The importance of ancient long-distance migrations in shaping the geographical structure of genera and families is becoming ever more apparent. The long-distance immigrants were not random samples of their floras, but had attributes which made them prime candidates for the intercontinental sweepstakes. High propagule dispersability was one such trait. I propose that these invasive species also must have produced large numbers of propagules across their ranges, by virtue of large population numbers and sizes. They probably were widespread, major elements in their floras. These ideas are supported by the fact that propagule pressure is a prime determinant of a contemporary species' invasion potential, as is the size of its native geographical distribution. I propose that highly dispersable and propagule-rich lineages are likely to have high speciation rates, because access to new regions affords opportunities for ecological and geographical speciation. These lineages also may persist longer, being more broadly distributed in space. The evolutionary advantage of these lineages extends to periods of climatic change.

Despite its ancient origins, worldwide distribution, and adaptation to diverse habitats, Isoëtes species have a highly conserved morphology, making it difficult to resolve phylogenetic relationships using morphological characters. In this paper, we report the results from various analyses (maximum parsimony, maximum likelihood, and Bayesian inference) for Isoëtes species from around the world based on nucleotide sequences from the nuclear internal transcribed spacer (ITS) and chloroplast atpB/rbcL intergenic spacer regions. The trees resulting from our analyses of the combined data contain six major well-supported clades (bootstrap ≥ 90%, posterior probabilities = 1.00): A clade with possible Gondwanan affinities (I. australis, I. coromandelina, I. panamensis, I. cubana, I. jamaicensis); a South African clade (I. capensis, I. toximontana, I. stellenbossiensis, I. stephansenii); a largely Northern Hemisphere clade (I. nuttallii, I. orcuttii, I. minima, I. dixitei, I. abyssinica, I. olympica, I. longissima, I. velata); an Asian/Australasian clade (I. drummondii, I. gunnii, I. pusilla, I. kirkii, I. muelleri, I. taiwanensis, I. japonica, I. yunguiensis, I. habbemensis); a Mediterranean clade (I. histrix and I. setacea); and a poorly resolved clade consisting of 12 new world species (American species complex). Our results are compared to past classifications and various biogeographical scenarios are explored.

Recent phylogenetic investigations of Cupressoideae have found evidence to suggest that Cupressus is not monophyletic. This study tested the division of Cupressus into an Old World clade and a New World clade with complete sampling of the 28 extant species. Data from anatomy, biochemistry, micromorphology, reproductive development, reproductive morphology, and vegetative morphology were combined with molecular sequence data (matK, NEEDLY intron 2, nrITS, rbcL, and trnL) to produce the most complete hypothesis of evolutionary relationships within Cupressoideae to date. Callitropsis, Cupressus, and Juniperus formed a well–supported monophyletic group (100%). Within this clade, the only demonstrably monophyletic genus was Juniperus (100%). Monophyly of the 12 Old World species of Cupressus was well supported (100%). Old World species of Cupressus were sister to Juniperus (99%). Callitropsis and the 16 New World species of Cupressus were resolved as the sister group to the Old World Cupressus plus Juniperus clade (100%), rendering Cupressus polyphyletic. The relationship between Callitropsis and the New World species of Cupressus was not resolved. Based on the results of the combined analysis, generic circumscriptions were modified: Cupressus was restricted exclusively to Old World species and Callitropsis was expanded to include the New World species previously classified as Cupressus (seventeen new combinations in Callitropsis were made).

The genus Aristolochia sensu lato contains over 400 species from warm temperate to tropical regions worldwide. Taxonomic treatments of Aristolochia have been ambiguous and controversial. In a recent cladistic analysis based on morphological characters, it was proposed that the genus should be divided into four genera in two subtribes. To reconsider the systematics of Aristolochia sensu lato, we reconstructed its phylogeny based on nucleotide sequences of the chloroplast rbcL gene and the nuclear-encoded phytochrome A (phyA) gene for 19 representative species and the chloroplast matK gene of over 80 species. All phylogenetic trees produced with the three genes indicate that Aristolochia sensu lato is a monophyletic group, consisting of two lineages that correspond to the subtribes Aristolochiinae and Isotrematinae. The matK phylogeny shows that each of the lineages includes two sublineages. The Aristolochiinae clade is composed of the Aristolochia sensu stricto and Pararistolochia clades, and the Isotrematinae clade of the Isotrema and Endodeca clades. Chromosome numbers, including newly reported counts for 30 species, are predominantly congruent with the phylogeny: the Aristolochiinae clade shows chromosome numbers of 2n = 6, 12, 14, or 16, while the Isotrematinae clade is characterized by 2n = 32. In the Isotrematinae clade, the paralogous relationships of the phyA gene suggest that polyploidization might have occurred.

Ophiochloa bryoides, a new species in the Brazilian endemic genus Ophiochloa, is described and illustrated. It is similar to O. hydrolithica, the only currently known species in this genus, from which it differs because of its diminutive annual habit, the absence of an axillary inflorescence, and the occurrence of a single apical seta on the lower lemma. The affinity of Ophiochloa with Axonopus is briefly discussed.

In a recent treatment, the genus Panicum was restricted to subgenus Panicum based on molecular, morphological, and anatomical data. Also, other species of Panicum were transferred to different genera of the Paniceae, such as Dichanthelium, Hymenachne, Phanopyrum, and Steinchisma, while the remaining American species of Panicum were temporarily placed as incertae sedis taxa. Therefore, these incertae sedis species are in need of a new taxonomic status within the tribe. In this study, the taxonomic position of Panicum aristellum, an endemic species of central and southeastern Brazil, is evaluated using morphological and anatomical characters, together with sequence data from ndhF, a molecular marker from the chloroplast. The sequence of Panicum aristellum was analyzed together with other species of the subfamily Panicoideae. This species grouped with the genus Canastra in a well-supported clade. Several synapomorphies characterized the clade: caespitose plants, keeled sheaths, aristate spikelets, scabrous bracts, the number of nerves of the glumes and lower lemma, the presence of a lower palea and lower flower, a non-indurate upper anthecium, and a similar geographical distribution. In addition, both species are C₃ with non-Kranz anatomy. As a result, the new combination Canastra aristella is proposed and the species is compared to putatively related genera within the Paniceae.

A new species, Panicum complanatum from southeastern Brazil is described and illustrated, including a key to distinguish it from similar taxa. Panicum complanatum belongs to Panicum subg. Panicum and is characterized mainly by the presence of a regular row of flattened, long hairs at the ventral base of the upper lemma and palea.

The phylogeny of the Elaeodendron group was inferred in a simultaneous analysis of morphological characters together with nuclear (ITS and 26S rDNA) and plastid (matK, trnL-F region) genes. The circumscription of genera in this group has long been controversial, particularly with respect to Cassine and Elaeodendron. Cassine, narrowly defined so as to include three species native to southern Africa, was unambiguously supported as distinct from Elaeodendron. The widely distributed genus Elaeodendron was supported as a natural group, sister to Pleurostylia. Brexia, which has been variously assigned to the Escalloniaceae, Brexiaceae, and Grossulariaceae, was unambiguously supported as the sister group to the clade of Elaeodendron and Pleurostylia. Preliminary species sampling supported Empleuridium, which had been classified within the Rutaceae, as closely related to Mystroxylon, Pseudosalacia, and Robsonodendron. Allocassine and Lauridia were resolved as closely related to one another, supporting their previously inferred relationship. Maurocenia and Cassine were supported as closely related to one another, with evidence for Maurocenia being nested within Cassine. Lydenburgia abbottii was resolved as closely related to Lydenburgia cassinoides, supporting its transfer from Catha. Three new combinations are made: Elaeodendron bupleuroides (Guillaumin) R.H. Archer, Elaeodendron parvifolium R.H. Archer, and Elaeodendron pininsulare Hürl. subsp. poyaense (I.H. Müller) R.H. Archer.

Nylandtia (Polygalaceae) is a small South African genus of two or more species distributed mainly in the Cape region. Previous studies based on anatomical, morphological and molecular data have already revealed a close relationship between Nylandtia and Muraltia, a genus of 117 species that is nearly endemic to South Africa. New evidence from molecular studies of family Polygalaceae and genus Muraltia shows that Nylandtia is derived from genus Muraltia, and is nested in Muraltia subgenus Psiloclada. These results have prompted a morphological re-evaluation of the genera Nylandtia and Muraltia, supporting the conclusion that the two species of Nylandtia currently recognized, N. spinosa and N. scoparia, should be included in subgenus Psiloclada within the genus Muraltia. Only one nomenclatural change is necessary: Muraltia spinosa (L.) F. Forest & J. C. Manning, comb. nov.

Enriquebeltrania, a genus of trees and shrubs endemic to Mexico, traditionally has been included in Euphorbiaceae (tribe Adelieae, subfamily Acalyphoideae). It was previously thought to be monotypic with a disjunct distribution on the Yucatan Peninsula and along the Pacific coast in Jalisco and Sinaloa. There is some question about whether Enriquebeltrania should be treated as distinct from Adelia. Morphological and molecular characters (trnL-F spacer and rbcL DNA sequences) were utilized in phylogenetic analyses to determine if Enriquebeltrania belongs to the tribe Adelieae, to test whether it should be recognized as a genus separate from Adelia, and to determine the number of species that should be recognized. Results indicate that Enriquebeltrania does not belong to tribe Adelieae, that it should be recognized as a genus separate from Adelia, and that it consists of two species. The second species, Enriquebeltrania disjuncta, is named and described here.

AFLP and morphological data were used to reconstruct the phylogeny of Polylepis (Rosaceae). Results from the morphological analysis correlate well with earlier hypotheses about the evolution of the genus, showing a transition from tall, thin-leaved trees with large inflorescences to small trees with thick leaves and reduced inflorescences. While a basic phylogenetic signal is also discernible in the AFLP analysis, it is partly eclipsed in that samples from different species sometimes cluster according to geographic proximity rather than systematic affiliation. This structure is interpreted as indicative of frequent hybridization and introgression.

We investigated the colonization of the Indian Ocean archipelago of Socotra through phylogenetic analysis of Aerva (Amaranthaceae) based on nuclear and plastid DNA sequence data. The biogeographic history of the genus was tracked using ancestral area reconstructions and molecular dating. Three independent colonization lineages from the Eritreo-Arabian subregion of the Sudano-Zambesian Region were revealed: one endemic clade comprising Aerva revoluta/A. microphylla and once within A. lanata and A. javanica. Our results provide further support for the dominance of Eritreo-Arabian affinities in the flora of Socotra, in contrast to more rare affinities to Madagascar, the Mascarenes, southern Africa, and tropical Asia. Our data point towards colonization via dispersal, rather than a vicariance origin of the island elements. The overall biogeographic patterns of Aerva show only limited concordance with other taxonomic groups distributed on Indian Ocean islands.

The Chenopodiaceae includes taxa with both C₃ and C₄ photosynthesis with diverse kinds of Kranz anatomy and single-celled C₄ species without Kranz anatomy; thus, it is of key importance for understanding evolution of C₄ photosynthesis. All of the C₄ genera except Atriplex, which belongs to Chenopodioideae, are in the Salicornioideae / Suaedoideae / Salsoloideae s.l. (including Camphorosmeae and Sclerolaeneae) clade. Our study focused on the relationships of the main lineages within this clade with an emphasis on the placement of the single cell functioning C₄ genus Bienertia using maximum parsimony, maximum likelihood, and Bayesian inference phylogenetic analyses of the nuclear ribosomal ITS and five chloroplast DNA regions (atpB-rbcL, matK, psbB-psbH, rbcL, and trnL-trnF). Further we provide a detailed phylogeny of Alexandra and Suaeda based on ITS, atpB-rbcL, and psbB-psbH. Our molecular data provide strong statistical support for the monophyly of: (1) a Salicornioideae / Suaedoideae / Salsoloideae s.l. clade; (2) a Salicornioideae / Suaedoideae clade; (3) the subfamilies Salicornioideae, Suaedoideae (including Bienertia) and Salsoloideae s.l.; (4) the tribes Suaedeae, Salsoleae, and Camphorosmeae; (5) the Salicornieae if Halopeplideae is included; and (6) Suaeda if Alexandra is included. Alexandra lehmannii is therefore reclassified as Suaeda lehmannii and a new section of Suaeda is created, section Alexandra. There are four independent origins of C₄ photosynthesis within the Suaedoideae including two parallel origins of Kranz C₄ anatomy (in Suaeda sections Salsina s.l. and Schoberia) and two independent origins of C₄ systems without Kranz anatomy (in Bienertia and in Suaeda section Borszczowia).

The delimitation of the genus Hoya, with at least 200 species distributed from India and China to Australia, from its closest relatives in the Marsdenieae has long been problematic, precluding an understanding of the evolution and biogeography of the genus. Traditional circumscriptions of genera in the Hoya alliance have relied on features of the flower, but these overlap extensively between clades and may be evolutionarily labile. We obtained chloroplast DNA sequences to infer the phylogenetic relationships among a sample of 35 taxa of Hoya and 11 other genera in the tribe Marsdenieae, namely Absolmsia, Cionura, Dischidia, Dregea, Gongronema, Gunnessia, Madangia, Marsdenia, Micholitzia, Rhyssolobium, and Telosma. Trees were rooted with representatives of Asclepiadeae, Ceropegieae, Fockeeae, Periplocoideae, and Secamonoideae. Hoya and Dischidia form a monophyletic group, but the phylogenetic signal in the chloroplast data analyzed here was insufficient to statistically support the mutual monophyly of the two genera. A monophyletic Hoya, however, must include the monotypic Absolmsia, Madangia, and Micholitzia, a result congruent with their flower morphology. The data also identified several well-supported groups within Hoya. The morphologically unusual Gunnessia belongs firmly in the Marsdenieae, but it is not close to Hoya and Dischidia.

Erato DC. contains five species, distributed from Costa Rica to Bolivia, with its main center of diversity in Ecuador. The revision includes a new species endemic to Costa Rica and Panama, Erato costaricensis E. Moran & V. A. Funk. Morphological and molecular data support Erato as a monophyletic group, sister to Philoglossa. The phylogenetic analysis based on morphology used Munnozia Ruiz & Pavon, Chrysactinium (H.B.K.) Wedd., and Philoglossa DC. as outgroups. The phylogeny supports the monophyly of Erato, but the relationships among the species within Erato have only weak support. The genus is believed to be a recent radiation because of the morphological similarity among the taxa and their location in some of the youngest areas of the Andes.

Hypochaeris is thought to have arrived in South America by dispersal over the Atlantic Ocean from NW Africa during the Pliocene or Pleistocene. We used amplified fragment length polymorphism (AFLP) to unravel specific limits and relationships in the South American group of Hypochaeris (c. 45 species). The Moroccan endemic Hypochaeris angustifolia, which is sister to the entire South American group, was used as outgroup. Our AFLP analysis comprises 415 individuals from 32 South American species and is based on six primer combinations with 670 fragments scored. It provides important information for the delimitation of species and detection of closely related species pairs or groups. Most species are monophyletic and supported with > 90% bootstrap proportion. Hybridization is suggested between Hypochaeris chillensis and H. microcephala in Brazil. The internal nodes (or “backbone”) of the tree are not highly supported, but six major phylogenetic groups (also showing similarity in distribution and growth form) center around Hypochaeris apargioides, H. chondrilloides, H. microcephala, H. pampasica, H. sessiliflora, and H. tenuifolia. These results suggest that rapid migration into different geographical regions played an important role in the initial diversification of Hypochaeris in South America.