Phylogeny of representative plant species, including some for which the whole genome has been sequenced and some species for which whole-genome information is not available (shaded names). The number of known type I (red), MIKCC-group (green) and MIKC*-group (blue) MADS-box genes for extant plant species and the estimated minimal number of MADS-box genes for ancestral plant species are indicated on the corresponding branches. Numbers in yellow boxes indicate the number of type II genes that have not diverged into MIKCC- or MIKC*-group genes. The '?' indicates that no information on the number of the respective type or group of MADS-box genes is available. The red arrow denotes the time when the K domain joined a type II MADS domain, and the black arrow indicates the divergence of an ancestral MIKC-type MADS-box gene into MIKCC- and MIKC*-group genes. MYA, million years ago.