摘要:

Pollen of all the southern African members ofCanthium, KeetiaandPsydraxwas studied by means of LM, SEM and TEM. Palynologically these three genera can easily be distinguished from one another, exine structure and sculpturing being the most useful characters. The sexine is essentially perforate with short columellae not usually distinguishable in SEM in theCanthiumtype, coarsely reticulate with long columellae in theKeetiatype and more finely reticulate with short columellae in thePsydraxtype. PalynologicallyCanthiumsensu stricto (used here to refer to theCanthiumcomplex excludingPsydrax, KeetiaandPyrostria)is clearly distinct fromKeetiaandPsydrax, but similar to the other members of the Vanguerieae. This supports the proposed subdivision ofCanthiumsensu lato in southern Africa into these three genera. Differences amongst the variousCanthiumsensu stricto species suggest at least three different pollen sub‐types. Bridson's placement of C.inermeandC. suberosumin the subgenusLycioserissais supported by the pollen morphology. It is suggested that C.ciliatum, C. kuntzeanum, C. spinosumandC. vanwykiimay also belong to this subgenus. The following placements are supported by palynology:C. gilfillaniiandC. mundianumin the subgenusAfrocanthiumandC. setifloruminBullockia.

ISSN:0017-3134    

DOI:10.1080/00173139709362614

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The pollen size and exine structure of 11Thymusspecies from the Carpathians and Pannonia were studied by light and scanning electron microscopy using image analysis. Of the taxa studied,T. serpyllumhas the smallest pollen grains, andT. pulcherrimusthe largest. The pollen grains of all 11 species are hexazonocolpate, varying in shape from suboblate to euprolate. The exine is bi‐reticulate and scrobiculate. A correlation is found between pollen size and chromosome number. The value of pollen characters for taxonomic purposes and the position of the taxa studied within the framework of tribe Mentheae are discussed.

ISSN:0017-3134    

DOI:10.1080/00173139709362615

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The tribe Echieae of the subfamily Boragineae (Boraginaceae) is represented in southern Africa by the generaLobostemonLehm, andEchiostachysLevyns, endemic to the south‐western Cape region, and two species ofEchiumL.,E. plantagineumL. andE. vulgareL., both introduced weeds of cultivation. Pollen of all these genera was studied and only one pollen type is recognized. Grains are tricolporate, heteropolar and triangular in equatorial view; ora more or less circular and situated towards the broader pole; tectum reticulate with densely spaced lumina; suprateetal nodules are situated at margins of lumina. The P/E ratio varies from 1.08 to 1.63. Genera of the Echieae are sometimes placed in the tribe Lithospermeae. A comparison of the pollen of the studied genera with that ofLithospermum, confirms that the tribe Echieae should be retained. Pollen ofLithospermumis 6–8‐zonocolporate, usually more or less isopolar and with colpi rhombic in outline. The presence of zygomorphic flowers and absence of calciumcarbonate in the fruit wall also support the retention ofLobostemon, EchiostachysandEchiumin the Echieae. Pollen grain structure of the southern African Echieae reveals a close relationship between the genera and could support the merging ofLobostemonandEchiostachyswithEchium. LobostemonandEchiumcan, however, be separated on the position of an annulus.Echiumhas a minute collar or ring of 5–10 minute, sparingly hairy lobes, very close to the corolla base.LobostemonandEchiostachyshave densely hairy scales, tufts of hair, ridges or protuberances at or near the base of the filaments. Futhermore, the style is 2‐lobed inEchiumand simple inLobostemon.

ISSN:0017-3134    

DOI:10.1080/00173139709362616

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Five different types of pollen tetrads were detected from the short and long stamens of the male and hermaphrodite flowers of the androdioecious species,Mimosa pigraL. Light (LM) and scanning electron microscopes (SEM) were used in this study to redescribe the pollen forms and to identify the various pollen types encountered. An identification key and relative percentages of these pollen types were also presented. The study showed that the long stamens of the male flowers and those of the hermaphrodite ones have five (I, II, III, IV and V) and two (I and V) pollen types respectively, whereas the short stamens of both male and hermaphrodite flowers have only one pollen type (type I). We report here the first incidence of intra‐specific pollen polymorphism in androdioecious species.

ISSN:0017-3134    

DOI:10.1080/00173139709362617

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Optimal conditions forin vitrogermination and tube growth ofLimonium perezii(Plumbaginaceae) pollen were established. Boric acid, calcium nitrate, casein hydrolysate and sucrose were all important medium components. A dialysis tubing & filter paper support combined with using polyethylene glycol as an osmoticum in the medium provided appropriate physical conditions forL. pereziipollen germination. Anin vitropollen germination rate of about 40% was achieved. The longest pollen tube observed was four times the pollen grain diameter.

ISSN:0017-3134    

DOI:10.1080/00173139709362618

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Pollen development in 8‐year‐old hazel plants (Corylus avellanaL.) from Central Italy was monitored in order to investigate the chilling completion date of the catkins. Meiotic division occurred in September and pollen development continued until mid‐October when the first haploid mitosis divisions were observed. The catkins elongated gradually during the summer until mid‐October when their growth slowed. In mid‐December the catkins resumed rapid growth and released pollen. From the end of October the pollen grain volume decreased by 12% on average, reaching its minimum value on 6th November. From this time onwards volume increased again to reach its maximum value at the beginning of December, just before pollination. In mid‐October the daily mean temperature dropped below 12.4°C and remained at this low level during the succeeding period; a relatively high mean temperature, above 4.5°C, was recorded in the second week of December. The beginning of dormancy could be correlated with the slowing down of catkin growth and the decrease in the volume of the pollen grains after the first haploid mitosis. When the chilling requirement is fulfilled, at about 640 chill units, the pollen grain volume reaches its maximum value.

ISSN:0017-3134    

DOI:10.1080/00173139709362619

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The relevance of allergy skin prick testing in the diagnosis and treatment of seasonal allergic rhinitis and pollen asthma can usefully be interpreted in relation to the timing and duration of seasonal symptoms and the presence of pollen and mould spores in the air. This calendar has been constructed from three years continuous observations of pollen andAlternariamould spore counts between January 1993 and December 1995, using a Burkard 7‐day volumetric spore trap. Of the total airborne pollen, tree pollen comprises 65%, weeds and herbs 11% and grasses 18%. Unidentified pollen, “other”; group, accounts for6%of the total airborne pollen. The most numerous of the tree pollen is that of the introduced trees cypress(Cupressusspp.) and privet(Ligustrumspp.). Grass pollen is seen in small numbers throughout the winter but shows a rapid increase in spring to peak in mid to late November. Weeds pollinate from early spring through to summer.Alternariamould, which is a risk factor for childhood asthma, occurs mainly in late spring and summer but is present in small numbers intermittently throughout winter.

ISSN:0017-3134    

DOI:10.1080/00173139709362620

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Total soluble proteins were extracted from the pollenof Ipomoea fistulosaand subjected to ammonium sulphate precipitation at 80% saturation. Total protein was separated on SDS Polyacrylamide gel. Each band was recovered from the gel by electroelution avoiding the time‐consuming and expensive biochemical methods of column chromatography. The allergenic proteins were identified by skin tests. The fourth and the fifth band in the protein profile ofI.fistulosa, IF4(47 kDa) and IF5(42 kDa) were the two major allergenic components ofI.fistulosa.The protein profiles showed slight variations in the pollen collected from different geographical regions.

ISSN:0017-3134    

DOI:10.1080/00173139709362621

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The concentration of grass‐pollen allergens in settled dust was measured over a period of 11 weeks in ten homes, five situated in an urban area and five in a rural area, in southwestern Finland during the summer of 1995. Dust samples were collected once a week, using a vacuum cleaner equipped with a special collection device (ALK, Copenhagen) and with a replaceable glass‐fiber filter in a filter dish. All dust samples were analyzed by means of an IgG‐ELISA‐procedure using murine monoclonal antibodies. The allergenic activity of grass pollen in settled indoor dust was low compared with that of birch pollen previously analyzed in the same area. Counts of airborne pollen used in comparison were obtained from the Burkard sampling station in Turku. The grass pollen season is not continuous in this area, but has sporadic relatively low peaks, because a variety of grass species flower at different times. Airborne grass pollen counts in Turku exceeded the threshold value of abundant (> 30 grains per cubic metre of air, Rantio‐Lehtimaki et al. 1991) only six times during the investigation period. The highest concentration of indoor allergenic activity was found about 3 weeks after the grass pollen peak. The allergenic activity of settled outdoor dust intercorrelated with the activity in settled indoor dust. This study supports the assumption that grass pollen antigens are carried home by people and pets. The concentration of grass‐pollen antigens resuspended in the air from settled dust may sporadically reach a level which provokes symptoms in allergic persons.

ISSN:0017-3134    

DOI:10.1080/00173139709362622

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Ukraintseva, V. V.: Vegetation cover and environment of the “Mammoth Epoch”; in Siberia (Lagenbroad, L. D., Mead, J. I., and Hevly, R. H., eds). The Mammoth site of Hot Springs, South Dakota, Inc., 1800 Highway 18‐Truck Route, Hot Springs, South Dakota 57747–0606. 309 pp., $24.95.

ISSN:0017-3134    

DOI:10.1080/00173139709362623

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor