[93] It is difficult to identify from which indigo-yielding plants the indigotin blue in historic textiles derived. Currently new analytic methods are being developed at the research laboratories of the Cultural Heritage Agency of the Netherlands in collaboration with other institutions that would allow to differentiate between different indigo dyeing plants and thus to distinguish whether a textile had been dyed with woad or non-european indigio plants.  Notes from phone conversation with Art Gaibor Proaño, organic colour specialist, on 17 December 2020.