Successful pollination is a prerequisite for the reproduction of angiosperms (i.e., flowering plants). Nearly 90% of the 325,000 angiosperm species are pollinated by animals, and in adaptation to different pollination agents (e.g., bees, hummingbirds, hawkmoths), plants have evolved many amazing elaborations in flower color, shape, size, orientation, and pistil and stamen arrangements. Elucidating the genetic and developmental control of these pollinator-associated floral trait elaborations is essential to understanding angiosperm diversification and speciation. Although small RNAs are well-known regulators in almost every aspect of plant development and growth, their critical role in pollinator-associated floral trait elaboration has received much less attention. In this talk I will discuss our work in this area using monkeyflowers (Mimulus) as our model system. Main findings include: (i) The highly conserved miR390-tasiRNA-ARF pathway has been co-opted to regulate corolla tube formation, a key morphological innovation during angiosperm evolution; (ii) A taxon-specific, phased siRNA locus causes flower color diversification and pollinator-mediated speciation in Mimulus; (iii) A yet-to-be-identified miRNA controls organ identity in conjunction with the tasiRNA-ARF pathway.