Technical Abstract: Fertilization in higher plants requires intricate signaling between the male and female. The molecular details underlying this communication are of great interest, not only to understand plant reproduction but also to guide efforts in crossing plant species to generate new hybrids. On page 656 of this issue, Escobar-Restrepo et al. (1) show that cells in the female ovule express a protein--a type of receptor that is widely known to mediate cell-cell communication--that is required for fertilization. The unknown ligand(s) for the receptor may be present on or secreted by the pollen tube. Such a receptor-ligand interaction could control species-specific reproduction.