While pregnancy in humans and seed development in plants look very different, parallels exist—not least that the embryo develops in close connection with the mother. In animals, a whole network of signals from the mother is known to influence embryo development. In plants, it has been clear for a while that maternal signals regulate embryo development. However, the signal itself was unknown—until now. Plant scientists at the Institute of Science and Technology Austria (IST Austria), Central European Institute of Technology (CEITEC) and the University of Freiburg have now found that a plant hormone called auxin from the mother is one of the signals that pattern the plant embryo. Their study is published today in Nature Plants.