摘要:

SUMMARYCulturing experiments are described in which the life cycles of several clones ofPhaeothamnion borzianum, a supposedly palmelloid form of the latter, andSphaeridiothrix compressaare investigated. The three types of algae turned out to be quite distinct taxa, not at all connected by intergrading forms as has been suggested in the literature. A new genus – to be namedTetrachrysis– is proposed to accommodate the taxon, formerly regarded as a palmelloid phase ofPhaeothamn

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1980.tb00366.x

年代:1980

数据来源: WILEY

摘要:

SUMMARYThe life cycle of several clones ofPhaeoschizochlamys mucosa, Tetrachrysis minorspec. nov., andChrysosphaera botryoidesspec. nov. is described. Zoids were found to occur in the life cycle ofPhaeoschizochlamys;as a consequence, this genus is removed from the subclass Acontochrysophycidae to the Heterochrysophycidae, order Chromulinales. The newTetrachrysisspecies differs from the type species in this genus in mode of cell division and its copious mucilage investment; its systematic position is discussed. The newChrysosphaeraspecies differs from other algae in this genus in that it hasOchromonas‐like zoids instead of theChromulinatype described for the genusChrysosphaer

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1980.tb00367.x

年代:1980

数据来源: WILEY

摘要:

SUMMARYThe ovule primordium ofDichapetalum mombuttenseseems to be trizonate. The ovule is tenuinucellate and both integuments are of dermal derivation.During seed development the whole inner integument and a part of the outer integument are resorbed.The outer integument is vascularized. The seed‐coat is exotestal and consists of a differentiated outer layer of the outer integument and crushed remains of the middle layers. The endosperm is initially nuclear, later to become one cell layer thick.The systematic postion of Dichapetalaceae is discusse

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1980.tb00368.x

年代:1980

数据来源: WILEY

摘要:

SUMMARYWood anatomical generic descriptions ofHenriquezia, PlatycarpumandGleasoniaare given and compared with data from Rubiaceae. An attempt is made to construct a cladogram according to Hennig's principles. The resulting arrangement of the taxa concerned is discussed and compared with earlier conclusions based on phenetic comparison.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1980.tb00369.x

年代:1980

数据来源: WILEY

摘要:

SUMMARYThe ultrastructural changes during the microsporogenesis and gametogenesis inLiliumare studied in relation to the surrounding tissues. In this article the development of the microspore and pollen wall is presented. In relation to the increase in pollen volume the nexine is increased but this process is discontinuous. It is concluded that four periods of sporopollenin deposition can be distinguished. The mechanism of exine formation during the young microspore stage is the embedding of sporopollenin on a sexine matrix of polysaccharides, some proteins and osmophilic material. During this period the sporopollenin deposition on membrane‐like lamellae takes place on both sides of the exine. During the vacuolated microspore stage globules, containing sporopollenin are deposited on the exine too. After mitosis the “Pollenkitt” also contributes in sporopollenin addition to the nexine and sexine.Folds of the plasma‐membrane of the microspore are the origin of the membrane‐like lamellae. The pollen storage consists mainly of starch, lipid granules and li

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1980.tb00370.x

年代:1980

数据来源: WILEY

摘要:

SUMMARYIn theLiliumanther a peritapetal and tapetal membrane are made by the tapetal cells. During the young microspore stage the pro‐orbicules receive a matrix of mainly carbohydrates similar to that of the sexine. The plasma‐membrane of the tapetal cells forms membrane‐like lamellae. During the vacuolization of the microspore the orbicule diameter increases. In the channels made by the endoplasmic reticulum the globules of sporopollenin are produced. The lipid inclusions accumulate and globules containing carotenoid increase in the plastids. Both elements fuse and form the “Pollenkitt” during degeneration of the tapetal cell. Some sporopollenin globules fuse and form a second generation of orbicules. The cell of the middle layer next to the tapetal cell contains lipid granules. The other four cells of the middle layer lose their starch at the stage of the young microspore and after mitosis the lipid granules are produced. As a source for nutrients in the loculus the starch of the middle layer cells has an important function. An interaction model is schematically

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1980.tb00371.x

年代:1980

数据来源: WILEY

摘要:

SUMMARYThe features of the exine and orbicules in theLiliumanther were studied by scanning electron microscopy. The changes in the dimensions and shape of the orbicules and the elements of the exine during development are shown to indicate the course of sporopollenin deposition.In the discussion the data obtained are compared with the results of transmission electron microscopy.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1980.tb00372.x

年代:1980

数据来源: WILEY

摘要:

SUMMARY14C assimilates produced in a single shoot of a sand sedge plant proved to be translocated in the direction of the rhizome tip only. Labelled assimilates were found in all roots in the part of the plant system between the shoot administered with14CO2and the rhizome tip, in the youngest shoot and in the rhizome tip itself. The percentage of assimilates exported by the mature shoots proved to be 30–35%. The amount of assimilates exported by the youngest shoot decreased from 22% in a 1‐shoot system to zero in the bigger plant systems. In the 5‐shoot system also the export of the second youngest shoot started to decrease.In spite of the relatively great sink strength of the rhizome tip with regard to the assimilates exported by the nearby situated young shoots, the main source of assimilates for the rhizome tip proved to be the older shoots, lying at some distance. The ecological importance of this is that the rhizome tip will be able to cross unfavourable habitats, without the need for assimilates from the newly formed shoots in those hab

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1980.tb00373.x

年代:1980

数据来源: WILEY

摘要:

SUMMARYA survey is given of some taxonomic aspects ofRumex acetosellaL. s.s. and the criticalR. tenuifolius(Wallr.) Löve (both in the sense of Löve), and of the status ofR. tenuifoliusin the syntaxonomic literature pertaining to Northern Germany, The Netherlands, and a part of Central Europe. In several publications this latter taxon is recorded as characteristic of the ClassKoelerio‐Corynephoretea(or of some of its subordinate syntaxa). A number of relevés of stands of vegetation belonging to this syntaxonomic Class from the Netherlands and a few from the German Federal Republic are presented in which only hexaploidacetosellaoccurred. Such specimens may be narrow‐leaved, and although corresponding with the morphological description ofR. tenuifoliuscannot belong to this tetraploid species. The ecological amplitude ofR. acetosellas.s. (with 2n = 42) overlaps that of the tetraploidR. tenuifolius(Wallr.) Löve. Within theR. acetosellaaggregateR. tenuifoliusis a critical taxon whose morphological and ecological characteristics do not have an adequate diagnostic significance. The conclusion can be drawn, in anticipation of a forthcoming revision, that it is at least in The Netherlands and in Germany not recommendable to credit “R. tenuifolius” with any meaningful status in

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1980.tb00374.x

年代:1980

数据来源: WILEY

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1980.tb00375.x

年代:1980

数据来源: WILEY