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Morphological and molecular phylogenetic evidence indicate that Eleutherostylis Burret (Malvaceae, Grewioideae), a monotypic genus described from New Guinea, is best considered a synonym of Grewia L., a species-rich genus widespread across the Paleotropics and found in Africa, Arabia, Asia, Australia and the western Pacific. A new combination, based on E.renistipulata Burret, G.renistipulata (Burret) Dorr, comb. nov. , is proposed. Original material of the basionym could not be located and a neotype is designated. A lectotype is designated for G.morotaiensis Kosterm., a synonym of G.renistipulata ., Competing Interests: The authors have declared that no competing interests exist.

Bahiana is expanded from 1 to 2 species with the description of B.occidentalis K. Wurdack, sp. nov. as a new endemic of the seasonally dry tropical forests (SDTFs) of Peru. The disjunct distribution of Bahiana with populations of B.occidentalis on opposite sides of the Andes in northwestern Peru (Tumbes, San Martín) and B.pyriformis in eastern Brazil (Bahia) adds to the phytogeographic links among the widely scattered New World SDTFs. Although B.occidentalis remains imperfectly known due to the lack of flowering collections, molecular phylogenetic results from four loci (plastid matK , rbcL , and trnL-F ; and nuclear ITS) unite the two species as does gross vegetative morphology, notably their spinose stipules, and androecial structure. Spinescence in Euphorbiaceae was surveyed and found on vegetative organs in 25 genera, which mostly have modified sharp branch tips. Among New World taxa, spines that originate from stipule modifications only occur in Bahiana and Acidocroton , while the intrastipular spines of Philyra are of uncertain homologies.

Monadelpha L.J.Gillespie & Card.-McTeag., gen. nov. , is described as a new member of Euphorbiaceae tribe Plukenetieae subtribe Tragiinae, to accommodate Tragia guayanensis , a species known from western Amazonas, Venezuela and, newly reported here, from Amazonas, Brazil. The genus is unique in the subtribe for having 5-colpate pollen and staminate flowers with filaments entirely connate into an elongate, cylindrical staminal column terminated by a tight cluster of anthers. Phylogenetic analyses based on nuclear rDNA ITS and sampling 156 accessions across the diversity of Tragiinae (all 12 genera and 77 of ~195 species) also support Monadelpha as a distinct lineage that is separate from Tragia . A revised key to the genera of Tragiinae in South America and Central America is provided.

Pseudoflower formation is arguably the rarest outcome of a plant-fungus interaction. Here we report on a novel putative floral mimicry system in which the pseudoflowers are composed entirely of fungal tissues in contrast to modified leaves documented in previous mimicry systems. Pseudoflowers on two perennial Xyris species (yellow-eyed grass, X. setigera and X. surinamensis) collected from savannas in Guyana were produced by Fusarium xyrophilum, a novel Fusarium species. These pseudoflowers mimic Xyris flowers in gross morphology and are ultraviolet reflective. Axenic cultures of F. xyrophilum produced two pigments that had fluorescence emission maxima in light ranges that trichromatic insects are sensitive to and volatiles known to attract insect pollinators. One of the volatiles emitted by F. xyrophilum cultures (i.e., 2-ethylhexanol) was also detected in the head space of X. laxifolia var. iridifolia flowers, a perennial species native to the New World. Results of microscopic and PCR analyses, combined with examination of gross morphology of the pseudoflowers, provide evidence that the fungus had established a systemic infection in both Xyris species, sterilized them and formed fungal pseudoflowers containing both mating type idiomorphs. Fusarium xyrophilum cultures also produced the auxin indole-3-acetic acid (IAA) and the cytokinin isopentenyl adenosine (iPR). Field observations revealed that pseudoflowers and Xyris flowers were both visited by bees. Together, the results suggest that F. xyrophilum pseudoflowers are a novel floral mimicry system that attracts insect pollinators, via visual and olfactory cues, into vectoring its conidia, which might facilitate outcrossing of this putatively heterothallic fungus and infection of previously uninfected plants., (Copyright © 2020 Elsevier Inc. All rights reserved.)

We report on the discovery and characterization of a novel Fusarium species that produced yellow-orange pseudoflowers on Xyris spp. (yellow-eyed grass; Xyridaceae) growing in the savannas of the Pakaraima Mountains of western Guyana. The petaloid fungal structures produced on infected plants mimic host flowers in gross morphology. Molecular phylogenetic analyses of full-length RPB1 (RNA polymerase largest subunit), RPB2 (RNA polymerase second largest subunit), and TEF1 (elongation factor 1-α) DNA sequences mined from genome sequences resolved the fungus, described herein as F. xyrophilum , sp. nov., as sister to F. pseudocircinatum within the African clade of the F. fujikuroi species complex. Results of a polymerase chain reaction (PCR) assay for mating type idiomorph revealed that single-conidial isolates of F. xyrophilum had only one of the MAT idiomorphs ( MAT1-1 or MAT1-2 ), which suggests that the fungus may have a heterothallic sexual reproductive mode. BLASTn searches of whole-genome sequence of three strains of F. xyrophilum indicated that it has the genetic potential to produce secondary metabolites, including phytohormones, pigments, and mycotoxins. However, a polyketide-derived pigment, 8- O -methylbostrycoidin, was the only metabolite detected in cracked maize kernel cultures. When grown on carnation leaf agar, F. xyrophilum is phenotypically distinct from other described Fusarium species in that it produces aseptate microconidia on erect indeterminate synnemata that are up to 2 mm tall and it does not produce multiseptate macroconidia.

The systematics of Tryssophyton , herbs endemic to the Pakaraima Mountains of western Guyana, is reviewed and Tryssophyton quadrifolius K.Wurdack & Michelang., sp. nov. from the summit of Kamakusa Mountain is described as the second species in the genus. The new species is distinguished from its closest relative, Tryssophyton merumense , by striking vegetative differences, including number of leaves per stem and leaf architecture. A phylogenetic analysis of sequence data from three plastid loci and Melastomataceae-wide taxon sampling is presented. The two species of Tryssophyton are recovered as monophyletic and associated with mostly Old World tribe Sonerileae. Fruit, seed and leaf morphology are described for the first time, biogeography is discussed and both species are illustrated.

Humiriaceae have had little recent comparative morphological study except for their distinctive fruits. We surveyed the diversity of stamen structures in the family with consideration of dehiscence patterns and the evolutionary transitions between tetra- and disporangiate anthers. Novel interpretations of floral morphology support new combinations ( Duckesialiesneri K.Wurdack & C.E.Zartman, comb. nov. and Vantaneaspiritu-sancti K.Wurdack & C.E.Zartman, comb. nov. ) for two species formerly in Humiriastrum . We investigated all eleven species of Sacoglottis for diagnostic features that may contribute to better species delimitations, and describe Sacoglottisperryi K.Wurdack & C.E.Zartman, sp. nov. as an endemic of the Pakaraima Mountains in western Guyana. Finally, our survey across Humiriaceae for extrafloral nectaries (EFNs) revealed their presence on leaves of all extant species as adaxial basilaminar and/or abaxial embedded glands, in addition to the frequent occurrence of marginal glandular setae. The significance of inter-generic variation in gland position and anther morphology within the family are discussed.

Background: Plukenetia is a small pantropical genus of lianas and vines with variably sized edible oil-rich seeds that presents an ideal system to investigate neotropical and pantropical diversification patterns and seed size evolution. We assessed the biogeography and seed evolution of Plukenetia through phylogenetic analyses of a 5069 character molecular dataset comprising five nuclear and two plastid markers for 86 terminals in subtribe Plukenetiinae (representing 20 of ~ 23 Plukenetia species). Two nuclear genes, KEA1 and TEB, were used for phylogenetic reconstruction for the first time. Our goals were: (1) produce a robust, time-dependent evolutionary framework for Plukenetia using BEAST; (2) reconstruct its biogeographical history with ancestral range estimation in BIOGEOBEARS; (3) define seed size categories; (4) identify patterns of seed size evolution using ancestral state estimation; and (5) conduct regression analyses with putative drivers of seed size using the threshold model., Results: Plukenetia was resolved into two major groups, which we refer to as the pinnately- and palmately-veined clades. Our analyses suggest Plukenetia originated in the Amazon or Atlantic Forest of Brazil during the Oligocene (28.7 Mya) and migrated/dispersed between those regions and Central America/Mexico throughout the Miocene. Trans-oceanic dispersals explain the pantropical distribution of Plukenetia, including from the Amazon to Africa in the Early Miocene (17.4 Mya), followed by Africa to Madagascar and Africa to Southeast Asia in the Late Miocene (9.4 Mya) and Pliocene (4.5 Mya), respectively. We infer a single origin of large seeds in the ancestor of Plukenetia. Seed size fits a Brownian motion model of trait evolution and is moderately to strongly associated with plant size, fruit type/dispersal syndrome, and seedling ecology. Biome shifts were not drivers of seed size, although there was a weak association with a transition to fire prone semi-arid savannas., Conclusions: The major relationships among the species of Plukenetia are now well-resolved. Our biogeographical analyses support growing evidence that many pantropical distributions developed by periodic trans-oceanic dispersals throughout the Miocene and Pliocene. Selection on a combination of traits contributed to seed size variation, while movement between forest edge/light gap and canopy niches likely contributed to the seed size extremes in Plukenetia.

Eriolaenarulkensii Dorr, sp. nov . is described and illustrated. This attractive shrub is endemic to coastal Mozambique. The new species has apically winged seeds, which place it in a group of Malvaceae (Dombeyoideae) that is found in Asia and Madagascar and which had not previously been found in continental Africa.

Andeimalvaperuviana Dorr & C.Romero, sp. nov. , the third Peruvian endemic in a small genus of five species, is described and illustrated from a single collection made at high elevation on the eastern slopes of the Andes. Molecular phylogenetic analyses of nuclear ribosomal ITS sequence data resolve a group of northern species of Andeimalva found in Bolivia and Peru from the morphologically very different southern A.chilensis . The new species bears the largest flowers of any Andeimalva and is compared with Bolivian A.mandonii . A revised key to the genus is presented.

Raveniopsis microphyllus K.Wurdack, sp. nov. , a new species known only from a single peak in the Pakaraima Mtns. of Guyana, is described and illustrated. This white-flowered shrub adds to the many narrow-endemic Guiana Shield species in the genus, and is unique in bearing small, trifoliate, sclerophyllous leaves. Leaf anatomy and surface micromorphology of the new species were examined to document its montane adaptations. The multiple trichome types of the leaves and flowers of new species were characterized, and the systematics value of the considerable foliar trichome variation in Raveniopsis is discussed.

Dendrothrix condorensis K.Wurdack, sp. nov. from the sub-Andean cordilleras of Ecuador and Peru is described and illustrated. The new species is geographically widely separated from its likely closest relative, D. yutajensis , which is endemic to the Guiana Shield region of southern Venezuela and adjacent Brazil, and notably differs in leaf morphology. Vegetative (i.e., epidermal micropapillae, trichomes) and reproductive (i.e., cymule glands, flowers, pollen) micromorphological features were examined with SEM. Rare tristaminate flowers were documented among the typical bistaminate ones. Seeds and diagnostic features among the four species of Dendrothrix are compared.

Incadendron esseri K.Wurdack & Farfan, gen. & sp. nov. , from the wet sub-Andean cordilleras of Ecuador (Cordillera del Cóndor) and Peru (Cusco, Oxapampa) is described and illustrated. This recently discovered large canopy tree with a narrow elevational range presents an unusual combination of rare morphological characters in Hippomaneae including mucilage-secreting sheathing stipules, conduplicate ptyxis, and large, woody fruits. The broader significance of these characters in Hippomaneae is discussed. The morphology and anatomy of Incadendron were investigated, highlighting its fruit similarities with Guiana Shield endemic Senefelderopsis , and the systematics value of ptyxis variation, which remains poorly studied for the family.

The mid-Cenozoic decline of atmospheric CO2 levels that promoted global climate change was critical to shaping contemporary arid ecosystems. Within angiosperms, two CO2 -concentrating mechanisms (CCMs)-crassulacean acid metabolism (CAM) and C4 -evolved from the C3 photosynthetic pathway, enabling more efficient whole-plant function in such environments. Many angiosperm clades with CCMs are thought to have diversified rapidly due to Miocene aridification, but links between this climate change, CCM evolution, and increased net diversification rates (r) remain to be further understood. Euphorbia (∼2000 species) includes a diversity of CAM-using stem succulents, plus a single species-rich C4 subclade. We used ancestral state reconstructions with a dated molecular phylogeny to reveal that CCMs independently evolved 17-22 times in Euphorbia, principally from the Miocene onwards. Analyses assessing among-lineage variation in r identified eight Euphorbia subclades with significantly increased r, six of which have a close temporal relationship with a lineage-corresponding CCM origin. Our trait-dependent diversification analysis indicated that r of Euphorbia CCM lineages is approximately threefold greater than C3 lineages. Overall, these results suggest that CCM evolution in Euphorbia was likely an adaptive strategy that enabled the occupation of increased arid niche space accompanying Miocene expansion of arid ecosystems. These opportunities evidently facilitated recent, replicated bursts of diversification in Euphorbia., (© 2014 The Author(s). Evolution © 2014 The Society for the Study of Evolution.)

The angiosperm order Malpighiales includes ~16,000 species and constitutes up to 40% of the understory tree diversity in tropical rain forests. Despite remarkable progress in angiosperm systematics during the last 20 y, relationships within Malpighiales remain poorly resolved, possibly owing to its rapid rise during the mid-Cretaceous. Using phylogenomic approaches, including analyses of 82 plastid genes from 58 species, we identified 12 additional clades in Malpighiales and substantially increased resolution along the backbone. This greatly improved phylogeny revealed a dynamic history of shifts in net diversification rates across Malpighiales, with bursts of diversification noted in the Barbados cherries (Malpighiaceae), cocas (Erythroxylaceae), and passion flowers (Passifloraceae). We found that commonly used a priori approaches for partitioning concatenated data in maximum likelihood analyses, by gene or by codon position, performed poorly relative to the use of partitions identified a posteriori using a Bayesian mixture model. We also found better branch support in trees inferred from a taxon-rich, data-sparse matrix, which deeply sampled only the phylogenetically critical placeholders, than in trees inferred from a taxon-sparse matrix with little missing data. Although this matrix has more missing data, our a posteriori partitioning strategy reduced the possibility of producing multiple distinct but equally optimal topologies and increased phylogenetic decisiveness, compared with the strategy of partitioning by gene. These approaches are likely to help improve phylogenetic resolution in other poorly resolved major clades of angiosperms and to be more broadly useful in studies across the Tree of Life.

Background: Recent studies have shown that plant genomes have potentially undergone rampant horizontal gene transfer (HGT). In plant parasitic systems HGT appears to be facilitated by the intimate physical association between the parasite and its host. HGT in these systems has been invoked when a DNA sequence obtained from a parasite is placed phylogenetically very near to its host rather than with its closest relatives. Studies of HGT in parasitic plants have relied largely on the fortuitous discovery of gene phylogenies that indicate HGT, and no broad systematic search for HGT has been undertaken in parasitic systems where it is most expected to occur., Results: We analyzed the transcriptomes of the holoparasite Rafflesia cantleyi Solms-Laubach and its obligate host Tetrastigma rafflesiae Miq. using phylogenomic approaches. Our analyses show that several dozen actively transcribed genes, most of which appear to be encoded in the nuclear genome, are likely of host origin. We also find that hundreds of vertically inherited genes (VGT) in this parasitic plant exhibit codon usage properties that are more similar to its host than to its closest relatives., Conclusions: Our results establish for the first time a substantive number of HGTs in a plant host-parasite system. The elevated rate of unidirectional host-to- parasite gene transfer raises the possibility that HGTs may provide a fitness benefit to Rafflesia for maintaining these genes. Finally, a similar convergence in codon usage of VGTs has been shown in microbes with high HGT rates, which may help to explain the increase of HGTs in these parasitic plants.

Although much attention has been paid to the role of stabilizing selection, empirical analyses testing the role of developmental constraints in evolutionary stasis remain rare, particularly for plants. This topic is studied here with a focus on the evolution of a pollen ontogenetic feature, the last points of callose deposition (LPCD) pattern, involved in the determination of an adaptive morphological pollen character (aperture pattern). The LPCD pattern exhibits a low level of evolution in eudicots, as compared to the evolution observed in monocots. Stasis in this pattern might be explained by developmental constraints expressed during male meiosis (microsporogenesis) or by selective pressures expressed through the adaptive role of the aperture pattern. Here, we demonstrate that the LPCD pattern is conserved in Euphorbiaceae s.s. and that this conservatism is primarily due to selective pressures. A phylogenetic association was found between the putative removal of selective pressures on pollen morphology after the origin of inaperturate pollen, and the appearance of variation in microsporogenesis and in the resulting LPCD pattern, suggesting that stasis was due to these selective pressures. However, even in a neutral context, variation in microsporogenesis was biased. This should therefore favour the appearance of some developmental and morphological phenotypes rather than others., (© 2012 The Authors. Journal of Evolutionary Biology © 2012 European Society For Evolutionary Biology.)

Euphorbia is among the largest genera of angiosperms, with about 2000 species that are renowned for their remarkably diverse growth forms. To clarify phylogenetic relationships in the genus, we used maximum likelihood, bayesian, and parsimony analyses of DNA sequence data from 10 markers representing all three plant genomes, averaging more than 16kbp for each accession. Taxon sampling included 176 representatives from Euphorbioideae (including 161 of Euphorbia). Analyses of these data robustly resolve a backbone topology of four major, subgeneric clades--Esula, Rhizanthium, Euphorbia, and Chamaesyce--that are successively sister lineages. Ancestral state reconstructions of six reproductive and growth form characters indicate that the earliest Euphorbia species were likely woody, non-succulent plants with helically arranged leaves and 5-glanded cyathia in terminal inflorescences. The highly modified growth forms and reproductive features in Euphorbia have independent origins within the subgeneric clades. Examples of extreme parallelism in trait evolution include at least 14 origins of xeromorphic growth forms and at least 13 origins of seed caruncles. The evolution of growth form and inflorescence position are significantly correlated, and a pathway of evolutionary transitions is supported that has implications for the evolution of Euphorbia xerophytes of large stature. Such xerophytes total more than 400 species and are dominants of vegetation types throughout much of arid Africa and Madagascar., (Published by Elsevier Inc.)

Premise of the Study: Recent analyses employing up to five genes have provided numerous insights into angiosperm phylogeny, but many relationships have remained unresolved or poorly supported. In the hope of improving our understanding of angiosperm phylogeny, we expanded sampling of taxa and genes beyond previous analyses., Methods: We conducted two primary analyses based on 640 species representing 330 families. The first included 25260 aligned base pairs (bp) from 17 genes (representing all three plant genomes, i.e., nucleus, plastid, and mitochondrion). The second included 19846 aligned bp from 13 genes (representing only the nucleus and plastid)., Key Results: Many important questions of deep-level relationships in the nonmonocot angiosperms have now been resolved with strong support. Amborellaceae, Nymphaeales, and Austrobaileyales are successive sisters to the remaining angiosperms (Mesangiospermae), which are resolved into Chloranthales + Magnoliidae as sister to Monocotyledoneae + [Ceratophyllaceae + Eudicotyledoneae]. Eudicotyledoneae contains a basal grade subtending Gunneridae. Within Gunneridae, Gunnerales are sister to the remainder (Pentapetalae), which comprises (1) Superrosidae, consisting of Rosidae (including Vitaceae) and Saxifragales; and (2) Superasteridae, comprising Berberidopsidales, Santalales, Caryophyllales, Asteridae, and, based on this study, Dilleniaceae (although other recent analyses disagree with this placement). Within the major subclades of Pentapetalae, most deep-level relationships are resolved with strong support., Conclusions: Our analyses confirm that with large amounts of sequence data, most deep-level relationships within the angiosperms can be resolved. We anticipate that this well-resolved angiosperm tree will be of broad utility for many areas of biology, including physiology, ecology, paleobiology, and genomics.

The eudicot order Malpighiales contains ∼16000 species and is the most poorly resolved large rosid clade. To clarify phylogenetic relationships in the order, we used maximum likelihood, Bayesian, and parsimony analyses of DNA sequence data from 13 gene regions, totaling 15604 bp, and representing all three genomic compartments (i.e., plastid: atpB, matK, ndhF, and rbcL; mitochondrial: ccmB, cob, matR, nad1B-C, nad6, and rps3; and nuclear: 18S rDNA, PHYC, and newly developed low-copy EMB2765). Our sampling of 190 taxa includes representatives from all families of Malpighiales. These data provide greatly increased support for the recent additions of Aneulophus, Bhesa, Centroplacus, Ploiarium, and Rafflesiaceae to Malpighiales; sister relations of Phyllanthaceae + Picrodendraceae, monophyly of Hypericaceae, and polyphyly of Clusiaceae. Oxalidales + Huaceae, followed by Celastrales are successive sisters to Malpighiales. Parasitic Rafflesiaceae, which produce the world's largest flowers, are confirmed as embedded within a paraphyletic Euphorbiaceae. Novel findings show a well-supported placement of Ctenolophonaceae with Erythroxylaceae + Rhizophoraceae, sister-group relationships of Bhesa + Centroplacus, and the exclusion of Medusandra from Malpighiales. New taxonomic circumscriptions include the addition of Bhesa to Centroplacaceae, Medusandra to Peridiscaceae (Saxifragales), Calophyllaceae applied to Clusiaceae subfamily Kielmeyeroideae, Peraceae applied to Euphorbiaceae subfamily Peroideae, and Huaceae included in Oxalidales.

The complete sequence of the chloroplast genome of cassava (Manihot esculenta, Euphorbiaceae) has been determined. The genome is 161,453 bp in length and includes a pair of inverted repeats (IR) of 26,954 bp. The genome includes 128 genes; 96 are single copy and 16 are duplicated in the IR. There are four rRNA genes and 30 distinct tRNAs, seven of which are duplicated in the IR. The infA gene is absent; expansion of IRb has duplicated 62 amino acids at the 3' end of rps19 and a number of coding regions have large insertions or deletions, including insertions within the 23S rRNA gene. There are 17 intron-containing genes in cassava, 15 of which have a single intron while two (clpP, ycf3) have two introns. The usually conserved atpF group II intron is absent and this is the first report of its loss from land plant chloroplast genomes. The phylogenetic distribution of the atpF intron loss was determined by a PCR survey of 251 taxa representing 34 families of Malpighiales and 16 taxa from closely related rosids. The atpF intron is not only missing in cassava but also from closely related Euphorbiaceae and other Malpighiales, suggesting that there have been at least seven independent losses. In cassava and all other sequenced Malphigiales, atpF gene sequences showed a strong association between C-to-T substitutions at nucleotide position 92 and the loss of the intron, suggesting that recombination between an edited mRNA and the atpF gene may be a possible mechanism for the intron loss.

Species of Rafflesiaceae possess the world's largest flowers (up to 1 meter in diameter), yet their precise evolutionary relationships have been elusive, hindering our understanding of the evolution of their extraordinary reproductive morphology. We present results of phylogenetic analyses of mitochondrial, nuclear, and plastid data showing that Rafflesiaceae are derived from within Euphorbiaceae, the spurge family. Most euphorbs produce minute flowers, suggesting that the enormous flowers of Rafflesiaceae evolved from ancestors with tiny flowers. Given the inferred phylogeny, we estimate that there was a circa 79-fold increase in flower diameter on the stem lineage of Rafflesiaceae, making this one of the most dramatic cases of size evolution reported for eukaryotes.

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.

The rattlesnake fern (Botrychium virginianum (L.) Sw.) is obligately mycotrophic and widely distributed across the northern hemisphere. Three mitochondrial gene regions place this species with other ferns in Ophioglossaceae, while two regions place it as a member of the largely parasitic angiosperm order Santalales (sandalwoods and mistletoes). These discordant phylogenetic placements suggest that part of the genome in B. virginianum was acquired by horizontal gene transfer (HGT), perhaps from root-parasitic Loranthaceae. These transgenes are restricted to B. virginianum and occur across the range of the species. Molecular and life-history traits indicate that the transfer preceded the global expansion of B. virginianum, and that the latter may have happened very rapidly. This is the first report of HGT from an angiosperm to a fern, through either direct parasitism or the mediation of interconnecting fungal symbionts.

Parsimony, likelihood, and Bayesian analyses of nuclear ITS and plastid trnL-F DNA sequence data are presented for the giant genus Croton (Euphorbiaceae s.s.) and related taxa. Sampling comprises 88 taxa, including 78 of the estimated 1223 species and 29 of the 40 sections previously recognized of Croton. It also includes the satellite genus Moacroton and genera formerly placed in tribe Crotoneae. Croton and all sampled segregate genera form a monophyletic group sister to Brasiliocroton, with the exception of Croton sect. Astraea, which is reinstated to the genus Astraea. A small clade including Moacroton, Croton alabamensis, and C. olivaceus is sister to all other Croton species sampled. The remaining Croton species fall into three major clades. One of these is entirely New World, corresponding to sections Cyclostigma, Cascarilla, and Velamea sensu Webster. The second is entirely Old World and is sister to a third, also entirely New World clade, which is composed of at least 13 of Webster's sections of Croton. This study establishes a phylogenetic framework for future studies in the hyper-diverse genus Croton, indicates a New World origin for the genus, and will soon be used to evaluate wood anatomical, cytological, and morphological data in the Crotoneae tribe.

Parsimony and Bayesian analyses of plastid rbcL and trnL-F DNA sequence data of the pantropical family Euphorbiaceae sensu stricto (s.s.) are presented. Sampling includes representatives of all three subfamilies (Acalyphoideae, Crotonoideae, and Euphorbioideae), 35 of 37 tribes and 179 of the 247 genera of uniovulate Euphorbiaceae sensu lato (s.l.). Euphorbiaceae s.s. were recovered as a monophyletic group with no new adjustments in circumscription. Two clades containing taxa previously placed in Acalyphoideae are found to be successive sisters to all other Euphorbiaceae s.s. and are proposed here at subfamilial rank as Peroideae and Cheilosoideae. The remainder of the family fall into seven major lineages including Erismantheae and Acalyphoideae s.s. (parts of Acalyphoideae), Adenoclineae s.l., Gelonieae, articulated crotonoids and inaperturate crotonoids (parts of Crotonoideae), and Euphorbioideae. Potential synapomorphies and biogeographical trends are suggested for these clades. Acalyphoideae s.s., inaperturate crotonoids, and Euphorbioideae tribe Hippomaneae each have two major subclades that represent novel groupings without apparent morphological synapomorphies. Two subfamilies, 14 tribes, and 10 genera were found to be para- or polyphyletic. Noteworthy among these, Omphaleae are embedded in Adenoclineae, Hureae + Pachystromateae in Hippomaneae, Ditta in Tetrorchidium, and Sapium s.s. in Stillingia.

Phyllanthaceae are a pantropical family of c. 2000 species for which circumscription is believed to be coincident with subfamily Phyllanthoideae of Euphorbiaceae sensu lato (Malpighiales) excluding Putranjivaceae. A phylogenetic study of the family using DNA sequence data has delivered largely congruent results from the plastid atpB, matK, ndhF, rbcL, and the nuclear PHYC. Our analyses include sampling from 54 of 59 genera, representing all tribes and subtribes of Phyllanthoideae. The family falls into two major clades characterized by inflorescence and leaf anatomical features. Several traditional taxonomic groupings were retrieved with minor modifications, but most clades recovered are considerably different from previous non-molecular based ideas of relationships. The enigmatic genus Dicoelia and the geographically disjunct genus Lingelsheimia are shown to be embedded in Phyllanthaceae. The taxonomic status of Leptopus diplospermus (=Chorisandrachne) and the debated placement of Andrachne ovalis have been clarified, and Protomegabaria and Richeriella are newly placed. Paraphyly of Cleistanthus and Phyllanthus is confirmed, having three and four other genera embedded, respectively. Petalodiscus is also paraphyletic, including all other Malagassian Wielandieae.

Methods for identifying species by using short orthologous DNA sequences, known as "DNA barcodes," have been proposed and initiated to facilitate biodiversity studies, identify juveniles, associate sexes, and enhance forensic analyses. The cytochrome c oxidase 1 sequence, which has been found to be widely applicable in animal barcoding, is not appropriate for most species of plants because of a much slower rate of cytochrome c oxidase 1 gene evolution in higher plants than in animals. We therefore propose the nuclear internal transcribed spacer region and the plastid trnH-psbA intergenic spacer as potentially usable DNA regions for applying barcoding to flowering plants. The internal transcribed spacer is the most commonly sequenced locus used in plant phylogenetic investigations at the species level and shows high levels of interspecific divergence. The trnH-psbA spacer, although short ( approximately 450-bp), is the most variable plastid region in angiosperms and is easily amplified across a broad range of land plants. Comparison of the total plastid genomes of tobacco and deadly nightshade enhanced with trials on widely divergent angiosperm taxa, including closely related species in seven plant families and a group of species sampled from a local flora encompassing 50 plant families (for a total of 99 species, 80 genera, and 53 families), suggest that the sequences in this pair of loci have the potential to discriminate among the largest number of plant species for barcoding purposes.

Fossil data have been interpreted as indicating that Late Cretaceous tropical forests were open and dry adapted and that modern closed-canopy rain forest did not originate until after the Cretaceous-Tertiary (K/T) boundary. However, some mid-Cretaceous leaf floras have been interpreted as rain forest. Molecular divergence-time estimates within the clade Malpighiales, which constitute a large percentage of species in the shaded, shrub, and small tree layer in tropical rain forests worldwide, provide new tests of these hypotheses. We estimate that all 28 major lineages (i.e., traditionally recognized families) within this clade originated in tropical rain forest well before the Tertiary, mostly during the Albian and Cenomanian (112-94 Ma). Their rapid rise in the mid-Cretaceous may have resulted from the origin of adaptations to survive and reproduce under a closed forest canopy. This pattern may also be paralleled by other similarly diverse lineages and supports fossil indications that closed-canopy tropical rain forests existed well before the K/T boundary. This case illustrates that dated phylogenies can provide an important new source of evidence bearing on the timing of major environmental changes, which may be especially useful when fossil evidence is limited or controversial.

The classification of the Catesbaeeae and Chiococceae tribes, along with that of the entire Rubiaceae, has long been debated. The Catesbaeeae-Chiococceae complex (CCC) includes approximately 28 genera and 190 species primarily concentrated in the Greater Antilles (nearly 70% of the species), Central and South America, and in the western Pacific (three genera). Previous molecular studies, with broad sampling of the Rubiaceae, have shown the CCC to be a monophyletic group. The present study is a more detailed examination of the generic relationships within the CCC using two data sets, the nuclear ribosomal ITS regions and the trnL-F chloroplast intron and spacer. Maximum parsimony analyses lend further support to the previous hypotheses that the CCC is monophyletic and sister to Strumpfia maritima. However, within the complex several genera do not form monophyletic groups. Previous studies of the Rubiaceae suggest that the ancestral fruit type in the CCC is a multiseeded capsule. Indehiscent, fleshy fruits appear to have evolved three to four times within this lineage. Changes in floral morphologies within the complex tend to correspond to cladogenesis among and within genera. Finally, molecular analyses suggest one or possibly two long-distance dispersals from the Americas to the western Pacific.

Plastid matK and a fragment of the low-copy nuclear gene PHYC were sequenced for 30 genera of Phyllanthaceae to evaluate tribal and generic delimitation. Resolution and bootstrap percentages obtained with matK are higher than that of PHYC, but both regions show nearly identical phylogenetic patterns. Phylogenetic relationships inferred from the independent and combined data are congruent and differ from previous, morphology-based classifications but are highly concordant with those of the plastid gene rbcL previously published. Phyllanthaceae is monophyletic and gives rise to two well-resolved clades (T and F) that could be recognized as subfamilies. DNA sequence data for Keayodendron and Zimmermanniopsis are presented for the first time. Keayodendron is misplaced in tribe Phyllantheae and belongs to the Bridelia alliance. Zimmermanniopsis is sister to Zimmermannia. Phyllanthus and Cleistanthus are paraphyletic. Savia and Phyllanthus subgenus Kirganelia are not monophyletic.

Analysis of plastid rbcL DNA sequence data of the pantropical family Phyllanthaceae (Malpighiales) and related biovulate lineages of Euphorbiaceae sensu lato is presented. Sampling for this study includes representatives of all 10 tribes and 51 of the 60 genera attributed to Euphorbiaceae-Phyllanthoideae. Centroplacus and Putranjivaceae (Phyllanthoideae-Drypeteae) containing a paraphyletic Drypetes are excluded from Phyllanthaceae. Croizatia, previously thought to be a "basal" member of Euphorbiaceae-Oldfieldioideae (Picrodendraceae), falls within Phyllanthaceae. Phyllanthaceae with the mentioned adjustments form a monophyletic group consisting of two sister clades that mostly correspond to the distribution of tanniniferous leaf epidermal cells and inflorescence structure. With the exception of bigeneric Hymenocardieae and monotypic Bischofieae, none of the current Phyllanthoideae (Phyllanthaceae) tribal circumscriptions are supported by rbcL. Antidesma, Bischofia, Hymenocardia, Martretia, and Uapaca, all of which have previously been placed in monogeneric families, are confirmed as members of Phyllanthaceae. Savia is polyphyletic, and Cleistanthus appears paraphyletic. Paraphyly of Phyllanthus is also indicated, but this pattern lacks bootstrap support. Morphological characters are discussed and mapped for inflorescence structure, tanniniferous epidermal cells, breeding system, and fruit and embryo type. A table summarizes the main characters of six euphorbiaceous lineages.

Horizontal gene transfer (HGT) between sexually unrelated species has recently been documented for higher plants, but mechanistic explanations for HGTs have remained speculative. We show that a parasitic relationship may facilitate HGT between flowering plants. The endophytic parasites Rafflesiaceae are placed in the diverse order Malpighiales. Our multigene phylogenetic analyses of Malpighiales show that mitochondrial (matR) and nuclear loci (18S ribosomal DNA and PHYC) place Rafflesiaceae in Malpighiales, perhaps near Ochnaceae/Clusiaceae. Mitochondrial nad1B-C, however, groups them within Vitaceae, near their obligate host Tetrastigma. These discordant phylogenetic hypotheses strongly suggest that part of the mitochondrial genome in Rafflesiaceae was acquired via HGT from their hosts.

The snap-trap leaves of the aquatic waterwheel plant (Aldrovanda) resemble those of Venus' flytrap (Dionaea), its distribution and habit are reminiscent of bladderworts (Utricularia), but it shares many reproductive characters with sundews (Drosera). Moreover, Aldrovanda has never been included in molecular phylogenetic studies, so it has been unclear whether snap-traps evolved only once or more than once among angiosperms. Using sequences from nuclear 18S and plastid rbcL, atpB, and matK genes, we show that Aldrovanda is sister to Dionaea, and this pair is sister to Drosera. Our results indicate that snap-traps are derived from flypaper-traps and have a common ancestry among flowering plants, despite the fact that this mechanism is used by both a terrestrial species and an aquatic one. Genetic and fossil evidence for the close relationship between these unique and threatened organisms indicate that carnivory evolved from a common ancestor within this caryophyllid clade at least 65 million years ago.