and not as noticeably four sided pseudobulbs, and long and delicate inflorescence bearing a higher medium number of flowers than the large species, although also never surpassing ten.

Some species grow directly attached to the famous Sugarloaf Mountain in Rio de Janeiro which can be observed by the commuters in the cable car.

[32] The smaller species of Bifrenaria, which some taxonomists classify under the genus Adipe, are more common on less sunny areas and can be found between 300 and about 1,600 meters of altitude.

These also are plants of caespitous growth, almost all epiphytes, despite there is at least one record of Bifrenaria aureofulva living lithophylically in Chapada Diamantina, Bahia.