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本文补充发表绢蒿属一新种,即沙湾绢蒿Seriphidium sawanense Y. R. Ling & C. J. Humphries sp. nov. 相似文献
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中国绢螟属(Diaphania Hübner)记述 总被引:1,自引:0,他引:1
一、前言 绢螟(Diaphania Hubner,1818)在系统分类上隶属于螟蛾科(Pvralidae),拟螟亚科(Pyraustinae)。本属昆虫种类相当繁多,同时又多半是农林作物和热带经济作物上的害虫,至今全世界已经记述过的种类约在四百余种左右。这类螟蛾成虫一般皆是小形至中等大小的蛾类,翅面半透明,色泽鲜艳,绚丽夺目;于阳光或灯光照耀下,五彩缤纷,尤似丝 相似文献
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记述中国灰姑娘绢粉蝶Aporia potanini Alphéraky 1新亚种,灰姑娘绢粉蝶白色亚种Aporia potanini huanghaoi ssp.nov..模式标本分别保存于北京自然博物馆昆虫标本室、中国科学院动物研究所昆虫标本馆和中国农业大学昆虫标本室. 相似文献
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旧大陆的绢蒿属植物 总被引:1,自引:0,他引:1
本文报导了亚、欧、非三洲的绢蒿属[Seriphidium(Bess.)Poljak.]植物的系统分类、分布及区系地理等。在系统分类与分布项中,作者结合现代孢粉的研究,比较了该属与邻近属,如蒿属[Artemisia Linn.)、紊蒿属(Elacanthemum Y.Ling & Y.R.Ling)及百花蒿属(Stilpnole-pis Krasch.)的异同,该属分组特点及经订正与考证过的该属107种、27变种及补遗10种的正名、异名及其分布地区等;在区系地理项中作者讨论了该属起源中心、现代分布中心,同时将亚、欧、非三洲绢蒿属区系分5亚区、8地区成分加以论述。 相似文献
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绢毛蔷薇复合体的分类学研究:峨眉蔷薇与绢毛蔷薇同种吗? 总被引:4,自引:0,他引:4
绢毛蔷薇复合体包括绢毛蔷薇Rosasericea、蛾眉蔷薇R.omeiensis和毛叶蔷薇R.mairei三种.它们的形态特征相近,特别是峨眉蔷薇和绢毛蔷薇之间界限有时不明显,以致峨眉蔷薇的分类学地位长期以来争论不休.本研究对我国主要的标本馆所藏的峨眉蔷薇、绢毛蔷薇和毛叶蔷薇2000多份标本进行了形态对比研究.我们也对横断山区的峨眉蔷薇、绢毛蔷薇和毛叶蔷薇进行了野外观察,同时,我们还应用扫描电镜(SEM)对三者花粉及种皮表面结构进行研究.对小叶、花粉及种子的形态定量分析表明,毛叶蔷薇与其余两者的区别较为明显,但绢毛蔷薇和峨眉蔷薇无论在植株或是花粉形态,还是种皮表面特征方面都存在明显的连续性,但两者在大多数情况下又有一定的区别.两者的地理分布也有所不同.综合各种性状,我们将峨眉蔷薇处理为绢毛蔷薇的变种.同时,将与这两个分类群相关的6个变型作为异名处理.处理为绢毛蔷薇的4个异名分别是腺叶峨眉蔷薇R.omeiensis f glandulosa T.T. Yu & T. C.Ku,宽刺峨眉蔷薇R.omeiensis f.pteracantha Rehder & E.H.Wilson、光叶绢毛蔷薇R.sericea f. glabrescens Franchet和宽刺绢毛蔷薇R.sericea f.pteracantha Franchet.处理为峨眉蔷薇的2个异名分别是少对峨眉蔷薇R.omeiensis f.paucijuga T.T. Yu & T.C.Ku和腺叶绢毛蔷薇R.sericea f.glandulosa T.T.Yu & T.C.Ku.本文也给出了3个分类群详细的形态特征描述及地理分布. 相似文献
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Nitrogen Fixation Associated with the New Zealand Mangrove (Avicennia marina (Forsk.) Vierh. var. resinifera (Forst. f.) Bakh.) 总被引:2,自引:0,他引:2
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Nitrogenase activity in mangrove forests at two locations in the North Island, New Zealand, was measured by acetylene reduction and 15N2 uptake. Nitrogenase activity (C2H2 reduction) in surface sediments 0 to 10 mm deep was highly correlated (r = 0.91, n = 17) with the dry weight of decomposing particulate organic matter in the sediment and was independent of light. The activity was not correlated with the dry weight of roots in the top 10 mm of sediment (r = −0.01, n = 13). Seasonal and sample variation in acetylene reduction rates ranged from 0.4 to 50.0 μmol of C2H4 m−2 h−1 under air, and acetylene reduction was depressed in anaerobic atmospheres. Nitrogen fixation rates of decomposing leaves from the surface measured by 15N2 uptake ranged from 5.1 to 7.8 nmol of N2 g (dry weight)−1 h−1, and the mean molar ratio of acetylene reduced to nitrogen fixed was 4.5:1. Anaerobic conditions depressed the nitrogenase activity in decomposing leaves, which was independent of light. Nitrogenase activity was also found to be associated with pneumatophores. This activity was light dependent and was probably attributable to one or more species of Calothrix present as an epiphyte. Rates of activity were generally between 100 and 500 nmol of C2H4 pneumatophore−1 h−1 in summer, but values up to 1,500 nmol of C2H4 pneumatophore−1 h−1 were obtained. 相似文献
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《Journal of bryology》2013,35(2):265-268
AbstractThe widespread occurrence of a number of bryophytes on British saltmarshes is reported. The communities in which bryophytes are most frequently found are discussed. These communities are more common on marshes on the west coast of Britain. Differences between moss assemblages on salt marshes in England and Wales and in Scotland are emphasised and the greater range of habitat preference demonstrated by Grimmia maritima in Scotland is commented upon. 相似文献
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Abstract The anthers are tetrasporangiate. The anther wall comprises epidermis, fibrous endothecium, middle layer and tapetal layer. The tapetum is of the Glandular type and its cells remain uninucleate. Meiosis in pollen mother cells is normal and simultaneous cytokinesis leads to the formation of tetrahedral and decussate microspore tetrads. The pollen grains are shed at 2-celled stage. The ovule is campylotropous, bitegmic and crassinucellate. Meiosis in megaspore mother cell results in the formation of linear or occasionally T-shaped megaspore tetrad. The chalazal megaspore develops into Monosporic Polygonum type of embryo sac. Endosperm development is of the Nuclear type. 相似文献
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1. Vegetative mitosis of Porphyra umbilicalis var. laciniatais normal, the chromosome number as seen in late prophase beingfive. Special features of this mitosis are the appearance ofseveral stained chromatin segments in early pro-phase and theformation of a crescent-shaped group of chromosomes during metaphaseand anaphase. 2. Genuine monospores have not been seen in the material investigated. 3. Both spores and spermatia arise by repeated division of amother-cell and in identical ways. Evidence is presented toshow that the first division in the mother-cell forming sporesis longitudinal. There is no evidence of reduction divisionin this division, and the chromosome number in the mother-cellis five. 4. The first division in the germinating spore is mitotic andshows five chromosomes. 5. The Conchocelis-phase is haploid throughout and producesfertile cell rows and plantlets,but spore liberation has not been observed. It is suggestedthat the plantlets may grow out directly intothe leafy phase or may give rise to spores according to prevailingenvironmental conditions. 6. No evidence of sexual reproduction has been obtained in thepresent work and the role of the spermatium in the life-cycleis not clear. It is suggested that further work may profitablybe concerned with investigating the nature of the spermatium. 相似文献
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Martin Kieffer Michael P. Fuller Jean-Eric Chauvin Alain Schlesser 《Plant Cell, Tissue and Organ Culture》1993,33(3):303-313
The pollen development and androgenic ability of 18 kale (Brassica oleracea convar.acephala) genotypes was observed during an anther culture study. Anther culture was successful in 6 of the genotypes and the highest
yield obtained was 17 embryos per 100 anthers plated. Two stages of anther development were identified as being responsive
to anther culture. The first and most responsive was that corresponding to the late uninucleated stage and the second to the
late binucleated stage. These stages correspond with the onset of mitotic events in the microspores. Pollen viability was
studied and low viability was noted which declined to zero after 9 days of anther culture. The initial viability level however
was not clearly related to androgenic ability. The significance of the production of haploid and dihaploid kale genotypes
in the study and breeding of resistance to clubroot is discussed. 相似文献
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《Journal of bryology》2013,35(2):317-322
AbstractLamella margins of Polytriehadelphus from throughout the range of the genus have been examined by SEM. All specimens clearly referable on other characters to the genus have characteristically crenate lamella margins covered with angular flakes of epicuticular wax. In this respect they resemble species of Dawsonia but differ from all other Polytrichaceae examined. The lamella margin characters are useful for critical identification of non-fruiting plants of Polytriehadelphus from other vegetatively similar Polytrichaceae. They confirm that P. erieoides and the North American P. lyallii Mitt. do not belong to this genus. Polytriehadelphus has a trans-Pacific and essentially Southern Hemisphere distribution extending from Sulawesi and New Guinea through New Zealand and the Fuegian region to the northern Andes, with a north-western outpost in Costa Rica. It is likely that this distribution is derived from a continuous Antarctic range in the late Cretaceous, and that much of the radiation of the genus at the two northern ends of its present range took place in the mid to late Tertiary. Outlying stations on Tristan da Cunha and the Marquesas probably result from long-distance dispersal. 相似文献