
Flowers offering oil rewards to pollinators have evolved several times within Iridaceae, and oil-producing structures are particularly widespread in Sisyrinchium. Chauveau et al. conduct phylogenetic analyses to produce the first extensive phylogeny of the Sisyrinchium and deduce that glandular trichomes have evolved independently three times in the genus, being oil-secreting in two cases. These oil-producing trichomes may have played a key role in the diversification of the genus.