Chromosome numbers and distribution of the genus Pulmonaria (Boraginaceae) in Tuscany and neighbouring areas

Abstract

The investigation on the distribution of the genus Pulmonaria in Tuscany and neighbouring areas, has revealed that the cytotype with 2n = 16 (cfr. P. officinalis L.) occurs over a rather large area. This area in part overlaps that of the other two cytotypes with 2n = 22 and 2n = 28. While the former cytotype is distributed all along either side of the watershed of the Tosco-Emilian Apennines, the latter cytotype, besides overlapping the 2n = 16 and the 2n = 22 distribution areas to the north, extends its range southwards on the western side of the Apennines with populations scattered over the hills as far south as Monte Amiata and the hills north of Perugia in Umbria. Two somewhat aberrant chromosome numbers (2n = 25 and 2n = 26) have been found, albeit rarely, within 2n = 22 populations. Some hypotheses are offered regarding the origin of the various cytotypes through a change in basic chromosome number from x=7 to x=8, with subsequent hybridizations, leading to the establishment of the present chromosome races.

Key words:

• Pulmonaria
• Boraginaceae
• chromosome numbers
• geographical distribution
• Tuscany