Article

Euphorbia subsect. Galarrhaei includes about 200 species found in Eurasia. Previous karyological studies in the subsection report three basic numbers, x = 5, 6, 7 (most common), 8, and lO. There is a great diversity of chromosome numbers, since both dysploidy and polyploidy have played an important role in the evolution of the subsection. Neopolyploidy (2n = 14 ~ 28) and dysploidy (2n = 14 ~ 12) are here reported for populations of the E. flavicoma aggregate at the northem limit of its distribution area. Chromosomal changes show IittIe conco mitant morphological differentiation within the aggregate and are interpreted as being of recent date.