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The growth forms of bi- and pluriennial central European plant species were analyzed and summarized systematically by means of a dichotomous key. Ten growth forms are distinguished according to vegetative morphological characters of the plants: holoparasitic erosulate, (simple) erosulate, floating semirosette, succulent semirosette, tufted semirosette, (simple) semirosette, storage root semirosette, tuber semirosette, storage root rosette, and (simple) rosette bi- or pluriennial plants. Only very few species are strictly biennial or pluriennial. Each individual plant can be assigned to only one growth form system according to the life span (the system of bi-and pluriennials in the present case). However, several species include individuals that behave as annuals as well as biennials/pluriennials and/or periennials. The term "hapaxanthic" is discussed concerning to its reference level in relation to the plant organism. Three types of hapaxanthy can be distinguished in this context: Genet hapaxanthy with and without vegetative reproduction and ramet hapaxanthy.  相似文献   

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We report the first example of identification of an unknown flowering plant to family level using comparison of DNA sequences. The newly-discovered New Zealand plant had not been identified by traditional methods, but has been placed in the Gondwanic familyCunoniaceae on the basis of the sequence of its chloroplastrbcL gene. It has not flowered, but its vegetative characters are typical of the family. However, it is clearly unusual in several morphological and anatomical features and appears to match no known genus. We consider that, although it probably represents an unnamed new genus, it could possibly be a mutant dwarf form ofWeinmannia racemosa, so it is not prudent to name it at this time.  相似文献   

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The investigation of the vegetative characters of annual species from central Europe showed a hitherto not regarded large spectrum of 20 growth forms within this plant group. These growth forms can be identified by means of a dichotomous key. This is also a new method to present growth form systems. Although several surveys about growth forms have been carried out, the proposed systems are either incomplete or not consequent in the use of their classifying criteria. Moreover, annual species have never been investigated systematically according to their growth forms. Important characters which were used to characterize growth forms are the occurrence of a rosette, the presence or absence of supporting tissue which causes aerostability or aerolability, succulence, growth direction (plagiotropous, orthotropous) and metamorphoses (for scrambling). According to the mode of surviving the resting period, annuals can be grouped into therophytes, hydrophytes, and hemicryptophytes. Whereas therophytic and hydrophytic annuals perennate the winter exclusively as generative diaspores (seeds, spores), hemicryptophytic species survive as seedlings or young plants.  相似文献   

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This study investigated the effectiveness of three different instructional materials for learning how to identify fish at the species level in a blended classroom and out-of-classroom scenario. A sample of 195 first-year students of biology or geoecology at the University of Tuebingen participated in a course on identification of European freshwater fish species at a public aquarium. Prior to studying the species in the aquarium's fish tanks, students prepared themselves in a classroom nearby with one of three different learning materials: (1) preserved specimens and paper-based dichotomous identification keys; (2) digital videos; or (3) digital videos with preserved specimens and paper-based dichotomous identification keys. Students' acquisition of knowledge and their motivation were measured twice, once after preparing in the classroom and once after visiting the aquarium. Results showed that students who had prepared themselves with digital videos identified significantly more species correctly but were less motivated than those students who had learnt only with preserved specimens and dichotomous identification keys. When both instructional methods were combined students performed well in the post-tests and were motivated to learn, suggesting that the combination of both instructional approaches encourages motivation without any outcome losses.  相似文献   

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Species identification tasks are generally accepted as fundamental aspects of biodiversity education. Our educational training unit, therefore, focused on identification skills by introducing stuffed specimens in combination with identification books and preparation booklets.We limited the number of bird species to six. 492 secondary school pupils (163 from 8th grade [high stratification level] and 329 from 9th grade [medium stratification level]) participated in the study. Instruction-1 pupils received a hands-on lesson about the natural history of six bird species, while Instruction-2 pupils were taught in a conventional teacher-centred manner. Pupils from the hands-on classes achieved significantly better grades in two follow-up tests. The measure of well-being was significantly enhanced by the teaching technique, while interest, anxiety and boredom were not affected. Additionally, pupils appreciated the opportunity of self-regulation. In general, a shift from the unspecific to the specific was observed: for instance, from duck and gull to mallard and black-headed gull. A reduction in the number of species presented to pupils within a lesson seems to enhance learning and retention effects.  相似文献   

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The usefulness of the internally transcribed spacer 2 (ITS2) of the nuclear ribosomal gene complex is tested for providing taxonomic characters to identify Trichogramma species. The ITS2 sequences of a group of sibling species of the T. deion/T. pretiosum complexes were determined. A simple and precise identification key to the species of these assemblages was constructed using as taxonomic characters the size of the ITS2 and the difference in restriction length polymorphism of species with similarly sized ITS2. Individual wasps can be identified by amplification of their ITS2 with general primers, determining the size of the PCR product using standard agarose electrophoresis, followed in some species by a DNA-digestion with a restriction enzyme. Because this system works well for a number of closely related species we are hopeful that similar PCR-based identification can be extended to all species of the genus once their ITS2 sequences have been determined. The advantage of this identification system over the morphology-based system is that non-specialists are able to quickly and cheaply identify individual specimens. In addition, species specific primers were tested for the two most common species of these groups (i.e. T. pretiosum and T. deion). These primers can be used either as a direct identification tool or as a method to confirm the identification using the general key. The phylogeny of this group of wasps was also analyzed based on the ITS2 sequence.  相似文献   

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刚竹属(PhyllostachysSieb. et Zucc.)是一个主产于中国,大约有60种的竹亚科大属,当前其属内种间的划分和鉴定主要依据秆箨和新秆的特征。然而,本属植物的笋期大多仅持续20~30 d,其他时间很难见到鲜笋或新鲜秆箨和新秆。应用现今流行的分种检索表和形态特征来鉴别处于非笋期营养生长状态的竹种往往作用不大,这就需要重新寻找更多的证据来解决这一问题。据长期的野外调查和栽培植物的定点观察,一些性状,如秆的节内距、小枝及叶的排列方式、叶耳及繸毛存在与否及其排列方式、叶舌是否伸出、叶片背面毛被状况等可以作为本属植物非笋期分类的重要依据。如果把握得恰当,利用这些性状和其他特征的组合可以在非笋期将本属现知的所有竹种划分开来,并据此编制了此期的分种检索表。  相似文献   

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Bryophytes are a rewarding study group in field biology and the UK bryophyte flora has international importance to biodiversity conservation. We designed an identification key to common woodland moss species and compared the usability of two formats, web-based multi-access and printed dichotomous key, with undergraduate students. The rate of correct species identification and identification speed both showed an advantage for the printed dichotomous key. Our findings suggest that, even in the digital age, printed keys remain valuable in biological education and that quality of key design is more important than presentation medium. We discuss the relative advantages of multi-access and dichotomous keys and how to approach bryophyte identification with beginners.  相似文献   

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This annotated bibliography is provided in order to assess the achievements and gaps in the literature on vegetative identification of woody plants in the tropics. The bibliography includes 258 references divided into general references (48), pantropical and multi‐continental keys (4), Africa (46), Asia (53), Australia and New Guinea (21), and the Neotropics (86). Vegetative keys are not easy shortcuts to the identification of woody tropical plants to species. Identification of sterile material requires as much, if not more, training as that required for using keys that emphasize floral and fruit characters. Nevertheless, the literature surveyed in this bibliography may be helpful to biologists seeking references for the geographic region in which they work, models for the construction of vegetative keys and field guides, and/or the types of characters that should be observed in the field.  相似文献   

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This work describes the leaf anatomy of 16 species belonging to three genera of the Malpighiaceae family found in the Cerrado (Minas Gerais State, Brazil). The scope of this study was to support the generic delimitation by contributing to the identification of the species and constructing a dichotomous identification key that includes anatomical characters. The taxonomic characters that were considered to be the most important and used in the identification key for the studied Malpighiaceae species were as follows: the presence and location of glands; presence of phloem in the medullary region of the midrib; mesophyll type; presence and type of trichomes; and presence, quantity, and disposition of accessory bundles in the petiole. It was also possible to indicate promising characters for future taxonomic and phylogenetic studies in the Malpighiaceae family, especially for the Banisteriopsis, Byrsonima, and Heteropterys genera.  相似文献   

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A new plant, Dibracophyton acrovatum gen. et sp. nov., is described from the Lower Devonian (Pragian) Posongchong Formation of Wenshan District, southeastern Yunnan, China. The plant has creeping axes from which arise vegetative and fertile axes. The vegetative axes helically bear lateral dichotomous appendages with curved or round tips. The fertile axes possess terminal strobili with numerous fertile units arranged in irregular helices. Each fertile unit consists of a stalked long-elliptical sporangium, with dehiscence into two equal valves, and two discrete long-ovate bracts covering sporangium from above–below directions. A new genus and species is thus established based on these characters and is temporarily regarded as incertae sedis of Tracheophyta, although it perhaps closes to the barinophytes in affinity. Detailed comparisons with other plants having a similar architecture, i.e., sporangia closely associated with modified vegetative structures, are made. The discovery of D. acrovatum further enriches the composition of the Posongchong flora and demonstrates great morphological disparity of the Early Devonian vascular plants.  相似文献   

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Morphological identification of many fairy shrimp species is difficult because distinguishing characters are restricted to adults. We developed two multiplex polymerase chain reaction assays that differentiate among three Branchinecta fairy shrimp with distributional overlap in southern California vernal pools. Two of the species are federally listed as threatened. Molecular identification of Branchinecta from cysts allows for species surveys to be conducted during the dry season, expanding the timeframe for population assessment and providing a less intrusive method of sampling sensitive vernal pool habitats.  相似文献   

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Palynological characters of 18 species belonging to seven genera of the traditional subfamily Alsinoideae including Arenaria, Cerastium, Eremogone, Lepyrodiclis, Minuartia, Sabulina and Stellaria were studied in detail using light and scanning electron microscopy. Pollen grains of subfamily Alsinoideae are subspheroidal or prolate, pantoporate and 20.04 to 51.4 µm in size, prominent and sunken apertures uniformly distributed on the pollen surface. Two types of pollen grain ornamentation were observed, i.e. microechinate-punctate or microechinate-perforate. Echini are present on the surface of the pollen of all investigated species with medium, dense, or sparse echinodensity. These species exhibit variation in polar view, equatorial diameter, number of apertures, exine thickness, diameter of pore, appendages per pore, pore ornamentation, echini arrangement, echinidensity and shape of pollen. Based on qualitative characters, a dichotomous key has been developed for quick and easy identification. The present investigation contributes to the systematic approach using palynological characteristics and correct identification of species for members of subfamily Alsinoideae (Caryophyllaceae).  相似文献   

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Numerous anatomically preserved fragments of the Middle Pennsylvanian age filicalean fern, Botryopteris tridentata, occur in coal balls collected at the Pittsburgh and Midway Coal Company mine near Baxter Springs, Kansas. Included are the first fertile specimens of the species, evidence of complete vegetative frond architecture, and fronds that are specialized for vegetative propagation. Rhizomes are erect and unbranched, have helical phyllotaxis and short internodes, and typically display an ectophloic solenostele. Fronds are tripinnately compound with lobed pinnules that have open, dichotomous venation. Fertile pinnae or individual pinnules are interspersed among vegetative frond segments and produce sori of annulate sporangia beneath veins on the abaxial pinnule surface. Fertile pinnule lobes are rolled toward the abaxial surface to enclose the sori. Sporangia have a horizontally elongated biseriate annulus located near the short broad stalk and produce tetrahedral-shaped trilete spores with coarse spines. Epiphyllous branches diverge from the stipe or rachis, and some fronds produce only branches. This fern is reconstructed as having short stems. Helically arranged fronds are either pinnately dissected with lobed vegetative pinnules and abaxially rolled fertile pinnules or are specialized for vegetative propagation. The latter functioned as the foliar equivalent of stolons. While some characters of the B. tridentata plant are similar to those of Botryopteris forensis, generitype of the Botryopteridaceae, others are more comparable to those of Psalixochlaena cylindrica, generitype of Psalixochlaenaceae, suggesting the need for reevaluation of systematic relationships among species of the Botryopteridaceae and Psalixochlaenaceae.  相似文献   

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It has been suggested that few students graduate with the skills required for many ecological careers, as field-based learning is said to be in decline in academic institutions. Here, we asked if mobile technology could improve field-based learning, using ability to identify birds as the study metric. We divided a class of ninety-one undergraduate students into two groups for field-based sessions where they were taught bird identification skills. The first group has access to a traditional identification book and the second group were provided with an identification app. We found no difference between the groups in the ability of students to identify birds after three field sessions. Furthermore, we found that students using the traditional book were significantly more likely to identify novel species. Therefore, we find no evidence that mobile technology improved students’ ability to retain what they experienced in the field; indeed, there is evidence that traditional field guides were more useful to students as they attempted to identify new species. Nevertheless, students felt positively about using their own smartphone devices for learning, highlighting that while apps did not lead to an improvement in bird identification ability, they gave greater accessibility to relevant information outside allocated teaching times.  相似文献   

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