A small flowered variant of Aristolochia pallida had been overlooked for years until investigation revealed there's another species belonging to the extremely variable pallida-complex in 2008. 

 

Originating from the central mountains in Spain this tiny species can mainly be distinguished from the 'classic' A. pallida by the distribution area. 

Although not as large-flowered as other species from the same clade A. castellana produces amazing, erect zic-zac shoots with flower buds in every leaf axil.