摘要:

SUMMARYNavicula heimansii(Naviculasubgen.Navicula) is described with some notes on ecology and distribution in The Netherlands.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1982.tb01588.x

年代:1982

数据来源: WILEY

摘要:

SUMMARYThe latex ofAsclepias curassavicaL. was shown to contain 40–60 mg.ml–1cardenolides and 0.4–0.6 mg.ml–1esterified triterpenes. The dynamics of14C incorporation of D‐glucose‐U‐14C, acetate‐1‐14C and mevalonate‐2‐14C into esterified triterpenes and cardenolides in excised stem parts have been studied. The results obtained indicate that glucose is a very effective precursor in latex triterpene synthesis. The three precursors used were only slightly involved in cardenolide synthesis. The results are discussed in relation to the view that both latex constituents probably have differe

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1982.tb01589.x

年代:1982

数据来源: WILEY

摘要:

SUMMARYDuring a period of eight years demographic studies were made of a coastal population ofAnthyllis vulnerariaL. var.langeiJalas and of an inland population of its var.vulneraria. The coastal population was found in open dune vegetation on a sandy soil, whereas the inland population occurs in a relatively dense, calciphilous grassland vegetation on a loamy soil. Intermittent periods of drought occur both along the coast and inland, but the dune biotope is considerably more arid than the inland one. In the interior, the more fertile soil supports a much denser and richer biocenosis than does the dunal habitat, and this has important consequences for the population biology. In the coastal region much more extreme population density fluctuations take place, whilst the correlation between these fluctuations and the fluctuations of the abiotic environment (drought) are more evident than they are inland. The dunal form is obviously better adapted to periodic droughts,i.e., to an abiotic factor which is not dependent on population density. In the interior, such biotic factors as competition and predation have a much greater influence owing to the more complex mutual relations between individuals and to the richer composition of the total biocenosis. There are differences in germination ecology, in mortality of seedlings and juvenile plants, in reproduction strategy, and in seed predation between the two populations studied. The coastal populations and the inland ones are each to a large extent build up by pure lines on account of the almost obligatory autogamy; these lines exhibit genetically controlled differences in pubescence.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1982.tb01590.x

年代:1982

数据来源: WILEY

摘要:

SUMMARYThe development of microsporangium, male and female gametophytes, endosperm, embryo and seed‐coat ofEriocaulon xeranthemumMart. has been studied.The microsporangium wall consists of an epidermis, an endothecium, a middle layer and a glandular tapetum. The endothecium is fibrous. Quadripartition in the microspore mother cells is successive. At shedding the pollen grains are 3‐celled and spiraperturate.The female gametophyte is of thePolygonumtype. The three antipodal cells give rise to a conspicuous antipodal cyst, which breaks down before fertilization. The endosperm isab initionuclear. Both apical and basal cells contribute to the formation of the embryo proper. In the mature seed, the embryo is small with an incipient internal differentiation into cotyledonary and epicotylary sectors. Both integuments contribute to the seed coat. The pericarp is 3‐layered, thin‐walled and mem

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1982.tb01591.x

年代:1982

数据来源: WILEY

摘要:

SUMMARYNectarinia osea(Nectariniidae) is a bird that bores holes into matureMalvaviscusflowers. Experiments with cut‐off styles from flowers, and grafting of styles onto buds, show that the protruding style is the effective stimulus for sunbirds to bore holes in theMalvaviscusflower

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1982.tb01592.x

年代:1982

数据来源: WILEY

摘要:

SUMMARYA brief description of theSambucetum ebuliin The Netherlands, not having been described before, is presented. The emphasis is put upon the community structure, distribution and syntaxonomy of the community. The syntaxonomical position of the community remains unclear since it is found on the boundary of its distribution.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1982.tb01593.x

年代:1982

数据来源: WILEY

摘要:

SUMMARYFrom 1978 to and including 1980 the author studied Dutch pastures inundated in winter and spring. The ecology and taxonomy of the following communities are described in this paper:Class:Plantaginetea majorisR. Tüxen and Preising 1950Order:Agrostietalia stoloniferaeOberdorfer, Müller and Görs 1967Alliance:Lolio‐Potentillion anserinaeTüxen 1947  Ranunculo‐Alopecuretum geniculatiTüxen 1937   Subassociations:typicumsubass.nov.     rorippetosum sylvestrissubass.nov.     equisetetosum palustrissubass.nov.  Nasturtio‐Alopecuretum geniculatiass.nov.  Triglochino‐Agrostietum stoloniferaeKonczak 1968   Subassociations:ranunculetosum repentissubass.nov.      juncetosum gerardiisubass.nov.     inopssubass.nov Agrostio‐Trifolietum fragiferiass.nov.  Subassociations:typicumsubass.nov.     festucetosum rubraesubass.nov.     inopssubass.nov. Derivate community ofFestuca arundinacea‐[Lolio‐Potentillion] Basal community ofAgrostis stolonifera‐[Lolio‐Potentillion] Community ofScirpus maritimusandAlopecurus geniculatusClass:Asteretea tripoliiWesthoff and Beeftink 1962Order:Glauco‐PuccinellietaliaBeeftink and Westhoff 1962Alliance:Armerion maritimaeBraun‐Blanquet and De Leeuw 1936  Ononido‐Caricetum distantisRunge 1966  Juncetum maritimiBilik 1956Besides some comments are made on theAlopecurus arundinaceuscommunity, observed in Sweden, which is unclear syntaxonomically. The relation of these communities to one another and to the two major environmental factors – s

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1982.tb01594.x

年代:1982

数据来源: WILEY

摘要:

SUMMARYBy delaying pollination with flowers ofPetunia hybridafor up to 5 days, the viability of aged pollen and the numbers of seeds resulting from crosses declined with aging of either staminate or pistillate parent. In the resulting generation, given enough time to overcome transient maternal effects, plants from aged pollen were significantly heavier than were other plants. This suggests that there is selective mortality among stored pollen grains. This may have both basic and applied implications.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1982.tb01595.x

年代:1982

数据来源: WILEY

摘要:

SUMMARYPollen grains from four pollen source genotypes (H55, Oh43, K64 × K55, Ky49 × Ky27) were cultured on an artificial medium (15% sucrose, 0.6% bacto‐agar, 0.03% calcium nitrate, 0.01% boric acid) supplemented with four concentrations (0, 5, 25, 100 ppm) of gibberellin A3(GA3). At 1, 2, and 3 h after inoculation, germination percent and pollen tube length were measured. A highly significant concentration x pollen source genotype interaction for germination percent was obtained. Depending on the pollen source genotype, increasing GA3concentrations either substantially increased or did not alter germination percent. For pollen tube length, a highly significant concentration x pollen source genotype interaction was also obtained. However, depending on the pollen source genotype, increasing GA3concentrations either increased, decreased, or had no effect on pollen tube length. Any stimulatory effect of GA3on pollen tube length was expressed early in the germination process or between inoculation and one h after inoculation. The results suggested that heterozygosity level could be a contributing factor in the GA3response and within each pollen source genotype, the effects of GA3on germination percent and pollen tube length were independ

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1982.tb01596.x

年代:1982

数据来源: WILEY

摘要:

SUMMARYPoly‐ethylene glycol (PEG)‐400 was found to be superior to sucrose as the major component in media for the germination ofPetunia hybridapollen. PEG promotes pollen tube growth considerably more than sucrose. Pollen tubes grown on PEG resemble thein vivotubes much more than those grown on sucrose. The respiration rate of pollen germinating on sucrose is 33% higher than on PEG; the extra energy produced is clearly not related to tube gro

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1982.tb01597.x

年代:1982

数据来源: WILEY