摘要:

The history of study of these dinoflagellates is reviewed and emended diagnoses are proposed for the generaCtenidodiniumandDichadogonyaulax.A new species,Dichadogonyaulax sellwoodii,is described and illustrated from the Bathonian of the Isle of Skye, Scotland. The new combinationDichadogonyaulax norrisii(Pocock, 1972) is proposed and it is considered that forms described by Gocht (1970) asCtenidodinium pachydermum(Deflandre, 1938) may in fact be'attributable to Pocock's species. The speciesCtenidodinium continuumGocht, 1970, is briefly discussed and other Jurassic species attributable to these two genera are listed.

ISSN:0017-3134    

DOI:10.1080/00173137409429893

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Pollen deposition in a mixed deciduous forest in South Jutland, Denmark, was studied by means of pollen analyses (Andersen, 1970) and pollen collectors. In this connection it was important to know the wind conditions outside and inside the forest. Wind velocities and wind directions in the flowering seasons were measured at 2 stations in a 3-year period. High wind velocities prevail above the forest in spring and summer. At such wind velocities the difference in loss of large and small pollen grains by filtration in the tree tops is reduced. The winds inside the forest tend to turn into the direction of easiest flow. The velocities are about 20% of the outside wind before and 12–15% after the leafing. Single pollen grains released from the trees will be carried wide distances before deposition in the spring, and it is suggested that the tree pollen falls to the ground rather in aggregates or included in rain-drops.

ISSN:0017-3134    

DOI:10.1080/00173137409429894

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Eight pollen collectors of the Tauber type are exposed continuously in a mixed deciduous forest in South Jutland, Denmark. The results from 1967–1972 are reported. Exotic pollen carried over the forest from the outside vegetation was collected uniformly by the various collectors. The pollen was deposited mainly during the flowering seasons, but postseasonal deposition continued throughout the year. A dust storm deposited considerable amounts of pollen. Night frost caused aberrantAlnus-pollen deposition in one year. The trees in the forest flowered abundantly every second year.Tiliawas out of phase with the other trees, andFraxinusflowered abundantly only 1969. The local trees flowered particularly well in 1969 and nearly all other plants in 1968 and 1969. The weather in April was particularly warm and dry in these 2 years and may have stimulated the pollen production. The tree pollen productivity was calculated and compared with the results obtained for a previous period from moss samples.

ISSN:0017-3134    

DOI:10.1080/00173137409429895

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Records of air-borne pollen and spores were made during a six month period in the Stockholm area in 1972. This paper presents phenological data and volumetric measurements obtained by means of a Burkard trap. Attention was paid to both arboreal pollen and non-arboreal pollen and spores, identified to family, genus or species level. Spores of certain common Pteridophytes were also included in the investigation, but not Bryophytes or fungal spores.

ISSN:0017-3134    

DOI:10.1080/00173137409429896

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Spore walls ofLycopodium clavatum,after oxidation using ozone for varying times and treatment with dilute alkali, showed a striking loss of the outer layer (muri) of the exine. Almost all trace of the muri and undetermined portions of the remaining exine wall were removed after 20 hours' oxidation. The exine wall material seems to be evenly removed. The only degradation patterns observed are rare pits after 20 hours oxidation. A degradation-related colour change of the spore wall occurs after 11 to 16 hours' oxidation.

ISSN:0017-3134    

DOI:10.1080/00173137409429897

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Acetolysed and non-acetolysed pollen grains were examined by means of light and scanning electron microscopy. A short description of the pollen morphology of the parent speciesLinaria vulgarisandL. repensis presented. The frequency distribution of theP, EandP/Evalues of these species is shown in comparison with corresponding measurements of pollen grains from induced F1and F2individuals. The “species values” ofP, EandP/Ehave an expected normal distribution with short amplitudes. However, plants from the first filial generation of reciprocal crosses have as a rule extreme values widely separated and a bimodal distribution curve of theEvalues. A new method of wax-mounting of spores or similar objects on a specimen stub for SEM preparation is presented.

ISSN:0017-3134    

DOI:10.1080/00173137409429898

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

A new method of sectioning pollen grains by means of laser radiation is described. The grains applied to a specimen stub are exposed to ruby laser rays and subsequently examined under a scanning electron microscope (SEM). The pollen grains are split into pieces of different size suitable for an examination of structural elements. The practical value of the method is discussed. Data of the ruby laser apparatus: ruby crystal 50×5 (Ø) mm, xenon flash tubes, pulses of red light (6943 Å), pulse energy 2.0 J, pulse length 350 μs, peak power 40 kW, average power 5.7 kW, semipermeable mirror (reflection 36%), lens (F= 190 mm).

ISSN:0017-3134    

DOI:10.1080/00173137409429899

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

Pollen grains ofUlmus glabra, U. laevis, U. minorandU. procerahave been studied in a scanning electron microscope. The pollen grains are heteropolar with a smooth proximal polar area and a rough sculptured distal polar area. In the equatorial belt the interporal regions have distinct sculpturing and are bordered by low ridges.

ISSN:0017-3134    

DOI:10.1080/00173137409429900

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

The Late Cretaceous and Tertiary palynomorphProteaciditesCookson ex Couper 1953, is shown to be morphologically inhomogeneous. Two new genera,PropylipollisandCranwellipollisare proposed, to receive certain species excluded fromProteaciditesandProteaciditesis emended. The propriety of ascribing all species ofProteacidites(and the two new genera) to the family Proteaceae is briefly discussed. The natural affinity, as with many dispersed pollen, still remains in doubt.

ISSN:0017-3134    

DOI:10.1080/00173137409429901

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor

摘要:

35 species ofBauhiniaall occurring in Thailand have been studied by light and scanning electron microscopy. 15 pollen types based on sexine structure have been established. A correlation between pollen types and geographical distribution has been observed. On the basis of gross morphology there seems to be no reason for splitting up the genus into several smaller genera as proposed by some authors; however, raising the pollen types to taxonomic sections may be considered in a future revision.

ISSN:0017-3134    

DOI:10.1080/00173137409429902

出版商:Taylor & Francis Group    

年代:1974

数据来源: Taylor