The " scoparius " group is composed of Cytisus scoparius (Genisteae, Fabaceae) and its related taxa. Taxonomic and morphometric studies enabled us to delimitate 10 species divided into three sections: Alburnoides, Spartopsis and Verzinum. Phylogenetic analyses based on chloroplastic markers trnD-T and trnS-G and nuclear markers ITS, LEGCYCIAa, LEGCYCIAb and LEGCYCIAc revealed that sections Alburnoides and Verzinum, both monophyletic if C. striatus is included within section Alburnoides, are sister clades. Section Spartopsis, either paraphyletic or monophyletic depending on the position of C. commutatus (sect. Corothamnus), is more distantly related. Four cultivated hybrids result from crossbreedings between species of the " scoparius " group. The comparison of polymorphic ITS sequences obtained from cloning confirmed both parents at the origin of three of those hybrids and one parent for the fourth hybrid of the group. The use of trnD-T sequences determined the maternal parent at the origin of three of the hybrids. The addition of hybrid taxa in the phylogenetic analyses showed that hybrids between closely related taxa form a clade with their maternal parent and do not modify the relationships between non-hybrid taxa. However, hybrids between distant taxa do not necessarily place with one of their parents and can cause the collapsing of some clades and changes in the topology. More than 150 cultivars are also included in the " scoparius " group, 40 of which were characterised. Molecular data (ISSR, trnD-T sequences and microsatellites) were used to confirm and complete the genealogical information on 28 of those cultivar whose origin is resumed in a 7-generation pedigree on broom cultivars.
