Arabidopsis floral dip transformation is notable for a number of reasons. First, it is strikingly simple to perform. Agrobacterium is applied to flowering Arabidopsis plants that subsequently set seed, and transgenic plants are then selected among the progeny seedlings. Because no plant tissue culture is required, somaclonal variation is avoided, and the procedure can be performed easily by nonspecialists. Success rates are high: it is common that 1% of the progeny seedlings are transgenic. The biology behind the method is interesting: Arabidopsis and some related Brassicaceae are apparently unique in allowing exogenously applied Agrobacterium to colonize the interior of developing ovaries, where female gametophyte cell lineages are transformed. The availability of the method has had a transformative effect on the overall practice of plant molecular biology, as the generation and analysis of large numbers of transgenic plants is now routine in hundreds of laboratories. The method has been exploited in a genomics context to make stable gene knockout plant lines for most Arabidopsis genes.