This third part of this flora covers the remainder of the orchid family Spiranthoideae and the families Cranichideae and Vanilloideae.
Since the authors did not manage to reach all the herbaria in Colombia, nor all the material deposited outside Colombia, they decided to title this book Materials to the Orchid Flora of Colombia rather than "The Orchid Flora of Colombia". Even so, the authors have collected enough material to be published in a planned twenty volumes.
When there was high evidence that an orchid species found outside Colombia grew in Colombia too, the authors have also included it in their work, as it was not always possible to illustrate Colombian species on the basis of the material derived from the country – the quality of some specimens was not sufficiently good for an illustration. The comparison of the descriptions and illustrations should maximise the correctness of determination.