Plant development is strikingly plastic. Totipotent cell lines called meristems give rise to all post-embryonic organs—leaves, roots, flowers, for example—throughout the life of the plant. Unlike most multicellular eukaryotes, plants can change their final body plans dramatically in response to environmental and nutrient cues. Understanding how plants respond to their environment may shed light on how plants make developmental decisions that determine their final form. TOR is a conserved eukaryotic cell growth regulator. Recent work suggests that the TOR protein kinase plays a critical role in nutrient-responsive growth in a broad range of eukaryotes. After a brief survey of TOR signaling in yeast and mammals TOR signaling in plants will be surveyed.