bluuebunny/crossref_metadata_2025 huggingface dataset:
VARIATION IN INDIVIDUAL FLOWERING TIME AND REPRODUCTIVE SUCCESS OF AGALINIS STRICTIFOLIA (SCROPHULARIACEAE)
Authors: Dieringer Gregg
Published: January 2018

Field studies on two populations of Agalinis strictifolia were conducted over a 3‐year period to investigate the relationship between flowering time of individuals and plant size, flowering duration, flower and fruit production, fruit predation, and growth rate. Seasonal patterns of pollinator visitation were compared with those of individual flowering time, flower density, percent fruit production, and mean seeds/fruit. In general, early and middle flowering individuals (as determined by either first flowering date or peak flowering) were larger, flowered longer, and produced more flowers and fruits than late flowering individuals. Early and middle flowering individuals (based on first flowering date) also grew faster than late flowering individuals. Although early and middle flowering individuals produced more fruits, fruit predators did not damage a disproportionate number of fruits compared to late flowering individuals. Patterns of bee visitation showed no association with seasonal patterns of flower density, percent fruit production, mean seed/fruit, or individual flowering time. In populations of A. strictifolia, it would seem that biotic or environmental determinants of growth rate (hence size and reproductive success) may be more important in generating variation in individual flowering time than patterns of pollinator visitation or fruit predation.
FLAVONOID EVOLUTION IN DENDROSERIS (COMPOSITAE, LACTUCEAE) FROM THE JUAN FERNANDEZ ISLANDS, CHILE
Authors: Pacheco Patricia , Crawford Daniel J. , Stuessy Tod F. , O. Mario Silva
Published: January 2018

Leaf flavonoid chemistry was examined from the three subgenera and 11 species of the endemic genus Dendroseris (Compositae, Lactuceae) of the Juan Fernandez Islands, Chile. Eight of the species are restricted to the older island (Masatierra, ca. 4 million years old), which is also closer to the mainland. Three species, one from each subgenus, are restricted to Masafuera, which is younger geologically (1–2 million years old) and 145 km further west of Masatierra. A total of 16 compounds was identified, with the 7‐0‐glucosides of the flavones apigenin and luteolin accounting for 12 of the constituents. Two glucosides of the flavonol quercetin were detected. Despite considerable interpopulation variation within species, six of the taxa have distinctive flavonoid profiles. Although there are few absolute differences among the subgenera, they can be distinguished chemically. Subgenus Rea contains the greatest number of compounds, and a previous cladistic analysis based on morphological features suggested this subgenus as most primitive. Subgenus Phoenicoseris is considered highly derived morphologically, and it has a reduced flavonoid chemistry. Very little reduction in flavonoid diversity was seen in the morphologically specialized subg. Dendroseris as compared to subg. Rea. A trend in reduction of numbers of compounds was seen for two of the three species on the younger island of Masafuera when compared to their presumed ancestors on Masatierra. Flavonoids of selected species of Hieracium and Hypochaeris, presumptive mainland progenitors of Dendroseris, reveal a close chemical affinity with the former genus.
POPULATION GENETIC STRUCTURE IN DIPLOID BLUEBERRY VACCINIUM SECTION CYANOCOCCUS (ERICACEAE)
Authors: Bruederle Leo P. , Vorsa Nicholi , Ballington James R.
Published: January 2018

VacciniumsectionCyanococcuscomprises diploid, tetraploid, and hexaploid species (x = 12) all of which are highly self‐sterile. In order to assess the distribution of genetic variation within and among the diploids, population genetic analyses of allozyme data were conducted on three species:V. elliottii, V. myrtilloides, andV. tenellum. Populations were located throughout the range of these taxa in eastern North America. Data were collected at 20 loci, 12 of which are mendelian based on formal genetic analyses. Consistent with expectations for out‐crossing taxa, these species exhibited high levels of variation within populations. Eighteen loci were polymorphic with the number and frequency of alleles varying among taxa. Mean values for the number of alleles per polymorphic locus, proportion of polymorphic loci, and expected heterozygosity were 2.8, 48.2, and 0.148, respectively. High infraspecific genetic identities exceeding 0.9 indicated that these taxa are homogeneous. All populations were in Hardy‐Weinberg equilibrium with slight heterozygote excess observed inV. myrtilloidesandV. tenellum. Although total genetic diversity was lower than that observed for other predominantly out‐crossing species, it was apportioned similarly. The majority could be attributed to differences among individuals within populations. Conspecific populations were relatively undifferentiated with genetic differentiation similar to other self‐incompatible species.
BREEDING SYSTEM EVOLUTION IN LEAVENWORTHIA: BREEDING SYSTEM VARIATION AND REPRODUCTIVE SUCCESS IN NATURAL POPULATIONS OF LEAVENWORTHIA CRASSA (CRUCIFERAE)
Authors: Lyons Elizabeth E. , Antonovics Janis
Published: January 2018

Populations of Leavenworthia crassa (Cruciferae) studied for 3 years exhibited among‐ and within‐population genetic variation for a suite of floral and reproductive traits (flower width, petal length, anther position, ability to set seeds in the absence of pollinators, time to first flowering) associated with breeding system. We used electrophoretic markers to show that a population with small, monomorphically colored flowers with introrse anthers had a significantly lower outcrossing rate (t = 0.03) than did a population with larger, polymorphically colored flowers with extrorse anthers (t = 0.33). In the more‐outcrossing population the correlation between higher maternal plant outcrossing rate and the suite of six traits approached significance (P < 0.067), with greater petal size, greater flower width, and reduced ability to set seeds in the absence of pollinators contributing significantly. Plants in selfing populations had a generally higher reproductive success, with a higher number of flowers per plant, a smaller proportion of unfertilized ovules, a smaller proportion of fertilized ovules aborted, a higher rate of fruit set, and overall a larger number of seeds matured than did plants from the more outcrossing populations. Pollen limitation did not appear to account for lower reproductive success in outcrossing populations. Resource limitation did not differ substantially between populations. However, within‐ovary patterns of fertilization, abortion, and seed weight were significantly less random in outcrossing populations than in selfing populations, suggesting that differential gamete and embryo success may be responsible for lower reproductive success in outcrossing populations.
LIGHT‐DEPENDENT INHIBITION OF CELL DIVISION AND RHIZOID ELONGATION IN GEMMAE OF THE FERN, VITTARIA GRAMINIFOLIA
Authors: Sabba Robert P. , Hoffman Jennifer Ruth , Miller John H.
Published: January 2018

Gametophytes of the shoe‐string fern Vittaria graminifolia produce linear, six‐celled propagules called gemmae. The terminal cells of each gemma elongate into primary rhizoids in culture, and the inner body cells divide asymmetrically to produce prothallial or rhizoid initials. The initiation of both asymmetric cell division and rhizoid elongation is delayed by light intensities greater than 2 w/m2. The maximal rates of cell division and rhizoid elongation are unaltered. A 24‐hr pulse of high light intensity delays cell division and rhizoid elongation to the same extent, whenever applied during the first 3 d of culture. The model we propose for cell division hypothesizes the existence of a preparatory phase of finite duration prior to mitosis that is sensitive to light intensity. If a cell is irradiated by light intensities greater than 2 w/m2 while in the preparatory phase, its entrance into mitosis is delayed. A similar model is proposed for the initiation of rhizoid elongation. Despite the fact that both cell division and rhizoid elongation are dependent on photosynthesis, direct measurements of CO2‐uptake rates show that the inhibitory effects of high light intensities are not due to an inhibition of photosynthesis.
CAUSES AND CONSEQUENCES OF WITHIN‐TREE PHENOLOGICAL PATTERNS IN THE FLORIDA STRANGLING FIG, FICUS AUREA (MORACEAE)
Authors: Bronstein Judith L. , Patel Aviva
Published: January 2018

The obligate pollinators of figs (Ficus, Moraceae), species‐specific agaonid wasps, benefit figs only by transporting pollen between trees; larvae are seed predators. But given the high risk of mortality in flight between trees, adult wasps should prefer to pollinate and oviposit within inflorescences (syconia) at the same tree at which they developed. Flowering within individuals is tightly synchronous in most species, while different trees flower out of phase with each other, suggesting that fig phenology has evolved to assure outcrossing. However, some fig species show distinct within‐tree flowering asynchrony. It has been suggested that such asynchrony is an adaptation by which figs in seasonal environments can reduce pollinator mortality, by permitting wasps to persist on individual trees at times when flight would be impossible. We have evaluated and rejected the validity of this Seasonality Hypothesis for the Florida strangling fig, Ficus aurea, near its northern range limit. Crops of individual trees were most, not least, synchronous during the coldest, driest months of 2 years. Maximum asynchrony occurred in seasons that were probably most favorable for wasp transit between trees. However, temporal overlap of the phenological stages that permit wasps to remain on their natal trees was always very rare, implying that consecutive cohorts of developing syconia may be spaced in time to limit this occurrence. We suggest alternative costs and benefits for these phenological traits, as well as the proximate mechanisms that might produce them.
LANDMARK EIGENSHAPE ANALYSIS: HOMOLOGOUS CONTOURS: LEAF SHAPE IN SYNGONIUM (ARACEAE)
Authors: Ray Thomas S.
Published: January 2018

A new morphometric technique suitable for the description of leaf shape is presented that combines features of both outline and landmark approaches. The concept of homologous point landmarks is extended to higher dimensional features: homologous contours. This allows an integrated approach to morphometric analysis, which treats contours together with points while adhering to the practice of comparing only homologous features. The technique modifies eigenshape analysis by defining homologous contours as any contour bounded by two landmarks, containing no landmark on the contour. The contour need not be a closed curve and may occur in the interior as well as on the outline of the specimen. Collections of contours may be treated, and need not be contiguous. Homologous contours are divided into equal numbers of equal‐length steps on each specimen, and the angles representing each step as well as the proportional lengths of the contours are the data that enter into the analysis. The technique can be used to discriminate the shapes of leaves or other organs in systematic, ecological, or developmental studies.
GROWTH PATTERNS IN NUTATING AND NONNUTATING SUNFLOWER (HELIANTHUS ANNUUS) HYPOCOTYLS
Authors: Berg Arthur R. , Peacock Kenneth
Published: January 2018

Dark‐grown sunflower (Helianthus annuusL.) seedling hypocotyls (15–30 mm) were marked with two rows of lanolin‐coated resin beads, and the events of the following 24 hr, in physiological darkness, were recorded on time‐lapse video. Nutational movement of the hypocotyl, followed for 20–24 hr for each of 21 seedlings, was found to have a mean period of 153 ± 26 min (ca. 24 C). Displacement of each bead, with time, was measured with a microcomputer‐controlled video analyzer, and relative elemental elongation rate and relative growth rate analyses were carried out to determine the spatial and temporal distribution of growth. Relative elemental elongation rates were plotted against distance and time to produce “growth landscapes.” A strongly nutating seedling showed periodic fluctuations in local growth rates that alternated between values of 0.0 hr−‐1and >0.12 hr−‐1near the hypocotyl hook. Nearer the base, maximum growth rates were lower but local periodic changes still were evident. Seedlings, in which nutation appeared during the time period analyzed, showed non‐synchronous pulses of growth along the axis. With nutational development, these local growth fluctuations became synchronized along each side and phased (usually 180° out of phase) with the coordinated growth fluctuations along the opposite side. In some seedlings the changes from low to high local growth rates occur nearly simultaneously over two‐thirds of the active region. In others, basipetally traveling waves of growth are suggested by the growth landscapes.
THE DISTRIBUTION OF SELFING RATES IN HOMOSPOROUS FERNS
Authors: Soltis Douglas E. , Soltis Pamela S.
Published: January 2018

The models of Lande and Schemske predict that among species in which the selfing rate is largely under genetic control and not subject to tremendous environmental variation, the distribution of selfing rates should be bimodal. When this prediction was tested empirically using data from the literature for species of angiosperms and gymnosperms, the distribution of outcrossing rates for all species was clearly bimodal. To provide another empirical test of the prediction, we analyzed mating‐system data for 20 species of Pteridophyta (ferns). Homosporous ferns and their allies are unique among vascular plants because three types of mating are possible: intragametophytic selfing (selfing of an individual gametophyte); intergametophytic selfing (analogous to selfing in seed plants); and intergametophytic crossing (analogous to outcrossing in seed plants). The distribution of intragametophytic selfing rates among species of homosporous ferns is clearly uneven. Most species of homosporous ferns would be classified as extreme outcrossers. In contrast, a few species are nearly exclusively inbreeding. In only a few populations of Dryopteris expansa and Hemionitis palmata and a single population of Blechnum spicant do we see convincing evidence of a mixed mating system. The uneven distribution of selfing rates we observed for homosporous ferns, coupled with a corresponding bimodality of the magnitude of genetic load, strongly supports the model.
SEX POLYMORPHISM IN SILENE ACAULIS (CARYOPHYLLACEAE) AND THE POSSIBLE ROLE OF SEXUAL SELECTION IN MAINTAINING FEMALES
Authors: Shykoff Jacqui A.
Published: January 2018

Pollen accumulation rates and their relationship to stigma morphology and pollinator visitation behavior were compared between female and hermaphrodite sex morphs of the alpine plantSilene acaulisvar.subacaulescens(Caryophyllaceae). Although stigmas of female and perfect flowers collected comparable pollen loads, stigmas of female flowers became receptive earlier in anthesis and therefore recruited a larger number of pollen tubes. Together with early receptivity young female flowers had a larger stigmatic area with longer papillae than did perfect flowers. Pollinator behavior also differed between morphs, with bumble bees spending more time probing female than perfect flowers. Differences in stigma receptivity schedules of female and perfect flowers have consequences for different opportunities for sexual selection in the two sex morphs. Female flowers, by providing a more effective gametophytic screen, have the potential to produce higher quality offspring. This is proposed as a further compensatory advantage maintaining females, with a single fitness function, in populations containing hermaphrodites which have both male and female fitness functions.
TOOLS FOR STUDYING THE CHLOROPLAST GENOME IN THE TRITICEAE (GRAMINEAE): AN ECORI MAP, A DIAGNOSTIC DELETION, AND SUPPORT FOR BROMUS AS AN OUTGROUP
Authors: Kellogg Elizabeth A.
Published: January 2018

Data on variation in the chloroplast genome can be used to estimate the phylogeny of the wheat tribe (Triticeae), but two tools have been needed—a restriction site map for at least one frequent‐cutting enzyme, and a well‐supported outgroup. This paper presents an EcoRI map, as well as maps for six other restriction enzymes, for two members of the tribe (Elytrigia repens and Secale cereale). These are compared to the maps for Bromus tectorum, a possible outgroup, and for Briza maxima, Lolium perenne, and Festuca rubra, other members of the same subfamily (Pooideae). A unique deletion of ca. 700 base pairs was discovered that provides a distinctive marker for the cytoplasm of plants with the S genome. The deletion also appears in Dasypyrum villosum (V genome). Cladograms based on restriction site data are unequivocal in the support for Bromus tectorum as a near relative of the Triticeae; the chloroplast phylogeny is very similar to the morphological cladogram for a comparable set of taxa.
GENETIC DIVERSITY AND SPATIAL SUBDIVISION OF POPULUS TREMULOIDES (SALICACEAE) IN A HETEROGENEOUS LANDSCAPE
Authors: Jelinski Dennis E. , Cheliak W. M.
Published: January 2018

Trembling aspen (Populus tremuloides Michx.), a clonal angiosperm, is the most geographically widespread tree in North America. It is generally thought that most extant populations in the western interior of Canada and the United States became established shortly after glacial retreat, but sexual recruitment then effictively ceased owing to inimical climatic conditions. Six populations of trembling aspen were studied in the prairie and montane environments of Waterton Lakes National Park, Alberta. Vegetative tissues were analyzed for electrophoretically detectable variation in 13 enzymes encoded by 14 polymorphic loci and three monomorphic loci. All populations maintained high levels of inter‐ and intrapopulation diversity (P = 0.891; H = 0.319; A = 2.4). The mean fixation index, F, was ‐0.102, indicating some deviation from Hardy‐Weinberg expectations. Genetic differentiation (FST = 3.0) was apparent in this ecologically diverse, but geographically small‐scale, spatial setting. It is suggested that the maintenance of diversity in the absence of frequent modern‐day recruitment, and resistance to further geographic differentiation in this spatially heterogeneous environment reflect occasional seedling establishment through “windows of opportunity” and more importantly, the species' clonal morphology. The phalanx growth form and concomitant physiological integration between ramets combine to spread the risk of death and buffer the effects of selection over time and space.
VARIATION IN UV‐B SENSITIVITY IN PLANTS FROM A 3,000‐m ELEVATIONAL GRADIENT IN HAWAII
Authors: Sullivan Joe H. , Teramura Alan H. , Ziska Lewis H.
Published: January 2018

Interest in the potential consequences of stratospheric ozone depletion has led to numerous studies that have evaluated the effects of ultraviolet‐B (UV‐B) radiation on plant growth and productivity. However, few studies have been conducted on plants from natural ecosystems. Differences in solar UV‐B radiation along latitudinal or elevational gradients may have resulted in plants from diverse habitats developing contrasting sensitivities to UV‐B radiation. In this study, seeds were collected along a 3,000‐m elevational gradient in Hawaii and then germinated and grown in an unshaded greenhouse with either no UV‐B radiation or one of two daily UV‐B irradiances, 15.5 or 23.1 kj m2. Seedlings were grown for 12 weeks and harvested to determine whether UV‐B radiation altered plant biomass. The responses to UV‐B radiation varied among species, but, in general, sensitivity to UV‐B radiation was reduced as the elevation of seed collection increased. Of the 33 species tested, UV‐B radiation significantly reduced plant height in 14 species and biomass in eight species. Biomass increased in four species grown under UV‐B radiation. This study provides clear evidence that natural plant populations exhibit wide variation in UV‐B radiation sensitivity and that this variation is related to the natural (ambient) UV‐B radiation environment in which these plants grow.
RABL DISTRIBUTION OF INTERPHASE AND PROPHASE TELOMERES IN ALLIUM CEPA NOT ALTERED BY COLCHICINE AND/OR ULTRACENTRIFUGATION
Authors: Fussell Catharine P.
Published: January 2018

Neither colchicine nor ultracentrifugation, singly or in sequence, significantly alters the normal Rabl distribution of interphase or prophase telomeres in root tip cells of Allium cepa L. The position of telomeres was determined by C‐banding, which stains A. cepa chromosomes only at the telomeres. Centrifugation displaces mitotic figures toward one side of the cell, but otherwise their mitotic configurations are little changed. These light microscope results are interpreted to show that a) interphase and prophase telomeres are attached strongly to some component of the nuclear envelope; b) a colchicine‐sensitive component apparently does not attach interphase and prophase telomeres to the nuclear envelope; and c) chromosomes at all stages of the cell cycle are attached to some structure, nuclear envelope, and/or spindle fibers.
MYCORRHIZAE IN HAWAIIAN ANGIOSPERMS: A SURVEY WITH IMPLICATIONS FOR THE ORIGIN OF THE NATIVE FLORA
Authors: Koske R. E. , Gemma J. N. , Flynn T.
Published: January 2018

Endemic, indigenous, naturalized and cultivated angiosperms growing in a variety of habitats in Hawaii were examined for mycorrhizae. Of 147 species (representing 61 families) examined, 122 were mycorrhizal, and 98% of the latter formed vesicular‐arbuscular mycorrhizae (VAM). Ericoid, orchid, and ectomycorrhizae also were found. Mycorrhizae were most frequent in endemic species (90.3%) and least in indigenous species (71.9%). The incidence of mycotrophy in Hawaiian endemic species was significantly greater than in mainland species. In addition, VAM often were found in species belonging to families that typically lack mycorrhizae (Aizoaceae, Brassicaceae, Caryophyllaceae, Cyperaceae, Hydrophyllaceae, Juncaceae, Pandanaceae, and Urticaceae). Naturalized weedy species were highly mycorrhizal. The high incidence of mycorrhizae in endemic species suggests that VAM fungi and obligately mycotrophic plant species may have been present in the Hawaiian Islands from the earliest stages of the development of the angiosperm flora.
ALLOZYME VARIATION, GENECOLOGY, AND PHYTOGEOGRAPHY OF ANTENNARIA ARCUATA (ASTERACEAE), A RARE SPECIES FROM THE GREAT BASIN AND RED DESERT WITH SMALL DISJUNCT POPULATIONS
Authors: Bayer Randall J.
Published: January 2018

Antennaria arcuata (Asteraceae: Inuleae) is a rare sexual diploid species that occurs in three disjunct regions of Idaho, Nevada, and Wyoming. Isozyme diversity in six populations of the species from the three regions utilized 26 putative loci to provide clues to its population genetic structure. Results show that, in general, the amount of genetic diversity in A. arcuata is very low in comparison to other sexual species of Antennaria. The values of several genetic statistics such as mean number of alleles per locus, proportion of loci polymorphic, and observed heterozygosity, are significantly lower than populations of any of 17 other sexual species of Antennaria that have been studied previously. It is likely that the unusual disjunct and restricted distribution of A. arcuata is partially the result of its unusual ecology, as it occurs in moist basins having high concentrations of salts that are frequently disturbed by large grazing animals. Canonical correspondence analysis shows strong relationships between several edaphic, environmental, and geographic features and the genetic variation in the populations. The migration of A. arcuata to other regions since the end of the Wisconsinan might have been inhibited by the fact that suitable habitats occur as small isolated islands in a sea of inhospitable terrain, the dry sagebrush steppe.
PARTITIONING OF SPACE AND WATER BETWEEN TWO CALIFORNIA ANNUAL GRASSLAND SPECIES
Authors: Gordon D. R. , Rice K. J.
Published: January 2018

We examined the potential for resource partitioning between two sympatric species with similar phenologies but different rooting morphologies. The annual grass, Bromus diandrus (Roth.), and annual forb, Erodium botrys (Cav.), were grown in monoculture and 50:50 mixed stands at each of three densities (10, 30, 100 seeds/dm2) in a randomized complete block design. Plants were grown outdoors, in 1‐m‐tall 15‐cm‐diameter containers. Comparison of seed number produced per plant in mixture and in monoculture indicated greater effects of intraspecific than interspecific competition for Erodium. Such differences were not detected for Bromus seed number, and the converse relationship was suggested from Bromus shoot biomass. Final size inequality of Bromus populations tended to be higher in monoculture than in mixture; no patterns in Erodium size distribution over time or stand composition were evident. Bromus roots were primarily in the upper 10 cm of soil, while Erodium roots were bimodally distributed in the surface and deep soil. Roots of the two species in mixture showed a distribution pattern intermediate between those of the two monocultures. The rate of soil water depletion was higher in the high density than in the low density stands, but was not dependent on stand composition at a given density. Partitioning of belowground space and water resources by groups of species with different root morphologies may partially explain the high species diversity in the grassland.
A MACROMUTATION IN TRIPSACUM DACTYLOIDES (POACEAE): CONSEQUENCES FOR SEED SIZE, GERMINATION, AND SEEDLING ESTABLISHMENT
Authors: Jackson Laura L. , Dewald Chester L. , Bohlen Curtis C.
Published: January 2018

A recessive allele of a gene in Tripsacum dactyloides L. (eastern gamagrass) changes staminate florets to pistillate or hermaphrodite, and restores fertility to suppressed florets. There were ten to 25 times more seeds in the mutant pistillate form, and these were 0.32 to 0.59 times smaller than seeds from the normal form. Seeds from pistillate plants had significantly lower germination rates (22% vs. 50%), and seedlings grew 20% slower than those of normal plants in a greenhouse experiment. Pistillate seedling survival rates were lower in both high‐ (18.8% vs. 62.6%) and low‐ (52.8% vs. 72.6%) competition environments in a field experiment, and surviving seedlings were smaller. The maternal parent of volunteer seedlings next to a plantation of normal and pistillate plants was determined by dissecting the attached fruitcases of 1,313 seedlings. Pistillate plants in the plantation produced 90% of all seeds falling on the site but only 29% of the volunteer seedlings. The pistillate macromutation is not likely to spread in the wild due to morphological constraints on seed size and packaging.
DIFFERENTIAL ACTIVITIES OF ACID PHOSPHATASE FROM ADAXIAL AND ABAXIAL REGIONS OF LUPINUS LUTEUS (FABACEAE) COTYLEDONS
Authors: Asghar Rehana , DeMason Darleen A.
Published: January 2018

Acid phosphatases of abaxial and adaxial regions in the cotyledons of the Lupinus luteus which possess structurally distinct protein bodies were examined. Acid phosphatase activity was investigated by enzyme assays and by gel electrophoresis and was localized by cytochemical methods in the cotyledons of Lupinus luteus L. during germination and seedling development. Acid phosphatase activity was significantly higher in the adaxial (heterogeneous protein body) region as compared to the abaxial (homogeneous protein body) region of the cotyledon. The pH optimum of acid phosphatase from the abaxial region and from the adaxial region was 4.5 and 5.0, respectively. There were significant differences in substrate specificity and isoenzymic composition of the enzyme between the two regions. Isoenzymic composition changed during the course of germination and seedling development. Acid phosphatase was localized in the matrix of the homogeneous protein bodies and in the globoids of the heterogeneous protein bodies at imbibition. After germination (d 3, d 4, d 7) acid phosphatase was localized primarily in the inner cell walls and intercellular spaces of both regions. These results show that different isoenzymes of acid phosphatase show differential localization and the rate of acid phosphatase activation or synthesis differs in cells from the two regions of the cotyledon.
THE ULTRASTRUCTURE OF GLENODINIOPSIS STEINII (DINOPHYCEAE)
Authors: Highfill Joe F. , Pfiester Lois A.
Published: January 2018

The freshwater dinoflagellate Glenodiniopsis steinii Wolsoszyńska was examined using computer‐assisted three‐dimensional reconstruction of serially sectioned cells observed with the transmission electron microscope and images from the scanning electron microscope. Vegetative cells contain ultrastructure typical of freshwater dinoflagellates including trichocysts, mitochondria, Golgi bodies, starch grains, and lipid bodies. The chloroplast is a single, multilobed structure, not multiple discoid chloroplasts as previously described. The “C” shape of the nucleus is apparently due in part to the size and location of the pusule.
TRACING SPECIES INVASION IN CODIUM, A SIPHONOUS GREEN ALGA, USING MOLECULAR TOOLS
Authors: Goff Lynda J. , Liddle Larry , Silva Paul C. , Voytek Mary , Coleman Annette W.
Published: January 2018

The siphonous green alga Codium fragile occurs in many temperate marine regions and is composed of a number of distinct subspecies. Included in this taxon is the common open coast C. fragile subsp. fragile of the northeast Pacific and the weedy C. fragile subsp. tomentosoides which has invaded temperate marine communities in the Atlantic and Pacific oceans. The center of origin of this weedy subspecies is not known, although it is thought to have dispersed from the northwest Pacific. To examine the relationship of the weedy subspecies to the indigenous northeast Pacific form, chloroplast DNA was compared. Each of these subspecies has a restriction map that is uniform throughout its geographic distribution, and the patterns are distinct from each other and from other Codium species examined. However, the two share an almost identical genome size and arrangement of genes. A population in San Francisco Bay was found to be indistinguishable from the weed C. fragile subsp. tomentosoides from the Atlantic. The potential for using molecular data in solving systematic problems in Codium has been clearly demonstrated.
GENETIC DIVERSITY AND ORIGIN OF THE HAWAIIAN ISLANDS COTTON, GOSSYPIUM TOMENTOSUM
Authors: DeJoode Daniel R. , Wendel Jonathan F.
Published: January 2018

Gossypium tomentosumis the only member of the cotton genus endemic to the Hawaiian archipelago. It is morphologically distinct from other allopolyploidGossypiumspecies, and its phylogenetic relationships with them are uncertain. Chloroplast and ribosomal DNA restriction site variation were used to estimate the phylogeny of the allopolyploids.Gossypium mustelinumis resolved as sister to the remaining allopolyploid species, which include two species‐pairs,G. barbadense‐G. darwiniiandG. hirsutum(includingG. lanceolatum)‐G. tomentosum.This indication thatG. tomentosumis sister toG. hirsutumis supported by allozyme data.Gossypium tomentosumis proposed, based on biogeographic evidence and molecular data, to have originated by transoceanic dispersal from a Mesoamerican progenitor. Few restriction site variants were observed among the allopolyploids, suggesting that present lineages diverged relatively rapidly following polyploidization. Allozyme analysis of 30G. tomentosumaccessions collected from seven islands revealed relatively low levels of genetic diversity: 11 of 50 loci were polymorphic, mean number of alleles per locus was 1.24, and mean panmictic heterozygosity was 0.033. Little geographic patterning of allelic distributions was observed. Despite historical cultivation ofG. barbadenseandG. hirsutumin Hawaii and the existence of their naturalized derivatives, no allozyme evidence of interspecific introgression intoG. tomentosumwas detected.
IS ORGANELLE DNA STRICTLY MATERNALLY INHERITED? POWER ANALYSIS OF A BINOMIAL DISTRIBUTION
Authors: Milligan Brook G.
Published: January 2018

Although numerous exceptions are well known, organelle DNA is often exclusively or predominantly maternally inherited. In such cases, maternal inheritance is often documented by the study of progeny derived from crosses between parents with distinguishable organelle genotypes. These studies generally detect a single type of progeny, those containing organelles derived from only one of the parents; no progeny containing organelles derived either from the opposite parent or from both parents are found. However, in most cases the number of progeny examined is quite small. I present a simple binomial model of organelle inheritance to determine the power of such experiments to distinguish between the hypothesis of strict maternal inheritance and a more complex hypothesis involving the presence of both organelle types within a progeny array. Extremely large sample sizes of progeny are required to distinguish these two hypotheses with reasonable confidence when organelle transmission is not strictly maternal. As a result, studies involving simple progeny testing may be misleading. Larger samples, more complex breeding designs, or more sensitive molecular methods are required to document adequately strict maternal inheritance of organelles.
POPULATION STRUCTURE AND GENETIC DIFFERENTIATION IN NATIVE AND INTRODUCED POPULATIONS OF DESCHAMPSIA CAESPITOSA (POACEAE) IN THE COLORADO ALPINE
Authors: Gehring Janet L. , Linhart Yan B.
Published: January 2018

Deschampsia caespitosa is a widespread grass common in moist areas of the alpine tundra of the Rocky Mountains. Enzyme electrophoresis was used to examine population genetic structure along two soil moisture gradients in Rocky Mountain National Park, Colorado. Introduced plants used in a revegetation project were also sampled at one of the sites. At both sites, there were significant differences among subpopulations in allele frequencies, but these differences were distributed in a patchy fashion and were not correlated with the apparent soil moisture gradients. The degree of genetic subdivision differed between the two sites. At one site, gene flow appeared to be high and differences in allele frequencies are attributed to selection in a mosaic environment. At the other site, gene flow appeared more restricted and differences in allele frequencies between subpopulations are attributed to selection and limited gene flow acting simultaneously. Overall, 15% of the genetic variability is between subpopulations and gene flow is high, even between subpopulations separated by up to 1.5 km, but local conditions can apparently limit gene flow and increase the degree of genetic subdivision. The mean genetic distance between introduced plants and the native subpopulations was significantly higher than the mean genetic distance between all other subpopulations. Despite the high gene flow apparent in alpine tundra subpopulations of Deschampsia caespitosa, significant genetic structuring of these subpopulations has developed.
CLONAL INTEGRATION ACROSS A SALT GRADIENT BY A NONHALOPHYTE, HYDROCOTYLE BONARIENSIS (APIACEAE)
Authors: Evans Jonathan P. , Whitney Sheri
Published: January 2018

This study examined the benefits associated with resource sharing among interconnected ramets spanning a soil salinity gradient. Clones of Hydrocotyle bonariensis, a rhizomatous dune perennial, expand into salt marsh communities from surrounding upland dune systems in coastal North Carolina. In rhizome‐severing experiments conducted under both field and laboratory conditions, Hydrocotyle was shown to proliferate ramets under saline conditions, provided that these ramets were connected to other ramets growing in nonsaline conditions. Ramets that benefited from resource integration did not appear to be affected by local salt exposure in that these ramets were morphologically similar to those grown under nonsaline conditions. Supporting ramets incurred no net cost in terms of biomass or ramet production, but there was an increased percent allocation to roots and rhizomes. Ramets grown in saline conditions without the benefit of clonal integration showed high mortality and produced little or no net clonal growth. It is likely that the acropetal movement of water allowed Hydrocotyle clones to ameliorate the heterogeneous saline conditions associated with coastal environments.
POLLINATION OF TWO SYMPATRIC SPECIES OF DALECHAMPIA (EUPHORBIACEAE) IN SURINAME BY MALE EUGLOSSINE BEES
Authors: Armbruster W. Scott , Herzig Ann L. , Clausen Thomas P.
Published: January 2018

Dalechampia brownsbergensis and D. fragrans co‐occur in Suriname, and both are pollinated by fragrance‐collecting male euglossine bees. Dalechampia brownsbergensis appears to bloom year‐round and is pollinated by relatively few species of bees, including Euglossa tridentata and E. gaianii. In contrast, D. fragrans appears to bloom from late October through early December and is visited and pollinated by at least 13 species of euglossines. Field observations of pollination indicated that the two species did not share pollinators. However, when the flowers of D. fragrans were “transplanted” into a population of D. brownsbergensis, the main pollinator of D. brownsbergensis also visited the flowers of D. fragrans. The pollinators of D. fragrans, however, did not visit the flowers of D. brownsbergensis. Partial sharing of pollinators may have only a small negative impact on the two sympatric plant species at this site because they flower simultaneously only part of the year, and they are often spatially separated from one another.
CROP‐WEED HYBRIDIZATION IN RADISH (RAPHANUS SATIVUS): EFFECTS OF DISTANCE AND POPULATION SIZE
Authors: Klinger Terrie , Arriola Paul E. , Ellstrand Norman C.
Published: January 2018

Crop‐weed hybridization rates between an agricultural plot of cultivated radish and surrounding stands of wild radish (both Raphanus sativus L.) were measured. The crop and weed were fixed for alternate isozyme alleles to allow for identification of hybrids through progeny testing. Weed populations were planted in three sizes (one, two, and nine plants) and at three distances (1, 200, and 400 m) from the crop. Hybridization rates declined with increasing linear distance between crop and weeds. When observed rates of hybridization were corrected for frequency of recipient weeds, the potential level of hybridization actually increased with distance. The effect of population size on rate of hybridization was significant; the direction of the effect was dependent on crop‐weed distance. The observed relationship between population size and hybridization rates was not predictable according to current pollination ecology theory.
SEEDS AND SYSTEMATICS IN HYDROPHYLLACEAE: TRIBE HYDROPHYLLEAE
Authors: Chuang T. I. , Constance Lincoln
Published: January 2018

Scanning electron microscopic investigation of seed surfaces in tribe Hydrophylleae (Hydrophyllaceae) and seed development in Nemophila indicates the presence of four closely related genera (Ellisia, Hydrophyllum, Nemophila, Pholistoma) and one aberrant genus (Eucrypta), which should probably be transferred elsewhere. Comparative evidence from embryology, morphology, cytology, and palynology is roughly corroborative.
CLONAL STRUCTURE, GENOTYPIC DIVERSITY, AND SEED PRODUCTION IN POPULATIONS OF FILIPENDULA RUBRA (ROSACEAE) FROM THE NORTHCENTRAL UNITED STATES
Authors: Aspinwall Nevin , Christian Terry
Published: January 2018

Queen of the prairie, Filipendula rubra (Rosaceae), is a clonal plant species inhabiting calcareous fens and wet meadows of the northcentral United States. F. rubra reproduces asexually by underground rhizomes and sexually by seed. While many studies have explored genotype diversity in clonal species with limited sexual reproduction, fewer have been conducted on clonal species with the potential for extensive sexual reproduction. We studied the relationship between the extent of sexual reproduction and genotype diversity. Although genotype diversity in F. rubra was double that reported by others for 27 nearly obligate clonal plant species, it was still quite low. For 25 populations studied, the mean number of genotypes was 5.5 (range = 1–15; SE = 0.964) and the average proportion of distinguishable genotypes was 0.38 (range = 0.03–1.00; SE = 0.07). The production of viable seed was quite variable among populations (mean proportion of viable seeds = 0.242; range = 0.002–0.565; SE = 0.04). Considering that some inflorescences can produce over 5,000 seeds, the potential for recruitment of sexually produced individuals is very large. No correlation was found between seed production and genotype diversity as was expected in a self‐incompatible species in which one‐third of the populations possessed a single genotype. It was hypothesized that the low genotype diversity found in numerous populations may be due to competition limiting recruitment of new seedlings.
POLLINATION AND THE FUNCTION OF FLORAL PARTS IN CHAMAECRISTA FASCICULATA (FABACEAE)
Authors: Wolfe Andrea D. , Estes James R.
Published: January 2018

Chamaecrista fasciculata has a rigid upper petal that curves over nine of the ten anthers. The single anther is deflexed, as is the style. An experimental pollination study was designed to test the hypotheses that: 1) the rigid petal acts as flight guide to ensure pollination; and 2) the nine grouped anthers serve as fodder anthers, whereas the single deflexed anther functions in pollination. The rigid petal was removed from 97 flowers. Only 5% of the manipulated flowers set fruit in comparison to a fruit set of 47% for the control group. The results of the study support the flight guide hypothesis. Pollen from both sets of anthers is viable and germinates on receptive stigmas. A pollen flow experiment using powdered metals, backscatter scanning electron microscopy, and X‐ray microanalysis revealed that there is no difference in the frequency of pollen distribution from either set of anthers. Therefore, this study refutes the fodder/pollinating anther hypothesis.
THE DEVELOPMENTAL BASIS FOR SEXUAL EXPRESSION IN CERATONIA SILIQUA (LEGUMINOSAE: CAESALPINIOIDEAE: CASSIEAE)
Authors: Tucker Shirley C.
Published: January 2018

The flowers of Ceratonia siliqua, an anomalous caesalpinioid legume in the tribe Cassieae, are unusual in being unisexual and in lacking petals. Inflorescence development, organogeny, and flower development are described for this species. All flowers are originally bisexual, but one sex is suppressed during late development of functionally male and female flowers. Ceratonia siliqua is highly plastic in sexuality of individuals, inflorescence branching pattern, racemose or cymose inflorescences, bracteole presence, terminal flower presence, organ number per whorl, missing floral organs, pollen grain form, and carpel cleft orientation. Order of initiation is: five sepals in helical order, then five stamens in helical order together with the carpel. Each stamen is initiated as two alternisepalous primordia that fuse to become a continuous antesepalous ridge; in some flowers, the last one or two stamens of the five may form as individual antesepalous mounds. Petal rudiments are occasional in mature flowers. Position of organs is atypical: the median sepal is on the adaxial side in Ceratonia, rather than abaxial as in most other caesalpinioids. This feature in Ceratonia may be viewed as a link to subfamily Mimosoideae, in which this character state is constant.
ECOLOGICAL CORRELATES OF REPRODUCTIVE TRAITS OF MEXICAN RAIN FOREST TREES
Authors: Ibarra‐Manríquez Guillermo , Oyama Ken
Published: January 2018

Sexual systems of 139 tree species from a tropical rain forest at Los Tuxtlas, Mexico were investigated to: 1) estimate the relative proportions of hermaphroditic, monoecious, and dioecious species; 2) describe flowers, fruits, and seeds in terms of size and weight; 3) describe flowering and fruiting phenology; and 4) correlate sexuality to pollination and dispersal syndromes, and the successional status occupied in the forest. Hermaphroditism occurred in 63% of the species, monoecism in 9%, and dioecy in 27%. Nondioecious species had larger flowers, but dioecious species had more seeds per fruit. The dioecious condition was associated with small flowers pollinated with unspecialized insects and fleshy fruits dispersed by animals at both species and generic levels. Reproductive traits were more correlated among nondioecious species than dioecious species. Pioneer species had more seeds per fruit, and longer flowering and fruiting periods, but persistent species produced heavier seeds and fruits. Flower and fruit morphological traits, sexual systems, and tree guilds are related in a comprehensive way, and a flow model based on data from this study is presented.
ALLOZYME VARIATION WITHIN SOLANUM SECT. PETOTA, SER. ETUBEROSA (SOLANACEAE)
Authors: Spooner David M. , Douches David S. , M. Andrés Contreras
Published: January 2018

Enzyme electrophoresis was employed to measure genetic variation within and divergence among 32 populations of three species in Solanum sect. Petota (S. brevidens, S. etuberosum, and S. fernandezianum). These species are self‐compatible, diploid (2n = 2x = 24), and members of the monophyletic series Etuberosa. Solanum etuberosum is distributed in southern Chile, S. brevidens occurs in southern Chile and adjacent southern Argentina, and S. fernandezianum is endemic to Masatierra Island in the Juan Fernández Archipelago, 650 km west of continental Chile. Very low levels of observed heterozygosity (0.00–0.04) are found within populations of all three species. Interspecific mean genetic identities between S. brevidens and S. etuberosum (0.854) were similar to their intraspecific values (0.923, 0.865, respectively), with both species monomorphic for alleles at nine of the 12 loci examined. Solanum fernandezianum shows no heterozygosity and is more divergent to both S. brevidens (0.780) and S. etuberosum (0.698) than either is to each other. The divergence of S. fernandezianum to S. brevidens and S. etuberosum results from novel alleles at two of the 12 isozyme loci; in addition, it possesses only a subset of the variability found in S. brevidens and S. etuberosum at three other loci.
GEOMETRY OF HELIOTROPIC AND NYCTINASTIC LEAF MOVEMENTS
Authors: Herbert Thomas J.
Published: January 2018

Leaves that show nyctinastic and helionastic movements are usually more steeply inclined during the night and near midday than in the early morning or afternoon. But leaf movement is complex and there are many different combinations of leaf folding, axial rotation, or inclination of the midrib that result in changes in total leaf inclination. The complexity of leaf movement and amount of total leaf inclination can be described by plotting axial rotation or folding angle as a function of the angle of inclination of the midrib. The use of this method of description of leaf movement indicates that the variation between types of leaf movement may be continuous and not simply classifiable as diaheliotropic or paraheliotropic. Furthermore, this paper introduces a new method for characterization of the geometry of leaf movement that uses correlation between axial rotation and elevation as a tool for identification and quantification of leaf movement.