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Comprising ca. 200 species

The benefits of urban green and blue infrastructure (UGI) are widely discussed, but rarely take into account local conditions or contexts. Although assessments increasingly consider the demand for the ecosystem services that UGI provides, they tend to only map the spatial pattern of pressures such as heat, or air pollution, and lack a wider understanding of where the beneficiaries are located and who will benefit most. We assess UGI in five cities from four continents with contrasting climate, socio-political context, and size. For three example services (air pollution removal, heat mitigation, accessible greenspace), we run an assessment that takes into account spatial patterns in the socio-economic demand for ecosystem services and develops metrics that reflect local context, drawing on the principles of vulnerability assessment. Despite similar overall levels of UGI (from 35 to 50% of urban footprint), the amount of service provided differs substantially between cities. Aggregate cooling ranged from 0.44 °C (Leicester) to 0.98 °C (Medellin), while pollution removal ranged from 488 kg PM2.5/yr (Zomba) to 48,400 kg PM2.5/yr (Dhaka). Percentage population with access to nearby greenspace ranged from 82% (Dhaka) to 100% (Zomba). The spatial patterns of pressure, of ecosystem service, and of maximum benefit within a city do not necessarily match, and this has implications for planning optimum locations for UGI in cities.

summary Diploid populations of Parnassia palustris L. var. palustris and var. condensata Travis & Wheldon have a highly symmetrical karyotype, consisting of seven metacentrk and two submetacentric chromosomes. The gross morphology of the karyotype of tetraploid populations is indistinguishable from that of the diploids. Studies of meiosis in tetraploids of both varieties demonstrated a high frequency of quadrivalent formation, strongly suggesting an autopolyploid origin. Later stages of meiosis in the tetraploids are regular and the pollen shows no decrease in stainability compared with that of the diploids. Some evidence is presented to show that tetraploids of both varieties may have a wider ecological amplitude than do diploids.

Genomic in situ hybridisation (GISH) experiments involving hybridising labelled genomic DNA from the diploid species C. stagnalis, C. obtusangula and C. cophocarpa to chromosome spreads of the tetr...

Most phylogeographic studies on the Qinghai–Tibetan Plateau and in adjacent regions have focused on tree or shrub species, or on herbaceous species that mainly inhabit alpine meadows or grasslands. The phylogeography of herbaceous species that inhabit woodlands and shrubberies has been largely neglected. Here we investigate the evolutionary history of a woodland- and shrubbery-inhabited herbaceous species, Rhodiola chrysanthemifolia, which grows in southern Tibet and in the mountains of the Hengduan ecoregion. The cpDNA trnL-F, rpl20-rps12 and nrDNA ITS regions of 183 individuals from 13 populations were sequenced. The ITS dataset revealed a significant phylogeographic structure across the distribution range of R. chrysanthemifolia, while the cpDNA dataset showed no significant structure. Besides, analyses of molecular variance showed that among-population variation was described as 96.27 % of the total variation for ITS marker, much higher than that for cpDNA (63.68 %). Limited seed migration among populations together with inbreeding within populations of R. chsysanthemifolia may result in the different phylogeographic and genetic patterns for ITS and cpDNA markers in this species. A high frequency and an even distribution of private cpDNA haplotypes were discovered throughout the distribution range of R. chrysanthemifolia; ITS genotypes formed three main lineages which showed a geographical distribution pattern. Furthermore, populations with above-average gene diversity were evenly spread across the current distribution range of R. chrysanthemifolia, supporting the existence of microrefugia for this species during Last Glacial Maximum, even earlier glaciations, similar to the pattern of sympatric tree and shrub species of the Juniperus tibetica complex and Hippophae tibetana. Allopatric divergence of populations in isolated microrefugia could be responsible for large number of private cpDNA haplotypes across the current distribution range of R. chrysanthemifolia. The putative factors which drove diversification between R. chrysanthemifolia and R. alsia were also discussed.

The taxonomy of the genus Micranthes Haw. in Europe is reviewed and the morphological characters that can be used to discriminate between it and Saxifraga L. are discussed. A new classification of Micranthes stellaris (L.) Galasso, Banfi & Soldano is proposed, based on recent phylogeographical studies. In it, the species is divided into three subspecies, (a) subsp. stellaris, distributed from eastern N. America, Greenland and northern Europe, south and west to the Massif Central, the Iberian peninsula and ?Corsica; (b) subsp. hispidula (Rochel) Gornall, ranging from the Carpathians south to the Balkan peninsula, and (c) subsp. robusta (Engl.) Gornall, confined to the Alps. The first has four varieties, var. stellaris, var. gemmifera (D.A. Webb) Gornall, var. paucidentata Gornall and var. obovata (Engl.) Gornall. The last has two varieties, var. acaulis (Haller f.) Gornall and var. prolifera (Sternb.) Gornall. A new combination is also made for the viviparous morphs of M. clusii (Gouan) Fern. Prieto, Vazqu...

Nearly half of the species in the large genus Saxifraga belong to Saxifraga sect. Ciliatae, a largely Sino-Himalayan taxon. We report here that evidence from chloroplast DNA sequences (psbA-trnH, trnL-F) and from nuclear sequences (ITS) indicates that this section is monophyletic and composed of at least three main lineages, corresponding to (1) a clade made up of species from S. subsect. Gemmiparae, subsect. Cinerascentes, subsect. Flagellares and subsect. Hemisphaericae, in which the last three subsections are nested in the first; (2) a clade of species belonging to S. subsect. Rosulares (including S. subsect. Serpyllifoliae); and (3) a clade of species belonging to S. subsect. Hirculoideae. Species relationships in S. subsect. Rosulares and subsect. Hirculoideae are not well resolved. A molecular clock analysis indicates that the diversification of S. sect. Ciliatae into its three lineages dates from ca. 9.48 Ma, coinciding with orogenic events associated with one of the most important phases of uplift of the Qinghai-Tibet Plateau. Extensive diversifications within S. subsect. Rosulares and subsect. Hirculoideae have been more recent (ca. 4.51 Ma and 2.12 Ma, respectively), again correlated with Qinghai-Tibet Plateau uplift events and, in the case of S. subsect. Hirculoideae, have occurred at a rate comparable to that seen in the radiation of Hawaiian fruit flies.

Chloroplast DNA sequences show substantial variation between higher plant species, and less variation within species, so are typically excellent markers to investigate evolutionary, population and genetic relationships and phylogenies. We sequenced the plastomes of Taraxacum obtusifrons Markl. (O978); T. stridulum Travnicek ined. (S3); and T. amplum Markl. (A978), three apomictic triploid (2n = 3x = 24) dandelions from the T. officinale agg. We aimed to characterize the variation in plastomes, define relationships and correlations with the apomictic microspecies status, and refine placement of the microspecies in the evolutionary or phylogenetic context of the Asteraceae. The chloroplast genomes of accessions O978 and S3 were identical and 151,322 bp long (where the nuclear genes are known to show variation), while A978 was 151,349 bp long. All three genomes contained 135 unique genes, with an additional copy of the trnF-GGA gene in the LSC region and 20 duplicated genes in the IR region, along with short repeats, the typical major Inverted Repeats (IR1 and IR2, 24,431bp long), and Large and Small Single Copy regions (LSC 83,889bp and SSC 18,571bp in O978). Between the two Taraxacum plastomes types, we identified 28 SNPs. The distribution of polymorphisms suggests some parts of the Taraxacum plastome are evolving at a slower rate. There was a hemi-nested inversion in the LSC region that is common to Asteraceae, and an SSC inversion from ndhF to rps15 found only in some Asteraceae lineages. A comparative repeat analysis showed variation between Taraxacum and the phylogenetically close genus Lactuca, with many more direct repeats of 40bp or more in Lactuca (1% larger plastome than Taraxacum). When individual genes and non-coding regions were for Asteraceae phylogeny reconstruction, not all showed the same evolutionary scenario suggesting care is needed for interpretation of relationships if a limited number of markers are used. Studying genotypic diversity in plastomes is important to characterize the nature of evolutionary processes in nuclear and cytoplasmic genomes with the different selection pressures, population structures and breeding systems.

Niche and neutral processes drive community assembly and metacommunity dynamics, but their relative importance might vary with the spatial scale. The contribution of niche processes is generally expected to increase with increasing spatial extent at a higher rate than that of neutral processes. However, the extent to what community composition is limited by dispersal (usually considered a neutral process) over increasing spatial scales might depend on the dispersal capacity of composing species. To investigate the mechanisms underlying the distribution and diversity of species known to have great powers of dispersal (hundreds of kilometres), we analysed the relative importance of niche processes and dispersal limitation in determining beta-diversity patterns of aquatic plants and cladocerans over regional (up to 300 km) and continental (up to 3300 km) scales. Both taxonomic groups were surveyed in five different European regions and presented extremely high levels of beta-diversity, both within and among regions. High beta-diversity was primarily explained by species replacement (turnover) rather than differences in species richness (i.e. nestedness). Abiotic and biotic variables were the main drivers of community composition. Within some regions, small-scale connectivity and the spatial configuration of sampled communities explained a significant, though smaller, fraction of compositional variation, particularly for aquatic plants. At continental scale (among regions), a significant fraction of compositional variation was explained by a combination of spatial effects (exclusive contribution of regions) and regionally-structured environmental variables. Our results suggest that, although dispersal limitation might affect species composition in some regions, aquatic plant and cladoceran communities are not generally limited by dispersal at the regional scale (up to 300 km). Species sorting mediated by environmental variation might explain the high species turnover of aquatic plants and cladocerans at regional scale, while biogeographic processes enhanced by dispersal limitation among regions might determine the composition of regional biotas., We wish to thank Steven Declerck, and the Subject Editor Luis Mauricio, whose comments helped to improve the manuscript. This research was funded by the European Union project ‘LAKES – Long distance dispersal of Aquatic Key Species’, contract no. env4‐ct‐97‐0585, and ESF‐EURODIVERSITY project BIOPOOL, through the Spanish Ministry of Science project CGL2006‐02247/BOS. DSV was supported by Fundação para a Ciência e Tecnologia SFRH/BD/48091/2008, co‐financed by the European Social Fund (ESF).

Potamogeton filiformis, P. pectinatus and P. vaginatus are three closely related species that produce sterile hybrids. These hybrids can be extremely difficult to identify, especially if in a vegetative state. To solve this problem, a protocol involving restriction fragment length polymorphism analysis of internal transcribed spacer rDNA is described that allows all three species and their hybrids to be distinguished. Analysis of internal transcribed spacer sequences shows that P. filiformis is closely related to P. vaginatus (differing by only a single substitution), whereas P. pectinatus differs from both by three indels and at least 20 substitutions. Infra-specific sequence variation was seen only in P. pectinatus, in which material from arctic Russia differed from that from Scotland, the Nordic region, the Netherlands and Italy by seven mutations.

Pollen cell number was studied in 124 species of Saxifraga and six species of Micranthes. Binucleate pollen is present in all the six species of Micranthes studied and in 96 species of Saxifraga. Trinucleate pollen occurs in 28 species of Saxifraga and is confined to section Ciliatae subsection Hirculoideae, where it is a putative synapomorphy, and to two species of subsection Serpyllifoliae. Trinucleate pollen does not characterise the whole of section Ciliatae as has been thought. The state has probably evolved at least twice, and possibly three times, in the genus. One new nomenclatural combination is made in Micranthes.

A study of two varieties of Parnassia palustris L. var. palustris and var. condensata Travis & Wheldon (Celastraceae) by means of fluorescent in situ hybridisation has shown that autotetraploid populations of both taxa display the same number of 18S–26S rDNA loci as their diploid counterparts, rather than double the complement. Mitotic preparations of diploid and tetraploid var. palustris revealed six (five in one tetraploid accession) sites of hybridisation, whereas in both diploid and tetraploid var. condensata four sites were detected. Each site was located in a subtelomeric position on a separate chromosome. These findings contrast with most previous studies of autopolyploids, in which numbers of such loci have been reported to be twice that found in the diploid genome.

A population of pondweeds from the River Stour in Dorset intermediate in morphology between Potamogeton natans L. and P. nodosus Poir. is shown by means of isozyme evidence to be the hybrid P. × schreberi G. Fisch. It is represented by a single multi-enzyme phenotype which, together with its sterility, suggests it reproduces vegetatively and may well constitute a single clone. It is genetically distinct from the morphologically similar hybrid between P. lucens L. and P. natans (P. x fluitans Roth).

The genetic structure of populations of an arctic-montane herb, Saxifraga hirculus (Saxifragaceae), was analysed by means of chloroplast restriction fragment-length polymorphism. Sampled populations were distributed across Europe and North America (Alaska and Colorado). There was no evidence for geographically structured genetically divergent lineages, and although no haplotypes were shared between North America and Europe, the haplotypes from different continents were intermixed on a minimum spanning tree. European populations were much more highly differentiated and had much lower levels of haplotype diversity than their Alaskan counterparts. Centres of haplotype diversity were concentrated in those Alaskan populations located outside the limits of the last (Wisconsin) glaciation, suggesting that they may have acted as refugia during the Pleistocene. It was not possible to identify putative migration routes or corresponding refugia in the European genepool. One British population, from the Pentland Hills, was genetically very distant from all the others, for reasons that are as yet unknown.

The flavonoid chemistry of 16 species of Chenopodium was investigated, with an emphasis on C. album and its relatives. The chief compounds seen were 3-O-glycosides of quercetin, kaempferol and isorhamnetin. The latter two classes show a mutually exclusive distribution among the diploid and all but one tetraploid species. C. polyspermum is unusual in possessing O-methylation at the 4′-, 6- and 7-positions, and C. murale is the only taxon to have 7-O-glycosylation. Acylated glycosides are common. C. album and related hexaploid taxa display a single flavonoid profile, providing no support for the recognition of more than one species. The hexaploid flavonoid profile represents an almost perfect summation of those of the diploids, C. suecicum and C. ficifolium. This apparent additive inheritance supports the hypothesis that these species (or taxa very similar to them) are involved in the ancestry of C. album. Chromosome numbers are reported for 14 of the species.

Saxifraga viridipetala Z-X. Zhang & Gornall (Saxifragaceae) is described as a new species. Originating from south-western Sichuan province in China, morphological and molecular evidence (based on chloroplast trnL-F and nuclear ITS DNA sequences) indicate that S. viridipetala is closely related to S. gemmipara, in section Ciliatae. The new species can be diagnosed by its narrowly elliptic, pale green petals spotted purple in the proximal 4/5 part.

Forty populations of Potamogeton pectinatus L. were sampled from around the Baltic Sea basin. Analysis of 62 ISSR 'loci' showed that the number of clones per population is very variable but shows a tendency to decrease with latitude. Analysis of molecular variance revealed that, overall, just over half the variability is stored within populations and just under half between them (phi(ST) 0.496). In pairwise comparisons, most populations are significantly differentiated. Genetic distance between populations, as measured by phi(ST), increases with geographical distance. Levels of population differentiation, however, are lower on the southeastern Swedish coast than elsewhere, a reduction correlated with the importance of this area as a staging post for the massive migrations of waterfowl from arctic Russia and western Siberia. Cumulative plots of phi(ST) against geographical distance along this coast suggest that, although it does not prevent significant population differentiation, bird traffic reduces it over distances of 150-200 km.

Restriction fragment length polymorphisms in the internal transcribed spacer region of ribosomal DNA and in the chloroplast genome combine to confirm the existence of Potamogeton × bottnicus ( P. pectinatus × P. vaginatus ) in Britain. One of the parents, P. vaginatus , is not currently a member of the British flora, but did occur here in the past (the latest fossil fruits date from 30 000 BP) and the hybrid may therefore owe its origin to ancient cross-pollination involving indigenous material or to more recent long-distance dispersal.

Genetic diversity in British populations ofSaxifraga rivularisL. (Saxifragaceae) was assessed using isozymes, RAPDs, inter-SSRs and RFLPs of two non-coding chloroplast DNA regions. Low levels of variation were detected: only five molecular phenotypes were recovered, polymorphic for a single RAPD band andPgdenzyme phenotype. The problem of drawing conservation recommendations from studies that show low levels of marker variation is discussed, and the importance of recognizing the limits of molecular genetic data in conservation biology is emphasized.

Six hundred and forty-seven samples of Potamogeton coloratus from 60 ditches in the Gordano Valley, Somerset were analysed for variation at two polymorphic PGM isozyme loci using starch gel electrophoresis. A total of eight genotypes was detected, and a high level of partitioning of genetic variability between ditches was observed with FST=0.575. Genetic variability was shown to increase with distance from the head of the valley. The genetic subdivision of the population and pattern of increasing diversity downstream and downwind were attributed to genetic bottlenecks, associated with ditch cleaning events, and subsequent directional gene flow mediated by the prevailing wind and water currents.

In a review of chromosome numbers in the genus Potamogeton, we highlight numerous errors that have crept into the literature. These have resulted chiefly from reliance on abstracts in chromosome number indices and compilations, rather than on the original publications, but partly also because of misleading summaries even in the primary literature. We present a list of counts that we believe are original and genuine, and a list of those that were never made but which nevertheless appear in the literature. Scrutiny of the list of accepted counts indicates that aneuploidy is widespread in the genus and that transition between the two common chromosome numbers (2n=26 and 2n=28) has occurred several times. Currently available data are insufficient to resolve the question of the ancestral base number. We also present details of the first chromosome counts from English populations of five taxa: P. polygonifolius Pourr. (2n=28), P. pectinatus L. (2n=ca. 78), P. perfoliatus L. (2n=ca. 52), P.×nitens Weber (P. gramineus×P. perfoliatus) (2n=ca. 52) and P.×salicifolius Wolfg. (P. lucens×P. perfoliatus) (2n=ca. 52).

Outside North America Potamogeton epihydrus Raf. is confined to two areas of Britain. An investigation of British material from apparently native sites in the Outer Hebrides and from a canal in northern England (where it is believed to be introduced) revealed only a single isozyme genotype. Ten putative loci were resolved. The IDH phenotype was uniform and three-banded, consistent with heterozygosity (possibly caused by a duplicated locus or preserved by clonal growth). All other enzyme loci were homozygous.

1. The relative role of environmental and regional processes in determining patterns of biodiversity may vary across spatial scales. In inland aquatic communities, macrophytes and zooplankton have the potential to disperse over large spatial scales (hundreds of kilometres), but the role of environmental and regional processes in determining species richness (SR) at different spatial scales is poorly understood. 2. To assess the relative importance of environmental and regional processes acting on both regional (within-region) and continental (among-region) scales, we surveyed 139 waterbodies in five geographic regions (Spain, Italy, the Netherlands, Scotland and Norway) and in each region measured environmental variables, descriptors of connectivity and SR of two aquatic taxa, namely aquatic plants and cladocerans. 3. Analyses using boosted regression trees and generalised linear models, integrated with multiple imputation of missing data, indicated that both environmental and regional processes were related to local SR. 4. Total phosphorus was the main environmental correlate of SR, showing a unimodal relationship with both taxonomic groups. Conductivity and lake depth were also related to cladoceran SR, and Secchi depth was related to aquatic plant richness. 5. The SR of aquatic plants and cladocerans were significantly correlated, but this relationship was mainly indirect (i.e. determined by the effect of common environmental variables). 6. The limited role of connectivity and space (lack of spatial autocorrelation in model residuals) relative to environment suggests that dispersal limitation is not as important as the environment in explaining richness patterns for both groups within regions. However, region identity strongly influenced SR, which suggests an important effect of biogeographic factors (e.g. the level of endemicity; the number of unique species in each region) and/or dispersal limitation at the continental scale. 7. We conclude that environmental factors and biogeographic processes largely determine the patterns of local and regional SR in aquatic plants and zooplankton.

Intraspecific variation of four agamospecies of Hieracium sect. Alpina was studied using RAPD and isozyme techniques. No variation in either multiprimer RAPD or multi-enzyme phenotypes was observed within H. holosericeum, suggesting that this widespread species consists of only a single genotype. A low level of within-population isozyme variation was seen in H. tenuifrons and H. calenduliflorum, the origin of which appears to be consistent with somatic mutation. Most isozyme and all RAPD variation in these two species was partitioned between populations. A strong correlation with geography suggests that its cause may be due to polytopic (=polyphyletic?) origin or perhaps to mutation and dispersal. The most variable species was H. alpinum, in which isozyme variation occurred mostly within populations rather than between them, suggesting occasional sexual events or that the parents of H. alpinum were heterozygous. RAPD variation in this species, in contrast, was partitioned between Scottish and Swiss populations, suggesting the existence of geographical races.

The large genus Saxifraga, which consists of z400 morphologically and cytologically diverse species, has long been considered taxonomically complex. Phylogenetic analysis of over 2 500 bp of chloroplast sequence data derived from matK and rbcL was employed to examine relationships among sections of Saxifraga, the segregate genera Zahlbrucknera, Saxifragopsis, and Cascadia, and the relationships of these taxa to other Saxifragaceae sensu stricto. Phylogenetic trees resulting from separate analyses of the matK and rbcL sequences were highly congruent; phylogenetic analysis of a combined matKrbcL data matrix was therefore also conducted. Our analyses indicate that Saxifraga is polyphyletic, comprising two welldifferentiated clades. One clade, Saxifraga sensu stricto, is the sister to the remainder of the family and consists of Saxifraga sections Irregulares, Heterisia, Trachyphyllum, Cymbalaria, Mesogyne, Xanthizoon, Porphyrion, Ciliatae, Cotylea, Ligulatae, Saxifraga, and Gymnopera. With the exception of Gymnopera, the species-rich sections of this clade are monophyletic. Also part of this clade is the problematic Zahlbrucknera paradoxa, which is allied with members of section Saxifraga. A second major clade of Saxifraga species, Micranthes sensu lato, comprises the large section Micranthes, as well as the segregate genus Cascadia, and S. tolmiei of section Merkianae. This clade is allied with the Heuchera, Darmera, and Chrysosplenium-Peltoboykinia groups of genera. The segregate genus Saxifragopsis is only distantly related to species of Saxifraga, and is instead the sister to Astilbe. The monotypic Oresitrophe is confirmed as a member of the Darmera group of genera. These results suggest that the floral features used to define Saxifraga may simply be symplesiomorphic in these well-separated Saxifraga lineages. Furthermore, the enormous cytological diversity encompassed by Saxifraga likely represents two independent instances of extensive aneuploidy and polyploidy in Saxifragaceae.

Evidence from isozyme analyses indicates thatPotamogeton ×suecicus is the hybrid betweenP. pectinatus andP. filiformis. The hybrid appears to have arisen on several occasions. The isozyme profiles of this hybrid from the Rivers Wharfe and Ure in Yorkshire, south of the present limit of distribution ofP. filiformis, suggest that each population is a single clone; these clones may be relics from the Weichselian glacial period. Populations of the putative hybrid from the Rivers Tweed and Till are notP. ×suecicus but probably haveP. vaginatus andP. pectinatus as parents. If so, this is a remarkable example of a pondweed hybrid persisting vegetatively in an area outside the distributional range of one of its parents.

Genetic variability inPotamogeton pectinatus andP. filiformis was studied by means of isozymes. The overall levels of variability were similar to some other well studied hydrophilous species, and were shown to be distributed more between than within populations. This partitioning of variability was attributed to three main factors. (1) Clonal growth (as measured by the frequency of multi-enzyme phenotypes) was shown to be a major factor in both species, although more important inP. pectinatus. (2) Low levels of sexual reproduction were shown to be a likely contributor to the partitioning of variability inP. pectinatus; such reproduction is probably limited by seedling recruitment rather than by infrequent flowering. (3) Geographical isolation was indicated as a factor regulating gene flow at distances of more than about 1000 km in both species, with the data suggesting that dispersal between populations is mainly by seed rather than by vegetative means.

Species ofCoriariaare wind-pollinated and self-compatible. Discrepancies in the literature regarding sex expression in the genus may be attributed to inter- and intra-floral dichogamy. The southern hemisphere species and the HimalayanC. terminalisare evergreen phanerophytes or high elevation hemicryptophytes, which flower on new wood. Their racemes are many-flowered and are produced singly (terminal) or more usually in pairs in the axils at each node, and contain protogynous, hermaphrodite flowers. The northern hemisphere species are deciduous phanerophytes, which flower on old wood. Their racemes are few-flowered but aggregated in axillary clusters of up to 12 per node; sex expression is andromonoecious or monoecious (depending on species), with inter-floral protandry and intra-floral protogyny. In this lineage of species the evolution of a deciduous habit, the presentation of an initial male phase (inter-floral protandry), and the aggregation of many, few-flowered racemes at each node are interpreted as responses to selection pressures in the seasonal climate of a northern, mixed woodland environment.

The partitioning of genetic variability within and between twelve British populations of the anemophilous aquaticPotamogeton coloratusHornem. was investigated by isozyme analysis. Low levels of variability as measured by P, A and H were found. Calculation of Wright's F statistics revealed a high mean value of the overall inbreeding coefficient, (FIT = 0.939), which was attributed both to high levels of genetic subdivision among populations (mean FST = 0.702) and to a high frequency of inbreeding or clonal growth within them (mean FIS = 0.796). Only two populations are polymorphic; both inhabit sites with a long post-glacial history as wetlands. Populations of recent origin, as well as some of older vintage, contain only a single multi-locus isozyme genotype, homozygous at all loci except for IDH. A genetic bottleneck following the Devensian glaciation is discussed as a possible cause of the pattern of variation. Evidence for a duplicated IDH locus is presented.

Trichome anatomy was examined by light and scanning electron microscopy in 25 genera of Engler's Saxifragaceae from the southern hemisphere. Four principal categories of trichome were recognized: (1) multiseriate with a glandular head; (2) uniseriate with a glandular head; (3) uniseriate, eglandular; (4) unicellular, eglandular. The shape of eglandular hairs ranges from erect to sickle-shaped to T-shaped. The main taxonomic conclusions are as follows: (a) Vahlia should be excluded from tribe Saxifrageae and a possible relationship with Montinia investigated; (b) Francoa and Tetilla (tribe Francoeae) are closely related, although the relationship of the tribe to its parent subfamily, Saxifragoideae, is unclear; (c) Eremosyne is probably allied to the Escallonioideae; (d) subfamily Brexioideae is heterogeneous in trichome anatomy, but the relationships of its constituent genera remain problematic; (e) subfamily Escallonioideae is heterogeneous in trichome anatomy, although similarities between and within the constituent tribes do exist. Thus Cuttsia and Abrophyllum form a natural group (tribe Cuttsieae), to which Carpodetus (tribe Argophylleae) may also be related; similarity in trichome anatomy between Argophyllum and Corokia (tribe Argophylleae) is substantiated by an extensive survey of all the species, and the data tentatively suggest a possible hydrangeoid affinity for these two genera. Forgesia (tribe Forgesieae) is shown to possess the same kind of hairs in the flowers as Quintinia (tribe Escallonieae), and Choristylis (tribe Forgesieae) is shown to be remarkably similar to Escallonia , prompting a suggestion that the two tribes be merged. Trichome data support the inclusion of Anopterus and Polyosma in their own tribes, although their wider affinities remain unclear. Doubts about the inclusion of the glabrous Tribeles in Escallonioideae are expressed. Our material of the following additional genera Lepuropetalon, Tetracarpaea and Brexia was glabrous and little comment could be made about them.

SUMMARY The varieties of Parnassia palustris L. in the British Isles (var. palustris and var. condensata Travis & Wheldon) each have two cytodemes: a diploid (2n= 18) and a tetraploid (2n= 36). The distribution of the cytodemes is loosely correlated with the limits of the Devensian glaciation.

Details of leaf venation in 150 species of Saxifraga L. representing all 13 sections are reported. Three main patterns were observed: palinactinodromous, acrodromous and camptodromous. Species with lobed leaves have palinactinodromous patterns, whereas those with entire leaves are acrodromous or camptodromous. Thus species from sections Heterisia, Irregulares , Cymbalaria , Cotylea and Mesogyne are palinactinodromous; species from sections Saxifraga , Ciliatae , Bronchiales and Trachyphyllum , in which some have lobed and some have entire leaves, are either palinactinodromous or acrodromous, according to the leaf margin; species from sections Ligulatae and Porphyrion , whose hydathodes secrete calcium bicarbonate, have camptodromous venation. Intermediate states occur in section Gymnopera (between palinactinodromous and camptodromous) and in section Porphyrion subsection Oppositifoliae and section Xanthizoon (intermediate between acrodromous and camptodromous). The pattern of distribution across the genus and selected outgroups shows that the ancestral state is likely to be palinactinodromous.

Details of exine morphology (SEM studies of 132 species) and anatomy (TEM studies of 25 species) of Saxifraga are reported. The variation observed was compared with that found in an earlier survey. We suggest modifications to known types and subtypes and the addition of new ones, making a total of nine exine types and subtypes in Saxifraga. Taxonomic conclusions include the following. A novel exine type (Type 2.3), in which the single tectum has numerous microchannels, is a putative synapomorphy for sects. Heterisia and Irregulares. At least three species from sect. Ciliatae, viz., S. lychnitis, S. oresbia from ser. Lychnitidae, and S. nigroglandulifera from ser. Nutantes, have a novel type with a perforate-reticulate or perforate-rugulate tectum. Species from the rest of the section are uniformly finely striate. Section Saxifraga has Type 2.1, with a single tectum, Type 4.3, with a double tectum, and Type 2.2, which is intermediate to various extents. The origin of Types 2.1 and 2.2 from Type 4.3 is suggested. Within sect. Saxifraga subsect. Triplinervium, S. wahlenbergii is unique in possessing pollen with a secondary tectum (Type 4.3), resembling the exine of S. androsacea in subsect. Holophyllae. On this and other grounds, we support the transference of S. wahlenbergii to the latter subsection. Himalayan species with opposite rather than alternate leaves that were formerly assigned to sect. Porphyrion subsect. Oppositifoliae, have exines with supratectal ornamentation similar to that in subsect. Kabschia; in this respect they are unlike the European species with opposite leaves, which lack this ornamentation. Among the species with chalk-glands, exines lacking supratectal ornamentation are restricted to European species, viz. those in sect. Porphyrion subsects. Engleria and Oppositifoliae, and S. florulenta, offering morphological support for the transfer of the latter species to sect. Porphyrion. Saxifragella is recognised as a new section of the genus.

1. Using Organelle Markers to Elucidate the History, Ecology and Evolution of Plant Populations R.A. Ennos, W.T. Sinclair, X.-S. Hu and A. Langdon 2. Isolation Within Species and the History of Glacial Refugia C. Ferris, R.A King and G.M. Hewitt 3. The Use of Uniparentally Inherited Simple Sequence Repeat Markers in Plant Population Studies and Systematics J. Provan, N. Soranzo, N.J. McNicol, M. Morgante and W. Powell 4. The Use of RAPD Data in the Analysis of Population Genetic Structure: Case-studies of Alkanna (Boraginaceae) and Plantago (Plantaginaceae) K. Wolff and M. Morgan-Richards 5. Metapopulation Dynamics and Maring-system Evolution in Plants S.C.H. Barrett, J.R. Pannell 6. Identifying Multiple Origins in Polyploid Homosporous Pteridophytes J.C. Vogel, J.A. Barrett, F.J. Rumsey and M. Gibby 7. Population Genetic Structure in Agamospermous Plants R.J. Gornall 8. Monophyly, Populations and Species J.I. Davis 9. Reticulate Evolution in the Mediterranean Species Complex of Senecio Sect. Senecio: Uniting Phylogenetic and Population-level Approaches H.P. Comes and R.J. Abbott 10. The Value of Genomic In Situ Hybridization (GISH) in Plant Taxonomic and Evolutionary Studies C.A. Stace and J.P. Bailey 11. RAPDs in Systematics - a Useful Methodology? S.A. Harris 12. Nuclear Protein-coding Genes in Phylogeny Reconstruction and Homology Assessment: Some Examples From Leguminosae J.J. Doyle and J.L. Doyle 13. Spectral Analysis - a Brief Introduction M.A. Charleston and R.D.M. Page 14. Ribosomal DNA Sequences and Angiosperm Systematics M.A. Hershkovitz, E.A. Zimmer and W.J. Hahn 15. Proteins Encoded in Sequenced Chloroplast Genomes: an Overview of Gene Content, Phylogenetic Information and Endosymbiotic Transfer to the Nucleus B. Stoebe, S. Hansmann, V. Goremykin, K.V. Kowallik and W. Martin 16. Phylogenetics and Diversification in Pelargonium F.T. Bakker, A. Culham and M. Gibby 17. Integrating Molecular Phylogenies and Developmental Genetics: a Gesneriaceae Case Study M. Moller, M. Clokie, P. Cubas and Q.C.B. Cronk 18. Inferior Ovaries and Angiosperm Diversification M.H.G. Gustafasson and V.A. Albert 19. Intergrating Molecular and Morphological Evidence of Evolutionary Radiations R.M. Bateman Albert, The New York Botanical Garden, UK, J.P. Bailey, University of Leicester, UK, F.T. Bakker, University of Reading, UK, J.A. Barrett, University of Cambridge, UK, S.C.H. Barrett, University of Toronto, UK, R.M. Bateman, Royal Botanic Garden, Edinburgh, UK, M.A. Charleston, University of Oxford, UK, M. Clokie, University of Leicester, UK, H.P. Comes, Institut fur Spezielle Botanik und Botanisher Garten, Germany, Q.C.B. Cronk, University of Edinburgh, UK, P. Cubas, Institut Nacional de Investigaciones Agrarias, Spain, A. Culham, University of Reading, UK, J.I. Davis, Cornell University, USA, J.J. Doyle, Cornell University, USA, J.L. Doyle, Cornell University, USA, R.A. Ennos, University of Edinburgh, UK, C. Ferris, University of Leicester, UK, M. Gibby, The Natural History Museum, UK, V. Goremykin, Hans-Knoll-Institut fur Naturstoff-Forschung, Germany, R.J. Gornall, University of Leicester, UK, M.H.G. Gustafsson, The New York Botanical Garden, USA, W.J. Hahn, Columbia University, USA, S. Hansmann, Technische Universitat Braunschwieg, Germany, S.A. Harris, University of Oxford, UK, M.A. Hershovitz, Laboratory of Molecular Systematics, UK, G.M. Hewitt, University of East Anglia, UK, X-S. Hu, University of Edinburgh, UK, R.A. King, University of Leicester, UK, K.V. Kowallik, Heinrich-Heine-Universitat Dusseldorf, Germany, A. Langdon, University of Edinburgh, UK, W. Martin, Technische Universitat Braunschwieg, Germany, J.W. McNicol, Scottish Crop Research Institute, UK, M. Moller, Royal Botanic Gardens Edinburgh, UK, M. Morgan-Richards, Otago University, New Zealand, M. Morgante, Universita di Udine, Italy, R.D.M. Page, University of Glasgow, UK, J.R. Pannell, University of Oxford, UK, W. Powell, DuPont Agricultural Biotech, USA, J. Provan, Scottish Crop Research Institute, UK, F.J. Rumsey, The Natural History Museum, UK, W.T. Sincalir, The Scottish Agricultural College, UK, N. Soranzo, Scottish Crop Research Institute, UK, C.A. Stace, University of Leicester, UK, B. Stoebe, Heinrich-Heine-Universitat Dusseldorf, Germany, J.C. Vogel, The Natural History Museum, UK, N.J. Wilson, Scottish Crop Research Institute, UK, K. Wolff, The University of Newcastle upon Tyne, UK, E.A. Zimmer, Laboratory of Molecular Systematics, USA.

Following recent phylogenetic work segregating Micranthes Haworth from Saxifraga L. (Saxifragaceae) and to complete the transfer of names from Saxifraga to Micranthes in North America, we are proposing the new combination M. hitchcockiana (Elvander) Brouillet & Gornall.

The following new species, new variety, new name, and four new combinations are published for the forthcoming account of Saxifraga L. in the Flora of China, Volume 8: S. epiphylla Gornall & H. Ohba, sp. nov., S. gemmigera Engler var. gemmuligera (Engler) J. T. Pan & Gornall, comb. nov., S. heterotricha Marquand & Airy-Shaw var. anadena (H. Smith) J. T. Pan & Gornall, comb. et stat, nov., S. hypericoides Franchet var. aurantiascens (Engler & Irmscher) J. T. Pan & Gornall, comb. nov., S. hypericoides var. rockii (Mattfeld) J. T. Pan & Gornall, comb. et stat. nov., S. sinomontana J. T. Pan & Gornall, nom. nov., and S. sinomontana var. amabilis H. Smith ex J. T. Pan, var. nov. In addition, the names S. mengtzeana Engler & Irmscher and S. mengtzeana var. cordatifolia Engler & Irmscher are lectotypified here.

This book contains the proceedings of a meeting of the NATO Advanced Study Institute on Advances in Molecular Ecology, held at Erice, Italy in March 1998. There are 14 chapters, beginning with an overview of the history of the subject area which Gary Carvalho traces back to the ecological genetics school of A. J. Cain, P. M. Sheppard and E. B. Ford. This useful introduction sets the whole discipline in context and provides a basis for what follows. What does follow is an eclectic range of contributions which nevertheless give something of the flavour of the current state of the art. There are some theoretical chapters, dealing with the phylogenetic analysis of population data (Hillis); the estimation of migration rates, contrasting newer coalescent approaches favourably against the more conventional methods based on FST (Beerli); parentage analysis in plants (Schnabel); the relative merits of micro-and minisatellites as markers (Estoup & Angers); and, at the end of the book, a very useful review of many of the software packages that are available for conducting different aspects of population genetic analysis (Schnabel et al.). Microbes are the focus of three of the chapters, dealing with aspects of present-day (Muyzer) as well as palaeo-ecology (Rollo), and bacterial speciation (Young). The evolutionary implications of clonal reproduction are treated from an animal perspective in an excellent review by Vrijenhoek. Other topics of evolutionary importance addressed include the use of molecular markers in the study of natural selection (Mitton), hybridisation (Rieseberg), and differentiation in aquatic populations, both inland (Hebert) and at sea (Hauser & Ward).

Self- and cross-pollinations were made within and between selected species belonging to Boykinia, Peltoboykinia, Bolandra, Suksdorfia, Sullivantia, and Jepsonia (Saxifragaceae). Self-incompatibility is reported for the first time in Boykinia. No intergeneric hybrids were produced, supporting the separate integrities of the genera involved, particularly the segregation of Peltoboykinia. Intrageneric hybrids were made in Boykinia and Peltoboykinia. In the case of Boykinia, this supports the retention within it of the often segregated Telesonix. Crosses between the two North American Suksdorfia species failed, but for various reasons, this was taken to reflect the existence of two "biological species" rather than two separate genera.

Chromosome numbers are reported for the first time for Boykinia intermedia (2n = 14), B. major (2n = 28), Peltoboykinia watanabei (2n = 22), and Suksdorfia (= Hemieva) ranunculifolia (2n = 14). Additional counts are provided for eight other species of Boykinia (including Telesonix), Peltoboykinia, Suksdorfia, and Bolandra. Previous literature reports are reviewed and some errors pointed out. Chromosome numbers do little to resolve the problem of generic limits, with the exception of supporting the segregation of Peltoboykinia. They do, however, support the recognition of Boykinia intermedia as a species distinct from B. major.

An evaluation of the limits and infra-generic taxonomy of the genus Boykinia and its allies is presented. In the past, Boykinia has been split into the following segregate genera: Boykinia and Telesonix (from North America) and Neoboykinia and Peltoboykinia (from Japan). The situation is complicated by other closely related genera, the limits of which also need clarification. Narrowly defined, they comprise Suksdorfia, Hemieva, Bolandra, Sullivantia and Jepsonia (all from North America) and Hieronymusia (from South America). This monograph draws on a variety of sources for information, including a morphological comparison of all taxa, using a wide range of both living and herbarium material, and observations on leaf anatomy, trichomes, pollen grains and seeds; reference is also made to our previously published work on flavonoids, chromosome numbers and breeding relationships. General ecological observations were made during field work in western North America. The results of these investigations confirm that the genera form a closely related group. Much of the evidence combines to suggest the following conclusions. Boykinia includes nine species in three sections: section Boykinia (B. aconitifolia, B. intermedia, B. lycoctonifolia, B. major, B. occidentalis and B. rotundifolia), section Renifolium (B. ruhardsonii) and section Telesonix (B. jamesii and B. heucheriformis). Peltoboykinia (P. tellimoides and P. watanabei) is recognized as a distinct genus allied to both Saxifraga and Boykinia. Suksdorfia, expanded to include Hemieva and Hieronymusia, has three species: S. violacea, S. alchemilloides and S. ranunculifolia. Bolandra is very closely related to Suksdorfia but is retained as a separate genus containing two species, B. californica and B, oregana. Sullivantia and Jepsonia are accepted as genera related to, but distinct from, Boykinia.

GORNALL, R. J., 1987. An outline of a revised classification of Saxifraga. A revised classification of Saxifraga is presented in which 15 sections, 19 subsections and 34 series are recognized. A total of 394 names are accounted for, including the following new taxa, combinations and names: series Hirculoideae (Engler & Irmscher) Gornall, stat. nov.; series Lychnitidae (Engler & Irmscher) Gornall, stat. nov.; series Nulanles (Engler & Irmscher) Gornall, stat. nov.; series Cinctae (H. Sm.) Gornall, stat. nov.; series Gemmiparae (Engler & Irmscher) Gornall, stat. nov.; series Spinulosae (C. B. Clarke) Gornall, stat. nov.; subsection Rosulares Gornall, nom. nov.; subsection Serpyllifoliae Gornall, subscct. nov.; subsection Hemisphaericae (Engler & Irmscher) Gornall, stat. nov.; section Merkianae (Engler & Irmscher) Gornall, stat. nov.; subsection Stellares (Engler & Irmscher) Gornall, stat. nov.; series Birostres Gornall, ser. nov.; series Melanocentrae (Engler & Irmscher) Gornall, stat. nov.; series Astasianlhes (Sternberg) Gornall, stat. nov.; subsection Micranthes (Haworth) Gornall, stat. nov.; series Aulaxis (Haworth) Gornall, stat. nov.; series Dermasea (Haworth) Gornall, stat. nov.; series Micranthes (Haworth) Gornall, stat. nov.; scries Aretioideae (Engler & Irmscher) Gornall, stat. nov.; series Juniperifoliae (Engler & Irmscher) Gornall, stat. nov.; series Lilacinae Gornall, ser. nov.; series Marginatae (Engler & Irmscher) Gornall, stat. nov.; series Squarrosae (Engler & Irmscher) Gornall, stat. nov.; series Rigidae (Engler & Irmscher) Gornall, stat. nov.; subsection Engleria (Siindermann) Gornall, stat. nov; series Subsessiliflorae Gornall, ser. nov.; series Oppositiofoliae (Hayek) Gornall, stat. nov.; series Tetrameridium (Engler) Gornall, stat. nov.; subsection Mutatae (Engler & Irmscher) Gornall, stat. nov.; subsection Florulentae (Engler & Irmscher) Gornall, stat. nov.; section Odontophyllae Gornall, sect, nov.; series Biternatae (Engler & Irmscher) Gornall, stat. nov.; subsection Triplinervium (Gaudin) Gornall, stat. nov.; series Arachnoideae (Engler & Irmscher) Gornall, stat. nov.; subsection Tridactylites (Haworth) Gornall, stat. nov.

Geographic variation can lead to the evolution of different local varieties within a given species, therefore influencing its distribution and genetic structure. We investigated the contribution of plasticity and local adaptation to the performance of a common aquatic plant (Potamogeton pectinatus) in contrasting climates, using reciprocal transplants at three experimental sites across a latitudinal cline in Europe. Plants from 54 genets, originally collected from 14 populations situated within four climatic regions (sub- arctic, cold temperate, mild temperate, and mediterranean) were grown in three different localities within three of these regions (cold temperate, Nor way; mild temperate, The Netherlands; mediterranean, Spain). Tuber production was highest for the mild-temperate genets, irrespective of locality where the genets were grown. Selection coefficients indicated that populations at the European center of the species distribution perform better than all other populations, at all sites. However, marginal populations showed changes in life-histor y traits, such as compressed life cycles in the north and true perenniality in the south, that may allow them to perform better locally, at the limits of their distribution range. Our results thus suggest that local adaptation may overlap spatially with center–peripher y gra- dients in performance caused by genetic factors (such as genetic drift and inbreeding in range-marginal populations).

Summary. Cultivars of the putative hybrid Skimmia japonica Thunb. subsp. japonica x subsp. reevesiana (Fortune) N. P. Taylor & Airy Shaw have 2n = 30, regular meiosis (15 bivalents) and are highly fertile; they are best assigned to S.japonica subsp.japonica. It is doubtful whether this hybrid has ever been in cultivation. S. x confusa N. P. Taylor (S.japonica x anquetilia N. P. Taylor & Airy Shaw) has 2n = 30 and forms 15 bivalents at metaphase I; it is, however, largely sterile.