摘要:

SUMMARYIn this paper the morphology of pollen grains yielded by male Gymnosperm fructifications from the Jurassic flora of Yorkshire is studied and discussed.Several new male fructifications were found and described:Hastystrobusgen. nov. was erected for male cones yielding theEucommiiditestype of pollen grains. This genus is monotypic and the type speciesHastystrobus muiriiyielded pollen grains that agree withEucommiidites troedssonii. Hastystrobus muiriivery probably has Cycadalean affinities, because the whole abaxial surface of the microsporophylls is covered with sporangia.For the first time the male fructification ofGinkgo huttoni(Heer) Sternberg is described. It resembles in general the male fructification of the recentGinkgo bilobaL., and the pollen grains agree with those ofGinkgo biloba.Male cones associated withBrachyphyllum crucisKendall have been found and described. They yielded pollen grains that after short maceration were identifiable asCirculina, while after prolonged maceration they could be assigned toClassopollis multistriatusBurger.Brachyphyllum crucisis provisionally assigned to theHirmerella‐groupon the basis of its male cone and pollen grains. The cones were compared with other male cones containingClassopollispollen, which were also attributed to theHirmerella‐group. It is suggested that all members of theHirmerella‐grouphave an epidermis with a special type of stoma.Masculostrobus harrisiisp. nov. is described. This male cone resembles closely the male cone ofElatides williamsoni(Brgt) Sew., but its pollen grains are of theInaperturopollenites‐type, instead of thePerinopollenites‐type.The new speciesPityanthus scalbiensisyielding bisaccate pollen grains of a rather primitive type is described; there is almost no saccus infrastructure present.TheCzekanowskia‐group(includingLeptostrobusandSolenites) in all probability does not belong to the Ginkgoales but to the Conifers.An interesting find was that the pollen grains of the AraucariaceousBrachyphyllum mamillareBrgt are of two types : In type 1 the nexine and sexine are attached to each other, while in type 2 the nexine is loose from the sexine and is somewhat shrunk. In the latter type also pollen grains were found that are somewhat trilobate. A similar dimorphism of pollen grains was also found in the recentAraucaria araucana(Molina) K. Koch.The pollen grains from the various male fructifications were compared with those from other male fructifications related to them. If the cones were assigned to recent taxa, the pollen grains were compared with recent pollen grains from those taxa (Cycadales, Ginkgoales and Coniferospermae).The pollen grains were also compared with dispersed pollen grains, mainly from t

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1971.tb00688.x

年代:1971

数据来源: WILEY

摘要:

SUMMARYA number of metallic ions abolished the inhibition of IAA‐oxidase activity caused by DIECA. Contrary to Weber (1970), in our opinion, these results do not give any information on the metal naturally occurring in the IAA‐oxidase molecules. The restoration of the IAA‐oxidase activity is caused by the removal of the chelating substance by the metallic

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1971.tb00689.x

年代:1971

数据来源: WILEY

摘要:

SUMMARYCytological studies have demonstrated the occurrence of tetraploids (2n = 28) and hexaploids (2n = 42) of theRumex acetosellacomplex in Belgium. Diploids have not been encountered. In both the tetraploid and the hexaploid races angiocarpous plants have been recorded next to gymnocarpous ones. There is a correlation between the relative frequencies of the angiocarpous individuals and of the gymnocarpous ones in the hexaploid populations and the type of soil: on the loamy soils of Central and South Belgium almost exclusively angiocarpous plants occur in the populations, whereas in the populations on the sandy soils of the coastal area and of Belgian Brabant the gymnocarpous form predominates. Tetraploids are almost exclusively restricted to the populations found on the sandy soils of northern Belgium.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1971.tb00690.x

年代:1971

数据来源: WILEY

摘要:

SUMMARYA survey of the distribution and the periodicity of eightVaucheriaspecies (V. arcassonensis, V. compacta, V. coronata, V. intermedia, V. minuta, V. sphaerospora, V. thuretiiandV. vipera) on the Dutch salt marsh Springersgors in relation to environment and vegetation pattern of algae and higher plants is given. The quantitative changes occurring in the algal vegetation (green algae, blue‐green algae andVaucheriaspp.) on two permanent quadrates, checked monthly algae and higher plants is given over a period of two years, are given in relation to some important ecological factors. Both sample plots, situated at MHWS level on the tidal marsh, constitute an instable habitat with large changes in soil moisture content (42–165 g H2O/100 g soil) and in salinity of the soil moisture (0.8–72.4‰ C1−). The periodicity of fiveVaucheriaspecies could be correlated with the action of extreme environmental conditions (desiccation, high salinitie

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1971.tb00691.x

年代:1971

数据来源: WILEY

摘要:

SUMMARYPollen glutamate dehydrogenase is partially present in a masked form. Removal of the masking substances was carried out by several treatments like addition of polyvinylpyrrolidone to the extraction medium, storing of pollen extracts at different pH's and temperatures, fractionation with ammonium sulphate, and incubation with several hydrolytic enzymes. Only the use of polyvinylpyrrolidone and incubation with a few enzymes caused an increase of both amination and deamination activity, whereas the other treatments caused an increase of the amination activity and a decrease of the deamination activity.It is probable that the glutamate dehydrogenase (GDH) and the masking substances are associated through interaction of ionic groups and hydrogen bondings. Some substances may be bound by stronger links. The question whether the masked GDH is present as suchin vivoor whether it is formed during homogenization has been discussed.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1971.tb00692.x

年代:1971

数据来源: WILEY

摘要:

SUMMARYAn optical planimeter is described in which the light beam from a small source is collimated and subsequently focused on a photocell. It is shown that the area of even a thin leaf placed in the collimated part of the beam is measured accurately without the need for a correction for transmitted light. The instrument features linear response, digital read‐out, high speed, good stability, five ranges of 50 up to 1000 cm2, and an accuracy of 1% of the rang

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1971.tb00693.x

年代:1971

数据来源: WILEY

摘要:

RÉSUMÉLes espèces suivantes sont nouvelles pour la science:Sect.Palustria: T. hagendijkii.Sect.Spectabilia: T. duvigneaudii, T. reichlingii, T. zevenbergenii.Sect.Vulgaria: T. cerdanicum, T. minutissimum, T. rivulare.Sect.Erythrosperma: T. asturiense, T. dorchocarpum, T. xanthiense. Comme nouvelle forme est décriteT. braun‐blanquettii f. achyroc

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1971.tb00694.x

年代:1971

数据来源: WILEY

摘要:

SUMMARYThe chromosome number of 55 plant species collected in Southern France was determined.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1971.tb00695.x

年代:1971

数据来源: WILEY

摘要:

SUMMARYBactris×mooreiW. Boerhybr. nov., a spontaneous hybrid betweenB. oligocladaandB. humilis, is described. A few other cases of hybridization in palms and their significance for the delimitation of genera are discussed

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1971.tb00696.x

年代:1971

数据来源: WILEY

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1971.tb00697.x

年代:1971

数据来源: WILEY