Patterns of allozyme variation and clonal diversity in Carex lasiocarpa and C. pellita (Cyperaceae)

We compared genetic variability and clonal diversity in the closely related sedges Carex lasiocarpa and C. pellita using allozyme markers at 12 loci. Both species produce spreading rhizomes, occur in open habitats, and can form large clones; C. lasiocarpa primarily along lakeshores, or in bogs, fens, or marshes, and C. pellita more commonly along riverbanks and ditches or in wet meadows. Polymorphism was high in both species, similar to that of other rhizomatous Carex and to other species with comparable growth forms and life histories. Total gene diversity was higher for C. lasiocarpa (H_T = 0.266) than for C. pellita (H_T = 0.248), but the coefficient of differentiation among populations was lower. Rare alleles usually occurred as heterozygotes rather than homozygotes, and significant deviations from Hardy-Weinberg equilibrium were found at few loci, suggesting that both species are predominantly outcrossing. Mean clone size, diversity, and evenness were not significantly different between the two species, although populations varied from monoclonal to those where nearly every sampled shoot belonged to a different clone. No significant differences in genetic variation or clone size of C. pellita were found when comparisons were made between groups based on climate (warmer vs. cooler) or successional stage (pioneer vs. established). However, within C. lasiocarpa, genetic variability decreased and clone size increased in cooler climates and at established sites.     

Allozyme differentiation between the lowland Carex capitata and the alpine Carex arctogena (Cyperaceae) in Scandinavia

Within Scandinavia, Carex capitata s.l, is usually divided into two taxa: the lowland to lowalpine C. capitata s.s., and the alpine C. arctogena. The systematic status of these taxa is uncertain, reflected by their taxonomic treatment in different floras. In this study, allozymes were used to assess the degree of genetic differentiation between and within taxa. Ten populations of Carex capitata s.s. and eight of C. arctogena, from Norway and Sweden, were included in the study. Sixteen loci in eleven different enzyme systems were analysed: five were variable within or between taxa, three could be interpreted in all plants. In all, 20 different alleles were found. Four of these alleles were confined to C. capitata s.s., and two to C. arctogena. In C. capitata s.s., three loci (18%) were polymorphic, while all loci were monomorphic in C. arctogena. The number of alleles per polymorphic locus was 2.2 in C. capitata s.l. The taxa had completely different alleles at two loci {Pgi-2, Pgm-1). Nei's genetic identity was 0.86 between taxa, and ranged between 0.95 and 1 in pairwise comparisons of populations of Carex capitata s.s., while it was 1 in all comparisons between populations of C. arctogena. The distinction of C. capitata s.s. and C. arctogena as separate species agrees well with the amount of differentiation found between other congeneric species. It is suggested that the low genetic variation observed in both taxa is due to ancient founder events. The difference in genetic variability between taxa may be due to differences in immigration history: whereas C. capitata s.s. may have colonized Scandinavia from several close refugia after the last glaciation, C. arctogena may have reached Scandinavia after long-distance dispersal of a limited number of propagules.     

Allozyme variation and racial differentiation in Swedish Carex lepidocarpa s.l. (Cyperaceae)

Two morphological races have previously been recognized within the sedge, Carex lepidocarpa , in Sweden. These largely allopatric races are accorded specific status, as C. lepidocarpa s.s. and C. jemtlandica , in Scandinavian floras. A study of allozyme variation in populations from 80 Swedish sites supports the morphological evidence for racial differentiation within C. lepidocarpa. The two races differ from each other in terms of allele frequencies at polymorphic loci and also show different levels of within-population genetic diversity. Material that is morphologically referable to C. lepidocarpa s.s. is characterized by relatively high levels of allozyme variation, both within and between populations. Carex lepidocarpa s.s. is widespread in southern Sweden. In contrast, material that is morphologically assignable to C. jemtlandica shows low levels of within-population genetic diversity, and there is little differentiation between the geographically separated isolates of C. jemtlandica in northern Sweden and on the Baltic island of Gotland. The high degree of morphological similarity and moderate levels of genetic differentiation between the two races within C. lepidocarpa indicate that it is more appropriate to recognize the races as subspecies than as species. The low levels of genetic variation in C. jemtlandica , both within and between populations, suggest that C. jemtlandica may have arisen from C. lepidocarpa (or a near ancestor of C. lepidocarpa) as a result of population fragmentation and isolation in glacial refugia, or during the process of post-glacial colonization of Scandinavia. Lack of allozyme evidence for extensive hybridization between the two races of C. lepidocarpa , despite their ability to hybridize freely where their ranges overlap at present, supports the suggestion that the two races have had separate post-glacial histories.     

Genetic diversity and endemism in North American Carex section Ceratocystis (Cyperaceae)

Factors leading to endemism, and the evolutionary implications of endemism, can be explored by studying closely related taxa with variously restricted distributions. Such a model is provided by Carex section Ceratocystis (Cyperaceae); Carex cryptolepis, Carex sp. nov., and C. lutea are North American endemics with broad, restricted, and highly restricted distributions, respectively. The prediction that levels of genetic diversity are a consequence of distribution size was tested within a phylogenetic context using population level genetic variation at 18 allozyme loci. In contrast to expectations, mean proportion of loci polymorphic, number of alleles per polymorphic locus, and expected heterozygosity were significantly greater in C. lutea than either C. cryptolepis or Carex sp. nov. Although the possibility of a shift in breeding system, past introgression, or progenitor-derivative relationships could explain the relatively high levels of variation observed in C. lutea, these were dismissed on the basis of allozyme and nuclear ribosomal sequence data. We conclude that C. lutea maintains levels of genetic diversity typical of caespitose carices despite its narrow endemism and that the low levels of genetic variation in C. cryptolepis and Carex sp. nov. are likely the result of population fluctuations during Pleistocene glacial-interglacial cycles.     

Anatomical studies of Carex cuchumatanensis,C. decidua,and C. hermannh (Cyperaceae) and comparisons with north American taxa of the C. acuta complex

Foliar anatomy and micromorphology of perigynia and achenes were investigated for three taxa of theCarex acuta complex of sect.Phacocystis Dumort. in Middle and South America. Anatomical characters appear to be conservative, and show little variation amongC. cuchumatanensis Standl. & Steyerm.,C. decidua F. Boott, andC. hermannii Cochrane. Leaves of all species are amphistomatous, with stomates and papillae on both epidermal surfaces, and have a single layer of bulliform cells but differ in the number of vascular bundles. Perigynia have epidermal cells with thin, convex, outer walls that are collapsed in dired specimens, and epidermal cells of achenes each have a single, rounded, nodulose silica-body with a basal platform. Anatomical data are useful in resolving the affinities among these species, and show that they are anatomically indistinguishable fromC. lenticularis Michx. These four New World endemics differe substantially fromC. nigra (L.) Reichard.     

Carex sinosupina sp. nov. (sect. Lamprochlaenae,Cyperaceae) from Gansu,north central China

Carex sinosupina, a new species from Gansu, China is described and illustrated. This species is similar to C. aridula and C. ivanoviae, but differs by having broader leaves, 2.0–3.5 mm wide, perigynia 3–5‐veined abaxially and achenes concave at the middle of one lateral surface. Based on a field survey and SEM (scanning electron microscope) observation of the micromorphology of perigynia and achenes, the morphology and micromorphology of the new species, C. aridula and C. ivanoviae is compared.     

莎草科薹草属黑穗薹草组的植物地理学讨论

根据黑穗薹草组植物的外部形态、细胞染色体特征与地理分布之间的关系,结合地质历史事件推测了黑穗薹草组Sect.Racemosae G.Don.的起源、进化和迁移等问题。推测黑穗薹草组可能在早第三纪的始新世起源于我国的喜马拉雅-横断山地区;可能的迁移路径为：由起源中心向北部迁移至欧洲、中亚、俄罗斯西伯利亚地区,并通过格陵兰岛和白令陆桥到达北美洲地区;经过第四纪冰川后,一些分布于北美洲的物种又通过白令陆桥回迁到亚洲东部的俄罗斯远东地区,最终形成该组植物的现代分布格局。     

Patterns of allozyme and morphological differentiation in the Carex flava complex (Cyperaceae) in Fennoscandiaxs

Allozyme and morphological differentiation patterns within the Carex flava complex in Fennoscandia were described by means of multivariate analyses. As a result of these studies, and considering also data on ecology, distribution and hybridization, the following taxa were recognized: C. flava with no infraspecific taxa, C. lepidocarpa with two subspecies, ssp. lepidocarpa and ssp. jemtlandica, C. demissa with no infraspecific taxa, and C. oederi with three varieties, var. oederi , var. bergrothii , and var. pulchella. Carex lepidocarpa ssp. jemtlandica was allozymically divergent from ssp. lepidocarpa , indicating a long period of isolation of the two subspecies. A poor morphological separation in some localities is apparently due to secondary contacts in connection with recolonization of Fennoscandia after the last ice age, resulting in the formation of fertile hybrids and back-crosses. The subdivision of C. oederi into three varieties is supported by ecological data and it is suggested that they have originated by parallel ecotype formation under similar selective regimes in different areas. However, the varietal limits are not supported by differentiation in neutral (allozyme) characters. A phylogenetic hypothesis was constructed by means of neighbour-joining based allozyme data and it was indicated that C. demissa may be more closely related to C. lepidocarpa than to C. oederi. Previous treatments that have reduced the C. flava complex to one or two species may have been based on inappropriate species concepts, too coarse methods of analysis of morphological data, ignorance of patterns of co-occurrence and hybridization, or a combination of these factors.     

Growth pattern of Carex arenaria (Cyperaceae)

The origin of the orthotropic aerial shoot from the plagiotropic, horizontal rhizome of Carex arenaria L. (Cyperaceae) was studied. A previously proposed adnation or fusion of the first internode of the orthotropic shoot and the fourth internode of the plagiotropic shoot could not be anatomically confirmed. The rhizome branches sympodially and the point of branching results from intercalary meristematic activity in the plagiotropic shoot.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 146 , 145–151.     

福建薹草(莎草科)的考证

在整理和鉴定浙闽薹草属Carex植物的过程中,发现福建薹草Cares fokienensis Dunn较早发表但并未被注意。通过文献查阅、模式标本研究和野外观察,认为闽清薹草C.minqingensis Z．P.Wang、九仙山薹草C jiuxiangshanensis L.K．Dai＆Y.Z．Huang、苍绿薹草C.pallideviridis K．L．Chv（裸名）在果囊和雌花鳞片等鉴别性特征上与福建薹草并没有区别,应该处理为福建薹草的异名。     

关于中国薹草属高秆薹草组(莎草科)的分类问题

《中国植物志》中记载的薹草属高秆薹草组包括区别显著的两类植物,一类具有间断的穗状花序和叶状苞片,另一类穗状花序紧密、苞片鳞片状或刚毛状,宜分为两个不同的组：高秆薹草组和卵形薹草组。文中将高秆薹草组和卵形薹草组与近缘的薮薹草组进行了形态学比较,并提供了中国高秆薹草组和卵形薹草组的分类纲要。     

中国薹草属二柱薹草亚属（莎草科）增补

报道了发现于新疆布尔津的一个中国新记录种——卵形薹草Carex leporina L.,提供了其形态描述和线描图。该种因具有雌雄顺序的小穗和鳞片状的苞片而与卵果薹草C. maackii Maxim.近缘,但花序较短、小穗较少而与后者不同。这两种植物隶属于薹草属二柱薹草亚属卵形薹草组subgen. Vignea sect. Ovales。     

Numerical analysis of morphology of natural hybrids between Carex hostiana and the members of Carex flava agg. (Cyperaceae)

Uni‐variate and multi‐variate statistical methods, based on data taken from dried specimens, were used to determine the morphological variance of Carex hostiana 3 Carex flava agg. hybrids and to establish their parents among members of the C. flava complex. The following hybrids were found: C. demissa 3 hostiana [C. 3 fulva], C. hostiana 3 lepidocarpa [C. ×leutzii] and C. flava 3 hostiana [C. 3 xanthocarpa]. The least variable traits, namely beak length, utricle length, ratio of beak length to the overall utricle length, female spike width, and width of the lowest bract, proved to be the most useful in delimiting the hybrids. Carex flava 3 hostiana specimens usually have long utricles and beaks, wide male and female spikes, as well as wide bracts and leaf blades. Carex hostiana 3 lepidocarpa specimens are characterized by relatively short beaks (with low ratio of beak length to the overall utricle length) and narrow bracts. Common features of C. demissa 3 hostiana specimens, on the other hand, are male spikes with long peduncles, usually longly parted female spikes and a long beak compared to the overall utricle length.     

Mycorrhizal status of the genus Carex (Cyperaceae)

The Cyperaceae have generally been considered nonmycorrhizal, although recent evidence suggests that mycotrophy may be considerably more widespread among sedges than was previously realized. This study surveyed 23 species of Carex occurring in upland and wetland habitats in northeastern Illinois. Mycorrhizal infection by arbuscular fungi was found in the roots of 16 species of Carex and appears to occur in response to many factors, both environmental and phylogenetic. While some species appear to be obligately nonmycorrhizal, edaphic influences may be responsible for infection in others. In five of the seven Carex species that were nonmycorrhizal, a novel root character, the presence of bulbous-based root hairs, was identified. The taxonomically patchy distribution of the distinctive root hair trait suggests that these structures may have evolved several times within the genus. Evidence of multiple independent origins of the root hair trait lends support to the hypothesis that root hairs represent an adaptation to nonmycotrophy. Although taxonomic position does seem to be of importance in determining the mycorrhizal dependence of sedges, the pattern may be a patchwork of both mycorrhizal clades and clades that have adapted to the nonmycorrhizal state.     

Consistent and variable leaf anatomical characters in Carex (Cyperaceae)

The anatomy and morphology of leaves in Carex have the potential to be taxonomically useful. However, studies on the variability of leaf characteristics in the genus are sparse. Researchers therefore risk using leaf anatomical characters without the knowledge of whether they are consistent in a species. We examined 22 qualitative and seven quantitative leaf anatomy characters from transverse leaf sections to test their consistency across 11 Carex spp. The characters were clearly described and primarily microscopic. Some characters were found to exhibit high levels of intraspecific variation, whereas other characters exhibited high levels of consistency in a species, including the shape of the leaf section, the density of papillae and the size of epidermal cells. Caution must be applied when choosing leaf anatomy to delimit taxa because of the intraspecific variability found in some characters, but sufficient numbers of invariant characters exist to provide useful taxonomic separation. © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2013, 172 , 371–384.     

Systematics and evolution of Carex sects. Spirostachyae and Elatae (Cyperaceae)

Carex sect. Spirostachyae comprises 25 species displaying the centre of diversity in Eurasia, while sect. Elatae comprises 22 species displaying the centre of diversity in tropical African mountainous regions. Phylogenetic analysis of the 136 ITS and 108 5′trnK intron sequences of 23 species of sect. Spirostachyae and 20 species of sect. Elatae revealed that neither section is monophyletic. With the exclusion of C. montis-eeka (sect. Spirostachyae) and C. insularis, C. iynx and C. longibrachiata (sect. Elatae), the sects. Spirostachyae and Elatae constitute a monophyletic group of 38 species, 22 of which were previously included in sect. Spirostachyae and 16 of which were in sect. Elatae (considering C. thomasii as C. mannii ssp. thomasii). Two main groups with different edaphic preferences were identified in the core Spirostachyae, in congruence with some morphological features. One group comprises primarily acidophilus species including 11 species of sect. Spirostachyae and 16 species of sect. Elatae. The other group includes 11 basophilic species of sect. Spirostachyae. Incongruence between nuclear and plastid genomes was detected, suggesting hybridization or lineage sorting processes in the evolution of the core Spirostachyae.     

Carex yandangshanica sp. nov. (Cyperaceae; C. sect. Rhomboidales) from Zhejiang,China

Carex yandangshanica C. Z. Zheng & X. F. Jin, a new species of Carex sect. Rhomboidales Kükenth. from Zhejiang, China, is described and illustrated. The new species is similar to C. thibetica Franch. and C. brevicuspis C. B. Clarke, but differs from the former by having trabeculate leaves, pistillate spikes with 6–10 staminate flowers or without staminate flower at the apex, and achenes at apex contracted into a slightly curved beak, and from the latter by having lateral culms, trabeculate leaves, and elliptic, rubiginous and awned pistillate scales. SEM microphotographs of perigynia and achenes are provided for the new species and related taxa.