Biosystemalic study of the Ferula communis populations in NE of the Iberian Peninsula and in the Balearic Islands. this paper presents the results of a taxonomic revision of the collective species Ferula communis L. (Umbelliferae) in NE of the Iberian Peninsula and Balearic Islands. The main goal of the research has been to characterize the Ferula communis populations in the region under study and to place them into infraspecific taxa. The proposed classification is based on morphology, anatomy, phenology, karyology and numerical taxonomy. A new taxon is described: Ferula communis L. subsp. cardonae Sanchez-Cuxart and Bernal and two new nomenclatural combinations are proposed: Ferula communis L. subsp. catalaunica (Pau) Sanchez- Cuxart and Bernal and Ferula communis L. subsp. catalaunica var. microcarpa (Cauwet-Marc) Sanchez-Cuxart and Bernal. Description, phenology and chorology for each taxon are included. Also an identification key for infraspecific taxa and a list of new localities are provided.