bluuebunny/crossref_metadata_2025 huggingface dataset:
POPULATION STRUCTURE IN ZAMIA DEBILIS (ZAMIACEAE) I. SIZE CLASSES, LEAF PHENOLOGY, AND LEAF TURNOVER
Authors: Negrón‐Ortiz Vivian , Breckon Gary J.
Published: January 2018

Population structure, leaf phenology and leaf turnover were followed over a 29‐month period in Zamia debilis L.f. ex Aiton (Zamiaceae), an understory species in the Cambalache Forest in northern Puerto Rico. It was not possible to determine plant age or to measure the subterranean stems; size classes based on leaf number and leaf × leaflet number indices were used to determine population structure. Despite seasonal and year to year fluctuations in leaf number at the individual and population level, population profiles remained relatively constant. At any one time, over 50% of the population was composed of unbranched individuals with one or two leaves. Only 7% of the plants were branched. Plants with seven or more leaves comprised at a maximum 8% of the population, but accounted for 28% of the total foliage. Size classes based on leaf number and on a leaf × leaflet index gave approximately reverse J‐shaped curves typical of trees with shade tolerant seedlings and saplings. New leaves emerged throughout the year, with a peak at the beginning of the rainy season in May or June and lowest production during the dry months of February through April. Average leaf life expectancy was approximately 2.3 years. Leaf death occurred over an extended period of time by the loss of individual leaflets. Patterns in leaf production and loss differed between few‐ and many‐leaved plants. On the average, as the number of mature leaves on a plant increased, time between emergence of new leaves decreased. In many‐leaved plants more than one event of new leaf emergence per year was common. Individuals with one to three mature leaves and individuals with four or more mature leaves differed in their response to water stress: few‐leaved plants generally reduced the rate of new leaf production and retained old leaves longer. Plants with more than three leaves continued to produce new leaves, but the rate of leaf mortality increased so that most had a net leaf loss. There was no evidence that leaf emergence or retention were affected by cone production or seed maturation.
ADVENTITIOUS ROOT DEVELOPMENT IN TYPHA GLAUCA, WITH EMPHASIS ON THE CORTEX
Authors: Seago James L. , Marsh Leland C.
Published: January 2018

Adventitious root development was investigated in Typha glauca plants grown under experimental conditions with the previous year's dead, sterile stalk either emerged above or submerged below the surface of Hoagland's solution. Adventitious roots emerged from buds in which most primordia had been earlier formed. Most roots elongated to 14–19 cm in 3–4 weeks and produced abundant lateral roots to their tips. Root apical meristem organization was typically monocotyledonous with a single tier of ground meristem/protoderm over the procambium. The ground meristem had zones of periclinal divisions in its innermost and outermost layers; the innermost layer initiated the endodermis and midcortex, and the outermost layers initiated the hypodermis. Crystalliferous cells with raphides were produced in the midcortex, and aerenchyma resulted from the radial expansion of schizogenous air spaces and some lysigeny in the midcortex. The procambium produced a vascular cylinder with 10–13 phloem and xylem poles, 6–9 large metaxylem elements, and central sclerenchyma. As roots stopped elongating, they narrowed, the vascular cylinder diminished in size, typical aerenchyma was lost from the cortex, crystal production ceased, and the rootcap diminished in size with its storage starch used up. Growth was determinate in these adventitious roots. The results suggested that a periclinally derived outer ground meristem was a prerequisite for a hypodermis, which, in turn, was necessary as a structural framework for aerenchyma. Without a hypodermis, typical aerenchyma was not present.
WOOD SPECIFIC GRAVITY GRADIENTS IN TROPICAL DRY AND MONTANE RAIN FOREST TREES
Authors: Wiemann Michael C. , Williamson G. Bruce
Published: January 2018

Pith to bark specific gravity (SG) trends were investigated in 18 tropical dry forest and six montane rain forest tree species of Costa Rica. Eleven dry forest species showed statistically significant increases in SG with distance from pith. The increases ranged from 20–80%; the greatest changes were exhibited by species which are known to occur in tropical wet as well as tropical dry forests. The other seven species showed no change in SG with distance from pith. Of the montane forest species, one showed a significant decrease of 20%, and three showed significant increases ranging from 20–40%. Two species exhibited no change in SG. Comparison of these changes with trends found in tropical wet forest and temperate forest suggests that the increase in SG with size is most common in tropical wet forest, least common in temperate forest, and intermediate in tropical dry and montane forests.
WITHIN‐ AND AMONG‐TREE VARIATION IN FLOWER AND FRUIT PRODUCTION IN TWO SPECIES OF CARYA (JUGLANDACEAE)
Authors: McCarthy Brian C. , Quinn James A.
Published: January 2018

The patterns of variability in the production of staminate inflorescences, pistillate flowers, and fruits forCarya ovata(Mill.) K. Koch andC. tomentosa(Poir.) Nutt. at Hutcheson Memorial Forest (Somerset County, New Jersey) were examined over a four‐year period. We sought to determine 1) the patterns of variability in flowering and fruiting (within‐trees, among‐trees, and between‐years), 2) if variable flowering might account for observed nut‐bearing patterns, and 3) what were the relative contributions of intrinsic (genetic) and/or extrinsic (environmental) factors in determining flower production and fruit set. In general, our fine‐scale analysis of shoots within canopies did not reveal a distinct mast fruiting pattern. While the number of male and female flowers varied significantly (among trees and between years), fruit set was not markedly affected. Variability of flowering and fruiting among shoots within trees was low. Both flowering and fruiting were observed to have a strong genetic and/or microenvironmental basis; however, flowering appeared more plastic and thus more sensitive to yearly environmental vagaries than did fruiting. Favorable environmental conditions at the time of flower differentiation may result in increased flower production; but, this does not necessarily result in increased fruit set. Many pistillate flowers abscise around the time of pollination and fertilization, apparently adjusting fruit set to available shoot resources. Approximately 50% of the pistillate flowers of both species fail to set fruit. Overall, individual trees exhibit their own flowering and fruiting schedules, suggesting the need to account for this level of variability in future studies of mast fruiting.
EXPERIMENTAL STUDIES OF PONDEROSA PINE. III. DIFFERENCES IN PHOTOSYNTHESIS, STOMATAL CONDUCTANCE, AND WATER‐USE EFFICIENCY BETWEEN TWO GENETIC LINES
Authors: Monson Russell K. , Grant Michael C.
Published: January 2018

As part of an intensive study of heritable differences among the progeny of Pinus ponderosa parents from two contrasting habitats (coastal vs. interior, continental), we examined the potential for differences in photosynthesis rate, stomatal conductance, and photosynthetic water‐use efficiency. Plants from a cross between two coastal parents (ponderosa × ponderosa) exhibited lower photosynthetic water‐use efficiencies, relative to plants from a coastal × interior cross (ponderosa × scopulorum). The lower water‐use efficiencies in the ponderosa × ponderosa plants were evident as a lower ratio of external to intercellular CO2 concentrations and higher stomatal conductances at any given rate of photosynthesis. The ponderosa × scopulorum plants exhibited lower stomatal conductances over a range of leaf‐to‐air water vapor concentration differences, which was partially explained by lower stomatal densities. The ponderosa × scopulorum plants also exhibited lower maximum photosynthesis rates and lower needle nitrogen concentrations. Taken together, the results suggest that in adapting to drier habitats, P. ponderosa has acquired improved water‐use efficiencies and lower transpiration rates, but at the expense of reduced maximum photosynthesis rates.
POLLINATION BIOLOGY OF PLATANTHERA STRICTA (ORCHIDACEAE) IN OLYMPIC NATIONAL PARK, WASHINGTON
Authors: Patt Joseph M. , Merchant Mark W. , Williams ew R. E. , Meeuse Bastiaan J. D.
Published: January 2018

Platanthera striata Lindley is entomophilous and can produce seed via facultative self‐pollination and intraracemic and interracemic pollination. Capsule production is pollinator‐limited and seed set may be pollen‐limited. In experimental plants capsules produced via self‐ and intraracemic pollination contained fewer seeds with normally developed embryos than did capsules produced via interracemic pollination. The inflorescence of Platanthera stricta is fragrant and is attractive to a wide array of anthophilous insects. It is pollinated by a diverse assemblage of short‐tongued insects. The primary pollinators are Eustroma fasciata B. and McD. (Lepidoptera: Geometridae), Bombus flavifrons Cresson and B. melanopygus Nylander (Hymenoptera: Apidae), an undescribed species of Greya (Lepidoptera: Prodixidae), and several species of Empis, Rhamphomyia, and Anthepiscopus longipalpis Melander (Diptera: Empididae). Small amounts of glucose are present on the raceme. The extrafloral glucose may retain small pollinators on the inflorescence until they locate the floral spur aperture.
EXTENSIVE GENE DUPLICATIONS IN DIPLOID EUPATORIUM (ASTERACEAE)
Authors: Yahara Tetsukazu , Kawahara Takayuki , Crawford Daniel J. , Ito Motomi , Watanabe Kuniaki
Published: January 2018

An electrophoretic study of isozyme number for seven soluble enzymes revealed extensive gene duplications in eight diploid species of American Eupatorium belonging to three morphological groups. The enzymes isocitrate dehydrogenase, phosphoglucomutase, phosphoglucose isomerase, 6‐phosphogluconate dehydrogenase, and shikimate dehydrogenase occur as three to six isozymes in all species, whereas the minimal conserved number typical of diploid plants is two isozymes for each. Fructose 1, 6‐biphosphate aldolase is expressed as multibanded pattern suggesting fixed heterozygosity in all examined species. It was not possible to document gene duplication for triosephosphate isomerase from the electrophoretic patterns. All species examined have a chromosome number of 2n = 20, which has been regarded as the basic diploid number for Eupatorium. However, the detection of extensive duplications suggests that 2n = 10 may be the original diploid chromosome number in Eupatorium and that plants with 2n = 20 are of polyploid origin. This hypothesis would mean that extensive duplications at isozyme gene loci have been maintained since the origin of the genus, despite chromosomal diploidization having occurred.
FLORAL DEVELOPMENT OF COCHLOSPERMUM TINCTORIUM AND BIXA ORELLANA WITH SPECIAL EMPHASIS ON THE ANDROECIUM
Authors: Decraene Louis P. Ronse
Published: January 2018

The initiation and development of the flower of Bixa orellana L. and Cochlospermum tinctorium A. Rich, were investigated using the scanning electron microscope to elucidate the nature of the androecial development and the relationships of both taxa. Initiation of floral buds starts with the inception of five sepals in a 2/5 sequence between two bracteoles. The petals are formed successively on the irregular pentagonal apex in a phyllotactic pattern different from that of the calyx. Stamen development proceeds centrifugally on a broad circular primordium or ringwall, which attains its final size at the time of initiation of individual stamens. Stamen primordia arise in successive whorls without connection to the perianth. The residue of the apex is differentiated into a gynoecial circular primordium. In Cochlospermum 3 to 4 carpels are initiated; in Bixa no individual carpels are visible. The origin of the androecial circular primordium is discussed in relation to other types of androecial development. A comparison is made with existing theories of the evolution of multistaminate androecia. Few differences were found in the floral development of Bixa and Cochlospermum, except in the gynoecium. It is proposed to retain them in a single family Bixaceae for a number of reasons. The floral development supports a thealean, dillenialean, or violalean affinity rather than a malvalean. The inception of a broad androecial circular primordium is highly different from the development in Malvales, where more space for stamens is provided by the continuous growth of a tube.
GYNODIOECY IN SILENE VULGARIS (CARYOPHYLLACEAE): PROGENY SUCCESS, EXPERIMENTAL DESIGN, AND MATERNAL EFFECTS
Authors: Jolls Claudia L. , Chenier Thomas C.
Published: January 2018

This study documents the comparative success of seeds and seedlings of the perennial gynodioecious‐gynomonoecious weed,Silene vulgaris, in the greenhouse. The importance of experimental design is stressed by comparing two different statistical analyses of the data. Seeds were obtained from artificial pollinations in the field: self‐fertilization of hermaphrodites, and cross‐fertilizations of both hermaphrodites and females. One‐way analysis of variance using progeny type (selfed hermaphrodites, outcrossed hermaphrodites, and outcrossed females) as the treatment effect for each seed and seedling variable showed statistically discernable differences among progeny from different cross types. The significance of this type of ANOVA resulted from a reduced error term and positively‐biasedFratios. A factorial design showed no significant differences due to type of progeny in seed mass, days to germination, leaf number, area, or biomass at six weeks of age. There were, however, significant differences among seeds attributable to maternal parent for all seed and seedling variables. A higher proportion of seeds from outcrossed individuals germinated compared to that from self‐fertilization. When the data were analyzed to include and partition all sources of variation, differences among offspring appeared during germination, rather than during later development. Seed mass, cross type, and sex of maternal parent all significantly affected the likelihood of germination; however, they had decreasing predictive power, respectively. Inbreeding depression inSilene vulgarismay help maintain gynodioecy; however, the pleiotropic effects of both nuclear and cytoplasmic genes for sex expression also may affect fitness and the maintenance of females.
INFLUENCE OF THE PISTIL ON POLLEN TUBE KINETICS IN PEACH (PRUNUS PERSICA)
Authors: Herrero Maria , Arbeloa Arancha
Published: January 2018

Pollen tube growth has been studied in peach and has been related to changes in the pistil structures which the pollen tube has to traverse in its way from the stigma down to the ovule. Growth of the pollen tubes along the pistil is not continuous. While pollen tubes reach the base of the style 7 days after pollination, fertilization does not take place until 12 days later. Pollen tubes stop for 5 days at the top of the obturator and they further stop for 3 days before entering the ovule. The pollen tube growth is heterotrophic; starch, present all along the pistilar tract at anthesis, vanishes as the pollen tubes pass by. Discontinuous pollen tube growth appears to be controlled by the pistil. At anthesis the pistil is not fully matured. Maturation of the pistil implies a number of secretory processes that occur in a basipetal way starting from the stigma down to the style and ending in the ovule. Some of these secretions at the stigma and the style are triggered by pollination; others appear to be a maturative stage of the pistil and are produced in a discrete way. The fact that the pollen tube depends on these secretions together with the fact that these secretions are not continuously produced confer upon the pistil a role of controlling pollen tube kinetics and point out that, for a successful fertilization, male gametophyte development and pistil maturation need to by synchronized.
VARIATION IN VESSEL LENGTH AND DIAMETER IN STEMS OF SIX TROPICAL AND SUBTROPICAL LIANAS
Authors: Ewers Frank W. , Fisher Jack B.
Published: January 2018

Within‐species and within‐stem variation in vessel diameter and total vessel length were examined using the latex paint method on six species of tropical and subtropical lianas (woody vines). Narrow vessels were almost always rather short, but wide vessels ranged from short to long. Within Pithecoctenium crucigerum, larger diameter stems tended to have longer as well as wider vessels, with a maximum vessel length and width of 6.25 m and 366 μm, respectively. Within stems of Saritaea magnifica, P. crucigerum, Hippocratea volubilis, and Vitis rotundifolia, narrow vessels had lower mean, median, and maximum vessel lengths than wide vessels. Vessels with intermediate diameters tended to have intermediate lengths. In Stigmaphyllon ellipticum and Bauhinia fassoglensis the outer system of secondary xylem tended to have longer as well as wider vessels than the inner system. Those narrow vessels (<50 μm) that did occur in the outer system were short (<0.20 m), and were similar in length and diameter to those of the inner system.
PHYLOGENETIC IMPLICATIONS OF INFLORESCENCE AND FLORAL ONTOGENY OF MIMOSA STRIGILLOSA
Authors: Ramírez‐Domenech José I. , Tucker Shirley C.
Published: January 2018

Ontogeny of the inflorescence and flower of Mimosa strigillosa has been studied in order to explore the developmental basis for variation in number of parts, patterns of organ arrangement, and inflorescence architecture. Each racemose inflorescence of M. strigillosa has an acropetal order of initiation of bracts and flowers. Although flowers are initiated in acropetal order, they develop synchronously except for the basal flowers, which are retarded. The ring meristem in the calyx may be considered an expression of precocious fusion, a specialized condition within the genus. Two patterns of organ arrangement (nonsagittal and median sagittal) are distributed among 4‐ and 5‐merous flowers along the inflorescences. Variability in number of parts probably has evolved through reduction of a basic, pentamerous structure, through fusion or suppression. It is proposed that the number of parts and pattern of organ arrangement are correlated features.
EMBRYOLOGY OF CALYPSO BULBOSA. I. OVULE DEVELOPMENT
Authors: Law Sandra K. , Yeung Edward C.
Published: January 2018

Calypso bulbosa is a terrestrial orchid that grows in north temperate regions. Like many orchids, the Calypso has ovules that are not fully developed at anthesis. After pollination, the ovule primordia divide several times to produce a nucellar filament which consists of five to six cells. The subterminal cell of the nucellar filament enlarges to become the archesporial cell. Through further enlargement and elongation, the archesporial cell becomes the megasporocyte. An unequal dyad results from the first meiotic division. A triad of one active chalazal megaspore and two inactive micropylar megaspores are the end products of meiotic division. Callose is present in the cell wall of the megaspore destined to degenerate. In the mature embryo sac the number of nuclei is reduced to six when the chalazal nuclei fail to divide after the first mitotic division. The chalazal nuclei join the polar nucleus and the male nucleus near the center of the embryo sac subsequent to fertilization.
EFFECT OF LEAF ANGLE AND ORIENTATION ON PHOTOSYNTHESIS AND WATER RELATIONS IN SILPHIUM TEREBINTHINACEUM
Authors: Smith Marian , Ullberg ew
Published: January 2018

Leaf angle and orientation were measured for 217 leaves from two populations of Silphium terebinthinaceum Jacq., a prairie forb with large, unlobed leaves. Seventy‐five percent of leaves measured had an angle of deviation from horizontal of more than 60°, and 60% were oriented within 15° of North. Incident Photon Flux Density (PFD), leaf temperature, photosynthesis, stomatal conductance to CO2, internal CO2 concentration, transpiration, and water use efficiency (WUE) were measured on 67 pairs of leaves with the axes oriented in either a North‐South (N–S) or East–West (E–W) direction. Leaves with axes oriented N–S intercepted higher levels of PFD during morning and afternoon and exhibited higher diurnal rates of photosynthesis and WUE. Leaf temperature was reduced in N–S leaves during midday as compared to E–W leaves, and was lower in vertical leaves than in those in a horizontal position. Therefore, it was concluded that leaf orientation and verticality enhance carbon gain and minimize water loss—characteristics which may have adaptive significance in a hot, stressful prairie environment.
MORPHOLOGICAL STUDIES OF THE NYMPHAEACEAE SENSU LATO. XVII. FLORAL ANATOMY OF ONDINEA PURPUREA SUBSPECIES PURPUREA (NYMPHAEACEAE)
Authors: Williamson Paula S. , Moseley Maynard F.
Published: January 2018

Classification and phylogeny of the Nymphaeaceae are unresolved. This study provides floral anatomical data that will assist in elucidating generic interrelationships and systematic relationships to other taxa of angiosperms. The floral anatomy of Ondinea purpurea den Hartog subsp. purpurea has been examined utilizing light microscopy. The peduncle possesses stelar vascular bundle complexes and cortical vascular bundles. Cortical bundles terminate within the peduncle. Each bundle complex consists of 2 collateral bundles on the same radius, the inner bundle inverted; 2 protoxylary lacunae occur yet differ in structure and function. Progressing acropetally, the inner xylary lacunae become discrete mesarch strands surrounded centrifugally by a vascular cylinder formed by divisions and anastomosing of the bundle complexes. Together these become the massive receptacular vascular plexus. The plexus provides collateral traces to the floral organs. Each sepal receives 3 traces that separate from the plexus as 1–3 lateral traces. Petals are absent and no vestigial petal traces have been observed. Distally, the plexus forms several large strands of connate gynoecial and androecial traces termed the principal vascular bundles (PVBs). Ventral veins separate from the PVBs and the latter extend acropetally through the outer ovary wall. Branches of the ventrals and PVBs contribute to septal vascular reticula from which each ovule is supplied by one vascular bundle. Each stamen receives 1 trace from branches of the PVBs. The ventrals and PVBs terminate within the carpellary lobes. A comparative anatomical study is offered that supports the inclusion of Ondinea in the Nymphaeaceae sensu stricto.
GENETIC DIVERSITY, INTROGRESSION, AND INDEPENDENT DOMESTICATION OF OLD WORLD CULTIVATED COTTONS
Authors: Wendel Jonathan F. , Olson Paul D. , Stewart James McD.
Published: January 2018

Gossypium arboreum L. and G. herbaceum L. are the diploid species of cultivated cotton. Little is known regarding the time and place of domestication of either species. Because G. arboreum is known only as a cultigen, others have proposed that it arose from domesticated G. herbaceum during the more than 5,000‐year history of Old World cotton cultivation, with wild G. herbaceum subsp. africanum (Watt) Mauer as the putative ancestor of both species. An alternative hypothesis is that the two species have independent origins from progenitors that diverged prior to domestication. The relative merits of these opposing hypotheses were evaluated using data derived from starch gel electrophoresis of enzymes. One hundred and three accessions of G. arboreum and 31 accessions of G. herbaceum were examined for allelic variation at 40 allozyme loci. All measures of genetic variability demonstrated that G. arboreum contains greater diversity than G. herbaceum, although both species have relatively low levels of allozyme variation. In contrast to expectations based on morphology and other chemical data sets, the two species are highly differentiated with respect to allozyme composition. Gossypium arboreum and G. herbaceum each contain a large number of unique alleles and are fixed or nearly fixed for alternate alleles at 8 loci. Five allozyme loci have alleles that are rare in one of the two species but common in the other. Based on restricted occurrence of these alleles to areas with a long history of sympatric cultivation and the geographic distribution of a null allele, we suggest that a significant portion of the allelic diversity in both species results from historical, bidirectional interspecific introgression. The interspecific genetic identity estimate (0.74) is markedly lower than for documented progenitor‐derivative and crop‐ancestor species pairs. Based on these data, as well as previous cytogenetic data and the observation of F2 breakdown in interspecific crosses, we suggest that cultivated G. arboreum and G. herbaceum were independently domesticated from divergent ancestors.
MICROSPOROGENESIS IN PEANUT (ARACHIS HYPOGAEA)
Authors: Willcox Martha C. , Reed Sandra M. , Burns Joyce A. , Wynne J. C.
Published: January 2018

The stage of pollen development at the time of anther culture is an important factor in the production of haploids. The objectives of the current study were to develop a staining procedure for peanut (Arachis hypogaea L., ssp. hypogaea) microspores, to describe and document the stages of microsporogenesis in peanut, and to confirm a previous report concerning correlations of peanut floral bud shape with stage of microspore development. A staining procedure using propionic carmine provided adequate staining of pollen mother cells, microspores, and pollen. Pollen mother cells and microspores could easily be differentiated by their size and cell wall structure. Plants grown in a controlled environment were found to have highly synchronized microspore development, both within an anther and among anthers contained in the same bud. In addition, floral bud shape was confirmed as a reliable indicator of anther stage in peanuts.
COMPARATIVE GAS EXCHANGE OF LEAVES AND BARK IN THREE STEM SUCCULENTS OF BAJA CALIFORNIA
Authors: Franco‐Vizcaíno Ernesto , Goldstein Guillermo , Ting Irwin P.
Published: January 2018

Arborescent stem succulents in tropical and subtropical deserts depend on scarce and uncertain rainfall. Gas exchange and the diurnal acidity fluctuation of bark and ephemeral leaves were measured under both dry and moist soil conditions in Fouquieria columnaris (cirio or boojum tree) and Pachycormus discolor (torote bianco or elephant tree) and in stems of the columnar cactus Pachycereus pringlei (cardon) in the Central Desert of Baja California, Mexico. Results demonstrated that ephemeral leaves were the only site of exogenous CO2 assimilation in F. columnaris and P. discolor; there was no measurable gas exchange across the green photosynthetic bark. The pattern of gas exchange in F. columnaris and P. discolor was consistent with that of C3 plants. P. pringlei was shown to be a typical Crassulacean acid metabolism plant on the basis of acid fluctuations and gas exchange. Chlorophyll fluorescence studies of the green bark of F. columnaris and P. discolor indicated that this tissue is photosynthetically functional, and that CO2 assimilation can rise above the compensation point under high CO2 concentrations, such as may occur within the plant. The green photosynthetic bark of these species may be an adaptation for surviving prolonged drought and may function to recycle endogenous respiratory CO2, thus maintaining the plant's energy reserves and permitting rapid production of leaves in response to infrequent rains.
INFLORESCENCE SIZE AND FRUIT DISTRIBUTION AMONG INDIVIDUALS IN THREE ORCHID SPECIES
Authors: Calvo Ricardo N.
Published: January 2018

Fruit distribution among individuals in populations of three orchid species was analyzed. Fruit set was low in the three species. The distribution of fruits in the non‐autogamous species was skewed to the right, with high variance: mean ratios, and a moderate to high proportion of fruitless plants. Larger inflorescence size did not necessarily result in an increase in percent fruit set but tended to increase the probability to produce at least one fruit. Pollinator‐mediated selection on inflorescence size through fruit production may be limited by the low overall level of visitation and the resulting uncertainty of pollination at the individual level.
TRANSLOCATION IN POLYTRICHUM COMMUNE (BRYOPHYTA). II. CLONAL INTEGRATION
Authors: Thomas Robert J. , Schiele Edwin M. , Damberg Douglas T.
Published: January 2018

Polytrichum commune is a perennial moss that grows by rhizomatous production of interconnected shoots. It possesses a well‐developed internal system of food‐conducting tissue. Liquid scintillation determinations following pulse‐14CO2 treatment of a single shoot in rhizomatously connected groups indicate that tagged photoassimilates are transported into:1) newly developing stems during the early growing season; 2) shared rhizomes (with an increase observed in rhizome allocation toward the end of the year, as well as a year‐end percentage increase in starch reserves); and 3) mature neighboring shoots. Over the course of the growing season, photoassimilate export from pulse‐labeled shoots ranges between 12.9% and 21.4% of total tagged. The amount of export is significantly influenced by defoliation, shading, stem tip removal, and 50 ppm indole‐3‐acetic acid treatments performed on rhizomatously connected neighbor shoots. Physiological integration within P. commune can be inferred from these results. Control is exerted by endogenous hormones or by changes in the activity of sources and sinks.
PATTERNS AND PROCESSES IN THE DEVELOPMENT OF THE HIGH ANDEAN FLORA
Authors: Simpson Beryl B. , Todzia Carol A.
Published: January 2018

Previous work has suggested that the floras of the separate regions of the high Andes are the products of disparate geographical, ecological, and geological factors. Among the important factors that differ among the regions are distances from source areas of propagules, climates, and differential effects of Pleistocene glaciations. To ascertain the relative importances of these factors in shaping the modern floras, and to test hypotheses about the causes of observed generic diversity patterns, models of abundances of species per genus were tested against data from three samples representing the major vegetation zones of the high Andes (páramo, puna, and austral alpine). While originally proposed for intraspecific phenomena, abundance models (broken stick, log normal, geometric series, and log series) appear to be applicable to supraspecific taxa and were used to assess alternative hypotheses. Potential sources of genera now present in the sample areas were compared, and coefficients of similarity were computed between these samples and between each of them and two North American high‐elevation floras. Propagule types in the three Andean samples were also scored to see if methods of fruit dispersal differed. Results showed that all areas fit the geometric series model if abundance plots of ranked genera were compared, but these results were heavily influenced by the large number of genera represented by only one species. Both the puna and austral alpine samples fit the log series models, indicating that the habitats of these areas are relatively uniform and that arrival of propagules was random over time. The lack of a fit of the Colombian data to the log series or log normal models is due primarily to a large number of species‐rich genera relative to other areas. These findings support the hypothesis that there has been a pronounced level of autochthonous speciation in the Colombian Andes relative to other areas. Coefficients of similarity at the generic level show that a given flora is most similar to that of the nearest sample area within the same continent. However, the floristic similarity between Tierra del Fuego and the high mountains of Colorado is as high as that between the Tierra del Fuego sample and the neighboring Argentina sample, indicating that similarities in climate can be as important as distance in determining the composition of some Andean floras.
SEXUAL TETRAMORPHISM IN THYMELAEA HIRSUTA (THYMELAEACEAE): EVIDENCE OF THE PATHWAY FROM HETERODICHOGAMY TO DIOECY AT THE INFRASPECIFIC LEVEL
Authors: Dommée Bertrand , Bompar Jean‐Louis , Denelle Nicole
Published: January 2018

After more than 5 years of study on natural populations of Thymelaea hirsuta (L.) Endl. (Thymelaeaceae), four distinct sexual phenotypes are shown to occur: protogynous, protandrous, subandroecious (male), and subgynoecious (female) individuals. The four populations studied differ significantly in the relative abundance of sexual types. Plant size and sexual phenotype are independent in three populations. Each sexual form produces viable seeds. Growth and morphogenesis of the aerial vegetative and sexual parts are described and found not to be related to sexual phenotype. The system, called sexual tetramorphism, combines characteristics of subdioecy (subandroecious and subgynoecious individuals) and heterodichogamy (protogynous and protandrous individuals). High fruit production in females and protandrous plants vs. low fruit production in males and protogynous plants provides evidence of a strong tendency toward functional dimorphism. The probable specialization of protogynous types toward the male function and the obvious specialization of protandrous types toward the female function suggest an evolution from heterodichogamy to dioecy, sexual tetramorphism being the intermediate stage. Tetramorphism in T. hirsuta provides further support for the hypothesis of an evolutionary pathway from heterodichogamy to dioecy.
ROLE OF CALCIUM IN THE CALLOSE RESPONSE OF SELF‐POLLINATED BRASSICA STIGMAS
Authors: Singh Anuradha , Paolillo Dominick J.
Published: January 2018

In Brassica oleracea, sporophytic self‐incompatibility prevents germination of self pollen, or normal growth of self pollen tubes. After self‐pollination, the papillae of stigmas synthesize callose. The role of Ca++ in the formation of stigmatic callose was tested by adding compounds that interact with Ca++ to suspensions of pollen that were known to induce callose formation in self stigmas. The calcium channel antagonist, lanthanum, and the calcium chelating agent, EGTA, reduced or abolished the callose response to self‐pollen suspensions. In the presence of Ca++, the calcium ionophore, A23187, induced callose in stigmatic papillae when added to pollen suspensions, or alone. Therefore, callose deposition in response to incompatible pollinations appears to be a calcium‐dependent process. Pretreatment of pistils with 100 μm 2‐deoxy‐D‐glucose abolished the callose response to self‐pollination, while self pollen remained inhibited and cross pollen grew normally in treated pistils. Thus, callose formation in the stigma is not an essential part of the self‐incompatibility mechanism preventing the growth of self pollen in Brassica.
COMPARISON OF TETRAPLOID AND SINGLE GENE‐INDUCED GIGAS VARIANTS IN CHICKPEA (CICER ARIETINUM). I. ORIGIN AND GENETIC CHARACTERIZATION
Authors: Davis Thomas M. , Matthews Leslie J. , Fagerberg Wayne R.
Published: January 2018

Two genetic variants with increased organ size were independently derived from diploid (2n = 2x = 16) chickpea (Cicer arietinum L.) line ICC 640. Radiation‐induced mutant PM1101 had greatly enlarged leaves, leaflets, and pods, and an elongated stem with longer internodes but fewer nodes than ICC 640. F1, F2, and F3 data from crosses with ICC 640 showed that the mutant characteristics of PM1101 were the pleiotropic effects of a single, recessive genetic factor. For purposes of comparison, tetraploid derivatives of ICC 640 were produced by colchicine treatment of seed. In the tetraploids, leaflets and pods were enlarged, but less dramatically than in PM1101. Enlarged pollen grains and stomatal guard cells, and increased guard cell chloroplast number were found in tetraploids but not in PM1101, while both variants produced fewer seeds than ICC 640. Mutant PM1101 and the tetraploids represent two very different manifestations of gigantism in chickpea.
COMPARISON OF TETRAPLOID AND SINGLE GENE‐INDUCED GIGAS VARIANTS IN CHICKPEA (CICER ARIETINUM). II. MORPHOLOGICAL AND ANATOMICAL LEAF CHARACTERS
Authors: Fagerberg Wayne R. , Davis Thomas M. , Matthews Leslie J.
Published: January 2018

Two genomic variants of a chickpea (Cicer arietinum L.) parental line have been developed which exhibit gigas characters. The two genotypes were the result of a single‐gene mutation (gigas) and induced tetraploidy of a single parental line. The two genotypes plus parental strain were investigated to determine the similarity‐of‐effect of polyploidy and this single‐gene mutation on leaf anatomy and morphology. Leaves consisted of two rows of alternatively arranged leaflets. Both the tetraploid and parental lines had the same mean number of leaflets per leaf while the gigas plants had fewer, but mean total leaf surface area was greater in the gigas plants. Quantitative comparison of mesophyll and vascular tissue and air space volume density (Vv) showed that leaves of the tetraploid plants had the greatest mesophyll cell density (Vvm) and least air space density. Mesophyll cell density was equal in the parental and single‐gene mutant while parental leaves had the greatest vascular tissue density. The greater mesophyll cell density values of the polyploid were due to larger mean mesophyll cell size, not to greater cell numbers per unit area. Leaf models based on tissue density and leaflet size showed tetraploid plants had the greatest productivity potential per unit of leaflet surface area. However, if models were based on a whole leaf, gigas plants had the greatest productivity potential since they had larger total leaf area. The effectiveness of using structural models to predict physiological potential in plant tissues will be tested in future studies.
ADAPTATION TO SUBSTRATE‐AND LACK OF IT–IN ROCK OUTCROP PLANTS: SEDUM AND ARENARIA
Authors: Ware Stewart
Published: January 2018

Sedum pulchellum Michx. (Portulacaceae) and Arenaria patula Michx. (Caryophyllaceae) are winter annuals confined to and often dominating the very shallow soil of rock outcrops. Both occur only on limestone soils in the eastern (KY‐TN) portions of their ranges, but on a variety of substrates in the Interior Highlands. Such broad substrate distribution is usually accomplished by either wide physiological tolerance to soil chemistry or by ecotypic adaptation to substrate. In greenhouse tests of soil type tolerance, A. patula showed strong ecotypic adaptation, with limestone and sandstone populations each growing poorly on the other's native substrate. In contrast, all S. pulchellum populations were strongly inhibited by nonlimestone soils, either acidic (sandstone, granite, shale) or basic (dolomite), even when the nonlimestone soil was its native habitat. Thus, this species shows neither broad ecological tolerance nor ecotypic adaptation. In the shallow soil habitat, S. pulchellum has virtually no competitors, so it is able to survive and reproduce on some nonlimestone substrates (e.g., sandstone) despite its very slow growth. Despite very similar habitats, ecological life histories, and geographical ranges, these species do not occupy their broad range of substrate types by the same means.
FLORAL DEVELOPMENT IN OTTAWA AND FLOREX RED CLOVER TRIFOLIUM PRATENSE (PAPILIONOIDEAE: LEGUMINOSAE)
Authors: Retallack Beth , Willison J. H. Martin
Published: January 2018

Floral development in Florex and Ottawa cultivars of red clover (Trifolium pratense L.: Leguminosae) was examined by scanning electron microscopy. No differences between the two cultivars were found. The terminal inflorescence is initiated in the axil of the penultimate bract before the final bract is initiated. After initiation of the final bract, the remnant apical dome is transformed to become the least mature part of the inflorescence dome. Subsequent inflorescences are initiated laterally in basipetal sequence. Inflorescence development is zygomorphic. This leads to an unusual pattern of floret initiation, the oldest florets resting basally and proximal to the penultimate bract. Florets develop with zygomorphic symmetry, each whorl of floral organs developing unidirectionally from the abaxial side. Initiation of the adaxial organ of each whorl is delayed until the abaxial organ of the succeeding whorl has been initiated. Thus there is overlapping development of the whorls of organs. The antepetalous stamens arise in close association with their respective petal primordia. As development proceeds, the corolla tube and the staminal tube exhibit basal zonal growth. In the mature flower, above the distal zone of fusion of the keel petals, marginal cells project and interlock, producing a pollination mechanism that can be sprung by the pollinator.
STARCH GEL ELECTROPHORESIS OF PLANT ISOZYMES: A COMPARATIVE ANALYSIS OF TECHNIQUES
Authors: Kephart Susan R.
Published: January 2018

The use of genetic information expressed in isozymic form has enhanced our understanding of heritable variation within and among plant populations. For over three decades now, protein electrophoresis coupled with histochemical staining has provided data on the concordance of observable features in plants (e.g., morphology, cytology, ecological adaptation) with isozyme phenotypes. Yet inadequate dissemination of procedural details and varied investigative approaches have limited the comparative value of electrophoretic data and have made it difficult for novices to apply the technique to other experimental systems. Information gathered from over 25 laboratories utilizing enzyme electrophoresis is treated comparatively, providing access to protocols that often are either unpublished or widely dispersed in the literature. Analyzed in the review are methods and guidelines for enzyme extraction, effective storage of plant samples and buffers, efficient screening of taxa for enzymatic activity, and interpretation of diploid and polyploid banding patterns.
MORPHOMETRIC ANALYSIS OF EPIDERMAL DIFFERENTIATION IN PRIMARY ROOTS OF ZEA MAYS
Authors: Moore Randy , Smith Houston S.
Published: January 2018

Epidermal differentiation in primary roots of Zea mays was divided into six cell types based on cellular shape and cytoplasmic appearance. These six cell types are: 1) apical protoderm, located at the tip of the root pole and characterized by periclinally flattened cells; 2) cuboidal protoderm, located approximately 230 μm from the root pole and characterized by cuboidal cells; 3) tabular epidermis, located approximately 450 μm from the root pole and characterized by anticlinally flattened cells; 4) cuboidal epidermis, located approximately 900 μm from the root pole and characterized by cuboidal cells having numerous small vacuoles; 5) vacuolate cuboidal epidermis, located approximately 1,500 μm from the root pole and characterized by cuboidal cells containing several large vacuoles; and 6) columnar epidermis, located approximately 2,200 μm from the root pole (i.e., at the beginning of the zone of elongation) and characterized by elongated cells. We also used stereology to quantify the cellular changes associated with epidermal differentiation. The quiescent center and the apical protoderm have significantly different ultrastructures. The relative volume of dictyosomes increases dramatically during the early stages of epidermal differentiation. This increase correlates inversely with the amount of coverage provided by the root cap and mucilage.
WATER TRANSPORT PROPERTIES OF VINE AND TREE STEMS IN A TROPICAL DECIDUOUS FOREST
Authors: Gartner Barbara L. , Bullock Stephen H. , Mooney Harold A. , Brown V. By , Whitbeck Julie L.
Published: January 2018

Excised stem segments of vines had higher specific hydraulic conductivities (flow rate per pressure gradient per stem transverse area) than did trees during the dry season in a deciduous forest in Jalisco, México. Vine species averaged from 2.7 to 203 10‐3 m2 MPa‐1 s‐1 and tree species from 0.8 to 5.1 10‐3 m2 MPa‐1 s‐1. Only three of the 20 species retain their leaves during part or all of the dry season, and these included the vine and the tree with the lowest conductivities within their growth forms. An index of the mean diameter of the six widest vessels per sample was positively and significantly correlated with specific conductivity for the vines but not the trees. Stem density (g cm‐3, dry weight/wet volume) was not correlated with either specific conductivity or vessel diameter index for vines or trees.
LOSS OF FLORAL ORGANS IN ATELEIA (LEGUMINOSAE: PAPILIONOIDEAE: SOPHOREAE)
Authors: Tucker Shirley C.
Published: January 2018

Ateleia herbert‐smithii is unique among legumes in being a wind‐pollinated tree; carpellate and staminate flowers are restricted to different trees. Development of the two floral morphs, however, is essentially the same except for smaller carpels in functionally staminate flowers and failure of pollen formation in the anthers of functionally carpellate flowers. The floral development of Ateleia herbert‐smithii is highly atypical among papilionoids and the tribe Sophoreae. Order of organ initiation is: sepals, solitary petal, carpel, and lastly all stamens in erratic order. Sepal order is unidirectional from the abaxial side, the normal pattern for papilionoids. Only one petal, the vexillum or standard, is initiated. Subsequent initiation is completely different from the usual unidirectional pattern of most papilionoids. A meristem ring forms, delimiting the solitary carpel centrally. Ten stamen primordia are initiated on the meristem ring, first laterally, then adaxially, and lastly abaxially. There is a tendency for antesepalous stamens to form before the antepetalous ones. The loss of four of the five petals is thought to alter drastically the subsequent organogeny as to position of organs and their order of initiation. Carpel initiation in Ateleia is precocious, but not uniquely so among legumes.
POLLEN APERTURE EVOLUTION AMONG THE SUBFAMILIES PERSOONIOIDEAE, SPHALMIOIDEAE, AND CARNARVONIOIDEAE (PROTEACEAE)
Authors: Feuer Sylvia
Published: January 2018

Pollen apertures were analyzed among the subfamilies Persoonioideae (seven genera; ca. 95 spp.), Sphalmioideae (one genus; one spp.), and Camarvonioideae (one genus; two spp.). Pollen was examined by light microscopy, cryosection, and transmission electron microscopy. Completed studies of pollen apertures among Grevilleoideae (ca. 40 genera; ca. 800 spp.), one of two major subfamilies in Proteaceae, provide a basis for comparison and analysis of aperture evolution among these subfamilies. Aperture characters within Persoonioideae are unique among Proteaceae examined to date. Five distinct aperture types occur among the three subfamilies, three of which (Placospermum, Persoonia, Bellendena) are restricted to Persoonioideae. Sphalmioideae and Camarvonioideae each exhibit a unique aperture organization. The most primitive aperture organization, and one unique to Placospermum, exhibits three main features: 1) a thin, granular endexine continuous around the grain; 2) a heterogeneous foot layer throughout the grain with increased disruptions at the aperture; and 3) only slight differences in exine characters between apertural and nonapertural regions. The Persoonia aperture type represents the next stage of aperture evolution which involves loss of endexine, restriction of a heterogeneous foot layer to the aperture, and marked differences in exine characters between apertural and nonapertural regions. The uniformly homogeneous ektexine in both nonapertural and aperture regions in Bellendena has developed independently. Sphalmium exhibits a primitively thin granular endexine though the restriction of endexine to the aperture is a derived condition. Carnarvonia exhibits several pollen characters also found among Grevilleoideae including: 1) a homogeneous nonapertural ektexine; 2) a slightly heterogeneous apertural ektexine; 3) a lamellate/granulate endexine organized into irregularly shaped “clumps” clustered around the aperture; and 4) a clear demarcation between apertural and nonapertural exine. These characters support the hypothesis that Carnarvonia may have diverged early from the pre‐Grevilleoids.