The occurrence of reticulations in the evolutionary history of species poses serious challenges for all modern practitioners of phylogenetic analysis. Such events, including hybridization, introgression, and lateral gene transfer, lead to evolutionary histories that cannot be adequately represented in the form of phylogenetic trees. Although numerous methods that allow for the reconstruction of phylogenetic networks have been proposed in recent years, the detection of reticulations still remains problematic. In this paper we present a Hybrid Detection Criterion (HDC) along with a statistical procedure that allows for the identification of hybrid taxa. The test assesses whether a putative hybrid is consistently intermediate between its postulated parents, with respect to the other taxa. The performance of the statistical method is evaluated using known hybrids of the genus Aphelandra (Acanthaceae) using two network methods: reticulograms and split decomposition graphs. Our results indicate that the HDC test is reliable when used jointly with split decomposition. On the other hand, the test lacks power and provides misleading results when using reticulograms. We then show how the procedure can be used as a tool to identify putative hybrids.

Using six plastid regions, we present a phylogeny for 26 species of the heterosporous fern genus Marsilea. Two well-supported groups within Marsilea are identified. Group I includes two subgroups, and is relatively species-poor. Species assignable to this group have glabrous leaves (although land leaves may have a few hairs), sporocarps lacking both a raphe and teeth, and share a preference for submerged conditions (i.e., they are intolerant of desiccation). Group II is relatively diverse, and its members have leaves that are pubescent, sporocarps that bear a raphe and from zero to two teeth, and the plants are often emergent at the edges of lakes and ponds. Within Group II, five subgroups receive robust support: three are predominantly African, one is New World, and one Old World. Phylogenetic assessment of morphological evolution suggests that the presence of an inferior sporocarp tooth and the place of sporocarp maturation are homoplastic characters, and are therefore of unreliable taxonomic use at an infrageneric level. In contrast, the presence of a raphe and superior sporocarp tooth are reliable synapomorphies for classification within Marsilea.

Polystichum has often been treated as a sub-cosmopolitan genus of 180-230 species (i.e., Polystichum s.l.), but several segregate genera, such as Cyrtogonellum, Cyrtomidictyum, Cyrtomium, Phanerophlebia, and Sorolepidium, have been recognized in various treatments. Together, these genera constitute the polystichoid ferns. We used a data set of 47 species of the polystichoid ferns and three outgroups, including new Rbcl sequences for six species in Asia, to address their phylogeny. Maximum-parsimony (MP) and Bayesian inference analyses were performed. The polystichoid ferns were resolved to include four major clades, the tropical American Phanerophlebia clade, the Cyrtomium s.s. clade, the Polystichum s.s. clade, and an eastern Asian clade containing Cyrtomium subser. Balansana, Cyrtogonellum, three sections of Polystichum, and Cyrtomidictyum (the BCPC clade). The Cyrtomium s.s. clade included 15 species of the genus but excluded subser. Balansana. The Polystichum s.s. clade was resolved as being monophyletic with relatively low bootstrap support, as long as Sorolepidium is included in Polystichum. The overall topology retrieved by the Bayesian analysis was similar to that of the MP tree, but generally had higher internal support. Based on the molecular phylogeny, three sections of Polystichum s.l., i.e., sect. Sphaenopolystichum, sect. Haplopolystichum, and sect. Crucifilix, may be more closely related to other members of the BCPC group. The eastern Asian BCPC group shared once-pinnate fronds, except for Polystichum sect. Sphaenopolystichum. Morphologically, once-pinnate leaf dissection and reticulate venation appear to be ancestral in the polystichoid ferns.

Subtribe Bletiinae (Epidendreae, Orchidaceae) is comprised of three neotropical, terrestrial, deciduous genera: Basiphyllaea, Bletia and Hexalectris. Basiphyllaea and Bletia are chlorophyllous, while Hexalectris is mycoheterotrophic. Morphological, molecular (ITS and trnL-F IGS DNA sequences) and combined phylogenetic analyses of subtribe Bletiinae were done to estimate the relationships of the genera and species. The best supported hypothesis of relationships was retrieved from the ITS analysis, which included more taxa than the combined analyses and had more phylogenetically informative characters. Basiphyllaea and Hexalectris are closely related and further studies are recommended to clarify the limits of these genera. In subtribe Blettiinae achlorophyllous plants are derived from chlorophyllous plants and plicate leaves are derived from conduplicate leaves. With regard to stems, coralloid stems were derived from tuberoid stems with small shoots.

In the present study, several multivariate analyses were carried out to assess the taxonomic relationships among European species of the genus Anthoxanthum. A total of 1787 Anthoxanthum specimens representing all European taxa were analyzed. Thirty macro-morphological (13 quantitative and 17 qualitative) and 29 micro-morphological (7 quantitative and 22 qualitative) characters were considered. First, resemblances between specimens were established independently for macro- and micro-morphological characters using Gower's similarity coefficient, and were represented by means of principal coordinates and cluster analyses. Subsequently, different multivariate analyses were applied to quantitative and qualitative macromorphological data to determine the most discriminant characters and the accuracy of the present taxonomic structure of the genus. Finally, dissimilarities among groups of individuals –species and populations- were estimated using the information radius measure and then represented in different dendrograms. Within annuals, Anthoxanthum gracile is clearly differentiated morphologically, yet no compelling morphological differentiation can be found between Anthoxanthum aristatum and Anthoxanthum ovatum. Moreover, the definition of subspecies in the annual taxa is not supported by our results. Then, within perennials, although the morphological relationships among Anthoxanthum amarum, Anthoxanthum odoratum and Anthoxanthum alpinum have also been resolved, further research is needed to assess the taxonomic position of the Macaronesian endemic Anthoxanthum maderense.

This study comprised a scanning electron microscope survey of abaxial epidermal features in subfamily Danthonioideae, with emphasis on North American Danthonia. The survey included 21 taxa, encompassing seven genera (Austrodanthonia, Cortaderia, Danthonia, Merxmuellera, Notodanthonia, Rytidosperma, Tribolium) and the eight North American Danthonia species. We investigated micromorphological characters to determine taxonomic utility and whether North American representatives of Danthonia are distinct. We examined micromorphological epidermal features: macrohairs, bicellular microhairs, prickle hairs, silica bodies, and stomata. We found no distinguishing characters at the subfamilial level. Danthonia is characterized by the absence of abaxial stomata and presence of bicellular microhairs with basal and terminal cells of equal length and microhairs with long basal cells relative to terminal cells. Prickle hairs in the abaxial epidermal costal regions of four species of North American Danthonia are reported for the first time.

Phylogenetic relationships among subfamilies of the well supported PACCAD clade of Poaceae remain uncertain. Several genera such as Micraira and Eriachne were considered incertae sedis in the most recent subfamilial classification of the grasses, but these two genera formed a well-supported clade in an analysis based on chloroplast and structural data. Another genus, Isachne, traditionally classified in the Panicoideae, also formed part of this well-supported clade. Despite strong molecular support for the clade, thus far no morphological synapomorphy has been found. Nevertheless, the strongly supported monophyly of this clade allowed us to suggest the recognition of a new subfamily within the PACCAD clade. Since there was already a name available, in this paper we propose the reinstatement and emendation of the circumscription of Micrairoideae. The reinstatement of Micrairoideae changes the acronym PACCAD to PACCMAD for this large clade of grasses.

Using ITS and atpB-rbcL spacer sequences of 38 (of 55) species of the highly disjunct Eurasian/North African Epimedium and all three species of its western North American sister genus Vancouveria, we reconstructed the phylogeny of these two genera and dated major splits with a molecular clock approach. Epimedium was found to be monophyletic with a stem age dated to between 9.7 and 7.4 million years ago (My). Within Epimedium, almost all sections as recognized in the most recent classification of the genus were found to be monophyletic but subg. Epimedium was found to be paraphyletic in relation to subg. Rhizophyllum. Range formation in Eurasia proceeded as follows: in a first step, the western Himalayan part of the generic distribution area (sect. Polyphyllon) was separated from the remainder, followed by a split between the Chinese distribution area (sect. Diphyllon) and the remainder, the separation of the highly disjunct range of E. pinnatum from the Caucasus plus E. perralderianum from North Africa (subg. Rhizophyllum) and the remainder, and in a last step the separation of the European E. alpinum plus the Turkish E. pubigerum from the range of the genus in Japan, Korea, northeastern China and Far Eastern Russia (sects. Epimedium and Macroceras). These results imply that the European mountain species are not most closely related to taxa in mountain areas towards the east (e.g., Caucasus, Himalayas) but rather to taxa in the Far East. Accordingly, in Epimedium the link between western Eurasia and eastern Asia apparently was not through intervening mountain regions but probably through a more northerly deciduous forest belt which does not exist any longer. The largest number of species of Epimedium is found in China (sect. Diphyllon: 44 species mainly in Hubei, Sichuan and Guizhou provinces). The age of this clade was dated to 0.52 to 0.4 My. This implies that the diversification of this group probably is the result of frequent range shifts in the Quaternary.

Geranium subsect. Mediterranea (Geraniaceae) consists of ten species. The highest diversity of the group is located in the Caucasus and neighbouring areas of Turkey and Iran, with five endemic species. Other species reach western Europe and northwestern Africa. In contrast to the current literature, we consider G. montanum and G. ibericum subsp. jubatum to be synonyms of G. ibericum. A univariate morphometric study revealed some valuable quantitative characters useful for the identification of these species. Micromorphological features of pollen, stigmas, seeds, and mericarps were investigated by SEM. A new key is provided, as well as new and detailed descriptions. Geranium kurdicum is here illustrated for the first time. Eleven lectotypes are designated, and distribution maps are presented. Maximum parsimony and Bayesian analyses of chloroplastic trnL-trnF and ribosomal nuclear ITS regions suggest that sect. Mediterranea is monophyletic. Two clades are recovered, one including the annual species and other with the perennials, in which G. tuberosum (subsect. Tuberosa) emerges within a paraphyletic subsect. Mediterranea.

The disjunction of the mesic coniferous forests of the Pacific Northwest (PNW) has long been of interest to biogeographers, and several hypotheses have been posed to explain the disjunct distribution pattern. Analysis of intraspecific chloroplast DNA variation (1785 bp of matK and 400 bp of rpl16) in Salix melanopsis allows these hypotheses to be tested. Our study confirmed the existence of three genetic races (uncorrected sequence divergence ranged from 0.7-1.1%) within the species, which differ in distribution and ecology. The mesic race, associated with mesic coniferous forests, was the focus of this study. This race consists of two major lineages (uncorrected sequence divergence ranged up to 0.28%), one of which is associated with an apparent glacial refugium south of glaciation in the northern Rocky Mountains. The three haplotypes that comprise the first lineage are largely segregated into separate river canyons that comprise the “Greater Clearwater Refugium”. The other major lineage includes three haplotypes that occur throughout the PNW, except in the core of the Clearwater refugium. Vicariance is implicated in the origin of this latter lineage. Dispersal both before and during the Holocene appears to have occurred: the colonization of the Cascade Range from the Rocky Mountains, and later the dispersal of the Cascade haplotype into the area formerly buried by Cordilleran ice. More limited dispersal of Rocky Mountain haplotypes has resulted in contact zones with elevated haplotype diversity. The results of this study allow us to refine previous phylogeographic hypotheses of the PNW. Phylogenetic relationships within Salix sect. Longifoliae, the group that includes S. melanopsis, were also inferred. The sequence data produced phylogenetic hypotheses that were congruent with those obtained from an earlier analysis of cpDNA restriction site data.

In 2002, a monophyletic group previously unrecognized within Brassicaceae was identified through phylogenetic analysis of morphological characters in combination with data from three DNA sequences (Bailey et al.: Syst. Bot. 27: 318–332). As understood at that time, the halimolobine alliance (herein tribe Halimolobeae) comprised ca. 44 species from Halimolobos, Mancoa, Pennellia, and Sphaerocardamum. Within this group, a number of nomenclatural problems have remained unaddressed, including the polyphyly of both Halimolobos and Mancoa. With a developing understanding of Brassicaceae phylogeny, the Halimolobeae is robust in the context of higher level analyses and therefore in need of formal nomenclatural revision. The present study uses new and existing data in phylogenetic analyses based on trnL-F, ITS, and pistillata intron 1 data along with SEM studies of Synthlipsis elata and S. greggii to provide the bases for recircumscription of taxa assigned to the Halimolobeae. As recognized herein, the tribe includes five genera [Exhalimolobos, Halimolobos (including Synthlipsis elata), Mancoa, Pennellia, and Sphaerocardamum] and 39 species with two centers of distribution, one in north-central Mexico and the other in the Andes. A synopsis and keys to all taxa of the tribe are presented. Fifteen new combinations are proposed (E. arabioides, E. berlandieri, E. burkartii, E. hispidulus, E. palmeri, E. parryi, E. pazense, E. polyspermus, E. weddellii, H. elatus, H. henricksonii, H. pubens, H. stylosus, P. lechleri, and P. parvifolia).

Palaua, a genus of 15 species endemic to the fog-influenced lomas formations amidst the coastal deserts of Peru and Chile, is characterized by its unique irregularly arranged, superimposed carpels. The only exception to this character is P. sandemanii, which has carpels arranged in a single whorl, the state observed in the potential sister groups. To investigate the monophyly of Palaua and to compare previous infrageneric classifications in a phylogenetic framework, parsimony and Bayesian analyses were performed using plastid (psbA-trnH intergenic spacer) and nuclear (internal transcribed spacers 1 and 2) DNA sequences. There is evidence for three clades within a monophyletic Palaua: one comprising the two small-flowered species, P. inconspicua and P. modesta, as sister to the rest of the genus, a second uniting all species with dissected leaves, and a third containing the rest of the genus (species with entire to shallowly lobed leaves; except P. guentheri). In contrast to our expectations, P. sandemanii could not be confirmed as sister to the rest of the genus, but rather is nested within a monophyletic Palaua. Parsimony-based reconstruction of the evolution of carpel arrangement showed that there was a change in Palaua from superimposed, irregularly arranged carpels to uniseriate carpels in P. sandemanii; however, Templeton and Shimodaira-Hasegawa tests did not reject the alternative hypothesis that the uniseriate carpels are ancestral. Besides carpel arrangement, leaf division (and not growth form) seems to be an appropriate character for infrageneric classification.

Morphological and molecular data were analyzed using parsimony to trace character evolution within Anagallis s.l., including Anagallis, Asterolinon, Pelletiera, Lysimachia nemorum, and L. serpyllifolia, which are distributed among two sister clades. The first clade, comprising Anagallis arvensis, A. foemina, A. monelli, Asterolinon, Pelletiera, Lysimachia nemorum, and L. serpyllifolia is supported by synapomorphies such as an annual, repeatedly branching habit, sessile leaves, flowers in almost all leaf axils, and membranous slightly dentate calyx margins, of which all but the last are homoplasious within Anagallis s.l.. The second clade, comprising Anagallis species only, is supported by a large number of synapomorphies, of which the majority are floral features. Placement of ten taxa, for which no DNA was available, is proposed based on morphological characters evaluated in the light of the result of the phylogenetic analysis of sequenced taxa.

Five new species of Gonolobus (Apocynaceae: Asclepiadoideae) are described from the Lesser Antilles: G. absalonensis, G. dussii, G. iyanolensis, G. waitukubuliensis, and G. youroumaynensis. The species exhibit distinct differences in floral characters, including the structure of corolline and gynostegial coronas. Gonolobus martinicensis is lectotypified. A key to Gonolobus in the Lesser Antilles is provided.

Labordia lorenciana is described and illustrated from Kaua'i, Hawai'i, U.S.A. This new species most closely resembles the O'ahu endemic species Labordia kaalae C. N. Forbes, from which it differs in having leaf bases deeply cordate to auriculate, adaxial leaf surfaces puberulent, and fruit valves 25–37 mm long, and longitudinally striate. Known from only four individuals, Labordia lorenciana is amongst ca. 120 other rare Hawaiian taxa that are limited to less than 50 individuals and is currently being cultivated for conservation.

We here describe and illustrate the new species Solanum humboldtianum Granados-Tochoy & S. Knapp and evaluate its conservation status. The species can be categorized as endangered (EN) and is threatened by urban and agricultural expansion and deforestation and is the first Colombian species of Solanum to receive this status. Solanum humboldtianum was first collected by the great naturalists Alexander von Humboldt and Aimée Bonpland in the early part of the 19^th century, but the specimens have lain unrecognised in herbaria for over 200 years. We document phenology, distribution and other ecological data for the species, and discuss the importance of the unification of herbarium work and in-depth field study of rare taxa such as this. We also discuss the relevance of older collections to the study of biodiversity and conservation today.

Phylogeny reconstructions based on DNA sequences from nuclear ribosomal internal and external transcribed spacers and plastid trnT-trnF regions were used to examine the taxonomy and biogeography of North American Gaillardia (Asteraceae). Phylogenetic analyses based on maximum parsimony, maximum likelihood and Bayesian inference criteria consistently recovered several well-supported clades. Gaillardia comosa, G. gypsophila, and G. suavis, forming sect. Agassizia, were placed sister to the rest of Gaillardia, in which the two major clades correspond to sects. Gaillardia and Hollandia. Section Hollandia consists of the Gulf Coast G. aestivalis complex. Three major, well supported clades were consistently recovered in sect. Gaillardia: (1) G. multiceps and G. turneri were sister to an Intermountain clade of G. parry, G. spathulata, and G. flava; (2) a paraphyletic G. pinnatifida and G. arizonica; and (3) G. pulchella, G. aristata, G. amblyodon, G. coahuilensis, G. mexicana, G. henricksonii, and G. powellii. Dispersal-Vicariance Analysis reconstructed a Chihuahuan Desert origin for Gaillardia, an inference consistent with earlier hypotheses. Major range expansions in Gaillardia included the following: (1) eastward expansion into central Texas and along the Gulf Coast in sect. Hollandia; (2) northwestern expansion, resulting ultimately in the Intermountain clade, but including also G. multiceps and G. turneri; (3) northward expansion of the G. pinnatifida complex; (4) easterly and especially northward expansion of G. amblyodon, G. pulchella, and G. aristata; and, possibly, (5) northward expansion onto the Great Plains by G. suavis.