Abstract: The nutlet micromorphology of 5 tribes, 15 genera and 32 species of Boraginoideae in China was examined using light microscopy (LM) and scanning electron microscopy (SEM). The results revealed that the shapes of nutlets are ovate, trullate, obovate, reniform, riangular pyramid and spherical; the surface ornamentations are wrinkle, strumae, verrucate, colliculate, pubescent, bristly and grapnel spine; and the micro-protuberances appear verrucate, undulate, aculeate, strumae, papilliform, colliculate, stelliform, hilly and tufted. The shape, surface ornamentation and micro-protuberance are different among some tribes, genera and species, which may be referred for the classification of Boragioideae.

Key words: Boragioideae, nutlet, taxonomy