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1.
Gerald D. Carr 《Brittonia》1975,27(2):136-141
In accord with its cytological and morphological distinctiveness and its geographical disjunction, the Sierran element ofC. pauciflora A. Gray is described as a new species,C. hooveri. Its chromosome number ofn = 7 is documented for the first time. Evidence from cytogenetic analysis of synthetic hybrids is presented to support the conclusion thatC. hooveri is more closely related toC. villosa DC. than toC. pauciflora. Characteristics of ligule morphology and the distribution of the peculiar saucer-shaped glands on the peduncular and receptacular bracts of these species also support the new interpretation.  相似文献   

2.
Although theCyclamen subg.Cyclamen spp. are morphologically variable, previous studies suggest a superficial cytological uniformity. New chromosome numbers and an indication of karyotypic instability are reported inC. hederifolium andC. africanum that reveal that the cytology of the subgenus is more complicated than previous accounts suggest. The possible significance of these phenomena is discussed. The diploid status ofC. purpurascens has been confirmed and a distinction between the three diploid karyotypes has been described. The cytological variation may help to explain the well documented morphological variation exhibited in these species.  相似文献   

3.
Clibadium L. (Asteraceae, Heliantheae) is a genus of 29 species distributed throughout latin America, from Mexico to Peru, and in the West Indies, with high numbers of species in Costa Rica, Colombia, and Ecuador.Clibadium includes shrubs and small trees; usually with loosely aggregated capitula; herbaceous phyllaries arranged in 1–5 series; receptacles usually paleaceous throughout; corollas of pistillate florets 2–4-lobed; corollas of the staminate florets 4–5-lobed; purple to black anthers; and chromosome numbers alln=16. Two sections of species previously recognized are here considered as subgenera (subg.Paleata and subg.Clibadium) containing two and four sections, respectively.Clibadium subg.Paleata contains five species distributed in sects.Eggersia (3 spp.) andTrixidium (2 spp.), and subg.Clibadium has 24 species distributed among sects.Clibadium (6 spp.),Glomerata (9 spp.),Grandifolia (5 spp.), andOswalda (4 spp.).  相似文献   

4.
Comparative morphological, karyological and chorological studies prove the distinctness of the SE European and Asiatic populations ofPulmonaria mollis s.l., to be treated asP. dacica (Figs. 4, 5).P. mollis s.str. is interpreted as a relatively young taxon, which probably has evolved from an older stock ofP. dacica ancestors during the Pleistocene (Figs. 6, 8) and might have migrated, perhaps with oak woodland communities, from SE to C. Europe. A similar evolution can be postulated for S—SE European dysploidP. rubra-carnica-stiriaca-vallarsae group; this may have involved still unknown tetraploids (P. carnica?, Fig. 7). This group is linked via the hypertriploid speciesP. vallarsae with theP. saccharata group and at least the eastern species of theP. australis group. The monotypic genusParaskevia apparently marks the earliest divergence from the common Tertiary ancestral stock (Fig. 8). It exhibits a tetraploid chromosome number (2n = 28) but has preserved the most primitive characters. — Some comments on the systematics and nomenclature ofP. australis andParaskevia are added.  相似文献   

5.
The chromosomes of several cultivatedTulipa species of subg.Leiostemones were examined in conventionally stained and C-banded preparations. The heterochromatin content varied from almost none to 45%. Several chromosome types were recognized with respect to chromosome morphology and heterochromatin distribution, and groups of species with common chromosome characteristics could be identified. These karyological relationships are discussed with respect to the groups formed on the basis of floral and bulb charateristics.  相似文献   

6.
The genus Cordyhmthus has considerable diversity in its inflorescences while the other genera of tribe Rhinantheae (Scrophulariaceae) uniformly have racemes or spikes. Four distinct inflorescence types are recognized and their homologies and evolutionary history are postulated. Thus it is suggested that the basic florescence type, the elongated spike (Type I), has undergone evolutionary reduction to a few-flowered spike and ultimately to a single-flowered florescence (Type II). Further evolution involving processes of compaction and clustering of the single-flowered florescences has resulted in glomerulate clusters (Type III) and spiciform clusters (Type IV). Knowledge of inflorescence homologies and distribution of the four inflorescence types in the genus has been of considerable aid in formulating a new infrageneric classification. Using evidence primarily from inflorescence, floral, and seed morphology, as well as from geographical distribution and ecology, a classification is proposed establishing three subgenera, namely subg. Dicranostegia, subg. Hemistegia, and subg. Cordylanthus, the last with three sections, sect. Cordylanthus, sect. Anisocheila, and sect. Ramosi.  相似文献   

7.
8.
Centaurea phrygia agg. was studied in part of Central Europe (Czech Republic, Slovakia and Ukraine) to evaluate its karyological and morphological variation. Three ploidy levels were found: diploid (C. pseudophrygia, C. stenolepis and several populations ofC. phrygia s.str.), tetraploid (C. oxylepis and several populations ofC. phrygia s.str.), and triploid (very rare, only single individuals). Only one taxon,C. phrygia s.str., comprises populations of two ploidy levels, but they seem to be geographically separated. Multivariate morphometric analysis confirmed the separation of the four taxa; the length and the width of appendages of middle involucral bracts, visibility of appendages of inner involucral bracts, the length and the width of an involucre, and the length/width ratio of middle cauline leaves are the most important discriminant characters. Several populations intermediate between two species (eitherC. pseudophrygia andC. stenolepis orC. oxylepis andC. phrygia s.str.) were found. Their possible origin from introgressive hybridization is discussed considering their morphology (intermediate between putative parental species), chromosome numbers (always the same as in putative parents), and distribution (both spatially and ecologically more or less intermediate between distribution ranges of putative parents). A determination key for the four studied species, including intermediates, is also presented.  相似文献   

9.
《Journal of Asia》2022,25(4):101989
DNA barcodes obtained from cytochrome c oxidase subunit 1 (cox1) offer a fast and easy way to identify a range of biological organisms. Culicoides (Diptera: Ceratopogonidae) are a group of small, blood sucking midges whose species are the vectors for some arboviruses, such as bluetongue virus, African horse sickness virus, epizootic hemorrhagic disease virus and equine encephalosis virus. Identification of these small insects is difficult so constructing DNA barcode libraries for species present in certain areas is helpful to clarify the taxonomy and assist non-specialist workers to identify species. In this study, we analysed specimens belonging to C. subgenus Hoffmania collected from 12 towns of Yunnan Province, China. Specimens were identified by morphology and processed to construct DNA barcodes. A total of 185 specimens referable to 6 morphological species were processed for cox1 and 28S rRNA sequencing. The resulting 185 cox1 sequences were assigned to 13 barcode index numbers (BINs) which include 9 novel BINs. Molecular and morphological evidence was used to support the transfer of 4 species previously assigned to C. subg. Avaritia into C. subg. Hoffmania. Molecular analysis revealed the presence of 7 potential cryptic species within C. innoxius, three within C. liui and two within C. insignipennis.  相似文献   

10.
Forty-four chromosome counts from the North American genusCallirhoe are reported, including first-recorded counts ofC. alcaeoides, C. digitata, C. bushii, C. triangulata, andC. involucrata var.tenuissima. Information concerning chromosome numbers from present and previous reports is summarized and evaluated. Observations are presented on meiosis for the genus in general, for male sterile individuals of gynodioecious species, and for selected F1 hybrids. Pollen fertility data are recorded for the latter. Chromosomally three species groups are recognized: an exinvolucellate, diploid species group withn=14; an involucellate, tetraploid and octoploid species pair,n=28 and 56; and an involucellate, diploid and tetraploid species group withn=15 and 30. Intrageneric relationships and those within the tribe Malveae subtribe Malvinae are discussed.  相似文献   

11.
A. Spencer Tomb 《Brittonia》1974,26(2):203-216
Chromosome numbers are reported from over 230 populations representing species in eight genera. First counts are reported for three species ofStephanomeria, five species ofLygodesmia, and one species ofPinaropappus. Base chromosome numbers,x = 6, 7, 8, and 9 are known in the subtribe;x = 9 is found in six of the 12 genera and presumably is the ancestral base number for the subtribe. Two phyletic lines, aMalacothrix line and aStephanomeria line are recognized on morphological grounds. A key to the 12 genera is provided.  相似文献   

12.
Chromosome counts of some Mongolian plants   总被引:1,自引:0,他引:1  
The paper gives the chromosome numbers of 45 species from 72 Mongolian localities, belonging to the genera:Amygdalus, Asparagus, Astragalus, Cancrinia, Caragana, Chamaerhodos, Chelidonium, Chesneya, Dianthus, Hypecoum, Lathyrus, Lilium, Oxytropis, Papaver, Potentilla, Schizonepeta, Sibbaldia, Thermopsis, Trifolium, Trigonella, Vicia. Chromosome morphology of three species ofChamaerhodos and taxonomical remarks on some other species are added. A new combinationSibbaldia sericea (Grubov) Soják is proposed.  相似文献   

13.
J. W. Boyes  B. C. Boyes 《Genetica》1975,45(3):273-287
Chromosome numbers of 28 species ofLauxaniidae range from 2n=8 to 2n=12 with one having 2n=8, three having 2n=10 and 24 having 2n=12. Total complement length averaged 58.1 μ for 71 complements measured. The species studied in detail are classified according to chromosome number and morphology. The two Chamaemyiid species studied have 2n=6 and 2n=15, the latter including several microchromosomes. The karyotypical reorganizations have clearly involved inversions and translocations and a progressive reduction of chromosome numbers.  相似文献   

14.
A review of current knowledge of chromosome numbers and modes of reproduction in the genusRubus L. is presented. Chromosome numbers from some species of subg.Malachobatus Focke together with results of crossing experiments are reported for the first time.  相似文献   

15.
The sesquiterpene lactone chemistry, chromosome numbers and morphology of selected Sonoran Desert Ambrosia taxa are reported. The sesquiterpene lactone distribution correlates with morphologically defined species groups.  相似文献   

16.
Twenty samples of Fagonia mollis and F. tristis of different geographic distribution were investigated for their flavonoids. Kaempherol and isorhamnetin 3-rutinosides were the major flavonoids of F. mollis, while F. tristis contained, in addition, 8-O-methylherbacetin. The flavonoid patterns are discussed in correlation with the geographic distribution of both species.  相似文献   

17.
Polycnemum majus A. Br. (Chenopodiaceae) represents one of the Euro-Asian species disappearing as a consequence of man's activities. The paper presents a brief survey of its morphology, distribution (with emphasis on the W part of Czechoslovakia), and taxonomy. The ecological characterization of communities with occurrence ofP. majus is given. From the karyological point of view,P. majus represents a further case of hexaploidy in theChenopodiaceae family, hitherto known in approximately 10% of genera. The basic chromosome number of x=9 is proposed, with respect to chromosome numbers ascertained inP. majus for the first time (2n=54) and inP. arvense (2n=18). The annual hexaploid speciesP. majus was proved to be potentially self-fertile.  相似文献   

18.
TheCalyptridium umbellatum complex (Portulacaceae), which has been treated as including from one to nine species, is shown to comprise three morphologically distinctive species. Two of these are common, wide-ranging, montane perennial herbs—C. umbellatum, which occurs over a large part of western North America, andC. monospermum, which largely replacesC. umbellatum in cismontane California. The third member of the complex is the rare or possibly extinctC. pulchellum. The perennial members of this complex are accorded the status of a separate genus,Spraguea, by most authors, but a comparative study of the morphology and karyology of all species ofCalyptridium shows this separation to be unwarranted. Chromosome numbers ofn = 22, obtained from eight populations ofC. umbellatum and six ofC. monospermum, constitute the first reported counts for these species. Hybridization studies involvingC. umbellatum andC. monospermum indicate that they are isolated by an incomplete noncrossability barrier.  相似文献   

19.
Eighteen species and subspecies (34 accessions) of Allium sect. Acanthoprason and 11 species (17 accessions) belonging to other subgenera and sections of Allium were karyologically investigated and include first reports for 12 species. The examined plants of 47 accessions were diploid, three accessions of two species were tetraploid, and in the A. bisotunense accession, we found a mix of di- and triploid individuals. B chromosomes were found in 10 accessions. A basic chromosome number of x = 8 was confirmed for all investigated members of subg. Melanocrommyum and subg. Allium, and x = 9 for Allium tripedale of subg. Nectaroscordum. Idiograms were drawn for each accession, and metaphase images are presented illustrating observed chromosomal variations. Also, karyotype features and asymmetry parameters were calculated for all accessions. Chromosomal aberrations, e.g. aneuploid cells or loss of whole or parts of chromosome arms, were rarely observed. In general, the karyotypes showed low variation in inter- and intrachromosomal asymmetry especially inside of the taxonomic groups, though satellited chromosomes were good markers for subgenera and even specific for two studied sections of subg. Allium. Six different types of satellites were recognized, two of them were newly described: Type P was prevalent in subg. Melanocrommyum, and type O in sect. Codonoprasum. Statistical analyses were performed on five karyological parameters to test correct relationships and also to test previous grouping hypotheses. Although our data confirm distinct karyological characters for the subgenera investigated, the remarkable morphological diversity inside of subg. Melanocrommyum is not mirrored by striking karyological differences.  相似文献   

20.
Mucuna comprises 105 species with an overall pantropical distribution and is divided into three subgenera: M. subg. Mucuna, M. subg. Stizolobium and M. subg. Macrocarpa. Although phylogenetic studies have supported the occurrence of three main clades, evolutionary relationships among them are not fully resolved. The objective of this study was to examine pollen grain morphology from representatives of all three subgenera and map these onto the phylogenetic trees generated by analysis of other characters. Pollen grain surface, form, size, and aperture number were compared. A Bayesian inference tree using matK sequences was constructed. The results indicate that the representatives of M. subg. Macrocarpa have the smallest pollen grains in the genus (a synapomorphic character here identified for this subgenus) and that species of subgenus Mucuna (those with umbelliform inflorescences) have the largest pollen grains. Additional morphological diversity of the pollen grain surface was noted: reticulate and/or micro-reticulate (in all three subgenera), perforate, gemmate or verrucose (only in M. subg. Mucuna). For all studied taxa, the pollen grains are triaperturate, except for two species of M. subg. Mucuna, which have tetraperturate pollen. The phylogenetic tree obtained using the matK marker resolved M. subg. Stizolobium as the earliest diverging lineage in Mucuna. Based on this phylogeny, a reticulate ornamentation pattern of the pollen surface may represent the ancestral state for the genus, while the larger pollen size and the foraminate, gemmate, and verrucose ornamentations are derived characteristics within the genus. These putative derived ornamentations have been observed only in neotropical species.  相似文献   

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