O. montiliensis was first described as a sub-species by Aubenas and Scappatichi from Drome in 2012 and its name is a reference to Montelimar, a town at the heart of the species known distribution.

It is one of the rarer members of the O. tetraloniae group with a distribution that was originally thought to be restricted to the banks of the rivers Roubion and Jabron that run through the plain of Montelimar. Further sites have since been identified and the species is probably more widespread, certainly within the department of Drome. As with most members of this group, identification is not easy and there are several other species with which it may be confused, not least the earlier flowering O. demangei.

The most important feature of this particular species and the group generally is the characteristic, complete band of submarginal hair encircling the labellum. The plant is tall, growing to an impressive 70cms with a widely spaced inflorescence of up to 8 medium sized flowers, significantly larger than those of O. demangei. Lip shape is highly variable and can range from occasionally fuciflorid to the more usual rectangular form. The perianth is normally pink and the petals often darker, particularly at the base, the sepals are distinctively long and narrow. O. montiliensis also differs from the latter in its phenology, first appearing in June and flowering through to mid July whereas O. demangei will have disappeared by the end of May.

The photographs are from the area of Eyzahut to the south west of the Vercors Massif, dating from the first week of June.