The monophyletic Brassicaceae genus Lepidium (cress) contains species with distinct mechanisms for dormancy and germination: (1) non-dormant seeds, (2) coat-dormant seeds, (3) embryo-dormant seeds. We compare these traits in an evolutionary frame by cross-species approaches. Our project focus is on the embryo and on temperature as the major environmental factor influencing dormancy. Embryo elongation growth - prerequisite to germination - is regulated by hormones and associated with a distinct embryonic expansion zone. This zone is determined and investigated regarding temperature responses and distinct dormancy mechanisms. The large Lepidium seed sizes allow tissue-specific transcript (transcriptome, qRT-PCR, SSH libraries) and hormone analyses. The evolution of the Brassicaceae DOG1 (DELAY OF GERMINATION1) genes is studied related to the distinct dormancies and beyond Lepidium in a set of phylogenetically meaningful selected species. This includes Brassicaceae producing heteromorphic seeds which - although derived from the same plant - show distinct dormancy and germination patterns