Credit: P. VARGAS, EXCEPT TOP LEFT, C. HERRERA AND TOP SECOND LEFT, O. F. SAPIR

Proc. R. Soc. B doi:10.1098/rspb.2009.2163 (2010)

Europe's carnations have diversified faster than any plant group studied so far — a surprising finding that counters the idea that European plants form new species more slowly than tropical plants.

Luis Valente of the Royal Botanical Garden of Madrid and his colleagues analysed specific DNA sequences from plants belonging to 104 species of European carnation (Dianthus spp., pictured) to trace the relationships among them. They found that carnations have been accumulating new species at the speedy rate of 2.2–7.6 per million years. By comparison, lupins (Lupinus spp.) of the tropical Andes have generated only 1.3–3.8 new species per million years.

One possible explanation offered by the authors is that carnations, which flower during dry summer months when pollinators are scarce, have developed diverse floral arrangements to compete for pollinators.