Vascostylis Prapawan 'Tanzanite'
AM/AOS is a combination of three
orchid genera: Ascocentrum x
Rhynchostylis x Vanda
One unique feature of orchids is the viability of hybrids not only between species, but between related genera. Traditionally, one of the definitions of a species is that it is reproductively isolated from its closest relatives. For example, real human-chimp hybrids are not seen. Because the orchid family is so recently evolved, physiological barriers to interspecific (between species) and intergeneric (between genera) hybrids are not well developed; seasonal, geographic and pollinator barriers suffice.
Perhaps as much because early orchid growers had not learned what constituted a valid species or genus as from a spirit of adventure, it was seen more than 100 years ago that hybridizing within the orchid family did not follow the same rules as in other groups of flowering plants.
By the beginning of this century, nomenclature rules had developed into the uniform naming of intergeneric hybrids. Hybrids between two genera are always a contraction of the two generic names, such as Brassocattleya (Brassavola x Cattleya), Odontonia (Odontoglossum x Miltonia) and Ascocenda (Ascocentrum x Vanda). Usually, hybrids with three genera in the background are also contractions. Brassolaeliocattleya (Brassavola x Laelia x Cattleya) and Vascostylis (Vanda x Ascocentrum x Rhynchostylis) are two of these. However, hybrid genera with three genera in their background can also end with -ara, which is used for hybrid genera of four or more genera. The genus name is derived from the originator's name (or choice of name) with an -ara suffix _ Potinara (Brassavola x Laelia x Cattleya x Sophronitis) or Vuylstekeara (Miltonia x Odontoglossum x Cochlioda).
Unfortunately, the genetic composition of a hybrid genus cannot always give all the cultural hints that a beginner might want. A classic example is the myth that all Cattleya hybrids containing Laelia are more temperature tolerant than pure-bred cattleyas. The type thought of by most in this myth have only Laelia purpurata in their background, and then only several generations back. Another example might be that all ascocendas are compact growing because of the Ascocentrum background. Again, this influence may be so far back that the plants themselves are indistinguishable from a regular standard Vanda. Horticulturally these are sometimes known as Vandacenda, although the use of that name is technically unjustified.