摘要:

The breeding system and factors affecting seed set in a population ofPotentilla palustriswere studied in Central Jutland, Denmark. The reddish‐brown, bowl‐shaped, and nectariferous flowers ofPotentilla palustrishad an average of 376795 viable pollen grains and 187 single‐ovuled carpels. The number of ovules per flower decreased significantly along an inflorescence, from 312 in the basal flowers to 97 in the flowers in distal positions. The flowers were protandrous and opened mainly during the day. Male and female phases lasted on average 1.6 and 3.0 days, respectively. Pollination experiments showed thatP. palustriswas facultatively autogamous to facultatively xenogamous. The plant was selfcompatible and auto‐deposition of pollen occurred, but insect polllination enhanced seed set. Outcrossing increased seed set compared to selfing. A long outcrossing distance increased seed set comparative to short distance crossings. Seed set per flower declined through the flowering season mainly due to a significant reduction in the number of ovules per flower with time and/or node position. It is suggested that intra‐plant competition for a limited amount of resource is the main factor limiting seed set in this population, but pollen limitation occur in late season. The quantitative and qualitative impact on seed set by pollinating insects is

ISSN:0107-055X    

DOI:10.1111/j.1756-1051.1992.tb01318.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Pinus sylvestrisandP. mugopopulations from Poland and Czechoslovakia were compared using genetic variability at isozyme markers, chloroplast DNA variation, and mating system measurements. Two isozyme loci were found to differ between the species.P. mugowas as variable at isozyme loci asP. sylvestris.Diagnostic cpDNA fragments were found using the restriction enzymeBcl‐I.Populations that were morphologically classified as hybrids were found to be pure species, based both on isozyme and cpDNA result

ISSN:0107-055X    

DOI:10.1111/j.1756-1051.1992.tb01319.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

A new name (Pteroceras semiteretifolium H. Æ. Peders.) and two new combinations (P. cladostachyum (Hook.f.) H. Æ. Peders., P. unguiculatum (Lindley) H. Æ. Peders.) are presented. The correct application of the name P. pallidum (Blume) Holttum is discuss

ISSN:0107-055X    

DOI:10.1111/j.1756-1051.1992.tb01320.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Tragia mitisis lectotypified andT. cinereais neotypified.T. abortiva, T. ashiae, T. crenata, T. doryodes, T. mixta, T. negeliensis, T. triumfettoidesandT. uncinataare described as new. The new combinationDalechampia pavoniifoliais made.Clutia lanceolatais extended to include African material and the new combinationClutia lanceolatassp.robustamade.

ISSN:0107-055X    

DOI:10.1111/j.1756-1051.1992.tb01321.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

ISSN:0107-055X    

DOI:10.1111/j.1756-1051.1992.tb01322.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Eighteen new species ofEuphorbiasubgenusEuphorbiaare described and their relationships discussed. All are endemic to Somalia, with limited distributions in the northern Regions. One,E. phillipsioides, has been identified mistakenly for some time asE. phillipsiae, which is shown to be conspecific withE. golisana. E. xylacantha, considered by N. E. Brown to be synonymous withE. monacantha, is reinstated as a distinct but variable species.

ISSN:0107-055X    

DOI:10.1111/j.1756-1051.1992.tb01323.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

The new speciesMaerua purpurascens(southern Somalia, on stabilized dune near coast) andCleome kersiana(northern Somalia, on semi‐desert gravel plain) are described and illustrate

ISSN:0107-055X    

DOI:10.1111/j.1756-1051.1992.tb01324.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

The crustose lichen flora of fifteen areas in boreal coniferous forests from southern Sweden to Lapland was surveyed. Many of these areas are included in a national programme for monitoring long‐term environmental change, the PMK programme. In all 190 species were recorded, 129 of them occurring on bark of conifers and lignum. Some species were found exclusively in forests with a long continuity. By using ordination and hierarchical classifications further species with similar habitat requirements were identified. An Indicator Species Index of Forest Continuity (ISIFC) was designed. Only two of the twenty index species occur on deciduous trees. The ISIFC was highly correlated with forest continuity and also with occurrence of species listed as threatened. Correlations with macroclimatic variables are considered sampling artifacts, and microclimatic factors are suggested to be of primary importance for species occurring in forests with a long continuit

ISSN:0107-055X    

DOI:10.1111/j.1756-1051.1992.tb01325.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

The taxonomy, ecology and distribution ofRinodina deflectens, R. interjecta, R. rinodinoides, R. tephraspisandR. trachyticaare treated. New combinations are made forR. interjectaandR. rinodinoides. R. melanocarpaandR. serpentiniare synonyms ofR. rinodinoides. R. badiellaandR. kentuckyensisare synonyms ofR. tephraspis, andR. ibericaofR. trachytica.

ISSN:0107-055X    

DOI:10.1111/j.1756-1051.1992.tb01326.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

ISSN:0107-055X    

DOI:10.1111/j.1756-1051.1992.tb01327.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY