Karyological observations on Artemisia alba Turra (Asteraceae)

Artemisia alba Turra from Calabria is karyologically studied (2n = 18). From the analysis of literature it results that this species shows three cytotypes, with a rather distinct geographical distribution: 1) diploids with 2n = 18, previously identified as A. alba subsp. chitachensis Maire (name which is here typified) or A. alba subsp. glabrescens (Willk.) Valdés-Bermejo. This diploid cytotype, known from Spain, Morocco and Bosnia-Hercegovina, occurs also in S Italy (Timpa di S. Lorenzo, Calabria). 2) Tetraploids with 2n = 36, generally identified with the typus sub-species. This cytotype appears the most widespread in northern part of the species range. 3) hexaploids with 2n = 54, known only from Abruzzo and Apulia. This cytotype seems of more recent origin, and is here considered of probable hybridogen origin between the 2n = 36 and 2n = 18 cytotypes. This unit can possibly be identified with A. columnae Ten. (= A. camphorata var. garganica Ten.). These latter names are lectotypified. We tested also the correlation of the ploidy level with the size of pollen-grains.