Little is known about the historical biogeography of alpine plants that are disjunctly distributed across the mountains of the Iberian Peninsula. Randomly Amplified Polymorphic DNA (RAPD) and chloroplast microsatellite (cpSSR) variation were surveyed in the Spanish alpine endemic, Senecio boissieri, to resolve the causes of its disjunct distribution in the southern Sierra Nevada and Baza, centrally located Sierra Guadarrama, and northern Cordillera Cantábrica. RAPD analysis identified two divergent genetic groups, one containing individuals from the Cordillera Cantábrica and another comprising individuals from the three other mountain ranges. Chloroplast DNA variation was much more limited with only one of forty‐two cpSSR loci examined showing polymorphism. At this locus the same allele occurred at high frequency in material from each mountain range. A possible reason for RAPD divergence in the Cantabrian material is its derivation from plants surviving the last glacial maximum in a northern refugium, isolated from the main distribution of the species spanning the area between the southern and central Spanish sierras. Postglacial fragmentation of the species range in southern and central Iberia would have resulted in the current disjunction of genetically similar populations in southern and centrally located mountains.

By means of a cluster analysis, we classified 135 relev6s of the forests of the Muniellos Reserve into 8 groups and the species in these relev6s into 28 groups. The concentration analysis applied allows to study the relationship between relev6 group and species group. The forest types in Muniellos Reserve are: mixed riverside forest, mixed forest with hazel, semideciduous pyrenean oak forest, xerophilous and mesophilous sessile oak forest, beech forest and open and thick birch forest. These forest types are characterized floristically, structurally and ecologically. The pattern of distribution of forest types in the Muniellos Reserve is also discussed; in the siliceous areas of the Orocantabric province this pattern is widespread, but differes to some extent from the accepted pattern.Nomenclature: According to Tutin etal. (1964Tutin etal. ( -1980, except for the following cases: Adenocarpus complicatus subsp, lainzii Castroviejo; Adenostyles pyrenaica = A. alliariae subsp, pyrenaica (Lange) P. Fourn.; Arrhenatherum bulbosum=A, elatius subsp, bulbosum; Brachypodium rupestre=B, pinnatum subsp, rupestre; Carex broteriana S amp.; Cystopteris viridula (Desv.) Desv.; Erica aragonensis = E. australis subsp, aragonensis (Willk.) P. Cout.; Festuca multiespiculata =-F. paniculata subsp, multiespiculata Rivas Ponce & Cebolla; Genista polygaIiphylla= G.florida subsp, polygaliphylla (Brot.) P. Cout.; Lastraea limbosperma (All.) J. Holub & Pouzar; Linaria glabrescens = L. saxatilis subsp, glabrescens (Lge.) Lalnz; Lithodora diffusa Lag.; Luzula henriquesii=L, sylvatica subsp, henriquesii; Prunella pyrenaica = P. grandiflora subsp, pyrenaica; Quercus x trabuttii Hy; Rhynchosinapis setigera = R. pseudoerucastrum subsp, setigera; Saxifraga lepismigena = S. clussi subsp, lepismigena; Simethis mattiazii (Vandelli) Scardo.

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FERNANDEZ PRIETO, J. A., VERA, M. L., ALVAREZ MARTINEZ, M. J., DIAZ, T. E., FERNANDEZ CASADO, M. A., FERNANDEZ‐CARVAJAL, M. C, GUTIERREZ VILLARIAS, M. I. & NAVA, H. S., 1993. Chromosome numbers and geographical distribution of Ulex europaeus subsp. europaeus (Leguminosae). Chromosome numbers are reported in Ulex europaeus subsp. europaeus (99 samples from northern Spain, France and Great Britain). Three levels of ploidy (diploid, tetraploid and hexaploid) have been detected; the diploid and tetraploid levels, hitherto unknown in this taxon, have been found exclusively in coastal areas of northern Spain and western France.

Micromorphology, cytogenetic analysis, isozyme assays, and in situ hybridization were used in order to analyse the diversity of Avaella in the north-west Iberian Peninsula. Among the taxa analysed, somatic chromosome numbers 2n = 4x = 28 and 2n = 8x = 56 were found.Differences in habit, micromorphology and MDH patterns were also detected. Chromosome C-banding pattern and results obtained from total genomic DNA in situ hybridization indicate that the different taxa analysed are closely related. The systematic position of the different taxa is analysed.