摘要:

The pollinium morphology of ten genera (AtherolepisHook, f.,DecalepisWight & Arn.[=BaeolepisDecne.,JanakiaJ. Joseph & V. Chandras.],FinlaysoniaWall.,GongylospermaKing & Gamble,GymnantheraR. Br.,HemidesmusR. Br.,MeladermaKerr,StelmacryptonBaill.,StreptocaulonWight & Arn.,UtleriaBedd. ex Benth. & Hook, f.) andRaphionacme abyssinicaChiov. of the Periplocoideae have been examined and compared withCynanchum ellipticum(Asclepiadoideae) using light‐, scanning‐and transmission electron microscopy. In the Periplocoideae four free pollinia are produced in each anther. The pollinia are not attached to a translator while in the anther. However, by anthesis the pollinia are deposited on the spoon of the translator. The pollinium is not covered by a pollinium wall (ectexine). The pollinium consists of loosely agglutinated, but not fused, tetrads. The only physical connection between the tetrads was observed when two pores, of adjacent tetrads, are opposite one other. In such cases the tectum and granular stratum of the adjoining tetrads may be fused. The wall structure of the tetrads forming the pollinium consists of a tectum and a granular stratum subtended by an intine.

ISSN:0017-3134    

DOI:10.1080/00173139809362633

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Pollen of two North American monotypic genera (PterostegiaandHarfordia) in the tribe Pterostegieae (including three varieties ofHarfordiaca. 22 specimens in total) was examined with light microscope and scanning electron microscope. Detailed descriptions of the inner surface of the tectum and endoapertures were investigated using freezing microtome sections in SEM. The pollen of Pterostegieae can be characterized as being usually 3‐colporate, lolongate or almost circular (more common inHarfordia)and having endoapertures with a subtectate‐microreticulate or ruglo‐/striato‐perforate exine sculpturing. The pollen grains ofPterostegiaandHarfordiaare very much alike and are therefore, not easily separable, although there are some slight variations (especially in pollen size and sexine patterns, etc.). The infratectum of pollen inHarfordiais covered with comparatively few and less dense granules than that ofPterostegiaand these characters are reported forPterostegia drymarioidesfor the first time here. This palynological detail (i.e., granular inner tectum surface) might be considered an important synapomorphic character, which reinforces the concept of a close relationship between the tribes Pterostegieae and Eriogoneae in the subfamily Eriogonoideae.

ISSN:0017-3134    

DOI:10.1080/00173139809362634

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Pollen of two North American monotypic genera (PterostegiaandHarfordia) in the tribe Pterostegieae (including three varieties ofHarfordiaca. 22 specimens in total) was examined with light microscope and scanning electron microscope. Detailed descriptions of the inner surface of the tectum and endoapertures were investigated using freezing microtome sections in SEM. The pollen of Pterostegieae can be characterized as being usually 3‐colporate, lolongate or almost circular (more common inHarfordia)and having endoapertures with a subtectate‐microreticulate or ruglo‐/striato‐perforate exine sculpturing. The pollen grains ofPterostegiaandHarfordiaare very much alike and are therefore, not easily separable, although there are some slight variations (especially in pollen size and sexine patterns, etc.). The infratectum of pollen inHarfordiais covered with comparatively few and less dense granules than that ofPterostegiaand these characters are reported forPterostegia drymarioidesfor the first time here. This palynological detail (i.e., granular inner tectum surface) might be considered an important synapomorphic character, which reinforces the concept of a close relationship between the tribes Pterostegieae and Eriogoneae in the subfamily Eriogonoideae.

ISSN:0017-3134    

DOI:10.1080/00173139809362635

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Teliospores ofUstilago maydis(De Candolle) Corda were irradiated with CuKα X‐ray with a BRON UM1 instrument at 35 KV, 20 mA and the resulting thin sections investigated with a TEM. The length of time of irradiation was 5 s, 15 s, 35 s, 60 s, and 300 s. The wall of the teliospore, which contains melanin, is extremely resistant, but increases in the radiation dose resulted in ultrastructural alterations. The endospore became swollen, the protoplasm contracted and the epispore disintegrated. The degradation of the electron dense particles in the exospore is obvious after a relatively short time of irradiation. The X‐ray effect explored the molecular structure of the wall. In highly magnified pictures several kinds of molecular systems were observed, including chain molecules and cyclic derivates among the other constituents of the melanin molecules.

ISSN:0017-3134    

DOI:10.1080/00173139809362636

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The pollen production (number of pollen grains per catkin) ofAlnus incanais studied along two vertical transects across the altitudinal limit of the species. Annual variation in pollen quantity, and a considerable reduction in the number of pollen are found with increasing altitude. Normal pollen is virtually not produced at the ecotone. It is suggested that parameters such as the temperature of the preceding summer, length of the growing season, and soil factors are limiting factors. A test study shows no germination of seed from the ecotone, and reduced fertility is suggested.

ISSN:0017-3134    

DOI:10.1080/00173139809362637

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Monitoring of airborne pollen grains in Cartagena (Spain) has been carried out over a period of three years from 18 March 1993 to 18 March 1996 using a volumetric capture device (Hirst Sampler, Lanzoni VPPS‐2000). A total of 59877 grains/m3belonging to 44 taxa were observed. The Urticaceae are the most common group, with altogether 18479 grains/m3. Other frequent taxa were Chenopodiaceae‐Amaranthaceae, Cupressaceae,Olea, QuercusPinaceae, Poaceae,Plantago, Platanus, Zygophyllumand Arecaceae. The weekly average was 384 grains/m3, with a maximum value of 2104 grains/m3during the month of May and a minimum value of 21 grains/m3during the month of October. The total and individual pollen concentration has been decreasing over these three years, probably due to the severe drought in the region. In 1996, the total pollen amount was 46% less than in 1993. A negative correlation was found between the total pollen content and rainfall, humidity and air pressure, and a positive one with sunshine. According to multiple regression analysis, 22% of the pollen concentration can be correlated with meteorological parameters.

ISSN:0017-3134    

DOI:10.1080/00173139809362638

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Two different types of sedimentation pollen traps (Tauber and Cundill designs) were tested together in a grassy glade within a pine forest in east Fife, Scotland over the period 1992–1995. The results from 1992 and 1993 are presented and demonstrate close similarities between the quantities of pollen of the major taxa captured by the two traps. Differences between the pollen values of Poaceae from the two traps may be attributed to localised release of pollen although variations inPinuspollen are less easy to explain. Problems were encountered in the use of the Tauber .trap because it acted as a pitfall trap for insects, amphibians and small mammals and this led to some samples from 1994 and 1995 being discarded. In general both the traps operated with the same level of efficiency although the Tauber trap requires the addition of a mesh or bactericide/preservative to counteract its tendency to act as a pitfall trap.

ISSN:0017-3134    

DOI:10.1080/00173139809362639

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A continuous two years (July, 1994 to June, 1996) survey of aeropalynoflora on an agricultural farm situated in the suburbs of Calcutta was carried out using a Burkard volumetric spore trap. A total of 46 pollen types were identified. The dominant pollen types recorded originated from Poaceae,Trema orientalisCyperaceae andCocos nucifera.These pollen types were subjected to clinical investigation to determine their degree of allergenicity on adult respiratory allergic patients by means of skin prick tests. A maximum allergenic response was shown toSaccharum officinarum(54.86%) followed byAzadirachta indica(52.93%) andPhoenix sylvestris(44.09%). Among the 46 recorded pollen types, 26 showed a positive skin reaction. Seasonal variations, diurnal periodicities and the vertical profiles of airborne concentrations of these allergenic pollen types were studied to evaluate the extent of exposure. The overall survey confirms the fact that all dominant airborne pollen types do not contribute equally to the aeroallergen load. Some pollen grains, though present in the air in lower concentration, were found to be allergenically significant.

ISSN:0017-3134    

DOI:10.1080/00173139809362640

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Only two angiospermous species grow in Antarctica, namelyColobanthus quitensis(Caryophyllaceae) andDeschampsia antarctica(Poaceae). Their pollen grains have been studied using light (LM) and scanning electron microscopy (SEM). Their morphology is characterized, described and illustrated. This contributes to a more comprehensive knowledge of the Antarctic flora and its use in palynostratigraphical investigations.

ISSN:0017-3134    

DOI:10.1080/00173139809362641

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Bibliography of European Palaeobotany and Palynology 1994–1995

ISSN:0017-3134    

DOI:10.1080/00173139809362642

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor