摘要:

AbstractA revision ofTaraxacumsect.PalustriaDahlst. is given; 48 species are dealt with, of which 29 are new; the descriptions of the latter partly have been borrowed from comments and provisional descriptions by Dahlstedt and Haglund, found in herbaria.T. lividum(Waldst.&Kit.) Petermann,T. tenuifolium(Hoppe) Koch andT. udumJord., so often and for so many years hidden in the lists as synonyms, are considered to be good species. The area of distribution, in a broad sense, covers the central part of Europe with an offshoot extending into Asia Minor. Due to agronomical measures the rich vegetations formed in the past by species of the section have sometimes dwindled considerably; some species even seem to have died out.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1965.tb00178.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

Abstract1)Dark‐grown gherkin seedlings contain the sugar derivatives of p‐coumaric acid and ferulic acid, present in both the cotyledons and hypocotyls, and a number of flavonols, occurring only in the cotyledons. Exposure of these seedlings to light results in an increase in the accumulation of these phenolic compounds after a lag of 1 1/2 to 2 hours.2)The responsivity of this effect to radiation in the blue and far‐red wavelength regions is higher than to red light. Both photoresponse I, the “high‐energy reaction”, and photoresponse II, the phytochrome reaction, seem to be involved.3)The distribution pattern of the phenolics in the hypocotyl changes in the course of the irradiation: An initial increase in the concentration of hydroxycinnamic acids is followed by a decrease, particularly in the apical part. The ratio of ferulic acid to p‐coumaric acid increases and is always higher in the lower part of the hypocotyl than in the apical part.4)The accumulation of hydroxycinnamic acids in the hypocotyl in red and far‐red light is largely dependent on the presence of the cotyledons. In blue light there is also a considerable synthesis when the cotyled

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1965.tb00179.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

Abstract1)Exposure to light of dark‐grown gherkin seedlings causes an expansion of the cotyledons and inhibits the elongation of the hypocotyls. As was found earlier for the light‐induced synthesis of phenolic compounds, at least two photoreactions seem to be involved: photoresponse I, the “high energy reaction”, and photoresponse II, the phytochrome reaction.2)The gherkin seedlings contain an enzyme which, purified, oxidizes indoleacetic acid (IAA)1) slowly. The IAA oxidase activity of a crude homogenate depends on phenolic cofactors; derivatives of p‐coumaric acid. Ferulic acid derivatives, flavonols and ascorbic acid, the latter two only from the cotyledons, antagonize this stimulation. The IAA oxidase activity of a homogenate from cotyledons changes on standing due to enzymatic reactions involving the modifiers.3)The photo‐inhibition of hypocotyl elongation can be counteracted by supplying IAA externally, indicating that light lowers the level of IAA. Application of the naturally occurring p‐coumaric acid cofactor of IAA oxidase to hypocotyl sections from dark‐grown gherkin seedlings results in growth inhibition.4)Qualitatively there is agreement between light‐stimulated synthesis of the p‐coumaric acid ester and inhibition of hypocotyl elongation, and between synthesis of IAA oxidase inhibitors and expansion of the cotyledons. The postulated causal relationship between light‐dependent phenol synthesis and photoinhibition of hypocotyl elongation can only exist, however, if but a fraction of the phenolic compounds participates in the IAA regulating system, and the enzymatic oxidation of IAA is coupled to the destruction of phenols.5)In at least one case the IAA oxidase hypothesis seems inadequate to explain the phenomena: the lag for inhibition of hypocotyl elongation in blue light is much shorter than

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1965.tb00180.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

AbstractIn our first paper dealing with this subject we have shown by means of a restrictednumber of observations made on a comparatively large number (20) of characters found in different plants that there is always a trend towards the development of an “ideal value”, i.e. towards the reduction of the degree of variability towards a minimum value.This time we have made our observations on a much larger scale but on a re‐stricted number of characters, viz. 1) the number of juga in the imparipinnate leaves of Sorbus aucuparia; 2) the length of these leaves; and 3) the number of primary rays in the umbels of Aegopodium fiodograria. It appeared that the place where the ideal value is found, is determined by the position which the varying part occupies in the organism. This apparently indicates that the degree of variability is primarily determined by some internal factor.A similar trend was observed in the degree of variability which is shown by the number of sepals and petals in the flowers of Ranunculusjcaria in the course of the flowering period, and in the degree of variability that was found in the shell shape of the Ostracoda Globorotalites bartensteinii in the successive layers of the Lower Creta

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1965.tb00181.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

AbstractA kinetic study of the interactions in the uptake of NH4‐, K‐, and Na‐ions by excised barley roots was performed using the continuous flow technique.In all cases the absorption of one ion was inhibited by the presence of a second ion, but the extent of the inhibition was limited. The presence of an inhibiting ion consistently resulted in an increase of the half‐value of the uptake vs. concentration relation of the inhibited ion.The difficulties encountered in the interpretation of these results in terms of ion competition are discussed. On the other hand, it is shown that the characteristic features of the interaction are readily reconcilable with the concept of carrier comp

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1965.tb00182.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

AbstractSo far ten species ofLiceaand one variety have been found in the Netherlands, of these four are new, viz.L. testudinacea, L. chelonoides, L. marginataandL. sinuosa. L. pusillavar.pygmaeais a new record for the Netherlands. The species are grouped in three subgenera:Orcadellaopening by means of a lid,Liceaopening along preformed lines held together by interlacing knobs, andPleomorpheopening irregularly or by an apical slit. A key to the species found in the Netherlands, all of which are figured, is given.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1965.tb00183.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

Abstract25 Purines and pyrimidines were tested for the effect on pollen tube growth and germination. 2‐Thiouracil most strongly stimulates tube growth. However, 2‐thiouracil decreases or does not affect metabolism of sugars. Some derivatives of thiouracil also stimulate tube growth, whereas others inhibit growth. Pollen growth response is markedly affected by the concentration of the compound tes

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1965.tb00184.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1965.tb00185.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

AbstractThree species of the genusPhaseolusL. are reported upon.1)Phaseolus lathyroidesL. the name of which seems to be synonymous withPh. semi‐erectusL., has 2n = 22. This is in accordance with previous counts.2)Phaseolus hysterinusDur. has 2n = 22, but many cells in the inner cortical layer of the root are polysomatic.3)Material ofPhaseolus sublobatusRoxb., a species recently studied by DATTA&SEN, has been studied again: 2n = 22 and in a small number of seeds 2n = 44 could be reported, hence a case of spontaneous tetraploidy inPhaseolus.Owing to the smallness of the chromosomes a complete analysis of the karyotype is nowhere attempted at and seems of dubious value for breeding work. At most can be stated that all three species in diploid condition show one large pair and one satellited pair of somewhat smaller chromosomes. These are present twice in the tetraploi

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1965.tb00186.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

Book reviewed in this article:HOWARD J. DITTMER, Phylogeny and Form in the Plant Kingdom. D. Van Nostrand Co.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1965.tb00187.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY