Nuclear ribosomal (26S) and chloroplast (trnL-trnF and atpB-rbcL spacer) genomic regions were sequenced from 29 exemplars of Timmiaceae and five outgroup taxa. Phylogenetic hypotheses were tested from analyses of the individual regions and a combined dataset, using both parsimony and Bayesian inference methods. Estimates of branch support were established using bootstrap analyses and Bayesian posterior probabilities. The analyses were used to test the monophyly of the species and the relationships among taxa in Timmiaceae, previously based on morphology. Phylogenetic inferences suggest that Timmia austriaca, T. megapolitana s.s., T. megapolitana subsp. bavarica, and section Norvegica represent monophyletic taxa. Timmia norvegica s.s., T. norvegica var. excurrens, and T. sibirica were non-monophyletic, but together form a single clade. We, therefore, recommend recognizing them as a single taxon, T. norvegica. A key to the taxa is presented.

The ranges of great camas (Camassia leichtlinii) and small camas (C. quamash) overlap extensively in the western United States. Previous systematic treatments of the genus are inconclusive, as a recent flora classifies C. leichtlinii as a subspecies of C. quamash. We investigated species boundaries and putative hybrid zones at multiple sites in the Willamette Valley of Oregon and in allopatric populations ranging as far north as British Columbia. Genotypic inferences from allozyme electrophoresis of 218 individuals yielded 12 resolvable loci across three buffer systems. Lower mean Nei's genetic identity (I) in interspecific pairwise comparisons (0.76) than in intraspecific comparisons (0.91 for C. quamash and 0.89 for C. leichtlinii) indicates that these taxa are readily distinguishable using allozymes. Furthermore, four alleles uniquely characterize either C. leichtlinii or C. quamash and five additional alleles are common in one species but rare in the other. In different, sympatric populations, C. quamash and C. leichtlinii also varied in interspecific genetic identity (Nei's I  =  0.66–0.87), and in the additivity of allozyme patterns for plants identified as putative hybrids based on morphology. Principal Component Analysis (PCA), hybrid indices, and the relatively large interspecific Nei's I suggest that hybrid formation and introgression are discontinuous, occurring extensively only at one site. For all populations, allozyme data support species-level distinction of C. quamash and C. leichtlinii.

Recent molecular data indicate that “Panicum” section Bulbosa does not belong in the genus Panicum. Previously published phylogenies strongly support its inclusion in the “bristle clade,” a monophyletic group in the Paniceae that includes the genera Setaria, Cenchrus, and Pennisetum, among others. The morphological synapomorphy for the clade is the presence of bristles (sterile branchlets) in the inflorescence, but Panicum bulbosum has no bristle-like structures at any stage of development, and is otherwise morphologically quite distinct from any of its close relatives. We have evaluated several possible taxonomic placements for section Bulbosa, reflecting the need to remove it from Panicum. Our conclusion, based on previously published molecular and current morphological data, is to erect a new genus, Zuloagaea, to accommodate section Bulbosa. We have also evaluated whether there are one, two, or three taxa within sect. Bulbosa. We have used principal components analysis of 33 morphological characters and find no distinct morphological groups within the section, and hence conclude that the group represents a single species.

Floral morphology of 16 species of Gunnera representing all six subgenera is examined and described using scanning electron microscopy (SEM). The evolution of 19 flower morphological characters is discussed. Eight of these characters are optimized on a current phylogenetic tree. Character evolution tends to be generally continuous over different clades and several parallel evolutionary patterns of floral reduction can be identified within the family. At one extreme stand species such as G. manicata and G. perpensa with mainly bisexual flowers bearing well-developed sepals and petals, and at the other stand species such as G. magellanica and G. herteri with perianthless staminate flowers, and pistillate flowers with only gynoecia and sepals. In between one finds a range of flower morphologies, bisexual or not, with petals and sepals present or absent, or discernable as reduced organs. Character-state reconstruction and morphological evidence suggest that flowers in Gunneraceae were bisexual in origin with a reduction leading to simple unisexual flowers. Among the examined characters, absence of reduced organs in the other gender, spathulate petals in the staminate flower, long styles, and the presence of well-developed bracts are typical for species of subg. Milligania. Basally connected sepal lobes with a strongly swollen base and reduced blade is found in all species of Panke and in G. magellanica (subg. Misandra). Selected synapomorphies are consistent with the deep phylogenetic division of Gunnera between the New and Old Worlds.

The North American genus Tidestromia (Amaranthaceae: Gomphrenoideae), with high levels of endemism in the Chihuahuan Desert, is subjected to phylogenetic analysis using 19 morphological characters. Species from genera most closely related to Tidestromia (Alternanthera, Froelichia, Gossypianthus, and Guilleminea), as well as the more distantly related genus Iresine, were used as outgroups. The monophyly of Tidestromia is well supported by four synapomorphies: alternate leaves, dichasial inflorescences, and pollen that is psilate (homoplasious) and with mesoporia that are narrowed distally. The single most parsimonious tree resolved T. valdesiana as sister to the rest of Tidestromia, which is apomorphically diagnosed by the presence of involucres. The annual habit supports a clade comprising T. carnosa, T. lanuginosa, and T. tenella, which is nested among the species with involucres. The phylogenetic relationships of the rest of the taxa remain unresolved. Traditional morphological evidence thus is important for circumscribing the genus Tidestromia, but shows limited utility for resolving species groups within this genus.

In many arctic-alpine plant groups, reticulate evolutionary histories have resulted in problems with species delimitation and phylogenetic reconstruction. In the Saxifraga rivularis complex (2n  =  26, 52), the number of species accepted ranges from a single polymorphic one (S. rivularis s.l.) to several (the circumpolar S. hyperborea, the amphi-Atlantic S. rivularis, the three amphi-Pacific species S. bracteata, S. flexuosa, and S. arctolitoralis, and S. debilis in the Rocky Mountains). A combination of molecular (AFLPs), flow cytometrical, and morphological data from samples covering most of the distribution range was used to delimit taxonomic species and to unravel their evolutionary relationships. Four lineages with distinct morphological differences were recognized, representing four species: the diploids S. bracteata, S. hyperborea (including S. flexuosa), and S. debilis, and the tetraploid S. rivularis (including S. arctolitoralis). Based on a synthesis of the available data we provide a taxonomic revision of the complex and propose one rank change (S. rivularis subsp. arctolitoralis comb. et stat. nov.). Genome sizes as well as the intermediate position of the S. rivularis lineage in the molecular and morphological analyses suggest a single allopolyploid origin from the S. bracteata and the S. hyperborea lineages, most likely in Beringia.

The monotypic genus Guamatela was originally described from Guatemala and has also been collected in Honduras and Mexico. This taxon has been placed in tribe Neillieae of Rosaceae based on its follicular fruits and persistent stipules, but it is anomalous in the tribe due to lack of endosperm, while some of its other characters, such as opposite leaves, lack of a well developed hypanthium, and fused styles, are unusual for the entire family. No other taxonomic placement has ever been proposed for Guamatela, however, and morphological characters alone do not suggest any likely alternative. DNA was extracted from two herbarium specimens of G. tuerckheimii, one collected in the state of Oaxaca, Mexico in 1969 and the other in the department of El Progreso, Guatemala in 2000. Phylogenetic analyses of the chloroplast rbcL, atpB, and matK genes amplified from the materials, along with sequences from representatives of most major eudicot groups, strongly support Guamatela as a member of the rosid order Crossosomatales, as circumscribed in APG II. None of the molecular data supports the inclusion of Guamatela in any described family in the order, and the unique combination of morphological characters does not fit the description of any of those families. Based on these results, we here propose the new family Guamatelaceae to accommodate this genus.

Phylogenetic reconstructions in the Mediterranean genus Erodium are for the first time performed using two matrices: one with 96 trnL-trnF sequences from Erodium (90 accessions plus four outgroups) and the other with 72 trnL-trnF sequences plus 23 morphological characters (66 species of a total of 74), using Maximum Parsimony (MP) and Bayesian Inference (BI). An association between reproductive properties (high selfing rates, flower asymmetry, insect-attraction structures), life form, and breeding system distributed in different lineages suggests multiple shifts from allogamy to autogamy in the course of evolution, whereas dioecy has occurred only once. The phylogenetic analyses revealed a remarkable capability for dispersal in Erodium because closely related species occur in different continents. Major lineages containing sublineages of species also from several continents lead us to interpret ancient dispersal activity. Establishment of Mediterranean-like climates in most continents may have been crucial in the evolution of Erodium, as manifested by occurrence of species of the Mediterranean floristic region in the four major lineages. The body of knowledge accumulated from molecular phylogenetics and morphology lead us to conclude that the Mediterranean region harbors the major center of diversity of Erodium, where active radiation in dry, disturbed environments, is still operating.

Cuphea is an endemic genus of the New World and the most speciose member of the Lythraceae with ca. 260 species classified in two subgenera and 13 sections. As a first attempt to construct a phylogenetic framework for the genus, data from morphology and nuclear ITS sequences for 53 species and four outgroup taxa were analyzed. Independent results employing morphological and molecular datasets confirmed Cuphea as monophyletic with Pleurophora as sister. The morphological strict consensus tree was substantially unresolved. The ITS parsimony and maximum likelihood phylogenies indicated South America as the initial center of diversification and identified a deep trichotomy, one branch of which was equivalent to subg. Cuphea. The ITS analyses also recognized seven well-supported clades, each composed of members from two to four taxonomic sections. Species of section Melvilla appear in five of the seven clades, supporting the hypothesis that the large, intensely-colored, bird-pollinated floral tubes that define the section are convergent, having evolved from smaller, more promiscuously-pollinated, green-tubed flowers. Sixteen endemic North American species have a single South American origin and form the core of a secondary center of Cuphea diversification in Mexico. The ITS analyses provide initial phylogenetic hypotheses for the genus that clarify relationships previously obscured by the highly homoplastic nature of the morphological taxonomic characters.

A combined parsimony analysis of the species of Phaseolus and closely related New World genera was performed with sequences from the nuclear ribosomal ITS/5.8 S and plastid trnK loci. Species relationships are resolved with high parsimony bootstrap support at all hierarchical levels. All species of Phaseolus, except five enigmatic ones, belong to one of eight clades. These eight clades show some morphological, ecological, or biogeographical distinction, and are informally recognized in a phylogenetic classification. The five enigmatic species, Phaseolus glabellus, P. macrolepis, P. microcarpus, P. oaxacanus, and P. talamancensis are weakly resolved as the sister clade to the Tuerckheimii group. An evolutionary rates analysis that biases for old age estimates suggests that the Phaseolus stem clade is the same age as the New World Phaseolinae crown clade with a maximum age of ca. 8 Ma. The Phaseolus crown is estimated to be no older than ca. 6 Ma, and the average age of the eight well supported crown clades within Phaseolus is ca. 2 Ma. The maximum age estimate of a Late Pliocene to Pleistocene diversification of Phaseolus post-dates the major tectonic activity in Mexico where Phaseolus diversity is centered.

Pomaria, traditionally placed in Hoffmannseggia or Caesalpinia, is shown to be a well-supported group of 15 species related to the Erythrostemon group of Caesalpinia sensu lato. Monophyly is well supported by analyses of both nuclear and chloroplast DNA data and by the presence of several unique morphological characters. Nine species of the genus are distributed in the arid and montane regions of the southwestern United States and adjacent Mexico, three species occur in temperate eastern South America, and three species are native to southern Africa. The genus thus exhibits both a New World amphitropical and a New World-African amphi-Atlantic distribution pattern. A biogeographical analysis suggests two dispersals within the genus account for the present distribution: one from North America to Africa and second from North America to South America.

The genus Adenia provides a natural experiment to investigate the evolution of growth form. Within the group, trees, shrubs, herbs, vines, and lianas are present. Using ITS1 5.8S ITS2 sequence data, a phylogeny of 67 of ~100 species of Adenia is inferred using parsimony and Bayesian analyses. Specific hypotheses of monophyly are also tested to couch the analyses of growth form evolution within a phylogenetic framework. Within the context of this phylogeny, synapomorphies for major clades are discussed, as are patterns of growth form evolution. Absolute divergence times of nodes are estimated using penalized likelihood, and speciation rate based on these times is inferred to be fast relative to some other lineages of life. By reconstructing evolutionary history on a sample of trees from the posterior distribution of the Bayesian analysis, it is estimated that succulent stems evolved ca. four times, and tubers ca. eight. Transitions between markedly different growth forms occur on the scale of a few hundred thousand to a few million years, and close relatives frequently have different forms with no intermediates. The rapid diversification rates, fast morphological transitions, and multiple origins of water storage tissue in roots and shoots are hypothesized to result from a shared developmental program for water storage tissue that is flexibly turned on and off during evolution in stems and roots.

A new species of Cipoia (Podostemaceae) from the state of Minas Gerais (Brazil) is described and illustrated: Cipoia ramosa. It is distinguished from the only other species in the genus, C. inserta, by its branched stems, stipules composed of two tooth-shaped appendages adjacent to the leaf base, anther thecae that remain at a prominent angle during and after anthesis, and an ovary that is longer than the stigmas at anthesis.

Ziziphus comprises approximately 170 species native to the tropics and subtropics. Two economically important species, Z. jujuba and Z. mauritiana, are cultivated for their fruit. Given the economic importance of these two species, we undertook a reexamination of the intrageneric phylogenetic relationships to identify their closest relatives and to test two alternative intrageneric classifications. These two classifications were tested by using a simultaneous analysis of morphological characters together with nuclear (ITS and 26S rDNA) and plastid (trnL-F) genes. The Old World and New World species of Ziziphus formed two separate well-supported clades. The Old World species of Ziziphus are more closely related to Paliurus than to the New World species, thereby rendering Ziziphus paraphyletic. Sarcomphalus is placed within the New World Ziziphus clade, which supports the transfer of Sarcomphalus to Ziziphus. The earlier placement of Condaliopsis in Ziziphus was supported for one species previously placed in Condaliopsis, Z. obtusifolia, but was contradicted for the other Condaliopsis-like species, Z. celata. Ziziphus celata is more closely related to Rhamneae than it is to Paliureae.

Phylogenetic analysis of DNA sequences from chloroplast regions and nuclear ribosomal ITS was conducted to test the monophyly of Cestrum sect. Habrothamnus and investigate its relationships with other sections of Cestrum. Molecular divergence was very low among the sampled species, suggesting a rapid diversification in Cestrum. Individual and combined analyses of these molecular data sets using maximum parsimony and Bayesian inference reject the monophyly of the traditionally recognized sections of Cestrum, including sect. Habrothamnus. Infrageneric classifications will require significant revision. Nevertheless, the resolved monophyletic clades in this molecular analysis are geographically structured.

South American Microgyne Less. is resurrected from the synonymy of Microgynella. Microgyne Cass. is a nomen nudum and therefore not validly published. The replacement generic name Microgynella, a homotypic synonym of Microgyne Less., is illegitimate and superfluous. A revision is presented for the two species of Microgyne, one herein described as new. The new species, Microgyne marchesiana, is described from Uruguay and is diagnosed by pinnatifid leaves, whitish pappus, and a thick testa. A neotype is designated for Microgyne trifurcata Less. Detailed descriptions and illustrations are provided for the two species, together with additional data on anatomy.

Sequence data from the nuclear internal transcribed spacer (ITS) were used to infer phylogenetic relationships within a morphologically, karyologically, and geographically well-defined group of species of Campanula (Campanulaceae), the Isophylla group. Although belonging to the same clade within the highly paraphyletic Campanula, the Rapunculus clade, members of the Isophylla group do not form a monophyletic group but fall into three separate clades: (i) C. elatines and C. elatinoides in the Alps; (ii) C. fragilis s.l. and C. isophylla with an amphi-Tyrrhenian distribution; and (iii) the garganica clade with an amphi-Adriatic distribution, comprised of C. fenestrellata s.l., C. garganica s.l., C. portenschlagiana, C. poscharskyana, and C. reatina. Taxa currently classified as subspecies of C. garganica (garganica, cephallenica, acarnanica) and C. fenestrellata subsp. debarensis are suggested to be best considered separate species. The molecular dating analysis, although hampered by the lack of fossil evidence, provides age estimates that are consistent with the hypothesis that the diversification within the garganica clade was contemporaneous with the climatic oscillations and corresponding sea-level changes during the late Pliocene and Pleistocene. Dispersal-vicariance analysis suggests that the garganica clade originated east of the Adriatic Sea, from where it reached the Apennine Peninsula.