bluuebunny/crossref_metadata_2025 huggingface dataset:
FLOWERING, SEX RATIOS, POLLEN‐OVULE RATIOS, FRUIT SET, AND REPRODUCTIVE EFFORT OF A DIOECIOUS TREE, MYRISTICA INSIPIDA (MYRISTICACEAE), IN TWO DIFFERENT RAIN FOREST COMMUNITIES
Authors: Armstrong Joseph E. , Irvine Anthony K.
Published: January 2018

The flowering of Myristica insipida R. Br. was studied in two rain forest communities in northern Queensland. This dioecious, subcanopy tree had a male‐biased sex ratio at both study sites. In the lowland population the male‐bias could be attributed to males (trees producing staminate flowers) starting to flower at a smaller average size than females (trees producing pistillate flowers). There were no intersexual differences in spacing or distribution within the study sites. Males trees flowered earlier, flowered longer, and produced over twice as many flowers as females during the study season. Although the onset of flowering was rather variable, 18–22 days following heavy rains, most trees had a synchronous period of maximum flowering. Pollination manipulations determined that there was no fruit development without pollination, and that increasing pollen loads resulted in increased fruit set with diminishing effect. Taking into account the sex‐ratios and intersexual differences in flower production, the pollen‐ovule ratio was calculated to be 16,000–19,000. Male trees were found to expend more energy on flowering than female trees. Open‐pollination resulted in 1.0% of female flowers setting fruit. The much greater cost of fruit production resulted in females expending 421% more energy on reproduction than males. Fruit and seed production were judged to be pollination‐limited. Nonetheless, this species exhibited several characteristics that are predicted if dioecy evolved by means of sexual selection.
FLORAL BIOLOGY OF MYRISTICA INSIPIDA (MYRISTICACEAE), A DISTINCTIVE BEETLE POLLINATION SYNDROME
Authors: Armstrong Joseph E. , Irvine Anthony K.
Published: January 2018

The floral biology and pollination of Myristica insipida were studied in two different rain forest communities in Queensland. Floral morphology of M. insipida resembles that of M. fragrans in virtually all respects. The majority of female flowers were receptive 48–72 hr. Male flowers were shorter‐lived, functional for 12–48 hr. Both male and female flowers opened daily between 1800 and 2200 hr, but the activity of floral visitors did not begin until the next morning. The inconspicuous, creamy‐white to light‐green flowers had a strong, pleasant “floral” fragrance. The male flowers only offered pollen as a reward, and female flowers, offering no reward, were judged to function by automimicry. A taxonomically diverse array of small, pollen‐foraging beetles were the effective pollinators, although thrips and ants were common floral visitors. In almost all respects, the beetle pollination syndrome of Myristica differs from the cantharophily of most other primitive angiosperms.
GROWTH OF LITTLE BLUESTEM (SCHIZACHYRIUM SCOPARIUM) (POACEAE) IN FUMIGATED AND NONFUMIGATED SOILS UNDER VARIOUS INORGANIC NUTRIENT CONDITIONS
Authors: Anderson Roger C. , Liberta Anthony E.
Published: January 2018

Little bluestem plants (Schizachyrium scoparium (Michx.) Nash) were grown in fumigated and nonfumigated soil under manipulated levels of three inorganic nutrients: nitrogen, phosphorus, or bases (Ca + Mg). Plants grown in nonfumigated soil had significantly (P < 0.05) higher tissue levels of inorganic nutrients (Cu, Zn, Al, S, Mg, Mn, Ca, and P), smaller shoots, less total biomass, fewer flowering plants but more VAM fungal colonization than plants grown in fumigated soil that were essentially nonmycorrhizal (colonization vs. 1.2 ± 4.9%, for plants grown in nonfumigated and fumigated soil, respectively). Levels of phosphorus (14–33 μg/g) available (Bray No. 1) in the soil prior to manipulation, which are adequate for little bluestem, likely resulted in the development of an ineffectual mycorrhizal association, which in turn, caused the depressed growth of plants in nonfumigated soil. Among plants grown in nonfumigated soil, there was significant variation in VAM fungal colonization and sporulation owing to nutrient treatment. Nitrogen treatment and deionized water control had significantly lower levels of colonization than phosphorus and base treatments. However, plants in the nitrogen and base treatments had significantly more spores/100 cc of rhizosphere soil than plants grown in the deionized water control.
A SIX‐YEAR STUDY OF FLAVONOID DISTRIBUTION IN A POPULATION OF LASTHENIA CALIFORNICA (ASTERACEAE)
Authors: Bohm Bruce A. , Herring Alex , Nicholls K. W. , Bohm L. R. , Ornduff Robert
Published: January 2018

A population of the annual Lasthenia californica in the Jasper Ridge Biological Preserve (of Stanford University) showed three major flavonoid pigment types (A, B and C; a fourth was seen in very low frequencies). The three more common types exhibited a suite of aurone and chalcone glucosides and a set of highly polar flavonoid glucuronides. Type C consisted solely of the base array; type B added luteolin 7‐glucoside to the base array, while type A exhibited the base array plus eriodictyol 7‐glucoside and flavonol 3,7‐diglycoside bisulfates. The rare type D profile resembled type A except that the diglycosides were not sulfated. Collections were made along one of several fixed transects annually from 1982 to 1987. The main transect studied (Transect No. I) can be divided into two distinct parts on the basis of a changeover of flavonoid pattern from a mixture of types B and C at one end to exclusively (or very nearly) type A at the other. The frequencies of types B and C varied from year to year with type C predominating every year. The frequency of type A plants remained remarkably stable over the six‐year period. Collections along other transects showed a similar constancy of both frequencies of the flavonoid types and location of the types along the transects. Growth experiments in a greenhouse showed that seeds from type A parents harvested in the field produced only type A progeny, while type B and C plants gave only type B and C progeny with type C predominating (a single type A progeny plant was obtained from a type C parent). Flavonoid diversity in L. californica appears to be genetically controlled and is influenced significantly by the flavonoid chemistry of the seed parent.
PITYOSTROBUS MAKAHENSIS, A NEW SPECIES OF SILICIFIED PINACEOUS SEED CONE FROM THE MIDDLE TERTIARY OF WASHINGTON
Authors: Crabtree David R. , Miller Charles N.
Published: January 2018

A single structurally preserved ovulate cone forms the basis for the description of a new species of Pityostrobus from the early Oligocene of the Olympic Peninsula of Washington. The specimen consists of about two‐thirds of a cylindrical cone. In living condition the cone was 8–10 cm long and 3.5–4 cm in diameter. Critical features of the cone include decurrent bract bases, an elongate bract‐scale adnation, perpendicular disposition of the proximal part of the scale, and seeds with vesciculate seed coat. An unusual feature of the cone is a distinctive cortical region of thin‐walled parenchyma, mineral‐filled lacunae, and resin canals. This region can be traced to the adaxial side of the scale where it can be recognized by an extensive development of resin canals in the adaxial ground tissue opposite the seed cavities, and by distinctive lacunae around the vascular bundles. The fossil shares several significant characters with modern cones of Abies, Pseudotsuga, Larix, Tsuga, and Picea, thereby calling to question the abietoid/pinoid division of the family, or suggesting that abietoid and pinoid genera of the early Oligocene had not yet diverged to the extent seen in the modern flora.
CLONE STRUCTURE IN FOUR SOLIDAGO ALTISSIMA (ASTERACEAE) POPULATIONS: RHIZOME CONNECTIONS WITHIN GENOTYPES
Authors: Maddox G. David , Cook Robert E. , Wimberger Peter H. , Gardescu Sana
Published: January 2018

We studied clone structure and degree of genotypic mixing of Solidago altissima L. (Asteraceae) clones in four old fields near Ithaca, New York. The fields differed in time from agricultural abandonment and were approximately 1, 5, 20, and 35 years old. In the three older fields, three 0.75 m2 plots were excavated intact and rhizome connections among ramets were mapped. In the youngest field 30 ramets were dug up singly. The genotype of all ramets was determined using electrophoresis of four polymorphic enzyme systems. Fields differed in the number and dispersion of genotypes within plots, and the degree of connection among ramets in the same clone. The one‐year‐old field was composed of single ramet genotypes which had probably established from seed the previous year. The five‐year‐old field contained many small contiguous clones of S. altissima with highly interconnected ramets. In the oldest two fields clones were highly intermixed and ramets of the same genotype were not extensively interconnected. These results demonstrate that clones of S. altissima display considerable phenotypic variability between fields and patterns of clone development may differ. The causes of this variability remain to be identified. We suggest that either selection for different genotypes or changing habitat conditions during succession may lead to changes in clone form.
PHYSIOLOGICAL AND MORPHOLOGICAL MODIFICATIONS OF PLANTAGO MAJOR (PLANTAGINACEAE) IN RESPONSE TO LIGHT CONDITIONS
Authors: Niklas Karl J. , Owens Thomas G.
Published: January 2018

Physiological and morphological differences between Plantago major L. (Plantaginaceae) growing in full sunlight and shaded conditions were examined. Photosynthesis of isolated leaves was saturated by irradiance around 300 μE m−‐2 sec−‐1 and 170 μE m−‐2 sec−‐1, respectively. In contrast to previous studies of sun/shade leaf responses, initial slopes of curves from shaded plants are significantly less than those taken from full‐sun plants. Within the 400–500 nm and 600–700 nm ranges, leaves 5.0 cm or longer are essentially opaque, transmitting less than 1.25% of incident light. Chlorophyll content per unit leaf area is nearly equivalent for leaves from plants growing under the two extremes in light levels. Morphometric comparisons indicate shaded plants bear fewer leaves, have less leaf overlap, lower total leaf area, and longer petioles than full‐sun plants. Leaf elongation rates are lower and the duration between the emergence of successive leaves is longer in shaded plants. Computer analyses of both types of rosette morphology reveal shaded plants have an equal or greater capacity to intercept light than full‐sun plants, principally because of the minimization of leaf overlap and the large variation in the deflection angles of leaves in shaded rosette morphologies. Simulations, calculated on the basis of light interception, and taking into account the transition between photosynthate‐importing and ‐exporting leaves, predict relative growth rates for full‐sun and shaded rosette morphologies that are in reasonable agreement with empirically determined leaf growth rates. However, the data indicate that significant physiological and morphological differences exist among leaves from a single rosette, and among developmentally comparable leaves from rosettes growing under different ambient light environments. Differences among leaves on a single plant must be accommodated in computerized techniques attempting to simulate light interception and its consequences on potential growth rates.
NODE COUNTING IN AXILLARY BUDS OF NICOTIANA TABACUM CV. WISCONSIN 38, A DAY‐NEUTRAL PLANT
Authors: McDaniel Carl N. , Sangrey Karla A. , Singer Susan R.
Published: January 2018

A mature, quiescent, primary axillary bud on the main axis of a flowering Nicotiana tabacum cv. Wisconsin 38 plant, when released from apical dominance and before forming its terminal flower, produced a number of nodes which was dependent upon its position on the main axis. Each bud produced about one more node than the next bud above it. The total number of nodes produced by an axillary bud was about 6 to 8 greater than the number of nodes present above this bud on the main axis. At anthesis of the terminal flower on the main axis, mature, quiescent, primary axillary buds had initiated 7 to 9 leaf primordia while secondary axillary buds, sometimes present in addition to the primary ones, had initiated 4 to 5 leaf primordia. When permitted to grow out independently, primary and secondary axillary buds located at the same node on the main axis produced the same number of nodes before forming their terminal flowers. In contrast, immature primary axillary buds which had produced only 5 leaf primordia and which were released from apical dominance prior to the formation of flowers on the main axis produced only as many nodes as would be produced above them on the main axis by the terminal meristem, i.e., “extra” nodes were not produced. Therefore, it is the physiological status of the plant and not the number of nodes on the bud at the time of release from apical dominance that influenced the node‐counting process of a bud. When two axillary buds were permitted to develop on the same main axis, each produced the same number of nodes as single axillary buds developing at these nodes. Thus, the counting process in an axillary bud of tobacco is independent of other buds. Axillary buds on main axes of plants that had been placed horizontally produced the same number of nodes as identically‐positioned axillary buds on vertical plants, indicating that gravity does not play a major role in the counting, by an axillary bud, of the nodes on the main axis.
OPTIMUM POLLEN AND FEMALE RECEPTOR SIZE FOR ANEMOPHILY
Authors: U Kyaw Tha Paw , Hotton Carol
Published: January 2018

A set of mathematical models is developed to describe the relationship between the sizes of pollen grains and female receptors which result in maximum anemophilous pollen transfer. The models predict anemophilous plants should have Stokes numbers in the range of 1.0 to 2.72. The Stokes number is a function of both pollen size and effective receptive surface size. The models were tested with data gathered for 28 assumed anemophilous species and 20 known zoophilous species. The models identify anemophily with an accuracy of approximately 75%. If pollen size alone is used to determine anemophily, then accuracy drops to only 50%. The Stokes number criterion reported here could help in the determination of anemophily of extant and fossil plant taxa.
NODAL SEPTA AND THE RIGIDITY OF AERIAL SHOOTS OF EQUISETUM HYEMALE
Authors: Niklas Karl J.
Published: January 2018

The biomechanical role of septate nodes (points of leaf attachment with transverse diaphragms of tissue) in the otherwise hollow aerial stems of Equisetum hyemale L. is examined by means of multiple resonance frequency spectra. Resonance frequencies were determined for intact shoots, as well as the same shoots through which metal needles were inserted to destroy septa at nodes. The elastic modulus (E) of shoots, before and after surgical manipulation, was calculated. Shoots with perforated septa had E values from 17 to 32% less than intact shoots. During winter months with subfreezing temperatures, shoots with intact nodal septa accumulated water (in the form of ice) in their internodal pith canals. Values of E calculated for a shoot with intact septa and internodal water, and for the same shoot without septa do not differ significantly. Calculations indicate that the mass of internodal water is a significant fraction of the mass sufficient to deflect and buckle shoots. The added mass of internodal water is sufficient to mask the actual elastic modulus of shoots. The data indicate that nodes with septa significantly influence the flexural rigidity of shoots, but that this influence changes as a function of the quantity of water found in pith cavities.
AN EVALUATION OF BAUM ET AL.'S ASSESSMENT OF THE GENOMIC SYSTEM OF CLASSIFICATION IN THE TRITICEAE
Authors: Jauhar Prem P. , Crane Charles F.
Published: January 2018

We have critically evaluated Baum, Estes, and Gupta's (1987) assessment of the genomic system of classification in the tribe Triticeae. They have raised some valid concerns about basing a taxonomic classification on genome relationships. However, some of their objections are ill‐founded. Baum et al.'s contention that genome analysis can only supplement other criteria in assessing phylogeny is inaccurate. Genome analysis by itself has yielded extremely useful information on phylogenetic relationships in the Triticeae, and their assertion that an individual morphological trait be given the same weight as genomic relatedness is not tenable. Moreover, these authors have adopted cladistic algorithms in the Triticeae, an analysis appropriate only in groups where reticulation has not occurred. Evolution in the Triticeae is highly reticulate, the main sources of reticulation being allopolyploidy and homoploid recombinational speciation.
EXTRACELLULAR FREEZING IN EQUISETUM HYEMALE
Authors: Niklas Karl J.
Published: January 2018

Extracellular freezing occurs within the pith cavities of Equisetum hyemale L. aerial shoots when they are exposed to subfreezing temperatures. The weight of plugs of ice within pith cavities correlates linearly with the weight of internodal tissues (r2 = 0.974, N = 10); ice plugs are 32–38% (33 ± 1.8%) the weight of intact shoots. Upon thawing, internodal water is gradually reabsorbed by excised shoots. Extracellular freezing can be induced by exposing excised shoots to gradually decreasing temperatures (5 C/day) to –20C, and is associated with a reduction in tissue water potential. Data indicate that internodal tissues behave as osmometers and dehydrate until reaching equilibrium with the chemical potentials of extracellular fluids within internodal pith cavities. Upon thawing, internodal water is reabsorbed by excised shoots and tissue water potential increases. Extracellular freezing may operate as a mechanism that reduces intracellular ice formation and tissue damage during extremely cold weather.
INTERACTION BETWEEN THE ECTOMYCORRHIZAL FUNGUS PISOLITHUS TINCTORIUS AND ROOT HAIRS OF PICEA MARIANA (PINACEAE)
Authors: Thomson J. , Melville L. H. , Peterson R. L.
Published: January 2018

The ectomycorrhizal fungus Pisolithus tinctorius interacts with roots of Picea mariana to form a typical mantle and Hartig net. Hyphae alter their growth pattern when in contact with susceptible root hairs in the mycorrhizal infection zone and grow acropetally, gradually covering the length of the hair to form a mantlelike structure. Initial contact with the hair may be influenced by a fibrillar material on the root hair surface. Although many root hairs become surrounded by fungal hyphae, they are not penetrated, and therefore are not entry points for this symbiotic fungus.
CHROMOSOME NUMBERS IN BROMELIACEAE
Authors: Brown Gregory K. , Gilmartin Amy Jean
Published: January 2018

Eighty‐three chromosome counts are reported for 72 taxa of the Bromeliaceae. Fifty‐eight of these counts are the first known chromosome number reports for their respective taxa. A model of chromosomal evolution in the Bromeliaceae (n = 25) is presented. The model is parsimonious and consistent with existing data on meiotic chromosome numbers within the family and in the closely related Velloziaceae (n = 9). Two hypothesized paleodiploids (n = 8 and n = 9) hybridized to form a tetraploid that in turn hybridized with the n = 8 lineage. The resultant n = 25 is the extant base number for the family. Two alternative hypotheses could explain the unique extant base number (n = 17) for Cryptanthus: 1) Cryptanthus represents the paleotetraploid level, i.e., prior to the second round of hybridization, or 2) the lower number represents the result of a more recent series of aneuploid reductions from n = 25. Given the existence of intergeneric hybrids involving Cryptanthus, aneuploid reduction is the more likely interpretation.
OVERLAPPING ORGAN INITIATION AND COMMON PRIMORDIA IN FLOWERS OF PISUM SATIVUM (LEGUMINOSAE: PAPILIONOIDEAE)
Authors: Tucker Shirley C.
Published: January 2018

The floral ontogeny of Pisum sativum shows a vertical order of succession of sepals, petals plus carpel, antesepalous stamens, and antepetalous stamens. Within each whorl, unidirectional order is followed among the organs, beginning on the abaxial side of the flower, as in most papilionoids. Unusual features include the four common primordia which precede initiation of discrete petal and antesepalous stamen primordia, and the marked overlap of organ initiations between whorls which are usually separately initiated. The stamens arise in free condition, then become diadelphous by intercalary growth at the base of nine stamens, and finally become pseudomonadelphous by surface fusion between the vexillary stamen filament and the adjacent edges of the filament tube. The early initiation of the carpel is not unique among papilionoids, but is somewhat unusual.
ROOT AERENCHYMA DEVELOPMENT IN SPARTINA PATENS IN RESPONSE TO FLOODING
Authors: Burdick David M.
Published: January 2018

Root aerenchyma, developed in response to flooding, was measured as specific gravity in previously existing (old) and newly developed (new) roots of Spartina patens in a 25‐day greenhouse experiment. Root specific gravity was related to porosity (fractional volume of aerenchyma): porosity = 1.026 – 0.969 × specific gravity, over a wide range of specific gravities (0.5 to 0.9). The specific gravity of flooded roots (new and old) decreased from 0.78 to 0.58 between day 5 and 25, while the specific gravity of old roots that remained drained did not change. After 5 days growth, newly produced roots were found to have less aerenchyma than their older counterparts, but after 25 days the specific gravity of new roots equaled that of old roots. In addition, flooding increased mortality of preexisting roots and inhibited growth of new roots.
SOURCE PLANTS FOR CARBONIFEROUS MICROSPORES: LYCOSPORA FROM PERMINERALIZED LEPIDOSTROBUS
Authors: Willard Debra A.
Published: January 2018

Permineralized Lepidostrobus specimens were examined from the Westphalian A of England, Westphalian B (Breathitt) of the Appalachian Basin, and the Westphalian D (Desmoinesian) of the Illinois Basin and Western Interior Coal Region to correlate species of the dispersed spore genus Lycospora with source cones and cone types (“species”) with parent plants. Based on 51 specimens of Lepidostrobus oldhamius sensu Balbach, three cone types, producing three species of Lycospora, are recognized. Lycospora pellucida occurs in smaller diameter cones with a prominently coronate stele; cones are associated with Lepidophloios harcourtii from the Westphalian A‐B. Lycospora pusilla occurs in larger diameter cones with a small “pith” containing elongate, sclerified, tanniferous cells from Westphalian D coal balls. Secretory cells also are present in sporophyll trace sheaths and in subarchesporial parenchyma pads in sporangia. The suggested plant source is Lepidodendron hickii. Lycospora granulata occurs in large cones with a large “pith” composed of thin‐walled parenchyma; no secretory cells were observed in the “pith,” sporophyll traces, or subarchesporial pads. These cones are associated with Lepidophloios hallii from the Westphalian D. Association of Lycospora species with source lycopods increases the possibilities of paleoecological interpretation using microspores from Carboniferous coals.
ABORTION OF FLORAL BUDS IN ACOMASTYLIS ROSSII PLANTS EXPOSED TO ARTIFICIAL ACID MISTS IN ALPINE TUNDRA
Authors: Funk Dale W. , Bonde Erik K.
Published: January 2018

Plants of Acomastylis rossii were treated over a three‐year period with artificial acid mists of pH 2.5, 3.5, or 4.5 prepared with sulfuric acid or nitric acid. Treatments were made in the field twice weekly for eight weeks during each of the three growing seasons. Significant decreases in the percentage of plants flowering were noted in each year of the study in plants treated with sulfuric acid mist at pH 2.5. Significant decreases in flowering with sulfuric acid at pH 3.5 and in leaf number with sulfuric acid at pH 2.5 and 3.5 occurred in the third year of treatments as well. Some individual plants flowered in one, two, or three of the years, indicating that new floral primordia were being produced during the treatment period. Plants that flowered produced viable, germinable seeds. No effects of nitric acid mists were noted during the study period. Treatments with citrate buffer solutions (pH 6.2) used to determine if the plants were responding to sulfate independently of pH showed no significant differences for any of the measurements taken. The observed decreases in flowering are apparently a sulfuric acid effect and are not attributable to hydrogen ions or sulfate ions independently of each other. Experiments with plants that had visible floral buds indicate that plants aborted the floral structures in response to direct contact of buds with solution from the acid mists. The growth form of the plants enhances contact by causing pooling of the solutions on top of the developing buds in pockets formed by the basal leaves.
AN ULTRASTRUCTURAL STUDY OF SPORE WALL MORPHOGENESIS IN EQUISETUM ARVENSE
Authors: Uehara Koichi , Kurita o
Published: January 2018

Spore wall morphogenesis of Equisetum arvense was observed by transmission electron microscopy. The spore wall of E. arvense consists of four layers: intine, exine, middle layer, and elater. The exine is formed after meiosis and consists of two distinct layers. The inner portion of the exine is formed in advance of the outer layer of the exine. The middle layer is deposited after the exine. The elater can be subdivided into two distinct layers. The inner layer comprises longitudinal microfibrils that surround the spore in spiral fashion. The elater appears as thin beltlike structures at the beginning of development. Numerous microtubules were observed on the inner surface of the plasmodial plasma membrane opposite the inner layer of the elater, suggesting that these microtubules are involved with the synthesis of inner elater microfibrils. The matrix of the outer elater is formed by discharge of granules from the plasmodial cytoplasm. The intine is the last component of the sporoderm to be formed.
STEREOLOGICAL ANALYSIS OF ULTRASTRUCTURAL CHANGES DURING INDUCED EPIDERMAL CELL REDIFFERENTIATION IN DEVELOPING FLOWERS OF CATHARANTHUS ROSEUS (APOCYNACEAE)
Authors: Verbeke Judith A.
Published: January 2018

Stereological principles were used to study epidermal cell redifferentiation during the post‐genital tissue union in the developing flowers of Catharanthus roseus. Volume densities of ultrastructural components at three separate stages of cell differentiation were analyzed and compared. Nuclear volume density decreased and vacuolar volume density increased throughout the period studied. The only other components whose volume densities changed significantly were plastids, mitochondria, and dictyosomes. For each of these organelles, the mean relative volume was greatest at the time of fusion. By 12 hr after fusion, however, the mean relative volume of each fell to a level significantly lower than its volume in the prefusion cells.
ONTOGENY AND PALEOECOLOGY OF THE MIDDLE PENNSYLVANIAN ARBORESCENT LYCOPOD BOTHRODENDRON PUNCTATUM, BOTHRODENDRACEAE (WESTERN MIDDLE ANTHRACITE FIELD, SHAMOKIN QUADRANGLE, PENNSYLVANIA)
Authors: Wnuk Christopher
Published: January 2018

Study of an in situBothrodendron punctatumcommunity in a strip mine in Bear Valley, Shamokin Quadrangle, Pennsylvania, provides new insights into the ontogeny of Middle Pennsylvanian arborescent lycopods and into the ecological and environmental characteristics of lycopod‐dominated clastic‐swamp communities.Bothrodendron punctatumbegan growth as a monocaulous stem. The first branches developed when the stem attained a minimum height of 5 m. Lateral branches bore terminal cones and were determinate and deciduous. They grew to a maximum length of 1 m, and became smaller and more closely spaced with increasing stem height. The branch scars were not disrupted by secondary stem growth indicating that the branches stayed attached until the stem attained its determinate growth limit. The plant grew to a height of 25 m. ThoughB. punctatumis an uncommon component of Euramerican floras, the plant could become locally dominant under favorable environmental and edaphic conditions. The upper canopy was formed byB. punctatumand contained emergents ofLepidodendron aculeatumand aSigillariaspecies. The understory contained pteridosperms and rareCalamites. Bothrodendron punctatumseems to have preferred environments transitional between clastic and peat swamp conditions. It was sensitive to local inhomogeneity in microhabitat characteristics, as well as to regional climatic fluctuations (drought stress). Both these variables produce specifically attributable effects on branch size and separation trends.
VARIATION IN GERMINATION RESPONSE TO TEMPERATURE IN RUBBER RABBITBRUSH (CHRYSOTHAMNUS NAUSEOSUS: ASTERACEAE) AND ITS ECOLOGICAL IMPLICATIONS
Authors: Meyer Susan E. , McArthur E. Durant , Jorgensen Gary L.
Published: January 2018

Seed collections from 72 rubber rabbitbrush populations occupying a range of habitats in western North America were incubated at 3 C in the laboratory. Collections from warm desert habitats required less than 2 weeks to achieve 90% relative germination under these conditions, while collections from montane habitats showed delayed germination requiring up to 20 weeks. When 13 representative collections were incubated at constant temperatures from 5 to 30 C, all germinated completely at 30 C within 4 weeks. Collections from warm desert habitats germinated rapidly over the whole range of temperatures. Montane collections sometimes exhibited dormancy at intermediate temperatures (15 and 25 C) even though they were ultimately able to germinate at lower temperatures. Results suggest that dormancy is conditional and temperature‐dependent in this species. Chilling the seeds extends the temperature range for germination downward to include the chill temperature itself. Germination response to temperature and its variation as a function of habitat are of apparent adaptive significance, serving to time germination so that the probability of seedling survival is maximized in each habitat. Within populations, response to temperature varied as a function of year of harvest and of within‐year harvest date, indicating that germination patterns are probably not under rigid genetic control but represent an integration of genetic and environmental factors.
EXPERIMENTAL STUDIES OF PONDEROSA PINE. II. QUANTITATIVE GENETICS OF MORPHOLOGICAL TRAITS
Authors: Grant Michael C. , Linhart Yan B. , Monson Russell K.
Published: January 2018

We studied fourteen morphological attributes of 511 seedling stage progeny involving crosses between Pinus ponderosa ponderosa parents as well as intervarietal crosses of P. p. ponderosa × P. p. scopulorum. Intravarietal progeny were distinctly differentiated genetically from intervarietal sibships in seven of the fourteen characters examined. The patterns of differentiation observed strongly suggest a syndrome of selective responses to increased water stress in the progeny with a scopulorum parent and for comparatively more rapid, columnar growth in the progeny of the intravariety crosses which involved only P. p. ponderosa parents. These differences are consistent with known ecological distinctions between the habitats of the two varieties. Narrow‐sense heritability estimates, obtained from half‐sib progeny analysis, indicated that considerable levels of additive genetic variance remain present in several traits. We could detect no relationship between the amount of additive genetic variance present for a particular character and its presumed relevance to fitness.
SEX EXPRESSION, BREEDING SYSTEM, AND POLLEN BIOLOGY OF RICINOCARPOS PINIFOLIUS: A CASE OF ANDRODIOECY?
Authors: Thomson James D. , Shivanna K. R. , Kenrick J. , Knox R. B.
Published: January 2018

A population of 54 Ricinocarpos pinifolius (Euphorbiaceae) plants contained male plants, which produced only staminate flowers, and hermaphrodites, which produced staminate and pistillate flowers. The fraction of pistillate flowers ranged continuously from 0 to 0.68. Insect pollination was effective and fruit set virtually complete except for losses to herbivores. Self pollen, outcross pollen from male plants, and outcross pollen from hermaphrodites were all equivalent in viability, germination, tube growth, ovule penetration, and fruit setting ability. Inbreeding depression was manifested as late abortion of some selfed seeds. Geitonogamous selfing is largely prevented by temporal separation of male and female functions within plants. This temporal separation, combined with population‐wide synchrony of flowering, may create unusual conditions allowing male plants at low frequency to match hermaphrodites in reproductive success.
FERTILIZATION AND ZYGOTE DEVELOPMENT IN THE BINUCLEATE DINOFLAGELLATE PERIDINIUM BALTICUM (PYRRHOPHYTA)
Authors: Chesnick Joby Marie , Cox Elenor R.
Published: January 2018

Peridinium balticum (Pyrrhophyta) exists as a symbiosis between a nonphotosynthetic dinoflagellate host and a chlorophyll c‐containing alga. It is hypothesized that P. balticum is an evolutionary link between primitive nonphotosynthetic and advanced photosynthetic dinoflagellates. This study documents pre‐ and postfertilization events of sexual reproduction in this unusual dinoflagellate for the first time. Light microscopy and TEM observations showed that gametes resemble vegetative cells except in the organization of their chloroplasts. Fusion of gametes occurred in a specific orientation, i.e., apical to sulcal area. The presence of an intact membrane between fusing pairs prior to plasmogamy was suggestive of enzymatic digestion of plates during fertilization. Rupture of this membrane triggers plasmogamy and karyogamy of the host, followed by that of the algal symbiont. A discussion of the cellular processes involved in gamete formation, fertilization, and zygote development is presented. The results of this investigation demonstrate that a synchronous sexual reproduction cycle has evolved for the symbiont and its dinoflagellate host.
EFFECTS OF POLLEN DONOR IDENTITY ON OFFSPRING QUALITY IN WILD RADISH, RAPHANUS SATIVUS
Authors: Marshall Diane L. , Whittaker Kellie L.
Published: January 2018

If pollen donor performance during mating correlates with differences in offspring growth and fitness, processes that sort among potential mates may directly improve offspring fitness. Here seeds sired by three pollen donors on ten maternal plants were grown for eight weeks in the greenhouse. The performance of the pollen donors during pollination and fertilization was known from a previous experiment. There were significant effects of paternity on two measures of early growth: leaf number and plant height. Paternal effects on three measures more closely related to fitness; final plant weight, day of first flower production, and total flower number were also significant. Under the conditions of this experiment, final plant weight was probably the best predictor of fitness. The pollen donor that sired the largest seeds in the previous experiment sired offspring that were largest after 8 weeks of growth. Half of the plants were grown under low‐water conditions. Paternal effects on growth were not masked by the environmental effects. In fact, some paternal effects became stronger under stress. This suggests that paternal effects could also be important in the field. Plants sired by donor A bolted very early when water was limited and would probably have an advantage in a season that was very short due to an early and severe drought. During fertilization and seed filling, seeds sired by this donor were more frequent on water‐stressed maternal plants than on control maternal plants (Marshall, 1988). The data from this experiment indicate a connection between pollen donor performance during mating and offspring growth. These results suggest that the processes that sort among potential fathers during pollination, fertilization, and seed filling, may improve offspring quality.
EFFECTS OF SALINITY, NITROGEN, AND POPULATION DENSITY ON THE SURVIVAL, GROWTH, AND REPRODUCTION OF ATRIPLEX TRIANGULARIS (CHENOPODIACEAE)
Authors: Drake Donald R. , Ungar Irwin A.
Published: January 2018

Populations of Atriplex triangularis were grown under laboratory conditions in a growth chamber and manipulated in an inland Ohio saline pond in order to examine the relative effects of salinity, nitrogen fertilization, and population density on growth, reproduction, and survival. For laboratory plants, nitrogen fertilization was the most important variable, with biomass and reproductive effort being greatest at the high nitrogen level. As salinity increased, biomass decreased only in plants not limited by nitrogen. Increasing density caused biomass per plant to decrease at both high and low nitrogen levels. For field plants, density was the most important variable, with biomass per plant and survival both decreasing as density increased. As density increased, size inequality among individuals increased but biomass per unit area and individual reproductive effort remained relatively constant. Nitrogen fertilization slightly enhanced survival, but did not affect biomass. It is suggested that density‐dependent processes may be significant even in relatively harsh physical environments.
JOHN HENRY SCHAFFNER (1866–1939) AND REDUCTION DIVISION IN PLANTS: LEGEND AND FACT
Authors: Troyer James R.
Published: January 2018

A persistent legend in the United States has maintained that John Henry Schaffner first observed the chromosomal mechanism of reduction division in plants but received no credit for this discovery. Subsidiary elements of the legend have held that Schaffner made his pioneering observations as a graduate student and as a result of conflict over them had to give up his studies without obtaining a doctoral degree. Although Schaffner himself and some of his close associates have claimed priority, historical and technical cytological discussions generally make no mention of him. This investigation includes an examination of original research literature relevant to the controversy over reduction which marked the years from about 1890 to about 1910. Although Schaffner did not discover all the details of meiotic chromosome behavior as later understood, in 1897 he was apparently the first to report for plants a qualitative reduction in the first division. He consistently repeated this report in three subsequent works. These results were strongly at variance with the views of leading botanical authorities. Analysis of the citation of Schaffner's publications by his contemporaries reveals a low recognition of him, especially by Eduard Strasburger and associates. Consideration of cultural and social factors operating in botany at the time sheds light on this situation. The proposal is advanced that it was largely through the influence of the Strasburger “school” that Schaffner initially failed to receive the credit that he merited, and that as a consequence this failure has been perpetuated in subsequent accounts. Subsidiary elements of the legend have bases in fact, although causal relations cannot be ascribed with certainty.
ULTRASTRUCTURE OF THE TRANSFER TISSUES DURING VIVIPAROUS SEEDLING DEVELOPMENT IN RHIZOPHORA MANGLE (RHIZOPHORACEAE)
Authors: Wise Robert R. , Juncosa Adrian M.
Published: January 2018

All water and nutrients required for the growth of the huge viviparous seedlings of Rhizophora mangle must be transported from the inner surface of the integument (maternal tissue), across a layer of persistent endosperm cells (seedling tissue), and to the surface of the cylindrical cotyledonary body. We describe the ultrastructure of these tissues at two functionally different stages of embryo and seedling development (i.e., 2–3 wk and 2–3 mo postgermination, respectively). Integumentary cells adjacent to the endosperm have unique plastids and divide more frequently than cells further away from the endosperm/integument interface. Later, fibrillar inclusions develop in vacuoles of the integument cells. The outermost layer of endosperm cells differentiates into transfer cells with wall ingrowths on the external walls, and the remainder of the endosperm degenerates during the embryo to seedling transition. The wall ingrowths gradually occlude the lumena of the transfer cells, a process which is complete long before the seedling abscises; therefore, the seedling may be photosynthetically independent throughout most of its development. The outer surface of the seedling cotyledonary body is minimally papillate and exhibits several ultrastructural specializations: centripetal degeneration of external walls which are bounded by electron‐dense deposits; numerous mitochondria; and plastids of unusual structure with many plastoglobuli, and which contain unique yellow pigments having absorption spectra characteristic of carotenoids. HPLC residence times of these pigments are unlike those of β‐carotene or other common carotenoids. Transfer tissues of Rhizophora may have functions not found in other plants, such as salt exclusion and facilitating viviparous germination, but the ultrastuctural correlates of these functions remain uncertain.
ULTRASTRUCTURAL CHANGES IN HAPLOID EMBRYOIDS OF LARIX DECIDUA DURING EARLY EMBRYOGENESIS
Authors: Rohr Rene , von Aderkas Patrick , Bonga Jan M.
Published: January 2018

Cultures of haploid tissue derived from megagametophyte tissue were investigated at various stages of embryoid development. At the earliest stage of development the cells were vacuolate and plastids and mitochondria were simple in structure. Eventually, embryonal domes were formed which in turn, produced suspensor cells. As the embryoid developed, its apical cells showed increased complexity of plastids, eventually developing chloroplasts and amyloplasts. In addition, the vacuolar volume in the cells was reduced, while vesicle production increased. Cristae in mitochondria became more apparent. In the suspensor cells, plastids remained as leucoplasts and amyloplasts without any internal membrane structures. Mitochondria became more developed and vesicle number increased in the long cells. Smooth endoplasmic reticulum, which was the most common form of this class of membrane, was reduced by the cotyledonary stage and replaced by rough endoplasmic reticulum. Phenolic deposits appeared with maturation of the suspensor, and an extracellular matrix of PATAg (Thiery) positive polysaccharide was detected between the cells.
ANALYSIS OF REVEGETATION DYNAMICS ON THE VOLCANO USU, NORTHERN JAPAN, DEFORESTED BY 1977–1978 ERUPTIONS
Authors: Tsuyuzaki Shiro
Published: January 2018

Vegetation dynamics were monitored from 1983 to 1987 near the summit of the volcano Usu which had almost completely been deforested by 1–3 m thick volcanic deposits in 1977–1978. A permanent quadrat survey for five years confirmed the high mortality of seedlings. Since seedling mortality appeared mostly due to the frequent erosion of the volcanic deposits, ephemeral annuals and well‐rooted perennials or woody plants were successful here. The high mortality of seedlings resulted in intensive fluctuation of plant density in all habitats. However, owing to the expansion of perennials, once they became established, the plant cover increased from year to year. In particular, Polygonum sachalinense and Petasites japonicus var. giganteus, seeds of which were frequently provided from their community vegetatively recovered on the wall of the caldera rim soon after the eruptions, were remarkably contributive to the revegetation. The excavation of those perennial plants demonstrated that they were derived not only from the seeds but also vegetatively from the old stumps buried in the former topsoil by extending their rhizomes up to the present ground surface.
VARIATION IN LEAFLET MORPHOLOGY AMONG POPULATIONS OF CARIBBEAN CYCADS (ZAMIA)
Authors: Newell Sandra J.
Published: January 2018

Caribbean cycads (Zamia L.) are well known for variation in leaflet morphology. Here, I examine the variation in leaflet morphology among five populations of Zamia in Florida. Variables measured were leaflet length and width, leaflet length: width ratio, leaflet surface area, rachis and petiole lengths, number of leaflets per leaf, and total leaf area. In addition to comparisons among the Florida populations, these populations are compared with three previously studied populations in Puerto Rico (Newell, 1986). For the most part, the populations exhibited significant differences in all variables. In spite of the extensive morphological variation in this group of plants, leaflet morphology has long been important in Zamia taxonomy. The Florida populations would be considered by some to be either one, two, or three different species. The Florida and Puerto Rico populations together might be considered as few as one species or as many as five species. Based upon the data presented here, the five Florida populations appear to represent a single species; and the three Puerto Rico populations appear to represent two additional species. Further clarification of the taxonomy of Caribbean Zamia will require additional characters such as cone morphology and protein or DNA patterns.
GENOTYPIC VARIATION AND INTEGRATION IN HISTOLOGICAL FEATURES OF THE GOLDENROD BALL GALL
Authors: Weis Arthur E. , Wolfe Cheryl L. , Gorman Wendy L.
Published: January 2018

The herb Solidago altissima (Compositae) forms a gall when attacked by the fly Eurosta solidaginis (Diptera: Tephritidae). We performed an experiment to determine how histological features of gall morphology contribute to previously observed genetic variation in gall diameter. Galls induced on 10 replicated plant clones were sectioned, and their internal tissues and cells measured. Four concentric tissue zones were identified, including a cytoplasmically rich tissue lining the insect's central chamber, and a cytoplasmically poor cortex. As expected, outer gall diameter differed among clones, with a broad sense heritability of 0.29. However, clonal differences for component tissue thicknesses were found for only two of the zones; cortex thickness showed the greater genotypic variation, with a broad sense heritability of 0.30. Path analysis was used to examine the contribution of the zone thicknesses, vascular supply and cell sizes to outer gall diameter at the phenotypic, genotypic and environmental‐developmental levels. These showed that cortex thickness was the single greatest determinant of gall size. At the phenotypic level, the single most important determinant of cortex thickness was the number of cortical cells, whereas the amount of cortical vascularization was second in importance. But, at the genotypic level of analysis, vascularization was the single most important determinant of genotypic differences in gall size. The larger the gall, the greater the protection to the inducing insect. Since the bulk of the gall consists of large, cytoplasmically poor cells, the insect gains protection while imposing a small cost on the plant.
POPULATION DIFFERENTIATION FOR PHENOTYPIC PLASTICITY IN THE STELLARIA LONGIPES COMPLEX
Authors: Macdonald S. Ellen , Chinnappa C. C.
Published: January 2018

Population differentiation for phenotypic plasticity of 12 morphological and reproductive traits was investigated in five populations of the Stellaria longipes complex including a population of the sand dune endemic S. arenicola. Population differentiation was detected for the mean (genotypic) value, amount of plasticity, and pattern of plasticity of traits. Average amount of plasticity was not related to degree of isozyme variability in the populations. Differentiation for pattern of plasticity was much more common than for amount. The direction and extent of divergence among populations was dependent on which of the three trait aspects was under consideration (mean, amount of plasticity, pattern of plasticity) and did not reflect their similarity as revealed by enzyme electrophoretic data. It was concluded that trait means, amounts of plasticity, and patterns of plasticity are independent of one another during evolutionary divergence and may be influenced by mosaic selection.