Karyological and taxonomic notes on Cytisus Desf. Sect. Spartopsis Dumort.and Sect. Alburnoides DC. (Genisteae, Leguminosae) from the Iberian Peninsula and Morocco

instability is a striking karyological feature of Cytisus. Chromosome numbe rs of taxa in Sect. Spartopsis and Sect. Alburnoides, both well represented in Morocco and the Iberian Peninsula, are presented here. We provide the f irst data on chromosome numbers for the Moroccan taxa: C. grandiflorus subs p. barbarus, and subsp. haplophyllus (n = 3, 2n = 46), C. maurus (2n = 48), C. megalanthus (n = 23), C. arboreus subsp. arboreus, subsp, baeticus, and subsp. catalaunicus (2n = 50), C. valdesii (n = 23). New populations from the Iberian Peninsula have been counted: C. grandiflorus subsp. grandifloru s (2n = 46), C. scoparius subsp. scoparius (n = 23), C. striatus subsp. eri ocarpus (n = 23, 2n = 46), C. multiflorus (n = 23), C. oromediterraneus (n = 23, 24). Our data confirm the instability of the chromosome number in Cyt isus. The presence of B chromosomes in C. valdesii and C, megalanthus, as w ell in other species, is discussed in relation to this instability and prev ious data. We suggest that instability of the chromosome number within a ta xon, and even in the same population may be related to the breakage of A ch romosomes and the appearance of B chromosomes. (C) 2001 The Linnean Society of London.