The coding region of the mat K gene and two intergenic spacers, psb A-trn H and trn L(UAA)-trn F(GAA), of cpDNA were sequenced to study phylogenetic relationships of 32 Paeonia species. In the psb A-trn H intergenic spacer, short sequences bordered by long inverted repeats have undergone inversions that are often homoplasious mutations. Insertions/deletions found in the two intergenic spacers, mostly resulting from slipped-strand mispairing, provided relatively reliable phylogenetic information. The mat K coding region, evolving more rapidly than the trnL-trn F spacer and more slowly than the psb A-trn H spacer, produced the best resolved phylogenetic tree. The mat K phylogeny was compared with the phylogeny obtained from sequences of internal transcribed spacers (ITS) of nuclear ribosomal DNA. A refined hypothesis of species phylogeny of section Paeonia was proposed by considering the discordance between the nuclear and cpDNA phylogenies to be results of hybrid speciation followed by inheritance of cpDNA of one parent and fixation of ITS sequences of another parent. The Eurasian and western North American disjunct distribution of the genus may have resulted from interrruption of the continuous distribution of ancestral populations of extant peony species across the Bering land bridge during the Miocene. Pleistocene glaciation may have played an important role in triggering extensive reticulate evolution within section Paeonia and shifting distributional ranges of both parental and hybrid species.

The internal transcribed spacers (ITS) of nuclear ribosomal DNA of 33 species of genus Paeonui (Paeoniaceae) were sequenced. In section Paeonia, different patterns of nucleotide additivity were detected in 14 diploid and tetraploid species at sites that are variable in the other 12 species of the section, suggesting that reticulate evolution has occurred. Phylogenetic relationships of species that do not show additivity, and thus ostensibly were not derived through hybridization, were reconstructed by parsimony analysis. The taxa presumably derived through reticulate evolution were then added to the phylogenetic tree according to additivity from putative parents. The study provides an example of successfully using ITS sequences to reconstruct reticulate evolution in plants and further demonstrates that the sequence data could be highly informative and accurate for detecting hybridization. Maintenance ofparental sequences in

Molecular phylogenetic studies of seven plastid DNA regions were used to resolve circumscriptions at generic and infrageneric levels in subfamily Tillandsioideae of Bromeliaceae. One hundred and ten tillandsioid samples were analyzed, encompassing 10 genera, 104 species, and two cultivars. Two species of Bromelioideae, eight species of the polymorphic Pitcairnioideae, and two species of Rapateaceae were selected as outgroups. Parsimony analysis was based on sequence variation of five noncoding (partial 5' and 3' trnK intron, rps16 intron, trnL intron, trnL-trnF intergenic spacer, atpB-rbcL intergenic spacer) and two coding plastid regions (rbcL and matK). Phylogenetic analyses of individual regions produced congruent, but mostly weakly supported or unresolved clades. Results of the combined data set, however, clearly show that subfamily Tillandsioideae is monophyletic. The earliest divergence separates a lineage comprised of Glomeropitcairnia and Catopsis from the "core" tillandsioids. In their present circumscriptions, genera Vriesea and Tillandsia, and their subgenera or sections, as well as Guzmania and Mezobromelia, are poly- and/or paraphyletic. Genera Alcantarea, Werauhia, Racinaea, and Viridantha appear monophyletic, but separation of these from Vriesea and Tillandsia makes the remainder paraphyletic. Nevertheless, Tillandsioideae separates into four main clades, which are proposed as tribes, viz., Catopsideae, Glomeropitcairnieae, Vrieseeae, and Tillandsieae.

Summary• The Ranunculus cassubicus complex, comprising diploids and polyploids, is a good model for studying the role of hybridization and polyploidy in the origin of apomixis.• Results from amplified fragment length polymorphism (AFLP) and simple sequence repeat (SSR) analyses performed on 448 individuals were combined with evidence from morphology, isozymes, karyology and distribution.• Our results indicated a unique hybrid origin for the apomictic hexaploid R. carpaticola from north-western Slovakia, involving two sexual parents: autotetraploid R. cassubicifolius from the northern pre-Alps, and diploid R. carpaticola from central Slovakia. The hybrids were intermediate to the parents, but unique alleles have resulted from genomic reorganisation in the allopolyploids, which might also have triggered apomixis. Their distribution patterns and estimated ages suggest that hybridization may be correlated with the last glacial period.• Hybridization seems to be the major origination for apomicts in the R. cassubicus complex. Polyploidy creates novel sexual genotypes and acts as a springboard for the production of new hybrids, but it only results in a combination with hybridization in apomixis. In turn, asexuality has permitted the perpetuation and establishment of ecologically divergent hybrid genotypes.

Phylogenetic relationships within tribe Phyllantheae, the largest tribe of the family Phyllanthaceae, were examined with special emphasis on the large genus Phyllanthus. Nuclear ribosomal ITS and plastid matK DNA sequence data for 95 species of tribe Phyllantheae, including representatives of all subgenera of Phyllanthus (except Cyclanthera) and several hitherto unplaced infrageneric groups, were analyzed. Results for ITS and matK are generally concordant, although some species are placed differently in the plastid and ITS trees, indicating that hybridization/paralogy is involved. Results confirm paraphyly of Phyllanthus in its traditional circumscription with embedded Breynia, Glochidion, Reverchonia, and Sauropus. We favor the inclusion of the embedded taxa in Phyllanthus over further generic segregation. Monophyletic Phyllanthus comprises an estimated 1269 species, making it one of the "giant" genera. Phyllanthus maderaspatensis is sister to all other species of Phyllanthus, and the genus appears to be of paleotropical origin. Subgenera Isocladus, Kirganelia, and Phyllanthus are polyphyletic, whereas other subgenera appear to be monophyletic. Monotypic Reverchonia is sister to P. abnormis, arborescent section Emblica to herbaceous Urinaria, free-floating aquatic P. fluitans to the weed P. caroliniensis, and the phyllocladous section Choretropsis to the delicate leafy P. claussenii. The unique branching architecture known as "phyllanthoid branching" found in most Phyllanthus taxa has been lost (and/or has been derived) repeatedly. Taxonomic divisions within Phyllantheae based on similar pollen morphology are confirmed, and related taxa share similar distributions. We recommend recognition of six clades at generic level: Flueggea s.l. (including Richeriella), Lingelsheimia, Margaritaria, Phyllanthus s.l. (including Breynia, Glochidion, Reverchonia, and Sauropus), P. diandrus, and Savia section Heterosavia.