abstract：:Accurate estimates of inbreeding depression are necessary in order to predict the evolutionary dynamics of a population, but many studies estimate inbreeding depression based solely on components of female function such as fruit set, seed set, and seed quality. Because total fitness is achieved through both male and f...

journal_title：American journal of botany

authors： Hayes CN,Winsor JA,Stephenson AG

更新日期：2005-01-01 00:00:00

abstract：:In the alpine landscape most plant populations are spatially isolated due to extreme patchiness and strong natural fragmentation. We used RAPD-PCR (randomly amplified polymorphic DNA polymerase chain reaction) for a study of the genetic diversity within and among 20 populations of Geum reptans, an outcrossing clonal p...

journal_title：American journal of botany

authors： Pluess AR,Stöcklin J

更新日期：2004-12-01 00:00:00

abstract：:We investigated the hypothesis that dandelion clones (Taraxacum officinale Weber, sensu lato; Asteraceae) differ in their floral stage timing characteristics under a constant set of environmental conditions. To test this hypothesis, plants representing nine different dandelion clones (identified by DNA fingerprinting)...

journal_title：American journal of botany

authors： Collier MH,Rogstad SH

更新日期：2004-11-01 00:00:00

abstract：:The endodermis of different species of the genus Equisetum has different configurations, two or one continuous layers or a sheath only around the vascular bundles. The question whether the endodermis contributes to the mechanical stability of the aerial shoots is investigated in two ways: In a direct approach, the end...

journal_title：American journal of botany

authors： Spatz HC,Emanns A

更新日期：2004-11-01 00:00:00

abstract：:The phylogenetic structure of ferns (= monilophytes) is explored here, with a special focus on the early divergences among leptosporangiate lineages. Despite considerable progress in our understanding of fern relationships, a rigorous and comprehensive analysis of the early leptosporangiate divergences was lacking. Th...

journal_title：American journal of botany

authors： Pryer KM,Schuettpelz E,Wolf PG,Schneider H,Smith AR,Cranfill R

更新日期：2004-10-01 00:00:00

abstract：:The last decade has witnessed a resurgence in the study of the evolution of plant development, combining investigations in systematics, developmental morphology, molecular developmental genetics, and molecular evolution. The integration of phylogenetic studies, structural analyses of fossil and extant taxa, and molecu...

journal_title：American journal of botany

authors： Friedman WE,Moore RC,Purugganan MD

更新日期：2004-10-01 00:00:00

abstract：:The shoot apical meristem (SAM) produces stem and initiates leaves. Its structure is maintained despite a continuous flow of cells basipetally from the distal portion of the meristem. The apoplasm and symplasm are the obvious means of cell integration, and their role in chemical cell-to-cell signaling is known. Howeve...

journal_title：American journal of botany

authors： Kwiatkowska D

更新日期：2004-09-01 00:00:00

abstract：:Leaf habit correlates with multiple physiological traits. Understanding ecophysiology is therefore dependent on knowledge of leaf habit. A variety of leaf habits exists within forest understory plant communities. Oxalis acetosella is one such understory plant and has long been considered a wintergreen, meaning that it...

journal_title：American journal of botany

authors： Tessier JT

更新日期：2004-09-01 00:00:00

abstract：:Seventy-four nucleotide sequences from the ITS regions of nuclear ribosomal DNA and 76 from the trnL-trnF spacer of chloroplast DNA were used to address the origin of tetraploid Cardamine amporitana, the conspecifity of central Italian and northeastern Spanish populations, and the possible cause for such geographic di...

journal_title：American journal of botany

authors： Lihová J,Fuertes Aguilar J,Marhold K,Nieto Feliner G

更新日期：2004-08-01 00:00:00

abstract：:The direct and indirect effects of vegetative herbivory on the mating system of Impatiens capensis were analyzed through a survey of herbivory in natural I. capensis populations and manipulation of leaf damage in the field. Across 10 wild populations of I. capensis proportion of cleistogamous flowers had a significant...

journal_title：American journal of botany

authors： Steets JA,Ashman TL

更新日期：2004-07-01 00:00:00

abstract：:Seedling establishment is central to population maintenance for nonclonal plant species. Plants with low recruitment rates are expected to have high survival rates, and life history theory indicates there should be a single curve for the trade-off between recruitment and mortality that applies to most or all plant spe...

journal_title：American journal of botany

authors： Forbis TA,Doak DF

更新日期：2004-07-01 00:00:00

abstract：:The pollination biology of the cactus Pachycereus pecten-aboriginum was studied in a tropical location in western Mexico (ca. 18° N latitude) to compare with data from a northern population (ca. 28° N latitude). Throughout this range, the nectar-feeding bat Leptonycteris curasoae is resident within the tropics but mig...

journal_title：American journal of botany

authors： Valiente-Banuet A,Molina-Freaner F,Torres A,Arizmendi Mdel C,Casas A

更新日期：2004-06-01 00:00:00

abstract：:Phylogenetic relationships and biogeography of the genus Cerastium were studied using sequences of three noncoding plastid DNA regions (trnL intron, trnL-trnF spacer, and psbA-trnH spacer). A total of 57 Cerastium taxa was analyzed using two species of the putative sister genus Stellaria as outgroups. Maximum parsimon...

journal_title：American journal of botany

authors： Scheen AC,Brochmann C,Brysting AK,Elven R,Morris A,Soltis DE,Soltis PS,Albert VA

更新日期：2004-06-01 00:00:00

abstract：:Exotic plant species can threaten closely related native congeners through asymmetric hybridization and subsequent backcrossing, the process known as genetic assimilation. I explore the initial stages of this process in Taraxacum ceratophorum (Asteraceae), the native alpine dandelion, and the invasive apomict T. offic...

journal_title：American journal of botany

authors： Brock MT

更新日期：2004-05-01 00:00:00

abstract：:Breadfruit (Artocarpus altilis, Moraceae), a traditional starch crop in Oceania, has enjoyed legendary status ever since its role in the infamous mutiny aboard the H.M.S. Bounty in 1789, yet its origins remain unclear. Breadfruit's closest relatives are A. camansi and A. mariannensis. DNA fingerprinting data (AFLP, am...

journal_title：American journal of botany

authors： Zerega NJ,Ragone D,Motley TJ

更新日期：2004-05-01 00:00:00

abstract：:In a detailed analysis of how limited seed dispersal can create spatial structuring of genetic variation, several nuclear microsatellites were assayed in seedlings from two forests of Pinus strobus, one old growth (OG) and the other (second site, SS) logged in ca. 1900. By using loci with a large number of alleles and...

journal_title：American journal of botany

authors： Walter R,Epperson BK

更新日期：2004-04-01 00:00:00

abstract：:The recent consensus that Amborellaceae, Nymphaeales, and Austrobaileyales form the three earliest-diverging lineages of angiosperms has led comparative biologists to reconsider the origin and early developmental evolution of the angiosperm seven-celled/eight-nucleate (Polygonum-type) female gametophyte. Illicium mexi...

journal_title：American journal of botany

authors： Williams JH,Friedman WE

更新日期：2004-03-01 00:00:00

abstract：:Chromosome numbers and karyotypes of species of Orobanche, Cistanche, and Diphelypaea (Orobanchaceae) were investigated, and 108 chromosome counts of 53 taxa, 19 counted for the first time, are presented with a thorough compilation of previously published data. Additionally, karyotypes of representatives of these gene...

journal_title：American journal of botany

authors： Schneeweiss GM,Palomeque T,Colwell AE,Weiss-Schneeweiss H

更新日期：2004-03-01 00:00:00

abstract：:The genus Caltha (Ranunculaceae) consists of 10 species of low-growing, perennial herbs distributed throughout the moist temperate and cold regions of both the Northern and Southern Hemispheres. Traditionally, the species have been divided into two sections: section Psychrophila in the Southern Hemisphere with diploph...

journal_title：American journal of botany

authors： Schuettpelz E,Hoot SB

更新日期：2004-02-01 00:00:00

abstract：:Molecular studies of apomictic plant species often detect more genotypic variation than predicted from their assumed reproductive mode. The two most commonly invoked mechanisms to explain these high levels of variation are recombination, via facultative sexuality, and mutation. The potential for sexual reproduction in...

journal_title：American journal of botany

authors： Houliston GJ,Chapman HM

更新日期：2004-01-01 00:00:00

abstract：:Gaura (Onagraceae: Onagreae) is a small North American genus of 21 species consisting mostly of night-blooming, moth-pollinated annuals and perennials. The current infrageneric classification based on differences in habit, floral symmetry, and fruit morphology recognizes eight sections within the genus. We examine the...

journal_title：American journal of botany

authors： Hoggard GD,Kores PJ,Molvray M,Hoggard RK

更新日期：2004-01-01 00:00:00

abstract：:We examined the effect of inbreeding on fitness (through both male and female functions) and changes in self-fertility in the partially self-incompatible species Campanula rapunculoides. Individuals in natural populations of C. rapunculoides varied extensively in their strength of self-incompatibility (SI). We crossed...

journal_title：American journal of botany

authors： Good-Avila SV,Nagel T,Vogler DW,Stephenson AG

更新日期：2003-12-01 00:00:00

abstract：:A conspicuous feature of Vochysiaceae flowers is their single fertile stamen. In some genera, the stamen is in front of a petal, whereas in others it is in front of a sepal. This difference has been attributed to two independent reductions, which implies the stamen is not homologous across the family. The observation ...

journal_title：American journal of botany

authors： Litt A,Stevenson DW

更新日期：2003-11-01 00:00:00

abstract：:The geographic distribution of diploid and tetraploid cytotypes and cpDNA haplotypes throughout the entire range of Aucuba japonica was investigated. We measured relative genome size using flow cytometry and sequenced two cpDNA intergenic regions, atpB-rbcL and psbA-trnH (GUG). Two haplotypes include both diploids and...

journal_title：American journal of botany

authors： Ohi T,Kajita T,Murata J

更新日期：2003-11-01 00:00:00

abstract：:Because leaf pubescence of the desert shrub Encelia farinosa increases in response to drought and influences photosynthesis and transpiration, we hypothesized that differences in water availability across the range of this species may result in genetic differentiation for pubescence and associated productivity traits....

journal_title：American journal of botany

authors： Sandquist DR,Ehleringer JR

更新日期：2003-10-01 00:00:00

abstract：:Extreme preformation, the initiation of leaves or inflorescences more than 1 yr before maturation and function, is common in arctic and alpine habitats. This extended pattern of development provides a potential means to alleviate an apparent asynchrony between carbon supplied by photosynthesis in the summer and carbon...

journal_title：American journal of botany

authors： Meloche CG,Diggle PK

更新日期：2003-09-01 00:00:00

abstract：:Studies of developmental stability can provide insights into the amount of genetic or environmental stress experienced by individuals or populations. In the present study, we used young plants of Acer platanoides (Norway maple) and Betula pendula (silver birch), two distantly related tree species with widely different...

journal_title：American journal of botany

authors： Black-Samuelsson S,Andersson S

更新日期：2003-08-01 00:00:00

abstract：:Seedling establishment has long been believed to be rare on alpine tundra because of predicted life history trade-offs, the clonality of alpine species, and the harshness of the alpine climate. Contrary to the idea that seedlings are rare on alpine tundra, a 4-yr demographic study of seedlings at Niwot Ridge, Colorado...

journal_title：American journal of botany

authors： Forbis TA

更新日期：2003-08-01 00:00:00

abstract：:Paniculate agaves from tropical deserts depend on nectar-feeding bats for their reproduction, while species from extratropical areas near the northern limit of Leptonycteris curasoae are pollinated by diurnal and nocturnal insects and birds. Agave angustifolia is a paniculate agave with a broad distribution in Mexico ...

journal_title：American journal of botany

authors： Molina-Freaner F,Eguiarte LE

更新日期：2003-07-01 00:00:00

abstract：:Many foliar pathogens require free water to germinate; therefore, disease pressure should favor plants that are able to repel water. For a suite of 18 sympatric clover species (Trifolium and Medicago, Fabaceae), we evaluated leaf traits affecting leaf wetness and susceptibility to infection by the fungal pathogen Stem...

journal_title：American journal of botany

authors： Bradley DJ,Gilbert GS,Parker IM

更新日期：2003-06-01 00:00:00

abstract：:Six of 14 species of Triteleia were studied. All possess septal nectaries, raphides in the ovary wall, an anatropous and crassinucellate ovule with a micropyle formed by the inner integument only, and parietal cells. A short and thick nucellus, which is not penetrated by the embryo sac, has a one-layered apical epider...

journal_title：American journal of botany

authors： Berg RY

更新日期：2003-06-01 00:00:00

abstract：:Expansion of Typha domingensis into areas previously dominated by Cladium jamaicense in the Florida Everglades has been linked to anthropogenic phosphorus (P) enrichment and increased hydroperiod. The principal stress factor for plants in flooded soils is biochemical reduction, the intensity of which is measured as re...

journal_title：American journal of botany

authors： Lissner J,Mendelssohn IA,Lorenzen B,Brix H,McKee KL,Miao S

更新日期：2003-05-01 00:00:00

abstract：:Fitness of interspecific hybrids is sometimes high relative to their parents, despite the conventional belief that they are mostly unfit. F(1) hybrids between oilseed rape (Brassica napus) and weedy B. rapa can be significantly more fit than their weedy parents under some conditions; however, under other conditions th...

journal_title：American journal of botany

authors： Hauser TP,Damgaard C,Jørgensen RB

更新日期：2003-04-01 00:00:00

abstract：:A long-term survey (1990-2000) of pollination modes of 86 tree species was carried out at Kakachi, a mid-elevation wet forest site in southern Western Ghats, India. Observations were made on 86 tree species. This comprises 80% of the total arborescent species present in the site. Approximately 75% of these species wer...

journal_title：American journal of botany

authors： Devy MS,Davidar P

更新日期：2003-04-01 00:00:00

abstract：:Floral characteristics such as morphology and flower color have been interpreted as adaptive traits that evolved through selective pressures generated by pollinators. Differences among populations in the expression of floral characters could result from natural selection for their adaptive value to local conditions. W...

journal_title：American journal of botany

authors： Silva-Montellano A,Eguiarte LE

更新日期：2003-03-01 00:00:00

abstract：:Phylogenetic analyses of Meliaceae, including representatives of all four currently recognized subfamilies and all but two tribes (32 genera and 35 species, respectively), were carried out using DNA sequence data from three regions: plastid genes rbcL, matK (partial), and nuclear 26S rDNA (partial). Individual and com...

journal_title：American journal of botany

authors： Muellner AN,Samuel R,Johnson SA,Cheek M,Pennington TD,Chase MW

更新日期：2003-03-01 00:00:00

abstract：:The American chestnut (Castanea dentata; Fagaceae) was a dominant canopy tree in the Appalachian Mountains of North America. Since the introduction of the chestnut blight fungus (Cryphonectria parasitica; Valsaceae) in America, the American chestnut has been reduced to a predominantly clonal, understory species. Our o...

journal_title：American journal of botany

authors： Stilwell KL,Wilbur HM,Werth CR,Taylor DR

更新日期：2003-02-01 00:00:00

abstract：:Clarkia (Onagraceae) is a genus of 42 annual species, mostly native to California, that has served as a model for many studies of plant evolutionary biology, particularly morphological, cytological, and genetic divergence; reproductive isolation; and speciation. Section Sympherica is the largest section with eight dip...

journal_title：American journal of botany

authors： Ford VS,Gottlieb LD

更新日期：2003-02-01 00:00:00

abstract：:Floral morphology of the 13 species of Moringa ranges from actinomorphic flowers with little hypanthium to highly zygomorphic flowers with well-developed hypanthia. Scanning electron and light microscopy were used to identify ontogenetic differences among two actinomorphic and eight zygomorphic species. All species sh...

journal_title：American journal of botany

authors： Olson ME

更新日期：2003-01-01 00:00:00

abstract：:Whereas the "law of the minimum" (LM) states that plant growth is limited by a single resource at any one time, the "multiple limitation hypothesis" (MLH) proposes that optimum plant behavior results from balancing resource costs and benefits so that all resources limit plant growth simultaneously. We tested the hypot...

journal_title：American journal of botany

authors： Rubio G,Zhu J,Lynch JP

更新日期：2003-01-01 00:00:00