"Much of our fascination with the data of evo-devo arises from the sheer novelty of discovery in biological domains that had been previously and totally inaccessible. These empirical gems also illustrate, even in these early days, the integrating power of scientific conclusions to translate a previous descriptive chaos into explanatory sensibility. As an example, consider the name given to the truly elegant theory of floral genesis, as developed by students of Arabidopsis, the "Drosophila" of angiosperm biology—the ABC Model (Coen and Meyerowitz, 1991; Weigel and Meyerowitz, 1994; Jurgens, 1997; Busch, Bomblies, and Weigel, 1999; Wagner, Sablowski, and Meyerowitz, 1999). In this elegantly simple model (see Fig. 10-12), based on genes with homeotic effects upon serially repeated structures arranged in systematic order (with repetition in concentric whorls rather than linearly along a body axis), A genes operating alone determine the form of the outermost whorl of leaf-like sepals; A plus B genes regulate petals in the next whorl within; B plus C genes mark the male stamens, while C genes working alone determine the most interior female carpels. Moreover, leafy, a "higher control" gene previously recognized as an initiator or suppressor of floral growth and placement in general (Weigel and Nilsson, 1995), apparently also regulates the more specific operation of the ABC series. (Busch et al., 1999, demonstrate that a protein produced by leafy bonds directly to a particular DNA segment of a C gene responsible for the generation of carpels.)"