首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
Chromosome numbers have been counted in 102 populations belonging to 34 taxa of Festuca L. section Festuca from the Iberian Peninsula. Four of these taxa have been counted for the first time and another three for the first time from the Iberian Peninsula. Furthermore, the levels of ploidy for another three taxa have been obtained for new populations within their distribution area, and for another 18 taxa the ploidy levels have been confirmed. Five levels of ploidy have been established for this section: diploid, tetraploid, hexaploid, octoploid and decaploid. There are 17 diploid taxa, eight tetraploid, three octoploid, two octoploid and one decaploid. The three remaining taxa represent polyploid complexes (one tetra-hexa-octoploid and two hexa-octoploids).  相似文献   

2.
3.
A revision of the three endemic Iberian species of Succisella G. Beck ( S. carvalhoana , S. microcephala and S. andreae-molinae ), based on herbarium studies, SEM photographs and field observations, is presented utilizing morphological, palynological, karyological, biogeographical and ecological characters. The distribution of the species in the Iberian Peninsula is shown in a grid map. Full synonymy is given for all taxa.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 144 , 351–364.  相似文献   

4.
Micromorphological features of the leaf-blade, lemma, and palea were examined under scanning electron microscopy (SEM) for 64 species of the genus Festuca L. occurring in the Iberian Peninsula. The objective of the study was to survey these characters for the first time in the whole of the genus Festuca in this region, to assess their taxonomic value, and to compare the variation with recent DNA sequence-based phylogenies. The principal features include the frequency, shape, and distribution of silica bodies, short cells, crown cells, and prickles, and the morphology of long cells. The abaxial lemma surface shows the most important taxonomical and phylogenetic characters. The variation observed was consistent with the subgenera and sections identified in molecular studies.  相似文献   

5.
The somatic chromosome number and detailed chromosome morphology have been studied in populations of seven species of Ranunculus, namely Ranunculus alpestris L., R.glacialis L., R. Thora L., R.seguieri Vill., R. Aconitifolius L., R.platanifolius L. And R. Acetosellifolius Boiss., from the Iberian Peninsula. Diploid levels have been found for these species in the samples studied. From the karyological data (karyograms, idiograms and asymmetry) relationships between these taxa are discussed.  相似文献   

6.
DIOSDADO. J. C, PASTOR, J. E. & VALDÉS, B. 1993. Contributions to the karyological study of the genus Ranunculus L. subgenus Batrachium (DC.) A. Gray from the Iberian Peninsula. The somatic and gametic chromosome numbers and detailed chromosome morphology are presented for eight taxa of aquatic ranunculi from the Iberian Peninsula. Within the subgenus Batrachium diploid and tetraploid levels have been observed (2 n = 16, 32) the commoner of which is the diploid. From the karyological data relationships have been established between the subgenus Batrachium and subgenus Ranunculus.  相似文献   

7.
Nineteen chromosome counts of 12 Artemisia species are reported from Armenia and Iran. Three of them are new reports, sewn are not consistent with previous counts and the remaining are confirmations of very scarce (one to three) previous data. Two basic chromosome numbers (x = 8 and 9) were found, each with several ploidy levels. Chromosome number reduction arising from fusion homozygosity was noted, confirming earlier studies.  相似文献   

8.
Chromosome numbers and measurements were recorded in 47 individuals of ten taxa of Primula , representing eight species and two subspecies from ten populations. The basic numbers of chromosomes were x  = 8, 9 or 11, and they were mostly metacentric, medium-long to medium-small, ranging in length from c . 3.6 µm to 1.6 µm. Diploid chromosome numbers of 2 n  = 2 x  = 24 and 22 were scored for the first time in P. loeseneri Kitag. and P. prenantha Balf. & Sm., respectively. A new ploidy level of 2 n  = 4 x  = 44 was found in P. burmanica Balf. & King. The recorded diploid numbers of the remaining species confirmed earlier reports. Interspecific variability in chromosome numbers was correlated with heterogeneity in their mean length. Comparison of the data with those in the literature revealed that the observed variability of chromosomal characters was compatible with the other taxonomic criteria and supports the current taxonomic delimitation. Chromosomal variation at the diploid level is the predominant feature in Primula evolution, and allopatric speciation has played a major role in its specific diversity. Subgen. Aleuritia could represent the main clade from which the other subgenera have evolved. The origin of the chromosome numbers, geographical distribution and evolution of the species were assessed, and the parallel polyphyletic mode of evolution in the genus was confirmed.  © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 150 , 211–219.  相似文献   

9.
Two new species of the genus Galium are described from the Iberian Peninsula: G. moralesianum Ortega-Olivencia & Devesa, and G. talaveranum Ortega-Olivencia & Devesa. The first grows on limestone or dolomitic-limestone outcrops in south-east Spain (the Segura and Gádor mountain ranges) and shows morphological similarities with G. boissieranum Ehrend. & Krendl, which is endemic to southern Spain (mountains of Málaga). The second inhabits the margins of water courses, alder stands and cork-oak dehesas (parkland-type systems) of the west of the Iberian Peninsula, and is morphologically reminiscent of G. mollugo L. The chromosome numbers of these two species and of G. boissieranum are given.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 143 , 177−187.  相似文献   

10.
Mitotic chromosome numbers are reported from 16 Hieracium and two Pilosella species from the Iberian Peninsula and the Balearic Islands that are little known cytogenetically. The chromosome numbers of Hieracium aragonense Scheele (2 n  = 27, 36), H. compositum Lapeyr. (2 n  = 27), H. murcandidum G. Mateo (2 n  = 27), H. spathulatum Scheele (2 n  = 27), H. segurae Mateo (2 n  = 27), H. teruelanum Mateo (2 n  = 27), H. valentinum Pau (2 n  = 27), Pilosella pseudovahlii (De Retz) Mateo (2 n  = 18), and P. tardans (Peter) Sójak (2 n  = 36) were determined for the first time. New cytotypes were detected in H. cordifolium Lapeyr. (2 n  = 27) and H. loscosianum Scheele (2 n  = 36). The karyotype of the studied species was similar in overall morphology and comprised metacentric and submetacentric chromosomes; secondary constrictions (up to two) were detected in the chromosome complements of some species.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 153 , 311–320.  相似文献   

11.
Chromosome counts are reported of 38 populations representing 24 species of the genus Cousinia from Iran, one of the main centres of speciation of the genus. Sixteen of the counts are new to science. Our results confirm that Cousinia exhibits a complex dysploid series ranging from x  = 13 to x  = 9. One of the basic chromosome numbers, x  = 9, is new for the genus and must be confirmed. Some considerations on the correlation between chromosome numbers and section classification are made.  © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 151 , 411–419.  相似文献   

12.
13.
This work comprises 24 reports of chromosome numbers in 24 Artemisia L. species from Asia. Ten are included in the subgenus Dracunculus Besser and the rest belong to other subgenera. Seven counts are new reports, 14 are consistent with scarce previous ones, and three contribute new ploidy levels. That carried out in A. medioxima reports the highest ploidy level ever counted for the genus (16 x ). There is only one species with x  = 8 as the basic chromosome number. In the remaining x  = 9-based species, ploidy levels range from 2 x to 16 x , illustrating the great role played by polyploidy in the evolution of the genus.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 153 , 301–310.  相似文献   

14.
Qualitative and some quantitative micromorphological characters of leaf blades, lemmas and paleas were examined using scanning electron microscopy for 29 species of Festuca subgenus Festuca, including the first observations on members of sections Amphigenes, Dimorphae and Cataphyllophorae. The aim of this study was to survey these features in the subgenus Festuca, to assess their taxonomical value. The observed patterns are compared with current taxonomic proposals based on molecular studies. The characters show important taxonomic value, mainly of the abaxial lemma. Characters showing the greatest variation are shape of long cells, shape of the periclinal walls, thickness of anticlinal walls, presence of prickles and abundance of silica bodies. The principal characters of the leaf-blade surfaces include the type and shape of short cells. Two different surface patterns were observed on the lemma, one, long cells rectangular to elongated, with flat to slightly convex periclinal walls and thickened anticlinal walls, for the sections Amphigenes and Dimorphae, and another, long cells rectangular to square, with concave periclinal walls and unthickened anticlinal walls, for the remaining sections. This study confirms the taxonomic value of micromorphological characters in the subgenus Festuca, and that abaxial lemma surface appears to be the most useful.  相似文献   

15.
Festuca L. has an important diversification centre in the Iberian Peninsula. We used chromosome counting, fluorescence (FISH) and genomic in situ hybridization (GISH), and DNA flow cytometry (FCM) to clarify the taxonomic position of several taxa, to search for phylogenetic relationships and to assess the extent and pattern of genome variation in fescues. The chromosome number of Festuca duriotagana var. barbata is determined for the first time and new ploidy level estimations are given for F. rothmaleri and F. summilusitana. In the latter species, besides the reported decaploid level, dodecaploidy was found in some populations, which points to the existence of an unrecognized taxon. Moreover, these differences were confirmed by FCM and a high positive correlation was found with the type of substrate where F. summilusitana was growing. For each section, a decrease of genome size with increase of polyploidy was observed. In general, in situ hybridization techniques failed to reveal phylogenetic relationships among the selected species. In FISH, a variation in the number of rDNA sites was observed in some species. GISH results indicate that F. henriquesii is not a progenitor of the studied polyploid species.  相似文献   

16.
Twenty chromosome counts are reported in the genus Cousinia and the monotypic genus Schmalhausenia , which are part of the Arctium group, from Armenia, Iran, Kazakhstan and Uzbekistan. Twelve are new and eight provide confirmation of scarce or disputable previous data. The correlation between karyological data, pollen type and molecular phylogeny is very close, and on this basis two main groups can be defined. One is the arctioid group, which comprises the genera Arctium and Schmalhausenia , and a small part of the genus Cousinia , with x  = 18. The other is the genus Cousinia s.s. , with a dysploid series ranging from x  = 13–11. Some considerations on the chromosomal evolution in the group are made.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Socety , 2003, 143 , 411–418.  相似文献   

17.
Twenty‐two chromosome counts are reported in 16 species, four subspecies and two varieties of the genus Centaurea. These are mostly Turkish local endemics of section Cheirolepis, a complicated group from the Eastern clade of the Jacea group. Twenty‐one reports are new. Prevalence of the basic chromosome number x = 9 among the eastern sections of the Jacea group is confirmed. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 159 , 280–286.  相似文献   

18.
19.
Chromosome study of the fern genus Cyrtomium (Dryopteridaceae)   总被引:1,自引:0,他引:1  
Cyrtomium (Dryopteridaceae) is an Asiatic genus comprising about 40 species characterized by having anastomosing veins that form areolae with included veinlets. Twelve chromosome counts representing 11 taxa were made in the present study. The chromosome numbers of six species endemic to China are reported for the first time: C. uniseriale , 2 n  = 164; C. guizhouense , 2 n  = 82; C. shingianum , n  = 82, 2 n  =  c .164; C. chingianum , 2 n  = 164; C. urophyllum , 2 n  = 82 and C. aequibasis , 2 n  = 123. The results were used to show that (1) C. uniseriale should be reduced to varietal status under C. balansae ; (2) subseries Balansana is not closely related to any other Cyrtomium species and should be separated from Cyrtomium ; and (3) C. guizhouense and C. lonchitoides are basal groups when subseries Balansana is not considered. These results were also supported by morphology. A high level of differentiation is a distinct characteristic in Cyrtomium . The genus has two reproductive types: sexual and apogamous. Sexual species are distributed mostly in China. Southwestern China is a modern diversity centre of Cyrtomium , with 80.6% of known species occurring there. Many species are endemic, most of which are sexual tetraploids or apogamous triploids. Both the apogamous reproductive type and polyploid species are adaptions to limestone habitats.  © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 150 , 221–228.  相似文献   

20.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号