
Trithuria is the sole genus of Hydatellaceae, a family of the early-divergent angiosperm lineage Nymphaeales. In order to help determine the early evolution of angiosperm cell-wall structures, Costa et al. use immunocytochemical techniques to examine arabinogalactan protein (AGP) epitopes in T. submersa and find intense labelling in the anthers and in the intine wall, the latter associated with pollen tube emergence. The results agree with labellings obtained for Arabidopsis and confirms the importance of AGPs in angiosperm reproductive structures as essential structural components and probably important signalling molecules.