摘要:

SUMMARYAn extensive investigation of the distribution and ecology of the desmids occurring in the broads area in the NW corner of the Dutch province of Overijssel revealed the presence of 245 taxa belonging to 206 species of which about 40 had not previously been recorded from the Netherlands. The present paper is the first of two sequential contributions forming an annotated list with corresponding figures of the recognised taxa.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1979.tb00353.x

年代:1979

数据来源: WILEY

摘要:

SUMMARYA comparison was made of the morphological development of the primary root systems of aerated and non‐aerated two weeks old bean plants (Phaseolus vulgarisL.). Elongation of the tap root axis was analysed with regard to cell division and cell extension. The development of non‐aerated root systems proved to be directly, locally inhibited in the tap root. Moreover, indirectly, the development of the secondary roots was stimulated. It is shown that branching density in itself is no valid criterion of branching activ

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1979.tb00354.x

年代:1979

数据来源: WILEY

摘要:

SUMMARYObservations are presented on the life histories and morphological variability of Swedish material ofChromastrum moniliforme(Rosenvinge) Papenfuss andChromastrum collopodum(Rosenvinge) Papenfuss. The life history ofC. moniliformefits in with the general pattern of the genusChromastrum, showing a combination of a gametophyte with a unicellular base and a tetrasporophyte with a septately germinating spore and a multicellular base. The same holds true forC. collopodum, except that in the tetrasporophyte the germination is occasionally aseptate. It is concluded that the nature of variation between some members of theAudouinella microscopica(Näg.) Woelkerling complex is largely genotypic, and our work does not support the hypothesis of their conspecificity.In addition, a brief survey is given of the genusChromastrumPapenfuss, with an evaluation of most morphotaxonomic characters. Some 60 described species are presently thought to belong to this genus. A considerable reduction of this number must be anticipated for two reasons: first, generations of one life history have usually been described as two different systematic entities; second, morphologically similar species may prove conspecific, in view of the variability of some characters in culture. The genusChromastrumis cosmopolitan, with probably a maximum diversity in the North Atlantic Ocean, and a low representation in tropical seas

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1979.tb00355.x

年代:1979

数据来源: WILEY

摘要:

SUMMARYThe cell wall organization of sub‐epidermal parenchyma of coleoptiles ofAvenaand the collenchyma ofApiumhas been investigated using staining techniques, freeze etching and the examination of shadowcast sections from which the embedding medium was removed. In the coleoptile parenchyma ofAvenait has been confirmed that in the cell wall adjacent to the plasmalemma the microfibrils are transversely oriented and at the outer surface of the wall a dispersed arrangement of microfibrils is present. Longitudinally oriented microfibrils are present in the corner thickenings of the walls. There was no evidence of the crossed polylamellate structure described as being present in collenchyma; epidermal parenchyna; and subepidermal parenchyma of some roots and hypocotyls.The collenchyma ofApiumshowed the presence of wall layers in which the microfibrils were alternately of transverse and longitudinal orientation. In some layers microfibrils with a different orientation were present.The wall organization of the subepidermal parenchyma ofAvenaand the crossed polylamellate organizationof Apiumcollenchyma are considered to be structural extremes of wall organization in elongating cells. The observations are discussed in relation to the ‘multi‐net growth’ hypothesis and the ‘ordered fibril’ hypothesis. It is concluded that the observed changes in microfibril orientation in the walls of elongating cells of collenchyma and subepidermal parenchyma can be best explained in terms of the concept of multi

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1979.tb00356.x

年代:1979

数据来源: WILEY

摘要:

SUMMARYThe ovules and seeds of the generaGeranium, Pelargonium, Erodium, Monsonia, andSarcocaulonare very similar. The ovule primordium ofGeraniumis trizonate. The outer and inner integuments are both of dermal derivation and initially only 2 cells thick, to become multilayered owing to mitotic activity in the inner cell layer. Shortly before fertilisation a development begins which ultimately results in a marked degree of campylotropy of the seeds. The mechanical layers consist of the sclerotised and crystal‐containing cells of the inner epidermis of the outer integument, and sclerotised cells of the outer layer of the inner integument which are star‐shaped in surface view. Nucellus and endosperm have disappeared almost completely in the mature seed. In several representatives of the family the seed‐coat contains st

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1979.tb00357.x

年代:1979

数据来源: WILEY

摘要:

SUMMARYAn androecial type is reported fromViscumaff.hildebrandtii(Kenya) which is radically different from other known types in the genus and even in the Order Santalales as currently understood. While in other known species anthers or anther cushions are individually fused with perianth members, those ofV.aff.hildebrandtiiare fused into a unified or bilobed, weakly vasculated central synandrium which represents the continuation of the floral axis and lacks any direct contact with perianth members. Somewhat intermediate situations seem to exist in several other African species.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1979.tb00358.x

年代:1979

数据来源: WILEY

摘要:

SUMMARYAnalysis of B.loranthoidesHook. f. and B.rhopalocarpaWarb., African species formerly admitted to sect.SquamibegoniaWarb., leads to the conclusion that these taxa must be placed inBegoniasect.TetraphilaA. DC. Both taxa are treated here as subspecies ofB. loranthoides: B. loranthoidesHook. f. subsp.loranthoidesandB. loranthoidesHook. f. subsp.rhopalocarpa(Warb.) J. J. de Wilde respectively. They are circumscribed and their synonymy, distribution, ecology and karyology is given.Begoniasect.TetraphilaA. DC. is circumscribed provisionally.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1979.tb00359.x

年代:1979

数据来源: WILEY

摘要:

SUMMARYTreatment with KOH or H2SO4of the lower part of petioles of leaf cuttings ofPhaseolus vulgarisbefore treatment with indoleacetic acid decreased the number of adventitious roots formed on the petioles.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1979.tb00360.x

年代:1979

数据来源: WILEY

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1979.tb00361.x

年代:1979

数据来源: WILEY

摘要:

H. Ellenberg:Vegetation Mitteleuropas mit den Alpen in ökologischer Sicht.Verlag Eugen Ulmer, Stuttgart 1978. 2nd completely revised edition, 981 pp., 499 figs., 130 tables. DM 120.‐. ISBN 3‐8001‐

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1979.tb00363.x

年代:1979

数据来源: WILEY