Características florales de las plantas visitadas por el zunzuncito (Mellisuga helenae). INTRODUCTION Hummingbirds and their food-plants rely to a large extent on each other for food supply and pollination service, respectively. This mutual relationship has co-evolved for mil-lions of years and across the Americas involv-ing over 330 hummingbird species and an estimated nearly 8000 plant species relying on hummingbirds as their principle pollinators (Feinsinger & Colwell 1978, Schuchmann 1999, Nicolson & Fleming 2003, Dalsgaard et al. 2011). Although birds other than hum-mingbirds also act as pollinators (Feinsinger & Colwell 1978, Rocca & Sazima 2008, Dals-gaard 2011, Kissling et al. 2011), humming-bird-plant interactions are one of the most striking examples of bird-plant co-evolution, and the associated morphological adapta-tions have been studied intensively (e.g., Snow