Taxonomic remarks on Isatis tinctoria (Brassicaceae) from Pollino National Park (Basilicata, Italy)

Isatis L. (Brassicaceae) is an Eurasian genus including 79 species (1). It is one of the most difficult cruciferous genera (2). Some species, in fact, are highly polymorphic in fruit morphology, the structures that provide the most diagnostic characters (3). In addition, due to the extreme variability in all morphological characters, the limits of many species are uncertain (4). Most if not all diagnostic characters used in earlier classifications are very variable and because of the unreliability of vegetative and floral characters it is difficult or impossible to identify many specimens when mature fruits are missing (5). The patterns of variation suggest that hybridisation may be widespread (4). Moreover, intermediate specimens are rather frequent, even between some taxa that are morphologically easily recognisable (4). In Italy, according to Conti & al. (6), Isatis is represented by 3 species: I. apennina Grande (= I. allioni P.W.Ball), endemic to Italy and France (south-west Alps and central Apennine), I. praecox Kit., an European taxon restricted to Lombardia, and I. tinctoria L., an Asiatic species widespread in central and south Italy. Floristic investigations in the Pollino National Park (on the Lucanian side) led to the discovery of a little population referable to I. tinctoria. However, a comparative study of the plants showed that they differ in many relevant characters. The fact that this Lucanian population has morphological dissimilarities involves its critical revision that could bring to a new taxonomic delimitation.