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Summary In order to assess the systematic relations within the tribe Genisteae, the water‐soluble seed proteins of 45 species have been studied serologically. The reaction was tested by immunodiffusion and the results have been processed by cluster analysis and by principal component analysis. Based on these data, the genus Cytisus s.l. (incl. Chamaecytisus, Sarothamnus and Corothamnus) represents a single homogeneous unit, except for C. sessilifolius, which appears to be more closely related to Laburnum and to Genista than to the other species of Cytisus. Also, C. emeriflorus is very similar to Lembotropis nigricans; its inclusion in the genus Lembotropis is sustained. Genista is much more complex; its section Asterospartum should be segregated as the genus Cytisanthus Lang, being internally homogeneous, distinct from all other sections and fairly close to Lygos. A new combination, Cytisanthus aetnensis (Biv.) comb, nova, is published. Genista pilosa and G. anglica seem very much isolated, but the authors do not intend to propose here a new taxonomic rank, due to the scarcity of data. Teline is very similar to Genista. Even more similar to Genista is Chamaespartium sagittale, which biochemically and morphologically fits very well in the subgenus Genista, in spite of its winged stem. In a general arrangement of the tribe, two groups of genera represent the extreme points of diversification: (1) Cytisus‐Lembotropis‐Calycotome and (2) Genista‐Teline‐Petteria‐Spartium and (with decreasing similarity) Cytisanthus and Lygos. Between these two groups there are a series of intermediate genera, that may be placed in one group or the other depending on the method of analysis: Adenocarpus, Argyrolobium (both of them should be included in the tribe), Cytisus sessilifolius and Laburnum. Ulex and Lupinus are very dissimilar from all other genera.

Within the genus Genista, the species belonging to the G. ephedroides complex are examined from karyological, molecular and phenetic point of view. All the examined taxa show a chromosome complement with 2n = 48, occasionally with some accessory chromosomes. In addition, the aneuploid number 2n = 44 was found only in G. ovina, while higher counts (2n = 72 and 2n = 96) are reported for G. tyrrhena ssp. pontiana. As concerns the DNA, the restriction fragment analysis of the ribosomal ITS1 (HaeIII, RsaI) and 5.8S-ITS2 (HaeIII) regions was used; the classification and ordination of the taxa allow to distinguish three clusters: the first including the S-Tyrrhenian taxa, the second all the Sardinian and Balearic taxa, and the third grouping G. numidica and G. cilentina. The phenetic analysis was performed by using 40 morphological characters processed by the NTSYSpc package. The relative cladogram distinguishes three main clades: the most isolated including the Sicilian species, the other two separating the Sardinian and Balearic species from the STyrrhenian and Algerian ones.

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