There is nothing easy about breeding large yellow cattleyas.
Hybridizers have been trying fervently since 1901, when the very first attempt at combining two lemon-hued species took place. Since then, there have been hundreds or even thousands of pairings – mostly with disastrous results.
The first problem, as breeders soon discovered, is that the color yellow in cattleyas is hopelessly recessive and is nearly always lost when another color is introduced. For example, a yellow flower crossed with a white flower does not yield any yellows. In fact, it yields purple.