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Premise: Volatile emissions from flowers and fruits play a key role in signalling to animals responsible for pollination and seed dispersal. Here, we investigated the pollination biology and chemical ecology of reproduction in Apodolirion buchananii, an African amaryllid that flowers in a leafless state soon after grassland vegetation is burnt in the dry late‐winter season. Methods: Pollinators were identified through field collection and pollen loads were quantified. Floral traits including spectral reflectance and scent chemistry were documented. Bioassays using cup traps were used to test the function of floral volatiles. Fruiting biology was investigated using controlled hand‐pollination experiments and chemical analysis of fruit scent. Seed germination was scored in greenhouse trials. Seed dispersal was monitored using observations and camera trapping. Results: The sweetly scented white flowers of A. buchananii are pollen‐rewarding and pollinated mainly by a diverse assemblage of bees. Cup‐trap experiments demonstrated that pollinators are attracted to phenylacetaldehyde, the dominant volatile in the floral scent. Plants are shown to be self‐incompatible, and the fleshy fruits were found to emerge from the soil six months after pollination during the peak of the summer rains. Fruits emit a diverse blend of aliphatic and aromatic esters and contain large fleshy recalcitrant seeds which germinate within days of fruits splitting open. Seed dispersal by ants was recorded. Conclusions: This first account of the reproductive biology of a species in the genus Apodolirion highlights an outcrossing mating system involving bees attracted to color and scent as well as the unusual fruiting biology and ant‐mediated system of seed dispersal. [ABSTRACT FROM AUTHOR]

Premise: Plants generate a wide array of signals such as olfactory cues to attract and manipulate the response of pollinators. The present study addresses the temporal patterns of scent emission as an additional dimension to the scent composition. The expectation is that divergent floral function is reflected in divergent qualitative and temporal emission patterns. Methods: We used GC‐ion mobility spectrometry with an integrated pre‐concentration for automated acquisition of the temporal trends in floral volatile emissions for N. viridiflorus, N. papyraceus, and N. cantabricus subsp. foliosus. Results: We found a considerable increase in scent emissions and changes in scent composition for N. viridiflorus at night. This increase was particularly pronounced for aromatic substances such as benzyl acetate and p‐cresol. We found no diurnal patterns in N. papyraceus, despite a similar qualitative composition of floral volatiles. Narcissus cantabricus subsp. foliosus showed no diurnal patterns either and differed considerably in floral scent composition. Conclusions: Scent composition, circadian emission patterns, and floral morphology indicate divergent, but partially overlapping pollinator communities. However, the limited pollinator data from the field only permits a tentative correlation between emission patterns and flower visitors. Narcissus papyraceus and N. cantabricus show no clear diurnal patterns and thus no adjustment to the activity patterns of their diurnal pollinators. In N. viridiflorus, timing of scent emission indicates an adaptation to nocturnal flower visitors, contradicting Macroglossum as the only reported pollinator. We propose that the legitimate pollinators of N. viridiflorus are nocturnal and are still unidentified. [ABSTRACT FROM AUTHOR]

* Premise o f the study: Theoretical models state that natural selection and mating patterns account for floral morph ratio in style-polymorphic plants. However, the demographic history of populations can also influence variation in morph ratios. If so, we hypothesize an association between the morph ratios and the genetic structure across populations. * Methods: We used nuclear microsatellites to assess genetic variation and structure in populations of Narcissus papyraceus, a style-dimorphic plant whose floral morph ratios (L-morph to S-morph) gradually vary throughout its distribution range in the southwestern Mediterranean Basin. We implemented analyses to relate the genetic features of populations with their morph ratios. * Key results: We found greater frequencies of the S-morph in central populations and declining frequencies toward the periphery. This geographic pattern was not associated with the genetic structure of populations. Instead, we found two distinct genetic groups, mainly separated by the Strait of Gibraltar, with a mixture of morph ratios within each one. Overall, there was a weak genetic structure. Genetic diversity was greater in central and southern dimorphic populations than in northern L-monomorphic populations. * Conclusions: Altogether, our results do not support the hypothesis that the demographic history of populations can account for the observed geographical pattern of morph ratios in N. papyraceus. We suggest that adaptive processes shown in previous studies in the species are the main determinant of the existing variation in the morph composition of populations. [ABSTRACT FROM AUTHOR]

* Premise of the study: The cells in plant tissue are joined together by a distinct layer called the middle lamella (ML). Understanding the mechanical properties of the ML is crucial in studying how tissue-level mechanical properties emerge from the subcellular-level mechanical properties. However, the nanoscale size of the ML presents formidable challenges to its characterization as a separate layer. Consequently, the mechanical properties of the ML under tensile loading are as yet unknown. * Methods: Here, we characterize the ML from a subcellular sample excised from two adjacent cells and composed of two wall fragments and a single line of ML in between. Two techniques, cryotome sectioning and milling with a focused ion beam, were used to prepare ML samples, and tensile experiments were performed using microelectromechanical system (MEMS) tensile testing devices. * Key results: Our test results showed that even at a subcellular scale, the ML appears to be stronger than the wall fragments. There was also evidence that the ML attached at the comer of cells more strongly than at the rest of the contact area. The contribution of the additional ML contact area was estimated to be 40.6 MPa. Wall fragment samples containing an ML layer were also significantly stronger (p < 0.05) than the wall fragments without an ML layer. * Conclusions: The tensile properties of the ML might not have a major impact on the tissue-scale mechanical properties. This conclusion calls for further study of the ML, including characterization under shear loading conditions and elucidation of the contributions of other extracellular parameters, such as cell size and shape, to the overall tissue-level mechanical response. [ABSTRACT FROM AUTHOR]

* Premise of the study: Pollinator shifts have been implicated as a driver of divergence in angiosperms. We tested the hypothesis that there was a transition from bird- to butterfly pollination in the African genus Clivia (Amaryllidaceae) and investigated how floral traits may have been either modified or retained during this transition. * Methods: We identified pollinators using field observations, correlations between lepidopteran wing scales and pollen on stigmas, and single-visit and selective exclusion experiments. We also quantified floral rewards and advertising traits. * Key results: The upright trumpet-shaped flowers of C. miniata were found to be pollinated effectively by swallowtail butterflies during both nectar-feeding and brush visits. These butterflies transfer pollen on their wings, as evidenced by positive correlations between wing scales and pollen loads on stigmas. All other Clivia species have narrow pendulous flowers that are visited by sunbirds. Selective exclusion of birds and large butterflies from flowers of two Clivia species resulted in a significant decline in seed production. * Conclusions: From the distribution of pollination systems on available phylogenies, it is apparent that a shift took place from bird- to butterfly pollination in Clivia. This shift was accompanied by the evolution of trumpet-shaped flowers, smaller nectar volume, and emission of scent, while flower color and nectar chemistry do not appear to have been substantially modified. These results are consistent with the idea that pollinator shifts can explain major floral modifications during plant diversification. [ABSTRACT FROM AUTHOR]

* Premise of the study: Reconstructing ancestral states is a useful method to understand the pathway and patterns of character evolution and to test specific hypotheses within a phylogenetic context. Using a phylogenetic hypothesis of the subgenus Amerallium and related subgenera based on molecular data, we reconstructed the evolutionary history of leaf blade anatomical characters and identified those characters that are most congruent with phylogenetic relationships. Furthermore, we used these character histories to investigate the evolution of terete leaves and explore a possible correlation between environment and leaf anatomy in the North American species. * Methods: Sixty-seven North American and Old World species were sampled from all major infrageneric taxa and lineages for transectional leaf anatomy. To provide a phylogenetic framework for interpretation, representatives of Old World Ameralluim and related subgenera were added to a published data matrix of North American taxa and ITS, ETS, trnL-F, and rpL32-trnL sequences. * Key results: Four anatomical characters, namely leaf-blade shape in transection, presence versus absence of palisade mesophyll, distribution and orientation of vascular bundles, and position of laticifer cells, were found to be congruent with phylogenetic relationships and useful diagnostic traits within North American species. Character reconstructions show that terete leaves in North American species evolved from flattened leaves via a possible transition from subterete to terete leaves. Furthermore, terete leaves possess traits that are indicative of possible adaptation to xeric environments. * Conclusions: The findings from this study provide valuable information for understanding the evolution of leaf-blade anatomy in North American Allium species. [ABSTRACT FROM AUTHOR]

Premise of the Study: Early plant taxonomists formed hypotheses about relationships among taxa based on characters such as morphology, anatomy, phytochemistry, ecology, and geography. Modern molecular systematic methods, based on DNA sequence variation, augment early methods and provide an additional line of evidence by which to evaluate taxonomic hypotheses. In North America north of Mexico, wild onions (Allium, Amaryllidaceae) are represented by 84 native species, 81 of which belong to subgenus Amerallium. On the basis of morphology, these species have been divided into eight informal taxonomic "alliances" hypothesized to represent shared evolutionary history among species. The main aim of this research was to test the monophyly of the alliances with molecular phylogenetic methods. Methods: We sampled 74 Amerallium species north of Mexico and two Mexican endemics and constructed a molecular phylogeny of subgenus Amerallium in North America based on predominantly noncoding sequences from two nuclear ribosomal RNA regions (ITS and ETS) and two plastid regions (trnL-F and rpL32-trnL). Key Results: Most clades are well supported in analyses of nuclear data and when nuclear and plastid data are combined. How ever, the plastid data alone did not produce a well-resolved or well-supported tree. Morphological alliances were sometimes congruent with groups recovered in the molecular phylogeny, but strict monophyly was observed in only three of eight alliances. Conclusions: We propose an infrageneric classification that recognizes two sections in New World Amerallium. Because there is substantial incongruence between morphological and molecular groups, we advocate retaining informal alliances rather than adopting formal subsections until further morphological and molecular analyses can be carried out. [ABSTRACT FROM AUTHOR]

Natural hybrids between rare and common sympatric species are commonly eradicated to avoid the potential extinction of the rare species, although there is currently no clear predictive framework to quantify this risk. As hybrids can have intrinsic value as new evolutionary pathways, further knowledge on the factors controlling hybridization is needed. In this study we evaluated the role of pollination patterns in hybridization events in two sympatric populations of Narcissus cavanillesii and N. serotinus in Portugal. Narcissus cavanillesii is a rare species, while N. serotinus is widely distributed across the Mediterranean. The hybrid, N. Xperezlarae, is quite frequent in southeastern Spain but is scarce in Portugal. Reciprocal manual crossings confirmed compatibility between the two species, although hybridization was more successful when N. cavanillesii participated as female. Narcissus cavanillesii and N. serotinus only shared one pollinator, Megachile sp. (Hymenoptera), which had low visitation rates and high flower constancy. No single isolation mechanism was fully effective in preventing hybridization. Temporal displacement of flowering peaks, strong pollinator specificity, and high flower constancy in the shared pollinator all contributed to limiting hybridization in this site. In other sympatric occurrences, different phenological windows and pollination assemblages may allow greater frequency of the hybrid. [ABSTRACT FROM AUTHOR]

Understanding gene movement patterns in unidirectional flow environments and their effect on patterns of genetic diversity and genetic structure is necessary to manage these systems. Hypotheses and models to explain genetic patterns in streams are rare, and the results of macrophyte studies are inconsistent. This study addresses Ritland's (Canadian Journal of Botany 67: 2017–2024) unidirectional diversity hypothesis, the one-dimensional stepping stone model, and the metapopulation model within and among populations. Hymenocallis coronaria, an aquatic macrophyte of rocky river shoals of the SE USA, was sampled in four river basins. Within populations and among populations <16.2 km apart had significant isolation by distance. However, the rate of gene flow decay was not consistent with a one-dimensional stepping stone model, nor was evidence strong or consistent for Ritland's hypothesis. Some evidence indicates that localized metapopulation processes may be affecting genetic diversity and structure; however, gene flow patterns inconsistent with the assumptions of the linear and unidirectional models are also a possible influence. We discuss three variants on the one-dimensional stepping stone model. Future research in linear environments should examine the expectations of these models. This study is also one of the first efforts to calculate population genetic parameters using a new program, TETRASAT. [ABSTRACT FROM AUTHOR]

We investigated the origin of styler polymorphisms in Narcissus, which possesses a remarkable range of stylar conditions and diverse types of floral morphology and pollination biology. Reconstruction of evolutionary change was complicated by incomplete resolution of trees inferred from two rapidly evolving chloroplast regions, but we bracketed reconstructions expected on the fully resolved plastidbased tree by considering all possible resolutions of polytomies on the shortest trees. Stigma-height dimorphism likely arose on several occasions in Narcissus and persisted across multiple speciation events. As proposed in published models, this rare type of stylar polymorphism is ancestral to distyly. While there is no evidence in Narcissus that dimorphism preceded tristyly, a rapid transition between them may explain the lack of a phylogenetic footprint for this evolutionary sequence. The single instances of distyly and tristyly in Narcissus albimarginatus and N. triandrus, respectively, are clearly not homologous, an evolutionary convergence unique to Amaryllidaceae. Floral morphology was likely an important trigger for the evolution of stylar polymorphisms: Concentrated-changes tests indicate that a long, narrow floral tube may have been associated with the emergence of stigma-height dimorphism and that this type of tube, in combination with a deep corona, likely promoted, or at least was associated with, the parallel origins of heterostyly. [ABSTRACT FROM AUTHOR]

Examines the phylogeny of tribe Amaryllideae of the Amaryllidaceae based on nuclear ribosomal DNA internal transcribed spacer sequences and morphology. Classifications of Amaryllidaceae tribe Amaryllideae; Morphological characters for cladistic analysis of Amaryllideae; Single most parsimomonious tree found by successive weighting of morphological characters across Amaryllideae.

Presents information on a study which investigated patterns of fruit and seed production on inflorescences of a population of Pancratium maritimum (Amaryllidaceae) in northwest Spain. Description of fruit and seed production under open pollination; Factors that affect flower patterns; Materials and methods used in the study; Results and discussion.

Presents the first family-wide phylogenetic analysis of Amaryllidaceae using three plastic DNA sequences and comments on the evolutionary and bigeographic implications of the results. List of Intrafamiliar classifications of Amaryllidaceae; Relationships within Amaryllidaceae; Character state evolution in the Amaryllidaceae.

Presents an abstract of the study `Hybrid complex in Lycoris, Amaryllidaceae,' by Siro Kurita and Hsu Ping-Sheng, presented during the 1996 Annual Meeting of the Botanical Society of America at the University of Washington in Seattle, Washington.

Presents an abstract of the study `Molecular systematics and biogeography of the Amaryllidaceae,' by Michael F. Fay et al. and presented during the 1995 Annual Meeting of the Botanical Society of America.