bluuebunny/crossref_metadata_2025_split huggingface dataset:
DEVELOPMENTAL ANATOMY OF CORALLOID ROOTS IN CYCADS
Authors: Milindasuta Boon‐earn 
Published: January 2018

Coralloid roots of cycads were found to originate endogenously from the pericycle of apogeotropic secondary roots or adventitious roots that have become exposed or nearly exposed to the soil surface. All mature coralloid roots are susceptible to infection by algal endophytes, which seem to enter from the soil through a break in the dermal layers.In the coralloid roots the algae inhabit intercellular spaces in a definite zone that arises from the protoderm, and in which the cells elongate radially following algal infection. The zone is completely surrounded by a persistent rootcap which is interpreted by most authors as a secondary cortex. The secondary cortex was shown to be derived from the rootcap in this investigation.
EFFECT OF THE CALYPTRA ON INTERCALARY MERISTEMATIC ACTIVITY IN THE SPOROPHYTE OF FUNARIA (MUSCI)
Authors: French J. C. , Paolillo D. J. 
Published: January 2018

The removal of the calyptra from the sporophyte of Funaria causes the seta to thicken dramatically. The growth patterns of the seta‐thickened and normal sporophytes are similar in that in either case elongation proceeds from the activity of an intercalary meristem in the subapical region. The absence of the calyptra during elongation does not inhibit growth. The first effect of removing the calyptra is to allow for increased lateral expansion of the cells produced from the meristem. Subsequently, there is an increase in the number of cells seen in transverse sections, compared to what is seen in normal sporophytes.Improved procedures for surface sterilization and in vitro culture have allowed the growth of young, excised sporophytes to maturity. Using these culture procedures it is shown for the first time that thickened setae are capable of long term (indeterminate) growth if capsules do not form.The normal seta is shown to be doubly tapered, with the maximum diameter reached after the first ⅓ of the length of the seta is attained. The tapering of the normal seta seems to result from an interaction between the intercalary meristem and the calyptra, which is also tapered.
INCREASE IN SIZE AND CELL NUMBER OF LATERAL ROOT PRIMORDIA IN THE PRIMARY OF INTACT PLANTS AND IN EXCISED ROOTS OF PISUM SATIVUM AND VICIA FABA
Authors: Thompson Anne , MacLeod Ronald D. 
Published: January 2018

Increase in cell number, and in anlage volume and length have been investigated during the development of lateral root primordia in roots of intact plants of Pisum sativum and Vicia faba and in excised roots of both species cultured in White's medium supplemented with 2% sucrose. With the exception of primordia in excised roots of Vicia, the general equation which best described increase in each aspect of primoridium growth measured against time was that for exponential growth. When the times necessary for cell number and primordium volume and length to double were determined at intervals over the period of development studied, however, they were found to vary. Similarly, estimates of the size of the proliferative fraction of cells at different times during anlage development indicated that this index of meristematic activity also fluctuated over the developmental period investigated, i.e., increase in cell number and in primordium volume and length do not occur in a truly exponential fashion as the primordia increase in size and cell number.One difference between anlage development in the roots of intact plants and in those grown in culture was that whereas the former primordia completed their development and emerged as lateral roots over the period of the investigation, the latter did not. Moreover, cell doubling time and anlage volume and length doubling times were longer, and the proliferation fraction of cells lower, over the whole period of, and at intervals during, primordium development in the excised roots compared with the results obtained for the roots of the corresponding intact plants.
REPRODUCTIVE ISOLATION BARRIERS TO GENE EXCHANGE BETWEEN SOLANUM CHACOENSE AND S. COMMERSONII (SOLANACEAE)
Authors: Summers Dennis , Grun Paul 
Published: January 2018

In contrast to the general intercompatibility of diploid species of tuber‐bearing potatoes of South America, Solanum chacoense Bitter and S. commersonii Dunal have well‐established internal barriers to gene exchange. Pollen tubes of S. commersonii are inhibited in growth down the style of S. chacoense. While S. chacoense pollen tubes are not inhibited in S. commersonii stylar tissue, seed development is abnormal, resulting in production of large numbers of seeds that are not filled out. Even the apparently normal F1 seed germinated poorly; approximately 0.1 germinable seeds were set per cross as compared with over 30 seeds per cross following intraspecific crosses. Lowland S. chacoense, including populations sympatric with S. commersonii, were not more effectively isolated from S. commersonii than were highland S. chacoense populations, over 500 km from the nearest S. commersonii. The F1 hybrids produced were vigorous and highly fertile. Crosses between unrelated S. commersonii‐chacoense F1 hybrids produced only 1.3 germinable seeds per cross. This reduction resulted from low numbers of berries set, few seeds per berry, and low seed germination.The F2 progeny were vigorous, but while many were both male and female fertile there were indications of an increase in sterility over that of the parents and F1's. The data were interpreted as indicating that the isolation barriers result from polygenic differences between the parent species and are composed principally of genes that function in several of the processes of seed setting. The accumulation of genes that keep these species isolated was interpreted as not having developed as a result of selection for such isolation in the region of overlap (Wallace effect), but rather as a byproduct of divergence that occurred during their allopatric evolution.
COMMUNITY STUDIES IN POLLINATION ECOLOGY IN THE HIGH TEMPERATE ANDES OF CENTRAL CHILE. I. POLLINATION MECHANISMS AND ALTITUDINAL VARIATION
Authors: Arroyo Mary T. Kalin , Primack Richard , Armesto Juan 
Published: January 2018

Pollination mechanisms and pollinators are reported for a total of 137 species (75% of the non‐abiotically pollinated flora) as they occur at three altitudinal levels (subandean scrub: 2,200–2,600 m; cushion‐plant zone: 2,700–3,100 m; subnival feldfield: 3,200–3,600 m) in the Andean (alpine) zone on the Cordon del Cepo (33°17'S) in central Chile as part of community oriented research in reproductive biology in the high temperate Andes of South America. Only around 4% of the species studied failed to be visited by potential pollinators. Hymenopterans (principally bees) are important pollinators of 50% of the biotically pollinated flora, butterflies of 24% and flies of 46%. Other vectors include beetles, moths, and hummingbirds. An estimated 17% of the flora is anemophilous.Bee species‐richness, specialist feeding, and melittophily reach maxima in the subandean scrub; thereafter, bees diminish rapidly in number, with bees pollinating only 13% of the subnival flora as contrasted with 68% of the subandean flora. Although fly and butterfly species‐richness also decline with increasing altitude, the proportions of species pollinated by these vectors actually increases. High‐altitude populations of melittophilous species with broad altitudinal ranges are invariably serviced by fewer bee species as compared with lower populations.The rich bee fauna at the lower end of the Andean zone in central Chile appears to have resulted from upward colonization from that of the subtending lowland Mediterranean sclerophyllous woodland vegetation. Altitudinal variation in pollination spectra is discussed in relation to contrasting life history characteristics and different modes of thermoregulation in the insect groups involved.
DECOMPOSITION DYNAMICS OF SPARTINA ALTERNIFLORA AND SPARTINA PATENS IN A NEW JERSEY SALT MARSH
Authors: Frasco Barbara A. , Good Ralph E. 
Published: January 2018

Decomposition dynamics of two salt marsh species, Spartina alterniflora tall (SAT) form and Spartina patens (SP), were investigated at Mud Cove, near Manahawkin, Ocean County, New Jersey. Decomposition rates were determined monthly over 371 days by measuring the amount of material lost from plastic net litter bags. Litter bags containing SP material were placed in both SP and SAT vegetation zones; litter bags containing SAT material were also placed in both of these zones. The material was analyzed for ash content, total carbon, Kjeldahl nitrogen, caloric content, fat, and crude fiber.Final weight loss values were as follows: SAT in SAT zone 72.4%, SP in SAT zone 56.9%, SAT in SP zone 46.7%, and SP in SP zone 26.4%. When SAT and SP material were placed in the same location (SAT or SP sites), the SAT material decomposed at a greater rate. If the same vegetation type (SAT or SP) were placed in both SAT and SP locations, the material at the SAT location decomposed at a greater rate than similar material in the SP location. The results indicate that while environmental characteristics (e.g., flooding) at a site influence the rate at which these two species will decompose, Spartina patens is inherently more resistant to decomposition.
CYTOEMBRYOLOGY OF ALLIUM TEXTILE NELS. & MACBR.
Authors: Khaleel Tasneem F. , Mitchell Becky B. 
Published: January 2018

Root tip mitosis, meiosis, sporogeneses, and the development of gametophytes are described for eight populations of Allium textile Nels. & Macbr., native to Montana. The basic chromosome number is n = 7, with tetraploids being predominant. Of the eight populations studied, only one was composed entirely of diploids (2n = 14). Meiosis is generally normal with bivalents and tetravalents formed during the process. Laggard chromosomes leading to the formation of micronuclei are frequently observed during microsporogeny.The anther wall is five‐layered and its development corresponds to the Monocotyledonous type. The tapetum is glandular and its cells remain uninucleate throughout microsporogeny. The adjacent anther locules coalesce before dehiscence. Pollen grains are shed at the three‐celled stage. A stomium is organized.Ovules are anatropous, tenuinucellar and bitegminal. The archesporial cell develops directly into a megasporocyte. Development of the female gametophyte is bisporic and corresponds to the Allium type. These observations support Traub's classification (1975) on Allium.
DEMOGRAPHIC ASPECTS OF FLOWER AND FRUIT PRODUCTION IN BEAN PLANTS, PHASEOLUS VULGARIS L.
Authors: Doust Jon Lovett , Eaton G. W. 
Published: January 2018

In this paper we assess the relative contributions to total pod yield of cohorts of flowers of known age. Bean plant (Phaseolus vulgaris L.) growth was monitored and 'births' of individual flowers were recorded and their fates followed. For every cohort of flowers an array of yield measures was calculated, including the mean and total cohort dry weight of fruits, and the numbers of viable and aborted seeds and completely undeveloped ovules. When mature, pods were removed from half of the plants. Plants whose mature pods were removed produced significantly greater numbers of flowers, ovules and viable seeds and a greater total weight of pods than did untreated plants. However, the proportion of ovules giving rise to viable seeds and to aborted seeds and undeveloped ovules was the same in plants of both groups. Approximately 50% of ovules of marketable pods, in all plants, yielded viable seeds.The 12 cohorts of flowers contributed markedly different amounts to plant yield. Early and later cohorts contributed much less than did middle cohorts in terms of marketable pod dry weight and numbers of fully developed seeds, aborted seeds, and undeveloped ovules. Peak productivity was therefore obtained from the middle phase of flowering in these annual bean plants. The lower pod yield of later cohorts is interpreted as a result of competition for limited resources between maturing pods and new flowers.We consider possible causes for the various fates of flowers and ovules and discuss flowers as plant modules suitable for demographic examination.
OBSERVATIONS ON THE MICROBODIES IN THE GENUS TILLANDSIA (BROMELIACEAE)
Authors: Brighigna Luigi , Fiordi Ambretta Cecchi , Palandri Maria R. 
Published: January 2018

Organelles morphologically similar to microbodies have been found in several tissues of atmospheric species of Tillandsia from different habitats. The presence of catalase was demonstrated by the DAB reaction thus confirming the microbody nature of these organelles. They are a feature of the Tillandsia species with normal photosynthetic carbon fixation and with CAM. Their size is consistently small.The nucleoid observed in the microbodies shows a characteristic morphology which has not been reported before within other plant microbodies. This nucleoid is composed of minute tubular structures, for which the authors here propose a three‐dimensional arrangement.
THE DISTRIBUTION OF ANTHOCHLOR FLORAL PIGMENTS IN NORTH AMERICAN COREOPSIS (COMPOSITAE): TAXONOMIC AND PHYLETIC INTERPRETATIONS
Authors: Crawford Daniel J. , Smith Edwin B. 
Published: January 2018

Anthochlors (chalcones and aurones) occur in floral tissues of all members of North American Coreopsis. The genus in North America consists of 46 species distributed in 11 sections, and a total of five chalcone aglycones are found in it. The chalcone butein occurs in all sections, and is the only anthochlor constituent in the closely related woody Mexican sections Electra and Anathysana. These two sections are viewed as primitive. The morphologically distinct but putatively unspecialized woody Mexican section Pseudo‐Agarista sequesters both okanin and butein; the same two anthochlors also characterize two additional sections of herbaceous perennials, Silphidium and Tuckermannia. Sections Euleptosyne and Pugiopappus, comprised of annuals restricted primarily to California, exhibit the rare chalcone stillopsidin in addition to butein and okanin. The remaining four sections, Palmatae, Coreopsis, Calliopsis and Eublepharis are among the more specialized in North America, and are sometimes considered to represent a distinct phyletic line or two related lines. All or some of the members of these sections sequester the very rare chalcone lanceolatin in floral tissues in addition to okanin.Butein is also present in some or all species in each section, and isoliquiritigenin occurs rarely in two sections. Those sections considered more specialized have additional anthochlors relative to primitive sections, and any compound found in a more primitive section also occurs in a more advanced one. Thus, the trend in floral anthochlors in North American Coreopsis is toward increased number of compounds rather than reduction.
PHOTOGRAPHIC VISUALIZATION OF FLORAL COLORS AS PERCEIVED BY HONEYBEE POLLINATORS
Authors: McCrea Kenneth D. , Levy Morris 
Published: January 2018

An inexpensive photographic technique for visualizing the ultraviolet and visible wavelengths perceived by honeybees is described. Using a standard daylight‐balanced color slide film and illumination from blacklight and filtered daylight fluorescent lamps, a recording balance was achieved which approximates the spectral sensitivity of the honeybee eye.The technique was used to illustrate floral features among Rudbeckia species and among color morphs of Phlox. The Rudbeckia have inflorescences that are similar in visible coloration but distinctive in ultraviolet patterning and Phlox color morphs are distinctive in visible coloration but similar in ultraviolet patterning. The efficacy of the technique was judged from comparison with in vivo reflectance spectra of the floral subjects. Generally, photographic visualizations of entomophilous flowering plants portray only the ultraviolet or the visible components of floral coloration. This technique emphasizes the importance of considering the entire spectrum of floral colors relevant to most insect pollinators.
FLORAL ORGANOGENESIS IN NICOTIANA TABACUM: A COMPARISON OF TWO CYTOPLASMIC MALE‐STERILE CULTIVARS WITH A MALE‐FERTILE CULTIVAR
Authors: Rosenberg Susan M. , Bonnett Howard T. 
Published: January 2018

Flower buds of two cytoplasmically male‐sterile cultivars and one male‐fertile cultivar of Nicotiana tabacum (L.) were studied by light and scanning electron microscopy to compare their floral ontogenies. In [gla]tbc, a cultivar with N. tabacum nuclear genes and N. glauca cytoplasm, the five small stamen primordia cease growth soon after they are initiated. They remain unchanged at the flanks of the ovary throughout flower maturation, so the mature flower appears stamenless. In `[pbg]tbc,‘ a N. tabacum cultivar with cytoplasm that was thought to have been derived from N. plumbaginifolia, the divergence from normal stamen development occurs before carpel emergence at which point the primordia are already notably smaller and less cylindrical than primordia of the male‐fertile cultivar. After carpel emergence the primordia continue to develop, forming pink structures called petalodes, which are more similar to petals than stamens. Histological sections show that formation of procambial vascular traces is similar in the abortive stamen primordia of [gla]tbc, the petalode primordia of `[pbg]tbc‘ and stamen primordia of male‐fertile N. tabacum.The two cytoplasmic male‐sterile cultivars studied here and one reported elsewhere show a common developmental stage at which the normal ontogenic pattern is altered. We suggest that this stage is the first visible point in N. tabacum androgenesis which requires genetic input from the mitochondrial genome.
INTERSPECIFIC HYBRIDIZATION AND TAXON UNIFORMITY IN ARABIS (CRUCIFERAE)
Authors: Rollins Reed C. 
Published: January 2018

Intermixed populations ofArabis holboelliiHornem. var.pendulocarpa(A. Nels.) Roll.,A. williamsiiRoll., and their putative hybrids; and ofA. holboelliivar.retrofracta(Grah.) Rydb.,A. drummondiiGray andA. divaricarpaA. Nels., the latter also considered to be a probable hybrid taxon, were studied in the field in Montana and Wyoming. In spite of the “intermediacy” of the putative hybrids in both cases, hybrid swarms were not found. In each instance, the “intermediate” as well as the taxa regarded as parental were remarkably uniform. The existence of three relatively uniform morphotypes in each of the several populations is contrary to the usual situation involving hybridizing taxa. A possible explanation is that seed production, at least in the “intermediate” morphotype individuals, involves apomixis, thus circumventing the usual sexual process that would result in a hybrid swarm. Amphiploidy as a possible mechanism for producingA. divaricarpaas a stable hybrid was ruled out in one population where the chromosome number 2n =14 was found in all three taxa present in the population.Arabis divaricarpa, widely distributed in northern North America, often occurs as a uniform morphotype where no other species ofArabisgrows. If it is of hybrid origin, as the evidence suggests, a mechanism other than sexual reproduction must be present to keep up uniformity and at the same time perpetuate the taxon. It is suggested that facultative apomixis is involved in the reproductive process and that it controls the genetic variability that would otherwise be present by insuring maternal inheritance in each successive seed crop.
SEQUENTIAL YIELD COMPONENT ANALYSIS AND MODELS OF GROWTH IN BUSH BEAN (PHASEOLUS VULGARIS L.)
Authors: Doust Jon Lovett , Doust Lesley Lovett , Eaton G. W. 
Published: January 2018

We describe the effect of repeated fruit harvest on yield and components of yield in bush bean, and we construct several growth models. Multiple‐regression analysis was used to estimate the relative contributions of individual components to overall yield, and a technique comparing ‘backward’ and ‘forward’ multiple regressions was used to identify points of direct and indirect influence on the ontogenetic series contributing to yield. By testing alternative models we were able to identify components which did not contribute significantly to yield.Plant height was an important direct and indirect determinant of yield in both treated and untreated plants. There were more compensation effects between components in plants which were continuously harvested, perhaps because pods no longer contributed photosynthate, or because harvested plants were ‘rejuvenated’ through bud release, thus more resource sinks were competing actively for limited resources. Competition between resource sinks apparently occurs earlier in the model sequence where pods are harvested continuously, and becomes important later, as pods mature, in plants left intact to the end of the experiment.The reciprocal of leaf area ratio was another major component of yield. In both treated plants and controls, this ratio of leaf area to total plant dry weight behaved indirectly, apparently influencing yield through other components.
THE MOTION OF WINDBORNE POLLEN GRAINS AROUND CONIFER OVULATE CONES: IMPLICATIONS ON WIND POLLINATION
Authors: Niklas Karl J. 
Published: January 2018

Comparisons are presented between the three‐dimensional airflow patterns created around and by a scale model of a conifer ovulate cone and the trajectories of windborne pollen grains around Picea, Larix, and Pinus ovulate cones. Three general components of the airflow pattern around an ovulate cone model are 1) doldrum‐like eddies, rotating over the adaxial surfaces of cone scales and directed toward attached ovules, 2) airflow spiralling around the cone axis along cone scale orthostichies and parastichies, and 3) a complex pattern of vortices (“umbilicus”) directed toward the leeward surface of the ovulate cone. The observed trajectories of pollen grains around cones of Picea, Larix, and Pinus conform to two of these three airflow components: 1) pollen grains are seen to roll along cone scales toward the distal scale margin and to become reentrained in airflow directed backward toward attached ovules, and 2) pollen grains passing around the cone are deflected into the “umbilicus” airflow pattern, where they either settle on or impact with cone scales (approach trajectories), or where they approach the leeward cone surface but are deflected away by airflow passing under the cone (Z‐shaped trajectories). Vectoral analyses of pollen grain motion reveal a complex pattern of trajectories influenced by boundary layer conditions defined by ovulate cone geometry and ambient airflow speed. Wind tunnel studies of ovulate cones subtended by leaves and stem indicate that leaves circumscribing the cone act as a snowfence, deflecting windborne pollen toward the cone.Vectoral analyses of airflow patterns and pollen grain trajectories close to ovulate cones indicate that wind pollination in conifers is a non‐stochastic aerodynamic process influenced by cone‐leaf morphology and the behavior of pollen grains as windborne particles.