摘要:

AbstractSeeds ofPolemonium reptansvar.reptans, a perennial herb of mesic deciduous forests in eastern North America, mature in late May‐early June, and a high percentage of them are dormant. Seeds afterripened (came out of dormancy) during summer when kept in a nylon bag under leaves in a nonheated greenhouse or on wet soil in a 30/15°C incubator. The optimum temperature for germination of nondormant seeds was a simulated October (20/10°C) regime. In germination phenology studies in the nonheated greenhouse, 20–30% of the seeds that eventually germinated did so in October, and the remainder germinated the following February and March. Since low (5°C) winter temperatures promote some afterripening (ca. 50%) and do not cause nondormant seeds to re‐enter dormancy, seeds that fail to germinate in autumn may germinate in spring. Thus, the taxon has very little potential to form a persistent seed bank. The large spatulate embryos and ability of seeds to afterripen at high temperatures means that seeds ofP. reptansvar.reptanshave nondeep physiological dormancy, unlike many herbaceous woodland species, which have morphophysiological

ISSN:0913-557X    

DOI:10.1111/j.1442-1984.1992.tb00219.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractSympatric local populations of leptosporangiate ferns found to vary in phenotypic tolerances of environmental variation in the common habitat were surveyed for allozymes as indicators of genetic variation. Each local population was also surveyed for pattern of ramet distribution. The species with the greater phenotypic tolerances,Deparia acrostichoides, was found to be more variable genetically than the species with lower phenotypic tolerances,Diplazium pycnocarpon. Levels of genetic variation among the two species indicated thatDeparia acrostichoidesis a late‐successional species andDiplazium pycnocarponis an early‐successional species, in agreement with a previous prediction. Ramet distribution patterns indicated a greater effect of intraspecific competition among ramets ofDiplazium pycnocarponthan among ramets ofDeparia acrostichoi

ISSN:0913-557X    

DOI:10.1111/j.1442-1984.1992.tb00220.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractDisporum sessile(Liliaceae), a perennial herb of temperate forests is composed of diploid (2n=16) and triploid (2n=24) populations. The size structure differed remarkably as triploid populations had few small plants and no seedlings. Triploid flowering plants were considerably larger than diploids. Triploids that flowered were 2.5 times larger than diploids that flowered and the size of vegetative ramets produced by triploids was twice as large. In triploids, fruiting rates were quite low only with inviable seeds and vegetative propagule size was greater than that of diploids. As regards growth parameters that help to increase plant size, triploids were superior to diploids. Differences in growth and reproductive parameters between diploids and triploids may contribute to forming different patch sizes.

ISSN:0913-557X    

DOI:10.1111/j.1442-1984.1992.tb00221.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractFrond morphology of the highly polymorphic, annual fernCeratopteris thalictroideswas examined for local populations in south and central Japan. Among the characters examined, frond length and frond dissection were most useful for recognizing several forms. Through the comparison of these characters among populations, a geographically clinal pattern of variation was recognized; plants in higher latitudes have smaller and less dissected fronds. Plants usually grow in rice paddies during a limited period from the harvest time to the beginning of the frost season. Concordance was observed between the degree of frond length and dissection of populations and the length of the viable period in their localities. The variability of cultivated progeny of selected populations from the south and the north suggests that there are at least two ecological lines; one is genetically restricted to large and much dissected fronds and the other to smaller and less dissected fronds. The latter may be an adaptation to the short viable period in rice paddies in northern regions. High phenotypic plasticity enables these lines to adjust well the degree of frond length and dissection to the length of the viable period in each locality.

ISSN:0913-557X    

DOI:10.1111/j.1442-1984.1992.tb00222.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractBiomass sex allocation ofAlnus firma, a wind‐pollinated self‐incompatible monoecious tree species, was directly measured at the inflorescence (prezygotic) stage. Sex allocation ratio at the fruit stage was estimated from the number of female inflorescences, percent fruit production, and the mean dry weight of a female inflorescence and a fruit catkin. Investment in male function far exceeds that in female function at the prezygotic stage. When the costs of fruit catkins and seeds were included in the estimation of female function, then the sex allocation bias was reversed towards female. Intrapopulational variation of the sex allocation ratio with respect to tree height and size was also investigated. A strong negative correlation was observed in both cases, although a positive relationship has been predicted by theorists and some previous empirical data have supported this predict

ISSN:0913-557X    

DOI:10.1111/j.1442-1984.1992.tb00223.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractFifteen Asiatic and four North American taxa of the genusDisporum(Liliaceae‐Polygonateae) were karyologically examined. The chromosome numbers and karyotypes ofD. multiflorum(2n= 14),D. sessilevar.sessilef.minus(2n= 16),D. sessilevar.micranthum(2n= 16), andD. taipingense(2n= 16) were determined for the first time. Thirteen additional chromosome counts and karyotype analyses were made for the following 11 AsiaticDisporumtaxa (SectionDisporum):D. calcaratum(2n= 14 and 16‐a new count),D. cantoniense(2n= 14 and 16),D. kawakamii(2n= 16),D. longistylum(2n= 16),D. lutescens(2n= 16),D. sessilevar.sessilef.sessile(2n= 16),D. shimadai(2n= 14),D. smilacinumvar.smilacinum(2n= 16),D. smilacinumvar.ramosum(2n= 16),D. uniflorum(2n= 16), andD. viridescens(2n= 16 + 1B‐a new count).The karyotypes of four North American taxa (SectionProsartes) were reported for the first time, although the same chromosome counts had been previously known for each taxon:D. hookeri(2n= 18),D. lanuginosum(2n= 18),D. maculatum(2n= 12), andD. smithii(2n= 16).D. maculatumpossesses a very characteristic satellite on the long arm of the fifth subterminal chromosome; the karyotype ofD. smithii(x= 8) is also characterized by possessing a minute satellite on the short arm of the fifth pair and also by a secondary constriction on the short arm of the sixth pair.One of the most noteworthy findings made in the present study is that the species of SectionDisporumand SectionProsartespossess conspicuously distinct cytological features in the size of resting nuclei and cells, interphase chromosomes, and mitotic prophase and metaphase chromosomes. The plants of SectionDisporumhave distinctly larger resting nuclei and cells than those of SectionProsartes; SectionDisporumpossesses a typical homogeneously diffused type (= densely diffuse type according to Tanaka, 1977) of interphase chromosomes, while SectionProsarteshas a prochromosome type; the condensation pattern of their prophase chromosomes is of a continuous type in SectionDisporum, while a proximal type occurs in SectionProsartes; SectionDisporumpossesses distinctly larger sized metaphase chromosomes, as compared with SectionProsartes. All of these karyological differences described above strongly support D. Don's original concept (1839, 1841) of treatingDisporumandProsartesas two separate g

ISSN:0913-557X    

DOI:10.1111/j.1442-1984.1992.tb00224.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractVolatile substances emitted from the flowers of eightMagnoliataxa (M. sieboldiissp.japonica, M. praecocissimavar.praecocissimaand var.borealis, M. tomentosa, M. salicifolia, M. obovata, M. denudata, and M. grandiflora) and oneMicheliaspecies (M. compressa) (Magnoliaceae) were examined and identified using GC‐MS. Volatile substances of theseMagnoliaandMicheliaspecies consist primarily of monoterpenoids and sesquiterpenoids produced by the mevalonate pathway, acetogenins by the acetate‐malonate pathway, and phenyl‐propanoids by the shikimate pathway. TheseMagnoliaandMicheliaspecies all possessed various combinations of volatile monoterpenoids, acetogenins, and phenylpropanoids, except forMagnolia obovata, which emitted primarily sesquiterpenoids. Free amino acids in pollen of 12Magnoliaand oneLiriodendronspecies were also analyzed, and their value as food sources for pollinators evaluated.Pollinators visiting the flowers of fiveMagnoliaspecies were collected in their native sites and identified. Their behaviors and roles as pollinating agents were ass

ISSN:0913-557X    

DOI:10.1111/j.1442-1984.1992.tb00225.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractCarex miserais a rare sedge, endemic to rocky outcrops and mountain summits within the southern Appalachian Mountains from northern Georgia to northern North Carolina. We assessed allozyme diversity for 406 individuals from nine populations over most of the geographic range. Twenty‐seven putative loci were assayed and eight (30%) were found to be polymorphic. Nei's gene diversity statistics (HT=0.043,HS=0.019,GST=0.551) indicated low levels of variation but relatively highly differentiated populations, suggesting little gene flow. Significant deviations from genotypic expectations under Hardy‐Weinberg equilibrium, high positive fixation indices, and the existence of small genetic neighborhoods within populations suggest that at least some inbreeding occurs. Cluster analysis of Nei's genetic identity statistics and principal component analysis of allele frequency data showed high similarity among the six southern populations with the two northern populations more differentiated from them and from each other. These results suggest that preservation of the northern populations is necessary to conserve the already low levels of genetic diversity within the spec

ISSN:0913-557X    

DOI:10.1111/j.1442-1984.1992.tb00226.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

ISSN:0913-557X    

DOI:10.1111/j.1442-1984.1992.tb00227.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY