The plant functional trait diversity research programme has expanded dramatically in the past two decades, as a result of the combination of a long-standing interest in fundamental syndromes of adaptive specialization behind the vast variety of form and function observed in nature on the one hand, and the pressing need to inform biodiversity policy in the face of rapid environmental change, on the other. Its first stages, focused on interspecific variability of traits assumed essential for plant growth, survival and reproduction, led to an unprecedented degree of collaboration in tools and communal data, and resulted in important stylized facts. From there, different paths branched out towards intraspecific variability, genomics, demography, biogeography, cascading into other trophic levels, and social perception and values.