Siwert Nilsson

Tree pollen spectra in the stockholm region (sweden), 1973–1980

Abstract By means of a Burkard Seven Day Recording Volumetric Spore Trap located in central Stockhom, about 20 m above ground level, pollen was sampled between March and August for eight consecutive years (1973–1980). The pollen spectra with special reference to trees, in particular Betula and Pinus, were compared as to amount and distribution of taxa. No co-variation between the two latter genera was noted. Betula showed a ± distinct biennial periodicity. The main pollen season is defined. Betula and Pinus showed slightly different patterns regarding beginning and duration of the pollen season; mean intensity is compared.

Trends of some airborne tree pollen in the Nordic countries and Austria, 1980—1993

Abstract Long term trends in the occurrence of airborne pollen might help in elucidating the probability or unlikelihood of developments which have been predicted in theory such as global warming or forest decline. We have investigated and compared the trends over a 14 year period (1980–1993) of five selected common tree pollen types (Alnus, Corylus, Betula, Pinus, and Ulmus) from three sites in North Europe (Stockholm, Trondheim, Turku) and one in Central Europe (Vienna) in terms of the start, peak, end, and duration of the season, peak values and annual totals, using data from the European pollen data bank. The existence of trends has been investigated by calculating correlation against years and the statistical significance of the regression lines has been examined at the 5% probability level (p<0.05). A consistent trend in the earlier commencement of the flowering season is observed in all cases, as well as an earlier incidence of peak days. A marked trend to an earlier end of the season was also foun...

Orbicules in Betula Pendula and their Possible Role in Allergy

Abstract The external morphology, internal structure and stainability for protein of orbicules in Betula pendula are examined by SEM and TEM. The pollen and the orbicule walls stain moderately for protein. The protein is localized mainly at the pollen aperture, in a thin layer between the exine and the intine and in the core and on the surface of the orbicules. The nitrocellulose membrane test indicates possible allergenicity of the orbicules as well as of the pollen. Since the orbicules of Betula pendula are 2–4 um in diameter, they can pass through the bronchiole of the lungs and cause bronchial asthma.

Comparison of airborne pollen grains in Huddinge and Stockholm, Sweden

SummaryAirborne pollen studies were carried out, by means of Burkard volumetric spore traps, at two different sites (the city of Stockholm and the suburb Huddinge) 15 km apart in the Stockholm region. Within the city of Stockholm the study was carried out in 1973–89 while in Huddinge the investigation period was 1977–82. In all the years under investigation the total pollen catch and the number of pollen types were higher in Stockholm than in Huddinge. The reason for this is not explained by the composition of the local vegetation surrounding the traps. It is concluded that parameters such as qualitative changes in the daily catches and occurrence during the main pollen season are more important than the absolute daily figures. The cyclic trends in the local annual sums over a long period of years do not show any periodicity that is altogether regular and reliable.

Recommended palynological terms and definitions

Abstract A number of palynological terms with their definitions has been circulated among the members of the ICP Working Group on Terminology. As a result, the following terms and definitions are recommended for general use: aperturate, apolar, bilateral, colpate, ectoaperture, endoaperture, heteropolar, inaperturate, isopolar, laesura, -lete, porate, radially symmetric(al). In addition, the following terms were recommended in Paris, 1975: columella, ectexine, endexine, exine, infratectum, intine, layer, nexine, sexine, sole (foot layer), sporoderm, stratum, tectum (complete tectum, partial tectum, absent tectum), wall. Terms not recommended: atectate, baculum, endexine s. lat., endexine s. str., micro.-, muritectate, nexine — 1, pedium, semitectate, subtectate, tectate. Rejected terms: foramen, non-aperturate.

The influence of the environment natural and experimental on the composition of the exine of allergenic pollen with respect to the deposition of pollutant mineral particles

Abstract Pollen material of the two anemophilous plants of known allergic significance Dactylis glomerata (Poaceae) and Betula verrucosa (Betulaceae) was collected at several places (in Sweden and France) and exposed to natural or experimental conditions. This material was analyzed with Electron Probe X Microanalysis (EPMA) (System ORTEC 5000) attached to a Scanning Electron Microscope (Jeol JMS 35), or with EDAX, a 10000 X-Ray Analyser, Link System, connected to a SEM-microscope (Jeol JSM 820). It is clear that the environment has an effect on such a co-inductor or adjuvant of allergenicity as K. The possible presence of pollutant inorganic (mineral) particles on the pollen grain surface may play a role in the allergenic activity. Pollen, consequently, may be used as sensitive biological indicators of atmospheric pollution.

Phylogenetic trends in the Alismatales with reference to pollen grains

Abstract The pollen morphology of Butomaceae, Limnocharitaceae and Alismataceae, the three families comprising the Alismatales, was studied using light and scanning electron microscopy. Pollen grains of the monotypic Butomaceae are monosulcate and boat‐shaped, those of Limnocharitaceae have 4–10 ill‐defined, fimbriate, globally distributed pores, and those of most Alismataceae are pantoporate and spheroidal, or rounded polyhedral. However, Alisma oligococcum has unusual 2‐porate, lens‐shaped pollen grains, indicating an isolated position in the family so far as apertures are concerned. Pollen morphological characters of the order were analysed using cladistic methods and a hypothesis for pollen evolution in the Alismatales is presented. Monosulcate pollen is clearly primitive in the order, as amongst monocotyledons in general, whilst derived pollen grains possess higher numbers of pores. Fimbriate aperture margins, areas of circumporal ornamentation and sunken apertures are also considered derived. The ge...

Exine Sculpture in Pariana Pollen (Gramineae)

Abstract Pollen grains of eieven species of Pariana, a small genus of herbaceous bamboos, were studied using LM, SEM and TEM. Ten of them have the Pariana stenolemma-type of pollen characterized by areolate exine due to relatively high and well separated denticulate processes on a slightly undulated tectum, vestigial columellae and no distinct annulus. At the pore edge the foot layer is thickened and folded. P. campetris (P. campestris-type) shows this exine feature only at magnifications higher than x 2000, whereas the denticulate processes are clearly visible at x 400 magnification in the other ten species. The pores are bordered by a distinct annulus. The high relief of the Pariana pollen forming a relatively rough surface would offer more friction in wind transport than the smooth surface of other grass pollen grains. Insects visiting the flowers have been observed which support the idea of possible insect pollination. If this would be the case, the parianas would be an example of correlation between ...

Pollen morphology and phylogeny of the Alyxieae (Apocynaceae)

The pollen of the tribe Alyxieae, including Alyxia , Chilocarpus , Condylocarpon , Lepinia , Lepiniopsis , Plectaneia and Pteralyxia , has been studied with light, scanning electron and transmission electron microscopy. It is characterised by relatively large, irregularly disposed and - unequal-sized pores. 2-porate grains are most common in the Alyxieae, and occur in all genera except for Condylocarpon . 1-, 3-, 4- and 5-porate pollen grains are less common. The orientation of the polar axis and the equatorial plane could not be determined in any of the genera. Within the Alyxieae, Chilocarpus and Plectaneia are the nearest to other Apocynaceae, showing an essentially similar exine ultrastructure. Alyxia , Lepinia , Lepiniopsis and Pteralyxia make up a derived group, characterised by large pollen grain size and a remarkable nexine structure. Pollen of Lepinia and Lepiniopsis might be derived on the basis of their fossulate-verrucate ornamentation. Condylocarpon pollen shows a deviating set of pollen features (tetrads, inaperturate, reduced exine) that suggest it to be neotenic. Pollen morphology supports preliminary results of cladistic analyses of chloroplast data, in which the tribe is a monophyletic group nested in a 3-colporate environment, Chilocarpus and Condylocarpon are sisters at the base of the tree, Plectaneia is sister to a clade made up by Alyxia , Pteralyxia , Lepinia and Lepiniopsis , of which Lepinia and Lepiniopsis are the most derived.

The systematic position of theHolarrheninae (Apocynaceae)

AbstractThe genusHolarrhena, described byRobert Brown in 1811, has had a problematic taxonomic history, in part due to a suite of characters that does not conform with accepted concepts within theApocynaceae. In a number of important taxonomic charactersHolarrhena is typical of subfam.Apocynoideae. But due to the relatively unspecialized structure of the anthers most recent authors have placedHolarrheng, together withCarruthersia andSpirolobium, as the subtribeHolarrheninae in subfam.Plumerioideae. For the present investigation the floral structure and pollen morphology ofHolarrhena, Carruthersia andSpirolobium were analyzed. From the chemical literature reports of the occurrence of steroidal alkaloids in thePlumerioideae were evaluated. Our results indicate that the three genera belong to subfam.Apocynoideae in the tribeNerieae, but that the “Holarrheninae” is an unnatural group, and that the three genera should be accommodated individually within the tribe.