We find this little tree, Guettarda platypoda DC. (Rubiaceae), regularly in the dune forests embedded in the large mangrove belt of the Amazon coast. Like in many Rubiacs, each tree belongs to one of two morphs, bearing or flowers with short or with long styles. The mechanics of pollination are different for the two ±morph-incompatible types, promoting outbreeding and enhancing genetic diversity in the population. #Rubiaceae #Guettarda #heterostyly #Amazonas #mangroves #dunes #pollinator #trees