This hybrid between O. regis-fernandii and O. eos was first described by Baumann and Kunkele in 1986 and formally named O x buttleri.

Due to a relatively short window of simultaneous flowering, this is not a common hybrid and obviously only occurs where their is an overlap of range between the two species. It can therefore be found on several Greek islands in the Aegean but perhaps occurs most frequently on Rhodes. It can also be found in south west Turkey.

Its appearance is relatively unvaried and usually emerges as a compressed version of O. regis-fernandii with a very similar perianth both in form and colouration. These plants can be easily overlooked in the field, particularly where they grow in close association with O. eos, which can sometimes form large colonies in suitable habitats.

The two parent species share identical habitat requirements comprising typical Aegean environments of phrygana, abandoned terraces and poor grassland on alkaline substrates. A particularly favoured habitat seems to be unkempt road and track sides. The picture is from Chios, dating from the 12th of April at a time when O. regis-fernandii was declining.