bluuebunny/crossref_metadata_2025 huggingface dataset:
STRUCTURE AND DEVELOPMENT OF THE SIEVE‐ELEMENT PROTOPLAST IN THE HYPOCOTYL OF PINUS RESINOSA
Authors: Neuberger Damian S. , Evert Ray F.
Published: January 2018

Hypocotyl tissue of Pinus resinosa Ait. was fixed in glutaraldehyde‐paraformaldehyde and postfixed in osmium tetroxide for electron microscopy. Although young sieve cells contain all the components characteristic of young, nucleate cells, they can be identified early in their development. Increase in wall thickness occurs early and rapidly. Concurrently, the plastids, which already contain starch granules, form both crystalline and fibrillar inclusions. As the sieve cell approaches maturity, an extensive network of smooth, tubular endoplasmic reticulum (ER), which becomes mostly parietal in distribution, is formed. At maturity, massive aggregates of this ER occur on both sides of sieve areas. These ER aggregates are interconnected with one another longitudinally by the parietal ER. In addition, the mature, plasmalemma‐lined sieve cell contains a degenerate nucleus, mitochondria, and intact plastids. Dictyosomes, ribosomes, and vacuolar membranes are lacking. P‐protein is not present at any stage of development.
REGIONS OF CELL WALL EXPANSION IN THE PROTONEMA OF A FERN
Authors: Stockwell Cynthia R. , Miller John H.
Published: January 2018

Protonemata of Onoclea sensibilis were grown for 7 days in darkness and were then transferred into light on new media, either liquid or agar‐solidified, which contained 0.15% colchicine. The growth of individual plants was observed on solid media in microchambers. Unequivocal evidence was obtained that cell wall expansion and an increase in cell diameter occurred in regions well behind the apex of the protonema. This finding is related to an hypothesis which proposes light‐induced changes in microtubule orientation and cell wall structure as an explanation for certain changes in cell form in fern gametophytes.
ABERRANT MICROSPOROGENESIS AND STERILITY IN IMPATIENS SULTANI (BALSAMINACEAE)
Authors: Tara C. P. , Namboodiri A. N.
Published: January 2018

Three mutants of Impatiens sultani (named as ‘Orange', ‘Crimson', and ‘Pink') show an unusually wide spectrum of aberrations in microsporogenesis. These aberrations range from premeiotic cytomixis to meiotic and postmeiotic irregularities such as precocious disjunction, tripolar separation of chromosomes, chromosome bridges, various patterns of atypical cytokinesis, supernumerary divisions of the meiotic products, and irregular divisions in the microspore. As a result of these abnormalities Orange is partially and Crimson and Pink are completely pollen sterile. The stigmas of Pink, besides, do not support pollen germination. The failure of pollen germination is attributed to the defective stigmatic fluid of Pink, which, compared to that of Orange and Crimson lacks organic compounds absorbing UV light at 261 nm. This constitutive deficiency in stigmatic fluid appears to be a little investigated facet of female sterility.
POLLEN PORE DEVELOPMENT AND ITS SPATIAL ORIENTATION DURING MICROSPOROGENESIS IN THE GRASS SORGHUM BICOLOR
Authors: Christensen Jon E. , Horner Harry T.
Published: January 2018

The spatial relationships observed during microsporogenesis and pollen development in Sorghum bicolor indicate that a strong polarization exists in the anther locule and within individual microspores and pollen grains. During all developmental stages, each sporogenous cell and its derivatives lie continuously adjacent to the tapetum. The microspores and pollen grains form depressions in the tapetal orbicular wall. When the single pore of each microspore is initiated, as a gap in the primexine, it too lies adjacent to the tapetum and remains tightly appressed there until pollen maturity. A sequence of polar phenomena in microspores and pollen grains centers on an axis through the pore and perpendicular to the tapetal surface. These events include migrations of the microspore and vegetative nuclei, initial placement of the generative cell opposite the pore and its later migration, and a polar engorgement process whereby the pore end of the pollen grain (adjacent to the tapetum) fills with starch grains first. The tapetal cytoplasm completely degenerates at precisely the time of pollen engorgement, and its degradation products are believed to be available for pollen uptake at this time. The continuous association of the sporogenous cells or their cellular derivatives and their pores with the tapetum is thought to play an indispensible role in pollen development in sorghum and probably in all other grasses as well. The consistent position of the pore adjacent to the tapetum should be considered another common feature of microsporogenesis in the Gramineae. The characteristic exine pattern forms over the operculum and annulus of the pore, but the lamellae, which underlie the annulus, form a highly modified multilayered nexine. Membrane‐like cores are observed in these lamellae and are believed to be involved in the initiation of sporopollenin deposition, but they are obliterated by pollen maturity. Neither the cores nor the lamellae are found in other parts of the pore or in the nonapertured wall.
UPTAKE BY AND FATE OF LYSOZYME IN ROOTS OF IASIONE MONTANA (CAMPANULACEAE)
Authors: Sung Z. R. , McLaren A. D.
Published: January 2018

A basic protein, lysozyme, labeled with fluorescein isothiocyanate, is readily taken up by roots of lasione montana. Most of the protein taken up is tightly bound to cell walls of the roots. Fluorescent protein is diluted in the growing region of a root as cells elongate and divide. Fluorescence remains in mature nongrowing regions and root cap cells for one to two weeks. Redistribution and translocation of the protein within the root is minimal or nil. A layer of chloroform‐soluble material that prevents lysozyme from interacting with stem cell walls exposed to fluorescent lysozyme was found on stems of germinating Iasione montana.
ULTRASTRUCTURAL STUDIES PLASMA MEMBRANE RELATED SECONDARY VACUOLES IN CULTURED CELLS
Authors: Mahlberg Paul G. , Turner F. R. , Walkinshaw C. , Venketeswaran S.
Published: January 2018

The plasma membrane of cultured cells of several plant species was observed to possess invaginations, or secondary vacuoles, of variable size in the adjacent cytoplasm. These structures, which occurred in cells at different phases in vacuolation, were very numerous in thin sections of some cells but fewer in others. In vacuolated cells enlarged secondary vacuoles protrude into the primary vacuole but are delimited from the tonoplast by an intermembrane zone of variable width. The plasma membrane at the orifice of an invagination may fuse and detach the secondary vacuole from the membrane to form in the cytoplasm a structure bounded by a single membrane. Complex accumulations of membranes consisting of spherical, tubular, and laminar structures, possibly containing cytoplasm, may develop within secondary vacuoles. Contents of many of these vacuoles arise from folds along its limiting membrane which pinch off into the interior of the secondary vacuole. A fibrous substance, possibly derived from the wall, is present in some secondary vacuoles. Observed folding of the plasma membrane and measurements of membrane width of various organelles and cytomembranes support an interpretation that endocytosis occurs in cultured cells.
PINUS WOLFEI, A NEW PETRIFIED CONE FROM THE EOCENE OF WASHINGTON
Authors: Jr. Charles N. Miller.
Published: January 2018

A silicified cone from the Late Eocene of Washington is described as a new fossil species of Pinus. The cone was probably 9–10 cm long and 3–5 cm at its widest diam in the living condition and is peculiar in having abundant resin canals in the secondary xylem of the axis arranged in three concentric rings near the cone base. The bract of the fossil is also unusual in having resin canals of distinctly unequal sizes and a vascular strand that is adaxially concave. In the absence of external features of the scale tips, these anatomical conditions along with the construction of the outer cortex of the axis of thick‐walled cells suggest closest affinity of the new species with the subsections Contortae, Oocarpae, and Sylvestres of the section Pinus, subgenus Pinus.
PITYOSTROBUS HALLII, A NEW SPECIES OF STRUCTURALLY PRESERVED CONIFER CONES FROM THE LATE CRETACEOUS OF MARYLAND
Authors: Miller Charles N.
Published: January 2018

Description of Pityostrobus hallii is based on lignitic cone pieces from an exposure of the Late Cretaceous Magothy Formation at Bethel, Maryland. The cones were about 15 cm long and 3 cm in diam in the living condition. Scale apices are papery thin like those of certain Recent species of Picea, but the presence of anatomical features typical of other genera as well as conditions that are not known to occur in present‐day pinaceous cones necessitates classification of the new species in an organ genus. Similar lignitic cones from the Magothy Formation of Delaware that were misidentified as specimens of Picea cliffwoodensis Berry belong to the new species.
INHIBITION OF NITRIFICATION BY CLIMAX ECOSYSTEMS. III. INHIBITORS OTHER THAN TANNINS
Authors: Rice Elroy L. , Pancholy Sunil K.
Published: January 2018

We obtained considerable evidence in earlier work that inhibition of nitrification begins during old‐field succession and increases to a maximum in the climax (Rice and Pancholy, 1972, 1973). Moreover, we found that tannins and tannin derivatives appear to be important inhibitors of nitrification. In the present project, other potential phenolic inhibitors of nitrification were identified in acetone extracts of entire plants of most herbaceous species and leaves of tree species important in an intermediate stage of succession and the climax in three vegetation types in Oklahoma. Attempts were made also to identify potential inhibitors in acetone extracts of soil from the top 15 cm of the oak‐pine climax. Seventeen potential inhibitors were identified from the eleven important species of plants surveyed. These were mostly phenolic acids and flavonoids, but one coumarin compound, scopolin, was found in high amounts in several species. The potential inhibitors were most common in green tops or green leaves, but roots, dead tops (of previous year), and dead leaves had high amounts of some compounds. Caffeic and ferulic acids were prominent in dead leaves or dead tops, and one flavonoid, myricetin, occurred in sizeable amounts in dead tops of Sorghastrum nutans. The aglycones of most of the compounds were tested against nitrification in soil suspensions, and all completely inhibited oxidation of NH+4 to NO−2 by Nitrosomonas at concentrations as low as 10−6 to 10−8 M. Oxidation of NO−2 to NO−3 by Nitrobacter, however, was affected much less severely by these inhibitors. The greater resistance of Nitrobacter is not significant biologically because inhibition of the first step carried out by Nitrosomonas effectively inhibits the entire process of nitrification. The 3‐glucoside of quercetin, isoquercitrin, inhibited the activity of Nitrosomonas completely at the same concentration as quercetin. We found a compound in large quantities in the oak‐pine climax soil which appeared in all tests to be a flavonoid aglycone, but we were never able to identify it to our satisfaction. This substance was extremely inhibitory to germination and seedling growth of ‘Crimson Giant’ radish seeds. These have hard seed coats and germinate very rapidly so most inhibitors do not affect their germination at all. It is likely that some, if not all, of the nitrification inhibitors identified may be important in inhibition of nitrification in the later stages of succession and in the climax along with the tannins.
GERMINATION AND SEEDLING RESPONSE OF ATLANTIC AND GULF COASTS POPULATIONS OF SPARTINA ALTERNIFLORA
Authors: Seneca Ernest D.
Published: January 2018

Germination response to thermoperiod and seedling response to photoperiod‐thermoperiod treatments and to uniform field conditions were compared for 12 populations of Spartina alterniflora Loisel. from along the Atlantic and Gulf coasts. Germination above 50 % was attained by seeds from all populations in 25–10, 30–15, and 35–20 C alternating diurnal thermoperiods following three months storage in estuarine water at 2–3 C. Except for Massachusetts, Connecticut, and Virginia, seedlings of populations from Ocracoke Island, North Carolina, and northward produced significantly more total biomass in the long‐ than in the short‐day photoperiod in the 30–26 C thermoperiod. Seedling biomass of populations southward of Ocracoke Island, North Carolina, was not significantly affected by photoperiod in either the 18–14 or 30–26 C thermoperiods. Seedlings of all populations from Georgia and northward were significantly shorter and produced significantly more culms in the short‐ than in the long‐day photoperiod in the 30–26 C thermoperiod. Seedlings from Mississippi and all populations from Virginia and northward had significantly lower shoot to root plus rhizome ratios under the short‐ than the long‐day photoperiod in the 30–26 C thermoperiod. Flowering occurred only in populations from Ocracoke Island, North Carolina, northward in the 30–26 C thermoperiod. In a field study, flowering occurred in a north to south sequence and in all populations by the end of the second growing season. Controlled environment and field seedling studies indicated that southern populations flowered later, exhibited longer growing periods, and were less sensitive to photoperiod than northern populations. New England, Mid‐Atlantic, South Atlantic, and Gulf coast populations differed in height, color, flowering time, length of growing period, and morphology through two growing seasons in the field study.
AN EVALUATION OF SELECTED PHYSICAL CHARACTERISTICS AND METABOLISM OF ENZYMATICALLY SEPARATED MESOPHYLL CELLS AND MINOR VEINS OF TOBACCO
Authors: Cataldo D. A. , Berlyn G. P.
Published: January 2018

An enzymatic digestion procedure is presented which allows for the isolation of large quantities of mesophyll cells and minor veins of Nicotiana tabacum L. cv. ‘Wisconsin 38’. Isolated mesophyll cells exhibited CO2 fixation rates in excess of 150 μmoles CO2 mg chl‐1hr‐1, while bundles consistently fixed CO2 at much lower rates, viz. 10–20 μmoles CO2 mg chl‐1hr‐1. Various physical and biochemical parameters of the isolates have been compared with intact leaf disks.
STRUCTURE AND DEVELOPMENT OF THE SIEVE ELEMENTS IN PSILOTUM NUDUM
Authors: Perry James W. , Evert Ray F.
Published: January 2018

Shoot tissue of Psilotum nudum (L.) Griseb. was fixed in glutaraldehyde and postfixed in osmium tetroxide for electron microscopy. Young sieve elements can be distinguished from contiguous parenchyma cells by their distinctive plastids, the presence of refractive spherules, and the overall dense appearance of their protoplast. The refractive spherules apparently originate in the intracisternal spaces of the endoplasmic reticulum (ER). With increasing age the sieve‐element wall undergoes a marked increase in thickness. Concomitantly, a marked increase occurs in the production of dictyosome vesicles, many of which can be seen in varying degrees of fusion with the plasmalemma. Other fibril‐ and vesicle‐containing vacuoles also are found in the cytoplasm. In many instances the delimiting membrane of these vacuoles was continuous with the plasmalemma. Vesicles and fibrillar materials similar to those of the vacuoles were found in the younger portions of the wall. At maturity the plasmalemma‐lined sieve element contains a parietal network of ER, plastids, mitochondria, and remnants of nuclei. The protoplasts of contiguous sieve elements are connected by solitary pores on lateral walls and pores aggregated into sieve areas on end walls. All pores are lined by the plasmalemma and filled with numerous ER membranes which arise selectively at developing pore sites, independently of the ER elsewhere in the cell. P‐protein and callose are lacking at all stages of development.
IS POLYPLOIDY NECESSARY FOR TISSUE DIFFERENTIATION IN HIGHER PLANTS?
Authors: Evans Lance S. , Hof Jack Van't
Published: January 2018

Measurements of relative DNA per nucleus of cells from various tissues show that cell differentiation can occur in the absence of polyploidy in higher plants. In Pisum polyploidy was present in roots, sepals, pods, pistils, and stamens but not in petals or leaves. In Triticum cells of leaves exhibited some polyploidy, but no polyploid cells were present in mature roots. No polyploid cells were found in any tissue of Helianthus examined (roots, cotyledons, stems, leaves, sepals, petals, pistils, and stamens). Therefore, as a general rule, polyploidy should not be considered essential in tissue or organ differentiation of higher plants. In Helianthus polyploidy is unnecessary for the completion of the life cycle.
DISTRIBUTION OF ENZYMATIC BROWNING OF YOUNG SHOOT HOMOGENATES IN THE AURANTIOIDEAE
Authors: Esen Asim , Scora Rainer W.
Published: January 2018

Distribution of polyphenol oxidase‐catalyzed browning of young shoot homogenates was studied in 428 accessions of the orange subfamily Aurantioideae. Browning and nonbrowning phenotypes were found in both tribes, namely Clauseneae and Citreae. The browning taxa had sufficient polyphenol oxidase activity and a presently unknown phenolic substrate, while the nonbrowning taxa were devoid of both. A third group of taxa contained the substrate only and they too were designated as browning since their homogenates turned brown when the enzyme from a known source was added. The color of homogenates was taxon‐specific in most browning and nonbrowning taxa. Within the genus Citrus, 4 out of the 16 species recognized by Swingle were browning and 2 were nonbrowning. Exceptions noted within either group of taxa were presumably hybrids or mutants. The significance of enzymatic browning as an additional taxonomic criterion in studying species relationships and as a genetic marker in identificaton of hybrid taxa was discussed.
DEVELOPMENT AND ORGANIZATION OF THE PRIMARY VASCULAR SYSTEM IN POPULUS DELTOIDES ACCORDING TO PHYLLOTAXY
Authors: Larson Philip R.
Published: January 2018

An actively growing cottonwood bud was embedded in epon‐araldite and serially sectioned at 2 μm. The sections were analyzed microscopically with the optical shuttle system of Zimmermann and Tomlinson, and all data were quantitatively recorded relative to the apex and to leaf plastochron index (LPI). Analysis of the sections revealed an acropetally developing procambial system organized according to a precise phyllotaxy. Six procambial strands could be recognized and followed long before the leaf primordia that they would enter were evident at the apex. Origin of these strands coincided with developmental events both in the parent trace and its primordium and in the antecedent leaf on the same orthostichy. Once a primordium and its trace attained a certain stage of development, trace bundles began to develop basipetally from the primordium base. These trace bundles appeared to be the earliest progenitors of wood formation in cottonwood. It was concluded that the concept of residual meristem and its corollary, the hypothesis that acropetally developing procambial strands determine the inception sties of new primordia, apply to the cottonwood apex.
GROWTH REGULATION BY ETHYLENE IN FERN GAMETOPHYTES. IV. INVOLVEMENT OF PHOTOSYNTHESIS IN OVERCOMING ETHYLENE INHIBITION OF SPORE GERMINATION
Authors: Fisher Robert W. , Miller John H.
Published: January 2018

The inhibitory effects of ethylene on spore germination were investigated. In darkness spore germination was completely inhibited by 10 μ1 · 1−1 ethylene. Light partially overcame this inhibition, and the effect of continuous irradiation with white fluorescent light saturated at about 450 μW · cm−2. Monochromatic red, blue and far‐red light were effective in overcoming ethylene inhibition, whereas green was not. Short periodic exposures to red or far‐red light were not sufficient to overcome ethylene inhibition. This suggested that phytochrome was not involved. The photosynthetic inhibitor DCMU blocked the effect of light. Infrared gas analysis showed that photosynthesis saturated at about 450 μW · cm−2 in white light. Red, blue and far‐red light were more efficient photosynthetically than green light; DCMU blocked photosynthesis. Normalized curves of photosynthesis and germination vs. light intensity showed a similar dependence on light energy. It was concluded that light appears to overcome the inhibitory effects of ethylene through some process dependent on photosynthesis.
THE EVOLUTION OF POLLEN TETRADS IN ONAGRACEAE
Authors: Skvarla John J. , Raven Peter H. , Praglowski J.
Published: January 2018

In Onagraceae, pollen is shed in mature tetrads in most Epilobieae, many species ofLudwigia(Jussiaeeae), and two closely related species of the large genusCamissonia(Onagreae). Mature tetrads ofCamissonia cardiophyllaand representative species ofEpilobiumandLudwigiawere examined with light, scanning, and transmission electron microscopes. Morphological diagnoses of monad units indicated that individual taxa could be readily distinguished. Statistical analyses of tetrads which remained after acetolysis treatment revealed significant differences in the strength of the binding mechanisms. Mechanisms of tetrad cohesion were found to consist of two principal types. Common to all taxa is cohesion of pollen wall surfaces at the aperture margins; this mechanism is well known in many angiosperm groups. With the exception ofCamissonia, the remaining taxa also display binding by means of short exine fragments between adjacent pollen units. These fragments, termed bridges and reported here for the first time, are located in the area extending from the aperture margins to near the center of the proximal exine faces. Thin sections reveal that layers of the bridges are identical with those of the exine. Comparisons were made between bridges and viscin threads, both of which occur on the proximal faces of the grains. Viscin threads are present on all pollen grains in Onagraceae and exhibit distinctive morphologies, and bridges were viewed morphogenetically as related to viscin threads but including an endexine layer and occupying a position near the apertures where cohesion of wall surfaces also occurs. In an evolutionary sense, the formation of mature tetrads almost certainly occurred independently inCamissoniaand may have done so inLudwigiaand the Epilobieae.
THE PHOTOINDUCTIVE CONTROL OF SEED WEIGHT IN CHENOPODIUM RUBRUM L.
Authors: Cook Robert Edward
Published: January 2018

The determination of mean seed weight in Chenopodium rubrum L., a short‐day, weedy annual, has been examined through the manipulation of photoperiod during the course of reproductive development. Individuals that develop seeds in relatively long photoperiods (15 L: 9 D) form many more seeds of smaller weight than individuals that develop seeds in relatively shorter photoperiods (12 L: 12 D). By altering the inductive photoperiod at different times during the course of reproductive development, it is shown that the effect of photoperiod is most strongly exerted between six and twelve days after the start of floral induction and is coincident with the determination of primordia as floral structures. The ecological significance of this early developmental determination is discussed.
THE SEASONAL CAMBIUM ACTIVITY OF CHILEAN AND CALIFORNIAN SHRUBS
Authors: Avila Guacolda , Aljaro Maria E. , Araya Sandra , Montenegro Gloria , Kummerow Jochen
Published: January 2018

The sclerophyllous evergreen shrub vegetation of southern California and central Chile is characterized by several examples of morphologically similar species. For each one out of a group of four Californian shrub species, four morphologically analogous sclerophyllous evergreens from Chile were chosen. In monthly intervals two‐year branchlets from these eight species were collected and their cambium activity was evaluated by means of a histological analysis. Similar shrub species from Chile and California show a surprisingly strong coincidence in their seasonal fluctuations of cambium activity regardless of their systematic position. This observation is interpreted to mean that convergence has taken place.
COMPARATIVE LEAF ANATOMY OF SOLIDAGO AND RELATED ASTERACEAE
Authors: Anderson Loran C. , Creech Jessica B.
Published: January 2018

Leaf anatomy of 63 taxa is investigated to elucidate generic relationships among Brachychaeta, Brintonia, Chrysoma, Euthamia, Gundlachia, Oligoneuron, Oreochrysum, Petradoria, and Solidago. All these genera have been included at one time or another within Solidago. Aster ptarmicoides is also studied because it hybridizes with some species of Solidago (sens. str.). Qualitative and quantitative differences in mesophyll, storage parenchyma, secretory apparatus, bundle sheath extensions, and midvein structure allow rather precise grouping of the taxa. Brachychaeta, Brintonia, Oligoneuron, Oreochrysum, and Aster ptarmicoides should be considered as constituents of Solidago. They all have bundle sheath extensions and little or no water storage parenchyma. In Solidago secretory cavities, when present, are shaped and positioned differently from those in Euthamia. The absence of bundle sheath extensions and various combinations of other anatomical features suggest that Chrysoma, Euthamia, Gundlachia, and Petradoria are generically distinct from one another and from Solidago.
MALE GAMETOPHYTE SELECTION IN A NATURAL POPULATION OF HAPLOPAPPUS GRACILIS (COMPOSITAE)
Authors: Jordan Robert G.
Published: January 2018

Distributions of two forms of the A chromosome of Haplopappus gracilis in a hybrid natural population and in artificial crosses are analyzed. Pollen bearing the standard type A chromosome is generally superior to that bearing the Mexican type A when they compete on homozygous pistils of either type, but there is no selection on heterozygous pistils. The distribution of sporophyte karyotypes in the natural population is not in equilibrium, and it is surmised that the standard type A chromosome is increasing in frequency in the population.
PHOTOPERIODISM IN SEEDLING STRAINS OF LEMNA PERPUSILLA: JUVENILITY WITHOUT OBVIOUS MORPHOLOGICAL CORRELATES?
Authors: Hillman William S.
Published: January 2018

Strains derived from seeds of L. perpusilla 6746 were tested for flowering on several media under 8‐hr days at various times after germination, always in comparison with the parent strain. They flowered slowly in experiments started 2 wk after germination and more rapidly 7 wk after and later, with many eventually approaching parental values. Juvenility as measured in this way was not associated with any obvious morphological difference between younger and older strains, or from the parent. A system based jointly on this effect and what is already known of vegetative senescence in Lemna should prove valuable for a general study of aging in plants.
DEVELOPMENTAL MORPHOLOGY OF COTTON FLOWERS AND SEED AS SEEN WITH THE SCANNING ELECTRON MICROSCOPE
Authors: Beasley C. A.
Published: January 2018

This report assembles and pictorially presents observations on the timing of relatively uniform and well‐defined developmental events in the cotton flower and its component parts. The first floral bud occurs on the 7–9th node approximately 35–40 days postemergence; 20–25 additional days elapse until anthesis. Floral parts are morphologically well defined by two weeks preanthesis. In about 85 % of the flowers the basal, abaxial surface of two of the three bracts contains an outer involucral nectary; occasionally, none, one, or three nectaries are found. The maximum rate of increase in floral bud length occurs during the 24 hrs preceding anthesis. Flower opening occurs at about daylight, although light is not required. Multipored pollen grains germinate in about ½ hr after deposition on the stigmatic hairs. Fertilization is accomplished, for most ovules, by the end of the first day postanthesis. Stomata are abundant, particularly at the chalazal ends of ovules. Fiber initials (epidermal cells of the ovule) begin their elongation phase on the morning of anthesis and are bounded by a thin primary wall. Areas of contrast (spots) observed through the scanning electron microscope are speculated to be organelles “seen through” the relatively amorphous fiber wall, which lacks extensive fibrillar orientation of cellulose. Fiber elongation ceases by about 24–28 days postanthesis, and by 50–70 days postanthesis fibers are mature and exhibit a thickened secondary wall and spiral twisting. Concomitant with the time of fiber maturity, the ovary wall splits and opens along locular suture lines.
TRISOMICS IN SOLANUM CHACOENSE: FERTILITY AND CYTOLOGY
Authors: Lee Heiyoung K. , Rowe P. R.
Published: January 2018

Twenty trisomic plants found in the progeny 3x x 2x crosses in Solatium chacoense and their F1 trisomies obtained by 2x + 1 X 2x crosses were studied with respect to their fertility and cytology. The female transmission of the extra chromosome in the trisomics varied from 2 to 60 %. The transmission frequencies of F1 trisomies were similar to their parent trisomies in most of the lines. The transmission through the pollen ranged from 0 to 20 %. Female and male fertility of the parent trisomies was high. They produced an average of 37 seeds per pollination as the female or as the male parent. The F1 trisomies produced about half the seed set of their parent trisomies. The extra chromosomes of six trisomies were identified by pachytene analysis. They were isochromosomes for the long arms of chromosomes I, IV and IX and the short arms of IV, IX and XII. Chromosome morphology of the extra chromosomes in pachytene stage was described. A chromosome association of 12 II + 1 I was found in 66 % of the cells at MI. About 29 % of the cells had one trivalent and 5 % had three or five univalents. The frequency of trivalent formation was not affected by the length of the extra chromosome. The possibility of univalent shift in secondary trisomies was discussed.
THE PICEA ABIES SHOOT APICAL MERISTEM IN CULTURE. II. DEPOSITION OF POLYSACCHARIDES AND LIGNIN‐LIKE SUBSTANCES BENEATH CULTURES
Authors: Romberger J. A. , Tabor C. A.
Published: January 2018

Excised shoot apical meristems of Picea abies seedlings grow and develop primordial leaves when cultured on Millipore (mixed esters of cellulose) filter membranes lying on a simple, defined medium gelled with agarose. When the cultures are removed from the membranes, each leaves a spot of altered light transmission, spectral characteristics, hygroscopicity, and chemical reactivity. These spots are the manifestation of deposition in the membrane pore space of polysaccharides, lignin‐like components, and probably other substances. Deposition of water‐insoluble, Schiff's reagent‐positive substances can be detected in the filter membranes after only 3–6 hr exposure to a meristem and continues for 10–15 days or longer. Precursors of the insoluble deposition materials can diffuse through at least nine layers of Millipore membrane before deposition at a site remote from living cells. Placement of a dialysis membrane between the meristem and the Millipore membrane prevents detectable deposition in the latter. The observations are consistent with the hypothesis that apical meristems can synthesize and export mobile precursors of cell wall components as well as any substances necessary to promote their condensation or polymerization into insoluble materials at remote sites. The system may be useful in studying synthesis of cell wall components and investigating the functional role of growth regulators in shoot apical development.
THE POLLINATION ECOLOGY OF SOLANUM ROSTRATUM (SOLANACEAE)
Authors: Bowers Karen A. W.
Published: January 2018

The pollination mechanisms and pollen vectors of Solarium rostratum have been examined by greenhouse experiments and field studies. Although the capacity for autogamy exists in this weedy annual, it rarely occurs because of two factors: (1) the morphology of the flower and (2) the foraging behavior of the various species of Bombus, the primary pollen vector in the regions studied. The percentages of geitonogamy and xenogamy are dependent on the flight pattern of the bees and the number of open flowers on a plant.
EFFECT OF AN AMMONIUM NITRATE PULSE ON THE GROWTH AND ELEMENTAL COMPOSITION OF NATURAL STANDS OF SPARTINA ALTERNIFLORA AND JUNCUS ROEMERIANUS
Authors: Gallagher John L.
Published: January 2018

A nitrogen (ammonium nitrate) pulse of 200 kg ha“1 was added to stands of tall (1.0–1.5 m) Spartina alterniflora, short (< 0.5 m) Spartina alterniflora, and Juncus roemerianus in a Georgia salt marsh in July. The major response ten weeks later was an increase in the aerial biomass and a sharp reduction in the C/N ratio in short Spartina alterniflora. One year after the treatment the difference between the biomass in enriched and control plots was greater than ten weeks after treatment, but the C/N ratio in the plants in the treated plots had risen to that of the controls. The availability of nitrogen appears to limit growth in the middle elevation Georgia salt marsh (short S. alterniflora), but not in the lower (tall S. alterniflora) or higher (J. roemerianus) portions.
FIBER INITIATION ON THE COTTON OVULE (GOSSYPIUM HIRSUTUM)
Authors: Stewart James McD.
Published: January 2018

Cotton ovules at the stage of fiber initiation were studied with a scanning electron microscope. On the day before anthesis the anatropous ovule had many anomocytic stomata, especially on the chalazal end. At anthesis, fibers first appeared at the crest of the funiculus and then around the lateral circumference of the ovule. Fiber initials were delayed for a few hours at the chalazal cap and for 3 or 4 days at the extreme end of the micropylar region. The morphological differentiation of a fiber began when an epidermal cell rounded up and protruded. After a brief period of diametric expansion, the initial began elongation toward the micropylar end. Between 2 and 3 days of age the fibers segregated into small groups, developed tapered tips, and began spiral growth. Fiber density was about 3,300 fibers per mm2, and the ratio of fiber initials to total epidermal cells was 1:3.7 at anthesis.
ADVENTITIOUS ROOT DEVELOPMENT FROM THE SEEDLING HYPOCOTYL OF LYCOPERSICON ESCULENTUM
Authors: Byrne John M. , Collins Kathleen A. , Cashau Pamela F. , Aung Louis H.
Published: January 2018

Tomato seedlings five through ten days old were used for this investigation. Adventitious roots were initiated from the pericycle of the tomato hypocotyl. The position of adventitious root development was irregular in the rhizogenic hypocotyl; however, the cellular pattern of individual root development was very regular. Four layers of pericycle derivatives participated in root histogenesis and a bi‐ or triseriate endodermal cover was derived from the endodermis. Fluorescent microscopy showed that Casparian strips on the meristematic endodermal cell walls were not removed biochemically but were displaced around the root primordium by anticlinal divisions and cell enlargement. Casparian strips were not synthesized by endodermal cover cells. The emergent root had a typical three tiered or closed pattern of apical organization, and quiescent centers were present in all emergent roots longer than 0.5–0.6 cm.
INFLUENCE OF FERULIC ACID ON MINERAL DEPLETION AND UPTAKE OF 86Rb BY PAUL'S SCARLET ROSE CELL‐SUSPENSION CULTURES
Authors: Danks Maureen L. , Fletcher John S. , Rice Elroy L.
Published: January 2018

The influence of 10‐4 m ferulic acid on mineral depletion and ion uptake in sterile cultures of Paul's Scarlet rose was examined. The effect of ferulic acid on the rate of depletion of Mg2+, Ca2+, K+, P, Fe3+, Mn2+, and Mo3+ from the medium during the 14‐day growth cycle varied with the age of the cells and the ion under consideration. In general, rates of uptake were higher than control rates in older cells and less than control rates in cells 3–5 days old. The degree of inhibition of uptake of 86Rb also varied with age. Young (4–5 day) cells showed approximately 50% inhibition at high concentrations of RbCl (system 2) and approximately 25% inhibition at low concentrations of RbCl (system 1). In contrast, the rate of 86Rb uptake in 10‐day cells was not significantly altered by incubation in ferulic acid.
PATTERNS OF CARBON ALLOCATION IN AN ARCTIC TUNDRA GRASS, DUPONTIA FISCHERI (GRAMINEAE), AT BARROW, ALASKA
Authors: Allessio M. L. , Tieszen L. L.
Published: January 2018

In Dupontia fischeri R. Br. the pattern of translocation of photosynthetically incorporated 14C was established within six hr after treatment in situ at Barrow, Alaska. More radiocarbon went to younger rather than older tillers. The most effective sinks were root, lateral root, and rhizome primordia and nonemergent tillers which were actively growing. Substantial amounts of radiocarbon appeared in the stem base and rhizome of the treated tiller. Although relatively little appeared in other plant parts, except for the sinks mentioned above, interdependence of tillers appeared to be maintained until flowering occurred. This pattern of distribution was established early in the season once the soil thawed, and growth began and was maintained until mid‐August. Some translocation to active growth centers occurred even while the soil was thawing. Redistribution of radiocarbon to new root and leaf tissues produced after the time of treatment was observed. There was no autoradiographic evidence during the season to indicate storage of large amounts of mobilizable photosynthate in the stem base or rhizome of a tiller at the time these field studies were carried out.
A DEVELOPMENTAL STUDY OF EXTRAFLORAL NECTARIES IN SLIPPER SPURGE (PEDILANTHUS TITHYMALOIDES, EUPHORBIACEAE)
Authors: Dave Y. S. , Patel N. D.
Published: January 2018

Slipper spurge (Pedilanthus tithymaloides) bears one or two stalked extrafloral nectaries on either side of the leaf base and one at the leaf tip. The mature nectary is differentiated into multicellular zones: head, neck, and stipe. The nectary arises as a small group of meristematic cells with densely staining cytoplasm and nuclei. The columnar secretory cells show changes in their chemical nature at different developmental stages of the nectary. There is a basipetal sequence in the development and decay of the tissues in the nectary. Decay of the nectary begins at the head, abscission occurs at the line between stipe and neck regions, and the scars of the fallen nectaries are left when the stipe cells also collapse.
CELL SHAPE AND WALL PATTERN IN RELATION TO CYTOPLASMIC ORGANIZATION IN PEDIASTRUM SIMPLEX
Authors: Millington W. F. , Gawlik S. R.
Published: January 2018

P. simplexis a single‐pronged, fenestrated species ofPediastrum.Comparison is made in regard to cell differentiation and structure withP. boryanum, a 2‐pronged, unfenestrated species, with emphasis on the origin of cell wall pattern and the regulation of cell shape. The characteristic wall pattern is initiated with the deposition of plaques of wall material of the outer wall layer when zoospores have assembled in the colony. The pattern is postulated to be templated in the plasma membrane. The inner, thicker wall layer is fibrillar and deposited from vesicles derived from the golgi apparatus. InP. simplex2–4 dictyosomes are present in contrast to the single dictyosome ofP. boryanum.The dictyosomes lie at the concave inner face of the nucleus. Blebs of its ribosome‐free outer membrane are contributed to the forming face of the golgi apparatus. Parallel microtubules underlie the plasma membrane in the aggregating zoospores and disappear after the initiation of wall formation. The possible role of microtubules and other organelles in the determination of cell shape inPediastrumis discussed.
GROWTH OF PHELLINUS (PORIA) WEIRII ON DIFFERENT VITAMINS AND CARBON AND NITROGEN SOURCES
Authors: Li C. Y. , Bollen W. B.
Published: January 2018

Mycelial growth of Phellinus weirii (Murr.) Gilb., a root pathogen of conifers in the Pacific Northwest, was studied in defined liquid media with different carbon and nitrogen sources and vitamins. The fungus grew significantly more on glucose, xylose, maltose, or fructose than on other carbon sources. Starch did not support growth. Maximum growth occurred in 4 weeks on all carbon sources except dextrin and sucrose, with which maximum growth occurred in 3 weeks. Of the nitrogen sources, peptone supported the best growth of the fungus; glutamic acid, serine, aspartic acid, alanine, leucine, ammonium sulphate, and urea supported significantly better growth than tyrosine, arginine, methionine, threonine, and glycine. Potassium nitrate, phenylalanine, sodium nitrate, lysine, proline, and cysteine inhibited growth. Thiamine hydrochloride was not absolutely required for growth of P. weirii, but better growth was obtained with its addition. The fungus showed no significant responses to a range of other vitamins.
THE ULTRASTRUCTURE OF ACACIA CORNIGERA L. BELTIAN BODY TISSUE
Authors: Rickson Fred R.
Published: January 2018

Beltian bodies of Acacia cornigera have evolved as multicellular structures which serve as food for protective ant colonies. At the ultrastructural level, Beltian body cells contain a large amount of protein and lipid that presumably contribute to the ant's nutrition. The non‐soluble protein is aggregated into tubules of two size classes: one is present in both the cytoplasm and nucleoplasm, and has an individual tubule diam of 75 A, while another size class, located in the cytoplasm, has a diam of 280 A. These two classes of protein tubules aggregate into units that occupy a high percentage of a cortical cell's volume. Numerous lipid droplets are present in the cytoplasm, adding an energy source to the ant's diet. Each droplet is surrounded by a single layer of filaments, the molecular composition of which is unknown at this time. This study indicates that the evolutionary development of this tissue has produced a highly desirable food source for the inhabiting ants.
DEVELOPMENT OF THE EPIPHYLLOUS INFLORESCENCE OF HELWINGIA JAPONICA (HELWINGIACEAE)
Authors: Dickinson Timothy A. , Sattler Rolf
Published: January 2018

The inflorescence of Helwingia japonica (Thunb.) Dietr. is initiated adjacent to the leaf axil on the adaxial side of the base of a leaf primordium during its second plastochron. The inflorescence which develops from the resulting primordium comes to be situated on the midrib of the mature fertile leaf, through the action of a basal, intercalary meristem. In fertile leaves this meristem develops beneath, as well as above, the insertion of the inflorescence primordium on the leaf primordium. The same meristem is present in sterile leaves as well. A separate, adaxial vascular bundle departs from the leaf trace in the base of the petiole and leads to the inflorescence, in the mature fertile leaf. This adaxial vascular bundle is absent in sterile leaves. It is argued that the vascular anatomy does not conclusively confirm the hypothesis that the epiphyllous inflorescence is the congenital fusion product of a leaf and an axillary inflorescence. Instead, it is suggested that the interplay of changes in the position of primordium initiation, and intercalary growth, offers an ontogenetic explanation of the situation, which in turn may be related to the phylogeny of the species in question. It appears to be misguided and futile to look for homologies (i.e., 1:1 correspondences) between fertile and sterile leaves, since 1:1 correspondences do not exist in this case.
VOLATILE GROWTH INHIBITORS PRODUCED BY SALVIA LEUCOPHYLLA: EFFECTS ON SEEDLING ROOT TIP ULTRASTRUCTURE
Authors: Lorber Peter , Muller Walter H.
Published: January 2018

Volatile monoterpenes emanating from leaves of Salvia leucophylla (Labiatae) are responsible for anatomical and physiological changes occurring in herb seedlings which were exposed to the vapors. Examination of treated root tip cells from Cucumis sativus by electron microscopy revealed widespread systemic disturbances. These included the accumulation of globules which appear to be lipid in nature in the cytoplasm, a drastic reduction in the number of a variety of intact organelles including mitochondria, and a disruption of membranes surrounding nuclei, mitochondria, and dictyosomes. These effects, coupled with the effects of environmental stress, may account for the failure of herb seedlings to survive in the areas adjacent to Salvia thickets.
CHROMOSOME MUTATIONS IN A FERN POPULATION GROWING IN A POLLUTED ENVIRONMENT: A BIOASSAY FOR MUTAGENS IN AQUATIC ENVIRONMENTS
Authors: Klekowski Edward J. , Berger Bernard B.
Published: January 2018

A population of royal ferns, Osmunda regalis, which is periodically submersed by the waters of the Millers River was found to have a very high frequency of chromosome mutations. The Millers River is located in western Massachusetts and is heavily polluted with industrial wastes. Approximately 43 % of meiotic samples collected in 1973 from the Millers River population were heterozygous for mutations such as paracentric inversions or reciprocal translocations, whereas less than 1 % of meiotic samples from nearby non‐polluted control populations were such heterozygotes. Cytological analysis within royal fern clones indicate that practically all of the chromosome mutations were post‐zygotically induced and that at least 64 % were induced since 1969. In the course of this study over 26,000 spore mother cells were analyzed for chromosome aberrations.
EFFECTS OF SIMULATED ACID RAIN ON PHASEOLUS VULGARIS L. (FABACEAE)
Authors: Ferenbaugh Roger W.
Published: January 2018

Experiments were performed to determine the effects of simulated acid rain on Phaseolus vulgaris L. At pH values below 3, plants exhibited a failure to attain normal height, had necrotic and wrinkled leaves, excessive and adventitious budding, and premature abscission of primary leaves. Histologically, leaves had smaller cells, less intercellular space, and smaller starch granules within the chloroplasts. Respiration rates of the treated plants increased only slightly at low pH values. Apparent rates of photosynthesis, however, increased dramatically. Both carbohydrate production and root biomass were reduced by low pH treatments, and application of Congo red indicator to the acid‐treated leaf tissue showed that the cell contents were acidified to a pH of below 4.0.
EXPERIMENTAL HYBRIDIZATION OF XANTHIUM STRUMARIUM (COMPOSITAE) FROM ASIA AND AMERICA. II. SESQUITERPENE LACTONES OF F1 HYBRIDS
Authors: McMillan Calvin , Mabry Tom J. , Chavez Pedro I.
Published: January 2018

Effects of hybridization on sesquiterpene lactones in Xanthium strumarium were studied for clues to the relationship of Old and New World populations. In crosses between indigenous Asiatic plants in the “strumarium” morphological complex and various American complexes that produce xanthinin as a major sesquiterpene lactone, the F1 hybrids contained xanthinin and the related compounds, xanthanol, xanthatin, and xanthinosin. In other crosses with various American complexes that produce xanthumin, the stereoisomer of xanthinin, the F1 hybrids contained xanthinin and xanthumin as well as xanthinin‐related compounds and their stereoisomers, xanthumanol, deacetoxylxanthumin, and tomentosin. The Asiatic plants of “strumarium” from Hong Kong involved in the crosses produce approximately equal percentages of xanthinin, xanthatin and xanthinosin, but those from India contain only xanthinosin. The putative introduction of the American morphological complex, “chinense,” contains xanthumin as the major component but shows chemical diversity that indicates genes derived from the indigenous “strumarium” complex.