共查询到20条相似文献,搜索用时 31 毫秒
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在野外考察和植物标本研究的基础上,结合孢粉学、细胞学和植物地理学资料,对中国及邻近地区的线蕨属植物进行了修订,初步鉴定出9种和1杂种。在线蕨C.elliptica下划分出5个变种。首次发现褐叶线蕨Colysis wrightii的孢子囊中有鳞片状隔丝。 相似文献
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线蕨种下分类和植物地理的研究 总被引:2,自引:0,他引:2
通过对红蕨属羽裂类群的300余个体腊叶标本的形态性状的统计分析,研究了各性状的变异幅度以及部分性状之间的相关性,并结合植物地理分布资料和和孢子形态将此类群初步处理为1种5变种。 相似文献
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Lin You-xing 《植物分类学报:英文版》1993,31(5):475-476
One new species of the genus Lepisorus (L. petiolatus Ching et Y. X.
Lin) and one new record of the genus Colysis (C. membranacea (Bl.) Presl) arereported from Guangxi, China. 相似文献
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湖南蕨类植物区系新资料 总被引:1,自引:1,他引:1
报道了湖南蕨类植物区系新记录17种(隶属7科,11属),它们是桫椤(Alsophila spinulosa)、长尾铁线蕨(Adiantunm diaphanum)半月形铁线蕨(A. philippense)、新月蕨(Pronephrium gymnopteridifrons)、密毛紫柄蕨(Pseudophegopteris hirtirachis)、禾秆紫柄蕨(P. microstegia)、金佛山溪边蕨(Stegnogramma jinfoshanensis)、假大羽铁角蕨(Asplenium pseudolaserpitiifolium)、都匀铁角蕨(A. toramanum)、长镰羽耳蕨(Polystichum falcatilobum)、瓦鳞耳蕨(P. fimbriatum)、棕鳞耳蕨(P. polyblepharum)、倒鳞耳蕨(P. retroso-paleaceum)、膜边肋毛蕨(Ctenitis clarkei)、三叉蕨(Tecaria subtriphylla)、指叶假瘤蕨(Phymatopteris dactylina)、掌叶线蕨(Colysis digitata)。 相似文献
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During field studies on the pteridophytes of Costa Rica, a peculiarly dimorphic polypodioid fern was found in the rain-forests of the Atlantic lowlands near Puerto Viejo. The variation in the fertile frond, ranging from simple and short petiolate to pinnatisect and long petiolate, coupled with peculiarly elongate and irregular sori, prompted further investigations. Additional herbarium specimens from localities in Mexico, British Honduras, Nicaragua, and Costa Rica showed intermixed variations between plants with all leaves simple (typified byPolypodium bradeorum Rosenstock) to plants with all leaves lobed or pinnatisect (typified byP. colysoides Maxon & Copeland). Other characters were judged sufficiently homogeneous to consider these individuals as conspecific underP. bradeorum. Morphological studies indicate parallel evolution of several characters in the Asiatic generaColysis, Microsorium, andLeptochilus on the one hand and the New World members ofMicro gramma, Pleopeltis, andPolypodium bradeorum on the other 相似文献
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Background and Aims
The gametophytes of most homosporous ferns are cordate–thalloid in shape. Some are strap- or ribbon-shaped and have been assumed to have evolved from terrestrial cordate shapes as an adaptation to epiphytic habitats. The aim of the present study was to clarify the morphological evolution of the strap-shaped gametophyte of microsoroids (Polypodiaceae) by precise analysis of their development.Methods
Spores of Colysis decurrens collected in Kagoshima, Japan, were cultured and observed microscopically. Epi-illuminated micrographs of growing gametophytes were captured every 24 h, allowing analysis of the cell lineage of meristems. Light microscopy of resin-sections and scanning electron microscopy were also used.Key Results
Contrary to previous assumptions that strap-shaped Colysis gametophytes have no organized meristem, three different types of meristems are formed during development: (1) apical-cell based – responsible for early growth; (2) marginal – further growth, including gametophyte branching; and (3) multicellular – formation of cushions with archegonia. The cushion is two or three layers thick and intermittent. The apical-cell and multicellular meristems are similar to those of cordate gametophytes of other ferns, but the marginal meristem is unique to the strap-shaped gametophyte of this fern.Conclusions
The strap-shaped gametophytes of C. decurrens may have evolved from ancestors with a cordate shape by insertion of the marginal meristem phase between the first apical-cell-based meristem and subsequent multicellular meristem phases. Repeated retrieval of the marginal meristem at the multicellular meristem phase would result in indefinite prolongation of gametophyte growth, an ecological adaptation to epiphytic habitats. 相似文献12.
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氢气是一种新型的清洁高效能源,制氢技术的创新是目前研究的热点。将新型的技术及材料应用到生物制氢工艺中,从而促进生物制氢技术的产氢效率和工程应用是研究的重点之一。该文阐述了光合细菌在固定化生长条件下发酵产氢的最新研究进展,从固定化技术的原理、固定化方法的应用进展及影响因素几个方面进行了综述,详细阐述了包括包埋、悬浮载体附着生长及固定生物膜法等几种固定化方法对光发酵产氢的作用,介绍了国内外用于固定化的新型材料,并对今后的研究重点及方向进行了展望。 相似文献
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N. I. Blokhina 《Paleontological Journal》2007,41(11):1040-1053
Some problems in the taxonomy of the Juglandaceae are discussed based on wood anatomy; the identification of fossil juglandaceous
wood is considered. Data on fossil wood of the Juglandaceae are summarized; a key for identification of wood anatomy in modern
and fossil Juglandaceae is compiled. Wood anatomical characters in members of the family are discussed in the light of major
evolutionary trends in the secondary xylem of dicots, and a comparative characterization of members of the family is developed.
A hypothesis is proposed that the subfamily Engelhardioideae is the most primitive member of the Juglandaceae based on wood
anatomy, the tribe Juglandeae and subfamily Platycaryoideae are slightly more highly specialized, and the tribe Hicorieae
is the most advanced. Evolutionary relationships between the members of the Juglandaceae are reviewed based on wood anatomy. 相似文献
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海南岛生态破坏分级初探 总被引:1,自引:0,他引:1
海南岛是我国仅次于台湾的第二大岛,占我国5×10~4km~2热带面积的7.0%左右,具有得天独厚的光、热等资源。解放三十多年来,海南岛的建设取得了不少成绩,但在开发过程中,也造成一定程度的失误,生态平衡出现某种程度的破坏。随着海南岛的建省,办大特区,大 相似文献
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V. R. Southgate D. Rollinson J. De Bont J. Vercruysse D. Van Aken J. Spratt 《Systematic parasitology》1990,16(2):139-147
Scanning electron microscopical studies of adult male and female Schistosoma nasale are reported. The tubercles on the dorsal and dorso-lateral surfaces of unpaired male S. nasale are devoid of spines. In paired male worms the tubercles on the dorsal surface are large and also are devoid of spines, but some tubercles on the dorso-lateral surface possess spines. Pit-like openings are visible on the surface of the smooth tubercles. The oral and ventral suckers on the male worm are well developed and are invested with spines, as are the gynaecophoric canal and flap. Ciliated sensory receptors are distributed over the surface of the male worm. The oral and ventral suckers of the female worm are much smaller than those of the male: spines occur on both suckers. The surface of the female is non-tuberculate and is thrown into transverse folds. Pit-like openings are visible at higher magnifications. The anterior end of the female is heavily invested in ciliated receptors, whereas the posterior end is heavily spined. The surface topography of S. nasale is discussed in relation to other species of Schistosoma. 相似文献
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W. B. RUDMAN 《Zoological Journal of the Linnean Society》1986,86(2):101-184
The genus Glossodoris Ehrenberg is reviewed and 28 species are placed in the genus. Seventeen species are fully described and of these, seven are named as new species. Four others are considered new to science, but insufficient material is available to name them. Published information on a further 11 species is included as is a discussion on phylogenetic trends within the genus. 相似文献
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Victor Benno Meyer‐Rochow 《Insect Science》2015,22(3):461-481
Similarities and differences between the 2 main kinds of compound eye (apposition and superposition) are briefly explained before several promising topics for research on compound eyes are being introduced. Research on the embryology and molecular control of the development of the insect clear‐zone eye with superposition optics is one of the suggestions, because almost all of the developmental work on insect eyes in the past has focused on eyes with apposition optics. Age‐ and habitat‐related ultrastructural studies of the retinal organization are another suggestion and the deer cad Lipoptena cervi, which has an aerial phase during which it is winged followed by a several months long parasitic phase during which it is wingless, is mentioned as a candidate species. Sexual dimorphism expressing itself in many species as a difference in eye structure and function provides another promising field for compound eye researchers and so is a focus on compound eye miniaturization in very small insects, especially those that are aquatic and belong to species, in which clear‐zone eyes are diagnostic or are tiny insects that are not aquatic, but belong to taxa like the Diptera for instance, in which open rather than closed rhabdoms are the rule. Structures like interommatidial hairs and glands as well as corneal microridges are yet another field that could yield interesting results and in the past has received insufficient consideration. Finally, the dearth of information on distance vision and depth perception is mentioned and a plea is made to examine the photic environment inside the foam shelters of spittle bugs, chrysales of pupae and other structures shielding insects and crustaceans. 相似文献
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Donald S. McLusky 《Aquatic Ecology》1993,27(2-4):489-493
The Proceedings of the ECSA 21 symposium on Marine and Estuarine Gradients are reviewed. It is emphasised that this is probably
the first time that a full set of papers on the tidal freshwater sections of estuaries has appeared. There is however some
ambiguity in the terminology applied to such waters, and a more consistent terminology is proposed. In particular the estuary
is defined as reaching upstream as far as the tidal limit, irrespective of salinity.
A wide variety of gradients within estuaries and coastal waters are considered, but it is apparent that the crucial spatial
gradients are based on salinity, oxygen and turbidity, and that many other gradients are co-variables with these parameters.
Temperature is also important for temporal gradients. 相似文献