摘要:

AbstractThe frequency of hybrids was monitored using progenies grown from seeds collected from open‐pollinated plants in mixed populations ofFarfugium hibernifloriumandF. japonicum. The results showed that hybrids are more frequently derived fromF. japonicumthan fromF. hiberniflorum. This directionality of hybridization and extraordinarily high frequency of hybrids among progenies grown from seeds from open‐pollinated plants ofF. japonicumenabled us to derive an empirical equation describing the frequency of hybridization as a decreasing exponential function of interspecific plant distance. The relationship between these two variables fitted a function describing pollen flow from a particular plant. This finding suggests that interspecific pollen exchange can be viewed simply as a process dependent of interspecific plant distance, and the actual rate of hybridization is determined by the level of cross‐compatibility of a particular sp

ISSN:0913-557X    

DOI:10.1111/j.1442-1984.1989.tb00051.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractOcimum americanumandO. basilicumbloom once a year. They produce flowers over a long period, a few flowers being produced each day. The flowers of both are short‐lived (3‐4 hours), bisexual, zygomorphic, and chasmogamic with anthers dehiscing in the bud stage. The open flowers offer nectar and pollen as rewards and are visited and sternotribically pollinated by day‐flying animals. The blossoms are flag‐shaped, and the reproductive organs are close to the lower corolla lip. The stamens and stigma show movements immediately after anthesis and remain for 20–30 minutes and this may cause self‐pollination. Both species reproduce primarily through autogamy. Flowers are open during 5:30–13:30 hr inO. americanumand during 7:00–13:00 hr inO. basilicum. Certain bee species likeApis florea, A. cerana indica, Amegillasp., andPseudapis oxybeloies, and the butterflySurandra queretroumare the most frequent and consistent visitors and can be pollinators for bot

ISSN:0913-557X    

DOI:10.1111/j.1442-1984.1989.tb00052.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractAn accession ofLotus alpinusSchleich. (2n=2x=12) from Turkey in which B chromosomes have been found was studied morphologically and karyologically. Chromosome numbers were observed in 519 cells from nine plants which all exhibited mixoploidy (2n=11, 12, 12 + 1B, 12 + 2B and over 20). Keel tip color, stem pubescence, and inflorescence size differed from a collection of this species from Switzerland. While the percentage of total lengths of the chromosome complements and the relative chromosome lengths in the two accessions were very similar, the total complement lengths differed considerably (23.14μm Turkey vs. 29.46μm Switzerland). This karyological difference is not considered to be the result of the presence of B chromosomes, but probably the result of hybridization between different genotypes. Aborted seed pods were observed which lent credibility to this hypothesis. Plants of this accession may have arisen as a result of hybridization betweenLotus corniculatusand/orL. alpinusas both diploid and tetraploid cytotypes are reported in the Turkey collection for these species. The data would lend support for their hybrid origi

ISSN:0913-557X    

DOI:10.1111/j.1442-1984.1989.tb00053.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractGermination responses ofTaraxacum platycarpumseeds to temperature were examined under laboratory conditions to investigate the emergence‐season choice mechanism of the seeds. Almost all the newly collected seeds were non‐dormant. Under constant temperature conditions, maximum percentage germination (approximately 90%) was attained at temperatures 6–16°C, where simple linear relationships were observed between the temperature and the rates of germination, i.e. the reciprocals of the time taken to germinate by seed subpopulations with 10–80% germination. Thermal time required for germination of the subpopulations ranged from 600 Kh (degree Kelvin × hours) to 1500 Kh with a relatively constant base temperature of about 2.5°C. Lower limit temperature for germination was slightly below 6°C. Higher limit temperature for germination has the normal distribution with the mean ±SD of 19±2.5°C. Pre‐exposure of imbibed seeds to temperatures higher than the higher limit temperature for germination, 25 and 30°C, had no effect on the germinability and the rate of germination at a circa‐optimum temperature. Moist chilling treatment at 4°C caused an increase in the variation of germination rate within the seed population, but no evidence for dormancy‐inducing or breakin

ISSN:0913-557X    

DOI:10.1111/j.1442-1984.1989.tb00054.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractDetailed information on the character states ofPseudopyxis depressaandP. heterophiylla, the only two representatives of the genus, are given. Particularly remarkable are the occurrence of both homo‐ (P. heterophiylla) and hetero(di)styly (P. depressa) and associated palynological differences, and the unusual fruits and diaspores, whose development is documented. Relationships between the two species are also discussed, and a section on the taxonomic position and history of the genus is include

ISSN:0913-557X    

DOI:10.1111/j.1442-1984.1989.tb00055.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractSelected character states of the presumed allies ofPseudopyxisare described, compared and discussed. Particular attention is paid to the fruits and diaspores and their ways of development and differentiation. It is presumed that 1)PseudopyxisandSerissaare closely allied, that 2) these two genera are, in turn, closely related toLeptodermisand the monotypicSpermadictyon(the latter possibly not generically distinct from the former), that 3)Paederialoosely links up to four mentioned genera, and that 4) the monotypicAitchisoniastands rather isolated on account of various peculiarities.

ISSN:0913-557X    

DOI:10.1111/j.1442-1984.1989.tb00056.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractThe flowers ofAnisomeles indicaandA. malabaricaare zygomorphic, bilabiate, gulletshaped and nectariferous, and are visited by insects as well as birds for nectar and/or pollen. The beesXylocopa latipes, X. Pubescens, Amegillasp.,Apis floreaandMegachilesp., and the sunbirds of the genusNectariniaare the principal pollinators ofA. indica, while the former three and the last and the waspRhynchium metallicumare forA. malabarica.Pollination byXylocopaandNectariniais nototribic and that byApis, Megachile, Amegillais noto‐ and/or sternotribic. The small bodiedTrigona, PseudapisandCeratinacollected pollen sternotribically. It is concluded that adaptation of both species to insect and bird pollination and to a flexible breeding system involving both selfing and crossing, safeguards their survival under changing environment

ISSN:0913-557X    

DOI:10.1111/j.1442-1984.1989.tb00057.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY