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 0 毫秒
1.
2.
The nine species of the genusAllomarkgrafia are treated synoptically, with a review of their systematics and nomenclature. Two new species,Allomarkgrafia ecuatoriana andA. insignis, and a new combination,Allomarkgrafia campanulata, are proposed here.  相似文献   

3.
4.
A survey of the genus Sorbaria (Rosaceae)   总被引:1,自引:0,他引:1  
A taxonomic revision of the Asiatic genus Sorbaria (Rosaceae). 4 species are recognized: S. sorbifolia (including S. stellipila), S. grandiflora (= S. pallasii incl. S. rhoifolia), S. kirilowii,(incl. S. arborea and S. assurgens ) and S. tomentosa (= S. lindleyana , incl. S. olgae and S. gilgitensis ) with var. angustifolia , comb. nov. (= S. aitchisonii ). Hybrids presumably between S. sorbifolia and S. grandiflora and S. sorbifolia and S. kirilowii are found cultivated.  相似文献   

5.
6.
Pollen grains from 15 species (18 taxa) of the genus Filipendula were examined with light and scan-ning electron microscopy. It was revealed that the pollen grains are isopolar, tricolporate, with scabrate or scabrate-microechinate surface. The pollen morphology was compared with the conventional classification sys-tems of the genus by different authors, and supported Shimizu's system (1961), in which the genus was divided into three subgenera. The monotypic subgen. Hypogyna is characterized by pollen lacking fastigium and thickened costae colpi. The other monotypic subgen. Filipendula differs from others by pollen having larger grain, larger pore size, longitudinally elliptic fastigium and thickened costae colpi. The largest subgen. Ulmaria is distinguished by pollen having rounded or latitudinally elliptic fastigium and thickened costae colpi. Sectional classification was not supported by the pollen morphology due to insufficient variability.  相似文献   

7.
A synopsis of the genus Atypus (Araneae, Atypidae)   总被引:1,自引:0,他引:1  
Twelve of sixteen Atypus species previously described, and one undescribed, are examined. Atypus javanus Thorell is re-diagnosed and the male is described. The vulva of this species, and of A. coreanus Kim and A. karschi Dönitz, arc illustrated for the first time. The taxonomic characters given by Kraus & Baur [ Verh, naturw. Ver. Hamb. 17 : 85–116(1974)] and additional details of male-and female genital organs are discussed. A granular texture on male chelicerae and front legs, presumably a stridulatory apparatus, is noted and used for distinguishing species. A deep cymbial pit of unknown function is illustrated and discussed. Specific character combinations for the species examined are presented in a table. Notes on relationships, habitat, zoogeography, web, phenology and development are given.  相似文献   

8.
9.
10.
The 19 species of the genus Mandevilla in Mexico and Central America are treated synoptically. New synonymy is provided and a new species, Mandevilla rigidifolia, is described.  相似文献   

11.
12.
While stigma anatomy is well documented for a good number of species, little information is available on the acquisition and cessation of stigmatic receptivity. The aim of this work is to characterize the development of stigma receptivity, from anthesis to stigma degeneration, in the pentacarpellar pear (Pyrus communis) flower. Stigma development and stigmatic receptivity were monitored over two consecutive years, as the capacity of the stigmas to offer support for pollen germination and pollen tube growth. In an experiment where hand pollinations were delayed for specified times after anthesis, three different stigmatic developmental stages could be observed: (1) immature stigmas, which allow pollen adhesion but not hydration; (2) receptive stigmas, which allow proper pollen hydration and germination; and (3) degenerated stigmas, in which pollen hydrates and germinates properly, but pollen tube growth is impaired soon after germination. This developmental characterization showed that stigmas in different developmental stages coexist within a flower and that the acquisition and cessation of stigmatic receptivity by each carpel occur in a sequential manner. In this way, while the duration of stigmatic receptivity for each carpel is rather short, the flower has an expanded receptive period. This asynchronous period of receptivity for the different stigmas of a single flower is discussed as a strategy that could serve to maximize pollination resources under unreliable pollination conditions.  相似文献   

13.
In this study, 68 specimens of the genus Lolium were scored for 27 characters, comprising 12 vegetative, 12 inflorescence and 3 seed characters. The aim of the study was to investigate the species relationships within the genus in Iran. The data were analysed using principal components analysis (PCA) and cluster analysis. Both analyses separated L. perenne, L. persicum, L. temulentum, L. multiflorum from each other. According to previous authors, L. rigidum and L. loliaceum show little difference from each other and are not separable to a species level. In this study these two species separated clearly from the other species, but were most closely related to L. perenne following cluster analysis and to L. multiflorum following PCA. L. persicum was found to be the most distinct species within the genus Lolium in Iran.  相似文献   

14.
We have classified 11 species recently recognized as belonging to the genus Elymus into a resurrected and legitimate genus Campeiostachys Drobov according to the International Code of Botanical Nomenclature. Our action is based on the rationale of monophyly, discrimination, and practicality discussed in detail. Currently Elymus contains a vast number of species with different genomes which often, but not always, can be differentiated by cytological and molecular features, but are difficult to separate by tr...  相似文献   

15.
Pyrus betulaefolia Bunge, considered as an intermediate between oriental and occidental pear groups, is one of the most important wild pear species. The number of its populations is decreasing because of habitat destruction, fragmentation, and continuous exploitation, so protection and conservation measures are urgently needed. Assessment of its genetic diversity and phylogeography are imperative for its efficient conservation. Two chloroplast DNA intergenic fragments were used to detect genetic diversity and phylogeography of 320 individuals from 18 wild P. betulaefolia populations. Haplotype variation, genetic differentiation, and historical events of the populations were estimated. The results showed that P. betulaefolia populations sampled in northern China contained a high level of genetic diversity (H T?=?0.826). A significant isolation-by-distance value (r?=?0.587, P?<?0.001, 1,000 permutations) among all 18 populations indicated a correlation between genetic divergence and geographic distance. Four population groups were identified in a neighbor-joining tree based on the genetic distance. Analyses of molecular variation showed that the genetic variation mainly existed among population groups, representing 64.61 % of the total variation. Phylogeographic analyses indicated that the populations of P. betulaefolia experienced a scenario of rapid range expansion, which probably occurred between 608,000 and 204,580 years ago. Meanwhile, both the restricted gene flow with isolation by distance and allopatric fragmentation were crucial processes responsible for shaping the genetic patterns of P. betulaefolia. The occurrence of specific haplotypes might be ascribed to an ancestral introgression or joint retention of an ancestral polymorphism with other Pyrus species at the northern edge of the distribution of P. betulaefolia. Three populations displaying a high level of haplotype diversity and unique haplotypes were assumed to be relict populations of Quaternary glaciation and should have conservation priority. Three additional large populations should also be preferentially protected by building natural preservation zones.  相似文献   

16.
Stomata on the pericarp of species of the genus Rosa L. (Rosaceae)   总被引:1,自引:0,他引:1  
Achenes of 36 species representing all subgenera and sections of the genus Rosa were studied. All have stomata on the pericarp that seem to be normal in appearance. They are usually few, scattered, mostly on the upper part of fruit, and open or closed. This is the first report of stomata on fruits of Rosa.  相似文献   

17.
对同一菌物不同形态型分别命名的做法于2011年结束,这就需要对非地衣化的多型性子囊菌和担子菌采用统一的命名。地衣生的Koordersiella属因此也只需要单一的名称,而后发表的Hansfordiellopsis就是该属的异名。此属共有5个种,包括在此发表的2个新组合:K.tenuissima和K.variegate combs.Nov.。本文列举了该属的地衣寄主和已报道的地理分布,同时也提供了已被接受的物种检索表。此外,在Hansfordiellopsis下发表的1个种和在Koordersiella下发表的2个种,因与该属的模式种显然为不同的属而被排除。由于缺乏分子序列数据,Koordersiella属在座囊菌纲(Dothideomycetes)中的系统学地位目前仍然不明确。  相似文献   

18.
19.
Zywiec M  Delibes M  Fedriani JM 《Oecologia》2012,169(3):713-722
Flower characteristics have been traditionally considered relatively constant within species. However, there are an increasing number of examples of variation in flower characteristics. In this study, we examined the variation in attracting and rewarding flower characters at several ecological levels in a metapopulation of Pyrus bourgaeana in the Do?ana area (SW Spain). We answered the following questions: what are the variances of morphological and nectar characters of flowers? How important are intra-individual and inter-individual variance in flower characters? Are there microgeographical differences in flower characters? And if so, are they consistent between years? In 2008 and 2009, we sampled flowers of 72 trees from five localities. For six flower morphological and two nectar characteristics, we calculated coefficients of variation (CV). The partitioning of total variation among-localities, among-individuals, and within-individuals was estimated. To analyze differences among localities and their consistency between years, we conducted generalized linear mixed models. The CVs of nectar characters were always higher than those of morphological characters. As expected, inter-individual variation was the main source of variation of flower morphology, but nectar characters had significant variation at both intra- and inter-individual levels. For most floral traits, there were no differences among localities. Our study documents that variation is a scale-dependent phenomenon and that it is essential to consider intra- and inter-individual variance when investigating the causes and consequences of variation. It also shows that single year studies of floral characters should be viewed with caution.  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