Variation and taxonomy of Biscutella valentina in Spain
Morphological studies have been made on herbarium specimens and 25 population samples of Biscutella valentina (Cruciferae) in Spain. The discontinuities in morphological characters warrant the recognition of three varieties, var. leptophylla, var. pinnata, and var. valentina, from the mass collections, and a fourth taxon, var. tenuicaulis, based on herbarium material. Experimental cultivation revealed that the combination of distinguishing characters for each taxon is genetically fixed while the observed phenotypic plastic range of the vegetative features is not wide enough to affect their taxonomic importance. Artificial crosses performed reciprocally in various combinations on seven of the populations representing three of the varieties resulted in the production of fertile hybrids. A key for identifying the varieties is presented.