Integrating Early Cretaceous fossils into the phylogeny of living angiosperms: Magnoliidae and eudicots

Over the past 25 years, discoveries of Early Cretaceous fossil flowers, often associated with pollen and sometimes with vegetative parts, have revolutionized our understanding of the morphology and diversity of early angiosperms. However, few of these fossils have been integrated into the increasingly robust phylogeny of living angiosperms based primarily on molecular data. To remedy this situation, we have used a morphological data set for living basal angiosperms (including basal eudicots and monocots) to assess the most parsimonious positions of early angiosperm fossils on cladograms of Recent plants, using constraint trees that represent the current range of hypotheses on higher-level relationships, and concentrating on Magnoliidae (the clade including Magnoliales, Laurales, Canellales, and Piperales) and eudicots. In magnoliids, our results confirm proposed relationships of Archaeanthus (latest Albian?) to Magnoliaceae, Endressinia (late Aptian) to Magnoliales (the clade comprising Degeneria, Galbulimima, Eupomatia, and Annonaceae), and Walkeripollis pollen tetrads (late Barremian?) to Winteraceae, but they indicate that Mauldinia (early Cenomanian) was sister to both Lauraceae and Hernandiaceae rather than to Lauraceae alone. Among middle Albian to early Cenomanian eudicots, we confirm relationships of Nelumbites to Nelumbo, platanoid inflorescences and Sapindopsis to Platanaceae, and Spanomera to Buxaceae. With the possible exception of Archaeanthus, these fossils are apparently not crown group members of living families but rather stem relatives of one or more families.     

Integrating Early Cretaceous fossils into the phylogeny of living angiosperms:Magnoliidae and eudicots

Over the past 25 years, discoveries of Early Cretaceous fossil flowers, often associated with pollen and sometimes with vegetative parts, have revolutionized our understanding of the morphology and diversity of early angiosperms. However, few of these fossils have been integrated into the increasingly robust phylogeny of living angiosperms based primarily on molecular data. To remedy this situation, we have used a morphological dataset for living basal angiosperms (including basal eudicots and monocots) to assess the most parsimonious positions of early angiosperm fossils on cladograms of Recent plants, using constraint trees that represent the current range of hypotheses on higher-level relationships, and concentrating on Magnoliidae (the clade including Magnoliales, Laurales, Canellales, and Piperales) and eudicots. In magnoliids, our results confirm proposed relationships of Archaeanthus (latest Albian?) to Magnoliaceae, Endressinia (late Aptian) to Magnoliales (the clade comprising Degeneria, Galbulimima, Eupomatia, and Annonaceae), and Walkeripollis pollen tetrads (late Barremian?) to Win-teraceae, but they indicate that Mauldinia (early Cenomanian) was sister to both Lauraceae and Hernandiaceae rather than to Lauraceae alone. Among middle Albian to early Cenomanian eudicots, we confirm relationships of Nelumbites to Nelumbo, platanoid inflorescences and Sapindopsis to Platanaceae, and Spanomera to Buxaceae. With the possible exception of Archaeanthus, these fossils are apparently not crown group members of living families but rather stem relatives of one or more families.     

Noncoding plastid trnT-trnF sequences reveal a well resolved phylogeny of basal angiosperms

Recent contributions from DNA sequences have revolutionized our concept of systematic relationships in angiosperms. However, parts of the angiosperm tree remain unclear. Previous studies have been based on coding or rDNA regions of relatively conserved genes. A phylogeny for basal angiosperms based on noncoding, fast-evolving sequences of the chloroplast genome region trnT-trnF is presented. The recognition of simple direct repeats allowed a robust alignment. Mutational hot spots appear to be confined to certain sectors, as in two stem-loop regions of the trnL intron secondary structure. Our highly resolved and well-supported phylogeny depicts the New Caledonian Amborella as the sister to all other angiosperms, followed by Nymphaeaceae and an Austrobaileya-Illicium-Schisandra clade. Ceratophyllum is substantiated as a close relative of monocots, as is a monophyletic eumagnoliid clade consisting of Piperales plus Winterales sister to Laurales plus Magnoliales. Possible reasons for the striking congruence between the trnT-trnF based phylogeny and phylogenies generated from combined multi-gene, multi-genome data are discussed.     

单子叶植物高级分类阶元系统演化: matK、rbcL和18S rDNA序列的证据

基于两个叶绿体基因（matK和rbcL）和一个核糖体基因（18S rDNA）的序列分析,对代表了基部被子植物和单子叶植物主要谱系分支的86科126属151种被子植物（单子叶植物58科86属101种）进行了系统演化关系分析。研究结果表明由胡椒目Piperales、樟目Laurales、木兰目Magnoliales和林仙目Canellales构成的真木兰类复合群是单子叶植物的姐妹群。单子叶植物的单系性在3个序列联合分析中得到98％的强烈自展支持。联合分析鉴定出9个单子叶植物主要谱系（广义泽泻目Alismatales、薯蓣目Dioscorcales、露兜树目Pandanales、天门冬目Asparagalcs、百合目Liliales、棕榈目Arecales、禾本目Poales、姜目Zingiberales、鸭跖草目Commelinales）和6个其他被子植物主要谱系（睡莲目Nymphaeales、真双子叶植物、木兰目、樟目、胡椒目、林仙目）。在单子叶植物内,菖蒲目Acorales（菖蒲属Acorus）是单子叶植物最早分化的一个谱系,广义泽泻目（包括天南星科Araceae和岩菖蒲科Toficldiaccae）紧随其后分化出来,二者依次和其余单子叶植物类群构成姐妹群关系。无叶莲科Petrosaviaceac紧随广义的泽泻目之后分化出来,无叶莲科和剩余的单子叶植物类群形成姐妹群关系,并得到了较高的支持率。继无叶莲科之后分化的类群形成两个大的分支：一支是由露兜树目和薯蓣目构成,二者形成姐妹群关系：另一支是由天门冬目、百合目和鸭跖草类复合群组成,三者之间的关系在单个序列分析和联合分析中不稳定,需要进一步扩大取样范围来确定。在鸭跖草类复合群分支内,鸭跖草目和姜目的姐妹群关系在3个序列联合分析和2个序列联合分析的严格一致树中均得到强烈的自展支持,获得的支持率均是100％。但是,对于棕榈目和禾本目在鸭跖草类中的系统位置以及它们和鸭跖草目-姜目之间的关系,有待进一步解决。值得注意的是,无叶莲科与其他单子叶植物类群（除菖蒲目和泽泻目外）的系统关系在本文中获得较高的自展支持率,薯蓣目和天门冬目的单系性在序列联合分析中都得到了较好的自展支持,而这些在以往的研究中通常支持率较低。鉴于菖蒲科和无叶莲科独特的系统演化位置,本文支持将其分别独立成菖蒲目和无叶莲目Petrosavialcs的分类学界定。     

EMBRYOLOGY AND KARYOMORPHOLOGY OF LACTORIDACEAE

The embryology and karyomorphology of Lactoris fernandeziana, representing the monotypic family Lactoridaceae, were studied in an attempt to clarify its relationships. Embryologically, Lactoris is characterized by a combination of many generalized, plesiomorphic features, which are mostly shared with Magnoliales and partly shared with Laurales and Piperales, and some specialized, apomorphic features including a tenuinucellate ovule, a small nucellus with early disintegrating nucellar tissue, a nonmultiplicative outer integument, an endothelium, and haustorial endosperm. Karyomorphologically Lactoris is confirmed to have 2n = 40 at metaphase, probably as a tetraploid of x = 10, and more or less distinctive features at inter- and prophase. Comparisons based on its embryological and karyomorphological features suggest that Lactoris is not closely related to any other family. Based on evidence from various sources, we hypothesize that an evolutionary line was derived from a common ancestor with Magnoliales, and then diverged into Lactoris, which retains many primitive magnolialean features, and Piperales (and possibly other groups) with more specialized characteristics. Lactoris seems best placed in its own order, Lactoridales, near Piperales.     

Angiosperm phylogeny inferred from 18S rDNA, vbcL, and atpB sequences

A phylogenetic analysis of a combined data set for 560 angiosperms and seven outgroups based on three genes, 18S rDNA (1855 bp), rbcL (1428 bp), and atpB (1450 bp) representing a total of 4733 bp is presented. Parsimony analysis was expedited by use of a new computer program, the RATCHET. Parsimony jackknifing was performed to assess the support of clades. The combination of three data sets for numerous species has resulted in the most highly resolved and strongly supported topology yet obtained for angiosperms. In contrast to previous analyses based on single genes, much of the spine of the tree and most of the larger clades receive jackknife support 250%. Some of the noneudicots form a grade followed by a strongly supported eudicot clade. The early‐branching angiosperms are Amborellaceae, Nymphaeaceae, and a clade of Austrobaileyaceae, Illiciaceae, and Schi‐sandraceae. The remaining noneudicots, except Ceratophyllaceae, form a weakly supported core eumagnoliid clade comprising six well‐supported subclades: Chloranthaceae, monocots, WinteraceaeICanellaceae, Piperales, Laurales, and Magnoliales. Ceratophyllaceae are sister to the eudicots. Within the well‐supported eudicot clade, the early‐diverging eudicots (e.g. Proteales, Ranunculales, Trochodendraceae, Sabiaceae) form a grade, followed by the core eudicots, the monophyly of which is also strongly supported. The core eudicots comprise six well‐supported subclades: (1) Berberidopsidaceae/Aextoxicaceae; (2) Myrothamnaceae/ Gunneraceae; (3) Saxifragales, which are the sister to Vitaceae (including Leea) plus a strongly supported eurosid clade; (4) Santalales; (5) Caryophyllales, to which Dilleniaceae are sister; and (6) an asterid clade. The relationships among these six subclades of core eudicots do not receive strong support. This large data set has also helped place a number of enigmatic angiosperm families, including Podostemaceae, Aphloiaceae, and Ixerbaceae. This analysis further illustrates the tractability of large data sets and supports a recent, phylogenetically based, ordinal‐level reclassification of the angiosperms based largely, but not exclusively, on molecular (DNA sequence) data.     

Gynoecium diversity and systematics of the paleoherbs

Gynoecium and ovule structure was compared in representatives of all families of the paleoherbs, including Nymphaeales (Cabombaceae, Nymphaeaceae), Piperales (Saururaceae, Piperaceae), Aristolochiales (Lactoridaceae, Aristolochiaceae), Rafflesiales (Hydnoraceae, Rafflesiaceae) and, in addition, Ceratophyllaceae and Nelumbonaceae, both of which were earlier included in Nymphaeales, but then segregated and with an unestablished position. In all representatives studied, the carpels are closed at anthesis. Carpel closure is attained in three different ways: (1) postgenital fusion of inner surfaces (Piperales, Aristolochiales); (2) occlusion by secretion or mutual appression of inner surfaces without postgenital fusion (Cabombaceae, Ceratophyllaceae, Nelumbonaceae (?) or (3) strong secretion combined with postgenital fusion at the periphery of the carpel (Nymphaeaceae). In Cytinus (Rafflesiaceae), after an earlier developmental stage with apparent postgenital fusion there is strong internal secretion (within the cell walls). Stigma shape tends to be double-crested in the basal taxa of each order: Cabombaceae (Brasenia), Saururaceae, and Lactoridaceae. In some Aristolochiaceae and Cytinus (Rafflesiaceae) they have two lobes in the transverse symmetry plane (i. e. at right angles to the median plane) or, if the carpels are united, the stigmatic lobes are commissural, accordingly. Stigmas are unicellular papillate and secretory in most taxa, but the papillae are uniseriate-pluricellular in some (not basal) Nymphaeaceae, Asaroideae (Aristolochiaceae) and Cytinus (Rafflesiaceae). Ceratophyllaceae have smooth stigmas. Intrusive oil cells in the carpel epidermis were found in Piperales and Aristolochiaceae. Mature ovules vary in length between 0. 2 mm and 2. 5 mm. Mature nucelli vary in breadth between 0. 03 mm and 1. 6 mm. These differences are larger than in the other major magnoliid groups. The outer integument is fully annular (not semiannular) in all taxa with orthotropous ovules (all Piperales and Barclaya of Nymphaeaceae) and also in some with anatropous ovules (some Nymphaeaceae, some Aristolochiaceae). The integuments are variously lobed or unlobed; both integuments tend to exhibit the same behaviour within a family, either both lobed or both unlobed. The results strongly support three pairs of families in sister group relationships, as suggested by studies based on other characters: Cabombaceae-Nymphaeaceae, Saururaceae-Piperaceae, and Lactoridaceae-Aristolochiaceae, and Hydnoraceae-Rafflesiaceae to some extent. Piperales and Aristolochiales are closer to each other than either is to Nymphaeales. Nelumbonaceae is isolated, as is Ceratophyllaceae, but the status of the latter is more difficult to interpret owing to apparent reduction in morphological, anatomical and histological traits.     

Utility of 17 chloroplast genes for inferring the phylogeny of the basal angiosperms

Sequences from 14 slowly evolving chloroplast genes (including three highly conserved introns) were obtained for representative basal angiosperm and seed-plant taxa, using novel primers described here. These data were combined with published sequences from atpB, rbcL, and newly obtained sequences from ndhF. Combined data from these 17 genes permit sturdy, well-resolved inference of major aspects of basal angiosperm relationships, demonstrating that the new primers are valuable tools for sorting out the deepest events in flowering plant phylogeny. Sequences from the inverted repeat (IR) proved to be particularly reliable (low homoplasy, high retention index). Representatives of Cabomba and Illicium were the first two successive branches of the angiosperms in an initial sampling of 19 exemplar taxa. This result was strongly supported by bootstrap analysis and by two small insertion/deletion events in the slowly evolving introns. Several paleoherb groups (representatives of Piperales) formed a strongly supported clade with taxa representing core woody magnoliids (Laurales, Magnoliales, and Winteraceae). The monophyly of the sampled eudicots and monocots was also well supported. Analyses of three major partitions of the data showed many of the same clades and supported the rooting seen with all the data combined. While Amborella trichopoda was supported as the sister group of the remaining angiosperms when we added Amborella and Nymphaea odorata to the analysis, a strongly conflicting rooting was observed when Amborella alone was added.     

Recognising angiosperm clades in the Early Cretaceous fossil record

Studies of the earliest Cretaceous angiosperms in the 1970s made only broad comparisons with living taxa, but discoveries of fossil flowers and increasingly robust molecular phylogenies of living angiosperms allow more secure recognition of extant clades. The middle to late Albian rise of tricolpate pollen and the first local dominance of angiosperm leaves mark the influx of near-basal lines of eudicots. Associated flowers indicate that palmately lobed ‘platanoids’ and Sapindopsis are both stem relatives of Platanus, while Nelumbites was related to Nelumbo (also Proteales) and Spanomera to Buxaceae. Monocots are attested by Aptian Liliacidites pollen and Acaciaephyllum leaves and Albian araceous inflorescences. Several Albian–Cenomanian fossils belong to Magnoliidae in the revised monophyletic sense, including Archaeanthus in Magnoliales and Virginianthus and Mauldinia in Laurales, while late Barremian pollen tetrads (Walkeripollis) are related to Winteraceae. In the basal ANITA grade, Nymphaeales are represented by Aptian and Albian flowers and whole plants (Monetianthus, Carpestella and Pluricarpellatia). Epidermal similarities of lower Potomac leaves to woody members of the ANITA grade are consistent with Albian flowers assignable to Austrobaileyales (Anacostia). Aptian to Cenomanian mesofossils represent both crown group Chloranthaceae (Asteropollis plant) and stem relatives of Chloranthaceae and/or Ceratophyllum (Canrightia, Zlatkocarpus, Pennipollis plant and possibly Appomattoxia).     

Phylogenetics of flowering plants based on combined analysis of plastid atpB and rbcL gene sequences

Following (1) the large-scale molecular phylogeny of seed plants based on plastid rbcL gene sequences (published in 1993 by Chase et al., Ann. Missouri Bot. Gard. 80:528-580) and (2) the 18S nuclear phylogeny of flowering plants (published in 1997 by Soltis et al., Ann. Missouri Bot. Gard. 84:1-49), we present a phylogenetic analysis of flowering plants based on a second plastid gene, atpB, analyzed separately and in combination with rbcL sequences for 357 taxa. Despite some discrepancies, the atpB-based phylogenetic trees were highly congruent with those derived from the analysis of rbcL and 18S rDNA, and the combination of atpB and rbcL DNA sequences (comprising approximately 3000 base pairs) produced increased bootstrap support for many major sets of taxa. The angiosperms are divided into two major groups: noneudicots with inaperturate or uniaperturate pollen (monocots plus Laurales, Magnoliales, Piperales, Ceratophyllales, and Amborellaceae-Nymphaeaceae-Illiciaceae) and the eudicots with triaperturate pollen (particularly asterids and rosids). Based on rbcL alone and atpB/rbcL combined, the noneudicots (excluding Ceratophyllum) are monophyletic, whereas in the atpB trees they form a grade. Ceratophyllum is sister to the rest of angiosperms with rbcL alone and in the combined atpB/rbcL analysis, whereas with atpB alone, Amborellaceae, Nymphaeaceae, and Illiciaceae/Schisandraceae form a grade at the base of the angiosperms. The phylogenetic information at each codon position and the different types of substitutions (observed transitions and transversions in the trees vs. pairwise comparisons) were examined; taking into account their respective consistency and retention indices, we demonstrate that third-codon positions and transitions are the most useful characters in these phylogenetic reconstructions. This study further demonstrates that phylogenetic analysis of large matrices is feasible.     

The diversity of stamen structures and dehiscence patterns among Magnoliidae

ENDRESS, P. K. & HUFFORD, L. D., 1989. The diversity of stamen structures and dehiscence patterns among Magnoliidae . Structure of stamens, particularly the patterns of anther dehiscence were studied over a wide range of families of the Magnoliidae with emphasis on the Magnoliales and Laurales as the most conservative orders of the angiosperms. Valvate dehiscence by proximal and distal stomial bifurcation was found (in addition to the already known Sarcandra and Polyalthia) for the first time in Degeneriaceae, Himantandraceae, Eupomatiaceae, in some additional Annonaceae, and in Peumus of the Monimioideae sensu lata. At least proximal bifurcations of the stomia occur in some Magnoliaceae and Ranunculaceae. An endothecial-like connective hypodermis was found (in addition to the already known Chloranthaceae and Magnoliaceae) in some Annonaceae, in Pseudowintera (Winteraceae), and in Thalictrum (Ranunculaceae). In the Annonaceae an endothecial-like connective hypodermis is partly correlated with valvate dehiscence by stomial bifurcations (as in many Hamamelididae). However, in many Magnoliidae stamens with this valvate pattern the anther is massive, especially in ‘laminar’ stamens, and the counterforce to the opening valves is therefore provided on the morphological and not on the histological level. Concomitant with valvate dehiscence by circular or elliptic flaps in the Laurales is often structural and functional dissocation of the two pollen sacs of a thcca, which is expressed by: (1) independent opening of each pollen sac, (2) lack of disruption of the interlocular zone of a theca, (3) frequent occurrence of asymmetry of the two pollen sacs of the theca, (4) frequent loss of one pollen sac per theca. In Berberidaceae with similar flaps asymmetry of the two pollen sacs of a theca is also common. These finds, together with the detection by paleobotanists of valvate anthers from the Lower Cretaceous, point to the probability that valvate anthers were more common in primitive angiosperms than previously thought.     

Systematics, biogeography and conservation of Lactoridaceae

Lactoridaceae are a monotypic family confined to the Juan Fernandez (= Robinson Crusoe) Islands, Chile, an archipelago four million years old. Interest in the lone species, Lactoris fernandeziana, has increased in recent years due to its suspected role in early angiosperm evolution, as well as its endangered conservation status. Reports of fossil pollen of Lactoris (as Lactoripollenites) from deep sea sediments of Cretaceous age off the western coast of South Africa provide evidence for southern hemisphere occurrence of the family 70–90 million years ago. This age, plus trimerous symmetry and simple morphology of the flower with three tepals, six stamens and three nearly free carpels with laminar placentation, involve the family with hypotheses regarding evolution of early angiosperms, especially paleoherb and monocot divergences. Based on cladistic analyses with morphological and nucleotide data, recommended taxonomic placement of Lactoris is as a monotypic order, Lactoridales, allied most closely to Aristolochiales, and also near Piperales. Approximately 1000 individuals of Lactoris are believed to exist, and genetic variation within and among populations as measured by isozymes and RAPDs is low. This, in part, could be due to the self-compatibility and geitonogamous breeding system of this wind-pollinated species. More efforts at ex situ conservation should be attempted so that this important angiosperm family is maintained for future evolutionary studies.     

Observations on the vegetative anatomy of Austrobaileya: habital, organographic and phylogenetic conclusions

For the single species of Austmbaileya (Austrobaileyaceae), quantitative and qualitative data are offered on the basis of a mature stem and a root of moderate diameter. Data available hitherto have been based on stems of small to moderate diameter, and roots have not previously been studied. Scanning electron microscope (SEM) photographs are utilized for roots, and show compound starch grains. Roots lack sclerenchyma but have relatively narrow vessels and abundant ray tissue. Recent phylogenies group Austrobaileyaceae with the woody families Illiciaceae, Schisandraceae, and Trimeniaceae (these four may be considered Illiciales), and somewhat less closely with the vesselless families Amborellaceae and Winteraceae and the aquatic families Cambombaceae and Nymphaeaceae. The vessel-bearing woody families above share vessels with scalariform perforation plates; bordered bars on plates; pit membrane remnants present in perforations; lateral wall pitting of vessels mostly alternate and opposite; tracheids and/or septate fibre-tracheids present; axial parenchyma vasicentric (sometimes abaxial); rays Heterogeneous Type I; ethereal oil cells present; stomata paracytic or variants of paracytic. Although comparisons between vessel-bearing and vesselless families must depend on fewer features, Amborellaceae and Winteraceae have no features incompatible with their inclusion in an expanded Illiciales.     

CUTICULAR ANATOMY OF ANGIOSPERM LEAVES FROM THE LOWER CRETACEOUS POTOMAC GROUP. I. ZONE I LEAVES

Angiosperm leaf cuticles from the oldest part of the Potomac Group reinforce previous paleobotanical evidence for a Cretaceous flowering plant diversification. Dated palynologically as Zone I of Brenner (Aptian?), these remains show a low structural diversity compared to later Potomac Group and modern angiosperms. All cuticle types conform to a single plan of stomatal construction that is unusual in its extraordinary plasticity: both the number of subsidiary cells and their arrangement vary greatly on a single epidermis, such that the stomata might be classified as paracytic, anomocytic, laterocytic, and intermediate. Such stomatal diversity is uncommon in extant angiosperms but is known from a few Magnoliidae. Many species possess secretory cells comparable to the oil cells of modern Magnoliidae, and a few show the bases of probable uniseriate hairs. None of the cuticle types can be assigned to a single modern family, but several show similarities with Chloranthaceae and Illiciales. These results support the concept that subclass Magnoliidae includes some of the most primitive living angiosperms.     

The four-celled female gametophyte of Illicium (Illiciaceae; Austrobaileyales): implications for understanding the origin and early evolution of monocots, eumagnoliids,and eudicots

The recent consensus that Amborellaceae, Nymphaeales, and Austrobaileyales form the three earliest-diverging lineages of angiosperms has led comparative biologists to reconsider the origin and early developmental evolution of the angiosperm seven-celled/eight-nucleate (Polygonum-type) female gametophyte. Illicium mexicanum (Illiciaceae; Austrobaileyales) develops a four-celled/four-nucleate female gametophyte. The ontogenetic sequence of the Illicium female gametophyte is consistent with that of all other Austrobaileyales and also with all Nymphaeales and is likely a plesiomorphy of angiosperms. A character analysis based on more than 250 embryological studies indicates that a transition from an ancestrally four-celled/four-nucleate Illicium-like female gametophyte to a seven-celled/eight-nucleate female gametophyte occurred in the common ancestor of the sister group to Austrobaileyales (a clade that includes monocots, eumagnoliids, and eudicots). Comparative analysis of reconstructed ancestral female gametophyte ontogenies identifies specific early stages of ontogeny that were modified during this transition. These modifications generated two important angiosperm novelties-a set of three persistent antipodal cells and a binucleate central cell, which upon fertilization yields a triploid endosperm. Early angiosperms are anatomically quite diverse in these two features, although triploid endosperm, composed of one paternal genome and two maternal genomes, is a conserved feature of the overwhelming majority of angiosperms.     

Multigene analyses identify the three earliest lineages of extant flowering plants

Flowering plants (angiosperms) are by far the largest, most diverse, and most important group of land plants, with over 250,000 species and a dominating presence in most terrestrial ecosystems. Understanding the origin and early diversification of angiosperms has posed a long-standing botanical challenge [1]. Numerous morphological and molecular systematic studies have attempted to reconstruct the early history of this group, including identifying the root of the angiosperm tree. There is considerable disagreement among these studies, with various groups of putatively basal angiosperms from the subclass Magnoliidae having been placed at the root of the angiosperm tree (reviewed in [2-4]). We investigated the early evolution of angiosperms by conducting combined phylogenetic analyses of five genes that represent all three plant genomes from a broad sampling of angiosperms. Amborella, a monotypic, vessel-less dioecious shrub from New Caledonia, was clearly identified as the first branch of angiosperm evolution, followed by the Nymphaeales (water lillies), and then a clade of woody vines comprising Schisandraceae and Austrobaileyaceae. These findings are remarkably congruent with those from several concurrent molecular studies [5-7] and have important implications for whether or not the first angiosperms were woody and contained vessels, for interpreting the evolution of other key characteristics of basal angiosperms, and for understanding the timing and pattern of angiosperm origin and diversification.     

Systematic relationships of theLactoridaceae,an endemic family of the Juan Fernandez Islands,Chile

The systematic relationships ofLactoridaceae are problematical, with alternative assignments toMagnoliales, Laurales, andPiperales. Phenetic analyses suggest thatLactoridaceae are best accomodated withinMagnoliales and are most closely related toAnnonaceae. Cladistic analyses indicate that the family is a relatively derived member of theMagnoliales, with affinities toAnnonaceae, Eupomatiaceae, Himantandraceae, andMyristicaceae. These analyses together with fossil pollen data are used to interpret the phylogeny ofLactoridaceae and its relatives.     

Phylogenetic analysis of Magnoliales and Myristicaceae based on multiple data sets: implications for character evolution

Magnoliales, consisting of six families of tropical to warm-temperate woody angiosperms, were long considered the most archaic order of flowering plants, but molecular analyses nest them among other eumagnoliids. Based on separate and combined analyses of a morphological matrix (115 characters) and multiple molecular data sets (seven variable chloroplast loci and five more conserved genes; 14 536 aligned nucleotides), phylogenetic relationships were investigated simultaneously within Magnoliales and Myristicaceae, using Laurales, Winterales, and Piperales as outgroups. Despite apparent conflicts among data sets, parsimony and maximum likelihood analyses of combined data converged towards a fully resolved and well-supported topology, consistent with higher-level molecular analyses except for the position of Magnoliaceae: Myristicaceae + (Magnoliaceae + (( Degeneria + Galbulimima ) + ( Eupomatia + Annonaceae))). Based on these results, we discuss morphological evolution in Magnoliales and show that several supposedly plesiomorphic traits are synapomorphies of Magnoliineae, the sister group of Myristicaceae (e.g. laminar stamens). Relationships within Annonaceae are also resolved with strong support ( Anaxagorea basal, then ambavioids). In contrast, resolution of relationships within Myristicaceae is difficult and still incomplete, due to a very low level of molecular divergence within the family and a long stem lineage. However, our data provide good evidence that Mauloutchia is nested among other Afro-Malagasy genera, contradicting the view that its androecium and pollen are plesiomorphic  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 142 , 125–186.     

Evidence for the monophyletic evolution of benzylisoquinoline alkaloid biosynthesis in angiosperms

Benzylisoquinoline alkaloids (BIAs) consist of more than 2500 diverse structures largely restricted to the order Ranunculales and the eumagnoliids. However, BIAs also occur in the Rutaceae, Lauraceae, Cornaceae and Nelumbonaceae, and sporadically throughout the order Piperales. Several of these alkaloids function in the defense of plants against herbivores and pathogens - thus, the capacity for BIA biosynthesis is expected to play an important role in the reproductive fitness of certain plants. Biochemical and molecular phylogenetic approaches were used to investigate the evolution of BIA biosynthesis in basal angiosperms. The occurrence of (S)-norcoclaurine synthase (NCS; EC 4.2.1.78) activity in 90 diverse plant species was compared to the distribution of BIAs superimposed onto a molecular phylogeny. These results support the monophyletic origin of BIA biosynthesis prior to the emergence of the eudicots. Phylogenetic analyses of NCS, berberine bridge enzyme and several O-methyltransferases suggest a latent molecular fingerprint for BIA biosynthesis in angiosperms not known to accumulate such alkaloids. The limited occurrence of BIAs outside the Ranunculales and eumagnoliids suggests the requirement for a highly specialized, yet evolutionarily unstable cellular platform to accommodate or reactivate the pathway in divergent taxa. The molecular cloning and functional characterization of NCS from opium poppy (Papaver somniferum L.) is also reported. Pathogenesis-related (PR)10 and Bet v 1 major allergen proteins share homology with NCS, but recombinant polypeptides were devoid of NCS activity.