首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   7篇
  免费   1篇
  2023年   1篇
  2018年   2篇
  2014年   1篇
  2006年   1篇
  1983年   2篇
  1982年   1篇
排序方式: 共有8条查询结果,搜索用时 250 毫秒
1
1.
A new lycopod, Novgorodendron conophorum gen. et sp. nov., is described from the Upper Visean deposits of the Kamenka River, near the town of Borovichi (Novgorod Region). The morphology of the leaf cushions of the new plant implies its intermediate position between the families Sublepidodendraceae Chaloner et Boureau and Lepidodendraceae Endlicher. The bases of the leaf cushions have peculiar conical appendages, a previously unknown morphological feature not recorded from other lycopods. We propose the term basal conical appendages for them. The interpretation of some epidermal elements in the leaf cushions of the Lepidodendraceae is revised. The structures of the leaf cushions that were previously treated as either stomata or cells with cystoliths are shown to be sunken multicellular trichomes.  相似文献   
2.
3.
4.
The dihydric phenolics from the leaves of 170 Ecuadorian Lycopodium specimens representing 49 species and varieties have been examined as semiquinones by EPR spectroscopy. An ester of dihydrocaffeic acid was observed in 137 extractors of specimens all confined to the subgenus Urostachya. The ester was not present in the subgenera Lycopodium and Lycopodiella, where the dominant phenolic acid was chlorogenic acid. The concentrations of the “Urostachyaester” were found to increase with increasing altitude. Hydroquinone and protochatechuic acid have been observed in a few specimens.  相似文献   
5.
6.
报道了中国西藏自治区蕨类植物新记录2属,即粉叶蕨属(Pityrogramma)和肋毛蕨属(Ctenitis),以及新记录15种1变种——疏叶卷柏(Selaginella remotifolia)、粉叶蕨(Pityrogramma calomelanos)、云南网藤蕨(Lomagramma yunnanensis)、灰绿耳蕨(Polystichum scariosum)、高大复叶耳蕨(Arachniodes gigantea)、兆洪鳞毛蕨(Dryopteris wuzhaohongii)、亮鳞肋毛蕨(Ctenitis subglandulosa)、高山蹄盖蕨(Athyrium silvicola)、卵果双盖蕨(Diplazium ovatum)、肉刺双盖蕨(D.simile)、瘤羽假毛蕨(Pseudocyclosorus tuberculifer)、耳羽钩毛蕨(Cyclogramma auriculata)、尖嘴蕨(Lepisorus mucronatus)、黑鳞瓦韦(L.sordidus)、喙叶假瘤蕨(Selliguea rhynchophylla)和灰茎节肢蕨(Arthromeris himalayensis var.niphoboloides)。该文还对墨脱鳞盖蕨(Microlepia medogensis)的分类学处理提出了新的建议。凭证标本保存在上海辰山植物标本馆(CSH)。  相似文献   
7.
A new genus of lycopods from the Devonian of New York State   总被引:2,自引:0,他引:2  
Drepanophycus colophyllus Grierson & Banks is transferred to llaskinsia Grierson & Banks on the basis of the morphology of its leaves and its anatomical structure. Slender, dichotomizing axes bear helically arranged leaves that are falcate, petiolate, simple, lanceolate and entire. A solid cylinder of metaxylem is surrounded by ridges of protoxylem. Pitting on tracheid walls is annular, helical, reticulate, scalariform to circular-bordered. This lycopod extends from early Givetian into early Frasnian time in the Catskill strata of eastern New York State. The effect of cleavage of fossiliferous rock on patterns observed on the exposed fossils and the bearing of recent research on the fossil history of lycopods are discussed.  相似文献   
8.
Baragwanathia abitibiensis is described from the Sextant Formation of northern Ontario, Canada (middle to upper Kmsian age). The plant remains are primarily compressions in which flattened xylem strands, epidermis with stomata, and cuticle are well preserved. Pyrite permineralization of the leaves was Ibiuid in one specimen. Comparison with B. longijolia Lang & Cookson indicates remarkable morphological similarities and probable anatomical similarities although details of the structure of the epidermis and cuticle are lacking in B. longijolia. No information is available on the outline of the cauline xylem strand in B. abitibiensis nor on the form and position of the sporangia it bore. Comparisons are also made to species of Drepanophycus. The age of/?, longijolia and the Baragwanathia Flora, is discussed with particular reference to the putative dating of some specimens as Silurian. The morphological and anatomical complexity of Baragwanathia is at a level of advancement typical of Early to Middle Devonian lycopods. There is no evidence of precursors to the genus associated with the fragments of land vascular plants in the well-dated Silurian sediments of Wales, Czechoslovakia, New York State, or Podolia.  相似文献   
1
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