bluuebunny/crossref_metadata_2025 huggingface dataset:
FREE AMINO ACID CHANGES DURING GERMINATION OF TELIOSPORES OF THE WHEAT BUNT FUNGUS, TILLETIA CARIES
Authors: Trione Edward J.
Published: January 2018

Teliospores were aerated and agitated in a mineral salts medium and their free amino acid contents were analyzed at eight different times, from shortly after imbibition of water until just before germ tube emergence. In addition to the common amino acids, eight unidentified ninhydrin‐positive components were detected. About 50 % or more of nearly each of the amino acids diffused out of the spores during the initial phase of germination. These released amino acids were actively taken up by the spores during the latter stages of germination. The free amino acids in largest amounts in the dormant spores of T. caries were arginine 15.0, glutamic acid 6.3, and alanine 3.7 μmoles per g dry spores. Together these three amino acids accounted for about 71 % of the total free amino acids in dormant spores of T. caries and T. controversa. The total amounts of free amino acids in spores of common bunt were much higher than in spores of dwarf bunt.
STRUCTURE AND DEVELOPMENT OF CLEISTOIODOPHANUS CONGLUTINATUS GEN. & SP. N. (ASCOBOLACEAE)
Authors: Bezerra Jose L. , Kimbrough James W.
Published: January 2018

Cleistoiodophanus represents a new coprophilous genus of the tribe Iodophaneae in the Ascobolaceae (Pezizales). The only species thus far discovered, C. conglutinatus, is described and illustrated. Aspects of its cytological development are described from cultures obtained from apothecia found on sheep dung near Gainesville, Florida. Plasmogamy occurs in acogonial coils, two or three cells of which give rise to ascogenous hyphae. Ascogonia are quickly enclosed by vegetative hyphae and the ascocarp continues in a cleistohymenial development. Unlike Iodophanus and related genera, the excipulum remains intact even after spore maturation and the asci push through the epihymenial regions to release spores. The asci are characteristically thickened at their apices, diffusely amyloid, and somewhat saccate. The asci are predominantly 8‐spored, but have been found with four or 16 spores per ascus. A previously undescribed Oedocephalum imperfect stage was induced in culture.
POLLINATION AND FRUIT‐SET IN ASCLEPIAS: A REAPPRAISAL
Authors: Wyatt Robert
Published: January 2018

Experimental pollinations ofAsclepias tuberosaL., the first for this species and second large‐scale effort for the genus, reveal trends toward local population differentiation. The species possesses a low level of self‐compatibility, the first documented report for the genus. Analysis of flowers visited by natural pollinators in populations across the eastern half of the United States demonstrated a linear relationship between pollinia removal and pollinia insertion. Clarifications in older literature regarding the specificity of the pollination mechanism, effective levels of pollination in natural populations, and the performance of experimental manipulations are made, and it is concluded that fruit‐set inAsclepiasis regulated by the interaction of both mechanical aspects of pollination and physiological aspects of fertilization and fruit development. A model incorporating these restraints is seen to predict fairly well the observed fruit to flower ratio of about 1:100 in natural populations.
RETICULATE THICKENINGS IN SOME SPECIES OF JUGLANS
Authors: Miller Regis B.
Published: January 2018

Reticulate thickenings in Juglans nigra, J. major, J. microcarpa, and J. californica (including J. hindsii) appear, under the transmitted light microscope, to be a cluster of very large or “gash‐like” vessel‐ray pits. The use of scanning electron microscopy shows that these so‐called pits are thickenings on the inside wall of the vessel.
POST‐POLLINATION PHENOMENA IN ORCHID FLOWERS. VII. PHOSPHATE MOVEMENT AMONG FLORAL SEGMENTS
Authors: Harrison Charles R. , Arditti Joseph
Published: January 2018

Radioactive phosphate applied to labella (lips, median petals), dorsal (median) sepals or stigmas of Cymbidium cv Jungfrau is transported to all parts of the flower. Transport levels vary depending on the sites of application or accumulation. Pollination or application of NAA to the stigma cause accumulation of 32P in gynostemia (columns) and ovaries. Translocation characteristics correlate with vascular anatomy of Cymbidium flowers.
ULTRASTRUCTURE AND ACID PHOSPHATASE IN PEDICEL ABSCISSION OF HIBISCUS
Authors: Gilliland Margaret G. , Bornman Chris H. , Addicott Fredrick T.
Published: January 2018

Pedicel abscission in Hibiscus rosa‐sinensis was investigated by light and electron microscopy. During the pre‐abscission period endoplasmic reticulum declined somewhat, dictyosomes increased in number and apparent activity, and mitochondria maintained their numbers. The observations suggested that dictyosomal vesicles were migrating to and fusing with the plasma membrane. The enzyme acid phosphatase was associated with dictyosomes and dictyosomal saccules, with small vacuoles and invaginations of the plasma membrane, and in the paramural region between the plasma membrane and the cell wall. Our interpretation is that acid phosphatase, (and probably also the enzymes involved in cell wall dissolution) are transported via an endoplasmic reticulum‐dictyosome‐vesicle carrier system to the paramural regions of the cell. In more general terms, our observations support the view that the enzymes involved in the cell wall hydrolysis of abscission are synthesized within a compartmentalized, lysosomal system prior to their release and action.
WOOD ANATOMY OF RORIDULACEAE: ECOLOGICAL AND PHYLOGENETIC IMPLICATIONS
Authors: Carlquist Sherwin
Published: January 2018

Description of quantitative and qualitative features of root and stem wood of the two species of Roridula, endemics of Cape Province, Republic of South Africa, are presented because no data on secondary xylem have hitherto been published for these shrubs. Of the two species, R. gorgonias has wood appreciably more primitive in such respects as longer vessel elements with more numerous bars on the scalariform perforation plates. This is interpreted as correlated with the fact that R. gorgonias occupies maximally mesic habitats (Sphagnum covered covered montane seeps). Roridula dentata shows more specialized wood features, hypothesized to be related to greater fluctuations in water availability in its characteristic habitats. These patterns parallel ecological correlations obtained for dicotyledons as a whole. Lack of procumbent ray cells may relate to limited stem diameter in the genus if procumbent cells tend to function in radial translocation of photosynthates. Wood anatomy of Roridula is congruent with relationships alleged by various authors to the genus Byblis, and very similar secondary xylem features can be found in such “rosoid” families as Saxifragaceae (sensu lato), Hamamelidaceae, Bruniaceae, and Grubbiaceae. Roridula should be excluded from Droseraceae, and should probably not be placed next to Droseraceae in a phylogenetic system.
ALLELOPATHY IN THE FIRST STAGES OF SECONDARY SUCCESSION ON THE PIEDMONT OF NEW JERSEY
Authors: Jackson James R. , Willemsen Roger W.
Published: January 2018

Ambrosia artemisiifolia (ragweed) is a dominant species in the first year of old field succession but rarely persists for more than two years. Ragweed and Raphanus raphanistrum (wild radish), also an early invader, failed to become re‐established in plots cleared of second stage perennial vegetation (dominated by Aster pilosus), despite the large number of seeds of these primary invaders present in the soil. Edaphic experiments revealed that this pattern of succession was not due to mineral or physical properties of the soil. Field soil from the second stage of succession inhibited the growth and germination of ragweed and wild radish while soil from the first stage had no effect. Inhibitory volatile materials from ragweed were not detected. However, root exudate of ragweed, and shoot extracts of ragweed and aster inhibited the germination and growth of early invaders of abandoned fields. These results indicate that the vegetational change from the first to the second stage of succession may be mediated at least partially by an allelopathic response. Chromatography and bioassay techniques revealed the inhibitory compounds to be phenolic acids, including caffeic and chlorogenic acids.
AN INTERPRETATION OF DOSE‐RESPONSE CURVES FOR LIGHT‐INDUCED CELL ELONGATION IN FERN PROTONEMATA
Authors: Greany Robin H. , Miller John H.
Published: January 2018

Protonemata of Onoclea sensibilis and Diyopteris filix‐mas elongate in response to both red and far‐red light. The promotion caused by far‐red is larger than that caused by red light. This phenomenon differs from a typical response to phytochrome, the photoreceptor pigment immediately suggested by the activity of red and far‐red light. The phenomenon has been explained by two different hypotheses, one of which holds that phytochrome is solely responsible for the response, whereas the other postulates an interaction between phytochrome and P580, a yellow‐green light absorbing pigment, to account for the response. The hypothesis that phytochrome is the sole photoreceptor leads to some specific predictions concerning the shapes of the dose‐response curves for light‐induced protonema elongation. These predictions were tested with both continuous and short‐term irradiation. In all instances saturating far‐red light caused greater elongation than did saturating red light, and no dose of red light duplicated the activity of saturating far‐red light. Other experiments tested the interactions of red and far‐red light and the effects of different doses of yellow‐green light on protonema elongation. The results of many of the experiments were not in agreement with the hypothesis that phytochrome is the sole photoreceptor, whereas they were in agreement with the assumption that filament elongation is controlled by both phytochrome and P580.
CHANGES IN THE CARBOHYDRATE CONSTITUENTS OF ELONGATING LOPHOCOLEA HETEROPHYLLA SETAE (HEPATICAE)
Authors: Thomas Robert J. , Doyle William T.
Published: January 2018

Sporophyte setae of Lophocolea heterophylla (a leafy liverwort) elongate solely as a result of the expansion of individual seta cells. Though seta walls thin considerably during elongation, colorimetric analysis indicates that 25‐fold increase in seta cell length is accompanied by a 2‐fold increase in cell wall carbohydrates. Carbohydrate reserves of setae were characterized histochemically and by paper chromatography. Starch diminishes during elongtion; polyfructosans and sucrose are replaced by fructose and glucose. Increase in wall material appears to be at the expense of these carbohydrate reserves in seta cells, and may be due as well to a transport of wall precursors from the gametophyte.
THE MORPHOLOGY AND RELATIONSHIPS OF RHODEA, TELANGIUM, TELANGIOPSIS, AND HETERANGIUM
Authors: Jennings James R.
Published: January 2018

This study deals with four form or organ genera from the Upper Mississippian (Chester Series) of the Illinois Basin, and provides evidence that they were produced by a single natural genus with gymnospermous affinity. The plant remains—compressions, impressions, petrifactions, and specimens that combine compression or impression with petrifaction—allow examination of both external morphology and internal anatomy. The specimens include foliage corresponding toRhodea, stems and petioles corresponding toHeterangium, and synangiate fructifications corresponding to eitherTelangiumorTelangiopsis.The stems and foliage are considered parts of the same plant because of the identity of the anatomical and cuticular features of petioles attached to stem and those petioles with attached foliage. The fertile material is regarded as part of the same plant because: (1) The anatomy of axes of the fertile specimens is like that of the sterile specimens. (2) A single specimen may contain both sterileRhodea‐type axes and fertile regions. (3) Axes bearing synangia have the same size and patterns of divisions as the sterile foliage. Features that indicate lyginopterid affinities include: (1) Equal forking of the petiole. (2) Presence of fiber bands in the outer cortex and sclerotic nests in the inner part of the cortex. (3) Crowded circular bordered pits on the lateral walls of the metaxylem tracheids. (4) The presence of a small amount of secondary xylem. A variety of structural details of the stem and petiole suggest the genusHeterangium.The phyletic position of the plant that producedRhodea, Telangium, Telangiopsis, andHeterangiumis reviewed in light of such discoveries as the presence of a planated frond that lacks a lamina and the presence of both monolete and trilete microspores in a single synangium.
PECTINASE IN ASCLEPIAS LATEX AND ITS POSSIBLE ROLE IN LATICIFER GROWTH AND DEVELOPMENT
Authors: Wilson Kathryn J. , Nessler Craig L. , Mahlberg Paul G.
Published: January 2018

A pectinase with a pH optimum of 5.2 is present in the latex of the common milkweed, Asclepias syriaca L. The enzyme was partially purified from the serum fraction of fresh latex by dialysis and ammonium sulfate fractionation. Enzyme activity was detected by a viscometry assay and by the dinitrosalicylic acid assay for reducing sugars. Pectin and polygalacturonic acid could serve as substrates for the enzyme. Pectolytic activity in latex presents a basis for describing the development of the non‐articulated branched laticifer system. Enzyme activity may facilitate intrusive tip growth of the laticifer among other cells by solubilizing pectic substances of the middle lamella and also may be important for loosening wall material of the laticifer itself to facilitate extension growth.
REACTIONS OF ALKALOID AND HISTOCHEMICAL INDICATORS IN LATICIFERS AND SPECIALIZED PARENCHYMA CELLS OF CATHARANTHUS ROSEUS (APOCYNACEAE)
Authors: Yoder Larry R. , Mahlberg Paul G.
Published: January 2018

Chromic acid, iodine‐potassium iodide and Dragendorff reagent were employed to identify reactive cells that may indicate sites of alkaloid accumulation in fresh tissues and latex of C. roseus. Laticifers in all parts of the mature plant and certain parenchyma cells in the cortex and pith regions accumulated reaction products of these alkaloid indicators. These same cells showed primary fluorescence, accumulated vital dyes and lipid indicators in excess of other cells, and exhibited a more intense nadi reaction than other cells. Tests on fresh tissues are interpreted to indicate possible qualitative and quantitative differences in alkaloid content between subterranean and aerial portions of the plant and between mature and immature tissues. These studies showed that reactive products are unevenly distributed in cells and organs of the plant and can be microscopically detected only in laticifers and specialized parenchyma cells.
LECLERCQIA COMPLEXA (LYCOPSIDA, MIDDLE DEVONIAN): ITS ANATOMY, AND THE INTERPRETATION OF PYRITE PETRIFACTIONS
Authors: Grierson James D.
Published: January 2018

The development and/or modification of special acid etching and macerating techniques permits pyritized fossils of Leclercqia complexa to be separated into their carbonaceous wall remains and pyrite lumen—pit casts. These carbonized and pyritic portions can then be studied separately by both light and SEM microscopy and information from both modes compared with that obtainable from carbonaceous compression fossils of L. complexa. This combination of techniques, preservation modes and methods of analysis, allows a synthesis of information obtainable from each, as well as providing a check on errors of interpretation due to preservation mode and method of observation. The developmental sequence of the secondary wall thickenings of the protoxylem elements is shown to be annular to connected annular and spiral, with both exarch and mesarch maturation. The metaxylem shows a transition through reticulate to multiseriate round, oval, and elongate bordered‐pitted tracheids. Different wall facets of separated pyrite tracheid casts can be examined by the SEM and variations in wall structure and pitting characterized. Cells of the outer cortex are 6 to 10 times longer than wide, have thickened vertical walls and end walls that vary from nearly horizontal to angles of overlap of 50 degrees.
ULTRASTRUCTURAL CYTOLOGY OF CALLUS CULTURES OF STREPTANTHUS TORTUOSUS AS AFFECTED BY TEMPERATURE
Authors: Endress Anton G. , Sjolund Richard D.
Published: January 2018

Tissue culture cells of Streptanthus tortuosus var. orbiculatus (Cruciferae) which have acquired a spherical viruslike particle located in their nucleoli, designated cell line STV, developed supergranal chloroplasts and lost the ability to differentiate vascular tissues. The effect of temperature on the ultrastructural cytology of one line of the STV tissue, STV‐I, was compared with the effect of temperature on the ultrastructural cytology of tissue culture cells lacking the viruslike particles (control cell lines). At 4 C, the cellular and ultrastructural appearance of control tissue culture cells differed from that of tissue grown at 22 C by producing increased amounts of endoplasmic reticulum and dictyosomes and by reduction of chloroplast thylakoids. STV‐I cells were generally moribund as a result of 4 C treatment. Chloroplast thylakoids were also reduced in control tissue following growth at 10 C and the apparent quantities of endoplasmic reticulum and dictyosomes were similar to those observed in control cells grown at the control temperature (22 C), but less than those observed in tissue subjected to 4 C. STV‐I tissue grown at 10 C demonstrated increased endoplasmic reticulum and dictyosomes and reduction of polysomal configurations. The mitochondrial morphology was variable and the cells contained supergranal chloroplasts and proplastids. At the control temperature (22 C), the fine structural appearance of control tissue culture cells was typical of parenchyma cells, but STV‐I cells contained mitochondria of variable morphology and two types of chloroplasts— normal and supergranal. Control tissue grown at 30 C also contained proplastids, but these proplastids contained starch in contrast to the proplastids in control tissue grown at low temperatures. The ultrastructural cytology of STV‐I cells grown at elevated temperature (30 C) was characterized by enlarged mitochondria containing massive lipid bodies and the presence of protoplastids with starch and supergranal chloroplasts.
RACIAL EVOLUTION IN ELEUSINE CORACANA SSP. CORACANA (FINGER MILLET)
Authors: Hilu K. W. , Wet J. M. J. De
Published: January 2018

Eleusine coracana ssp. coracana (finger millet, eleusine) is widely distributed in Africa and India as a cereal. The crop is cultivated in diverse eco‐geographical areas. Over this range of distribution, eleusine displays high variability in vegetative, floral and seed morphology. The intent of this study is to establish correlations between morphology and distribution, and to determine the intraspecific taxonomy of the crop. Three eco‐geographical races were determined: (1) an African highland race which is cultivated in the East African highlands, (2) a lowland race which is grown in the lowlands of Africa and South India, and (3) an Indian race with its center of distribution in Northeast India. In addition to these basic races, an Indian highland type was identified. The African highland race is the most primitive from which the lowland race evolved. The latter race was subsequently introduced to southern India where a secondary center of diversity became established. The Indian race originated from the lowland race, while the North Indian highland type can be derived from either or both of the two basic races in India. This study indicated that natural selection played a major role in the evolution of the crop. Artificial selection, although significant, was restricted within the limits imposed on it by the ultimate adaptation of the races to their environments.
DICHOTOMOUS BRANCHING IN MAMMILLARIA (CACTACEAE)
Authors: Boke Norman H.
Published: January 2018

Cruciate dichotomous branching is a regular phenomenon in at least two species of cacti: Mammillaria perbella and M. parkinsonii, and there is exomorphic evidence that it occurs in other species of this genus. The specimens examined showed no obvious changes in the phyllotaxy of the two shanks derived by dichotomy. In the ecologically and morphologically specialized Cactaceae, it is quite unlikely that dichotomous branching represents the retention of a primitive character. It is furthermore improbable that it is of taxonomic value above the species level.
CHROMOSOME COUNTS AND TAXONOMIC NOTES FOR COMPOSITAE FROM THE UNITED STATES AND MEXICO
Authors: Keil David J. , Pinkava Donald J.
Published: January 2018

Chromosome counts are reported for 167 taxa representing 160 species and 76 genera of Compositae. First reports for 27 species and 2 infraspecific taxa are included. New chromosome numbers are reported for 9 additional taxa. The genus Carminatia DC. is merged with Brickellia Ell. resulting in two new combinations: Brickellia tenuiflora (DC.) Keil & Pinkava and Brickellia recondita (McVaugh) Keil & Pinkava.
PHYLLOTACTIC CHANGE INDUCED BY GIBBERELLIC ACID IN XANTHIUM SHOOT APICES
Authors: Maksymowych Roman , Erickson Ralph O.
Published: January 2018

Gibberellic acid (GA) treatment of vegetative shoots of Xanthium leads to a change in phyllotaxis as diagnosed in transverse sections of apical buds. A method of analysis is proposed for estimating the phyllotactic parameters, the plastochron ratio, a, and the divergence angle, α, from measurements of the angular and radial positions of leaf primordia in sections. GA treatment significantly decreases the plastochron ratio, a, from 1.35 in controls, to 1.19 in GA‐treated plants, as shown by an analysis of variance, but has no significant effect on the divergence angle. The estimates of a and α are compared with the parameters of theoretical phyllotaxis models, leading to the designation (2, 3) for controls, and (3, 5) for GA‐treated plants, where the integers 2, 3, and 5 designate sets of contact parastichies. The change in a is interpreted as indicating a change in the relative position at which leaf primordia are initiated in the apical meristem, and this effect is discussed in relation to theories of leaf initiation.
ULTRASTRUCTURAL STUDIES OF SPERMATOGENESIS IN THE ANTHOCEROTALES. II. THE BLEPHAROPLAST AND ANTERIOR MITOCHONDRION IN PHAEOCEROS LAEVIS: LATER DEVELOPMENT
Authors: Carothers Zane B. , Moser John W. , Duckett Jeffrey G.
Published: January 2018

Chromatin condensation begins as the multilayered structure (MLS) in Phaeoceros reaches its maximally structured differentiation. As nuclear elongation and chromatin condensation proceed, the S2–4 strata disappear, and the nuclear beak extends between the S1 and the nearly spherical anterior mitochondrion. In a mature sperm the mitochondrion is elongate and lies completely anterior to the blunt front end of the nucleus. The 12 S1 tubules extend over the anterior mitochondrion and nucleus, but their number becomes reduced to five at the level where the nucleus' midportion is constricted. The anterior ends of the S1 tubules lie embedded in a rather conical osmiophilic crest. Flagellar insertion is restricted to the extreme anterior tip of the S1 tubules. The locomotory apparatus in Phaeoceros is compared with that of other bryophytes.
OBSERVATIONS ON INTROGRESSION OF TRIPSACUM INTO MAIZE
Authors: Stalker H. T. , Harlan J. R. , de Wet J. M. J.
Published: January 2018

Derivatives of a cross between diploid Zea mays L. and Tripsacum dactyloides (L.) L. (2n = 72) were compared cytologically and morphologically. The objective of this study was to detect introgression from Tripsacum to maize that might have occurred during seven backcross generations with maize. Thirty‐three morphological characters were used to analyze variation among aneuploid (20Zm + 2Td), 20‐chromosome recovered maize, and the recurrent maize parent plants. Aneuploid and maize checks were extreme types, with 20‐chromosome hybrid derivatives being morphologically intermediate. Several recovered maizes clustered with aneuploid plants and these hybrid derivatives have the greatest chance of Tripsacum introgression. Many traits such as endosperm abnormalities, tassel seed, albinos, tunicate glumes, tassel‐tipped ears, fasciated and branched ear, and male spikelets between rows of kernels were observed. Although the genetic basis of many traits is unknown, mutations, epistatic effects or expression of Tripsacum chromatin are possible causes. The number of abnormal and tripsacoid traits observed in 20‐chromosome recovered maizes indicates genetic transfer from Tripsacum to the maize genome.
DORMANCY AND GERMINATION IN SEEDS OF COMMON RAGWEED WITH REFERENCE TO BEAL'S BURIED SEED EXPERIMENT
Authors: Baskin Jerry M. , Baskin Carol C.
Published: January 2018

Common ragweed (Ambrosia artemisiifolia L.) was one of 19 herbaceous weedy species used by Beal in his buried viable seed experiment started in 1879. No seeds germinated during the first 35 years of the experiment when germination tests were performed in late spring, summer or early autumn. Germination did occur in seeds buried for 40 years when seeds were exhumed and tested for germination in early spring. Data obtained in more recent research provide the probable explanation for these results. Seeds of common ragweed that do not germinate in spring enter secondary dormancy by mid to late spring and will not germinate until dormancy is broken the following late autumn and winter. Thus, during the first 35 years of the experiment seeds were dormant when tested for germination, whereas seeds buried for 40 years were nondormant. Seeds buried 50 years or longer did not germinate when tested in spring, probably because they had lost viability and/or seeds germinated during burial and seedlings died.
THE NUCLEAR DNA CONTENT OF DEVELOPING BARLEY ALEURONE CELLS
Authors: Keown Ann Cosgrove , Taiz Lincoln , Jones Russell L.
Published: January 2018

The nuclear DNA content of developing barley aleurone cells was examined by Feulgen cytophotometry using the Cytophotometric Data Conversion (CYDAC) system. At no time in their development did aleurone cells exhibit a single peak corresponding to the triploid (3N) amount of DNA. Although considerable heterogeneity was observed at every stage of development, the mean nuclear DNA content approximately doubled from the earliest to the most mature stage.
MINERAL CYCLING AND THE NICHE OF SPANISH MOSS, TILLANDSIA USNEOIDES L
Authors: Schlesinger William H. , Marks P. L.
Published: January 2018

On the southeastern coastal plain, the occurrence and abundance of the epiphyte Spanish moss (Tillandsia usneoides L.; Bromeliaceae) are linked to the availability of minerals in the canopy of potential host trees. Trees with high rates of foliar leaching (e.g., cypress and oaks) provide an abundant supply of minerals (Ca, Mg, K, and P) in precipitation collected beneath the canopy. In forests of these species Spanish moss is more abundant and has higher mineral concentrations than in pine forests (e.g., phosphorus 0.04–0.06% dry weight versus 0.03–0.04%). In growth‐chamber experiments the growth of Spanish moss increased in response to added phosphorus in the range of concentrations observed in field precipitation collections (0–200 μg/l). In addition to the availability of minerals, the rate of bark sloughing from host trees and allelopathic effects may also control the local distribution of Spanish moss. Light and moisture appear to be less important factors. Thus, within a favorable climatic range, mineral and bark characteristics of host trees may be used to illustrate a niche hypervolume for this species.
THE ULTRASTRUCTURE OF DRY AND IMBIBED COTYLEDONS OF SOYBEAN
Authors: Webster Barbara D. , Leopold A. Carl
Published: January 2018

Ultrastructural observations of parenchyma cells of cotyledons of soybean (Glycine max (L.) Merr.) indicate that a 20‐min period of imbibition brings about extensive changes in membranes and organelles. The plasma membrane, which in cells of dry seeds is disorganized and disrupted, becomes relatively intact and continuous. A network of endoplasmic reticulum vesicles and tubules, no evidence of which can be discerned in dry seeds, appears extensively dispersed through the cytoplasm and around the margin of protein bodies. Mitochondria in dry tissue are distorted in shape and nearly devoid of internal structure. In imbibed cells they are round or oval and are bound by an intact membrane enclosing numerous cristae and a dense stroma. Starch grains develop in proplastids. Circular or whorled membranous structures appear in the cytoplasm. The swiftness with which membranes and organelles are structurally altered during imbibition is a reflection of their effectiveness in rapidly modifying solute loss and solvent entry.
INVESTIGATIONS OF ANGIOSPERMS FROM THE EOCENE OF SOUTHEASTERN NORTH AMERICA: PHILODENDRON LEAF REMAINS
Authors: Dilcher D. L. , Daghlian C. P.
Published: January 2018

Large leaves, new to the fossil record, from the Claiborne Formation in western Tennessee have been collected and analyzed. Careful analyses of venation and cuticular anatomy indicate that these fossil leaves contain specific characters found in modern species of the genus Philodendron subgenus Meconostigma. Features of venation were taxonomically more useful than other features. Reports of fossils of the Araceae are scarce and those few fossils assigned to the family frequently have been inadequately studied. This report establishes a reliable and carefully documented occurrence of the Araceae in the fossil record, and provides information concerning the differentiation of the family in time and the distributions of the genus Philodendron.
THE CYTOLOGY AND DERIVATION OF A TEMPERATURE‐SENSITIVE MEIOTIC MUTANT IN THE FERN CERATOPTERIS
Authors: Hickok Leslie G.
Published: January 2018

Meiotic mutants were obtained from an inbreeding program following a hybridization between two diploid species of the homosporous fern Ceratopteris. The mutants are characterized by high levels of asynapsis at high temperatures (27 C, 33 C) and by aberrant spindle function at low temperatures (18 C). Spore viabilities vary with temperature and are highest at 23 C. Occasional restitution during the first division results in the production of dyads of diploid spores, some of which are viable. The inbreeding program was characterized by the expression of high levels of apparent heterozygosity in spite of intragametophytic selfing. It appears that segregation within the inbreeding program was responsible for the production of the mutants. The apparent heterozgosity and segregation can be explained by a previously documented genetic system within the polyploid homosporous ferns.
ULTRASTRUCTURAL FEATURES OF THE DIVIDING MEIOCYTE OF ONOCLEA SENSIBILIS
Authors: Marengo Norman P.
Published: January 2018

The ultrastructure of the anaphase of the second meiotic division of the meiocyte of Onoclea sensibilis is characterized by a compact plate of mitochondria without the usual double limiting membrane and with single‐layered cristae continuous from one side of the mitochondrion to the other. Amyloplasts occur proximal to the plate and lipid droplets are randomly distributed throughout the cell.
RAPID CHEMICAL DEHYDRATION OF PLANT MATERIAL FOR LIGHT AND ELECTRON MICROSCOPY WITH 2,2‐DIMETHOXYPROPANE AND 2,2‐DIETHOXYPROPANE
Authors: Lin Chin Ho , Falk Richard H. , Stocking C. Ralph
Published: January 2018

A rapid and simple procedure was used for chemical dehydration of plant tissue during sample preparation for light and electron microscopy. Chemically fixed tissues were washed with distilled water and then rapidly dehydrated with either 2,2‐dimethoxypropane or 2,2‐diethoxypropane for 15 minutes. Light microscopic observation of paraffin‐embedded tissue or tissue embedded in Spurr's plastic showed excellent preservation. Electron microscopic examination of plastic‐embedded tissue showed well maintained ultrastructural morphology. The dehydration procedure was also successfully applied to plant tissue destined for examination in a scanning electron microscope.
A STUDY OF THE RELIABILITY OF SYNCHRONY IN THE DEVELOPMENT OF POLLEN MOTHER CELLS OF LILIUM LONGIFLORUM AT THE FIRST MEIOTIC PROPHASE
Authors: Shull J. K. , Menzel Margaret Y.
Published: January 2018

Lilium longiflorum anthers have been used by a number of investigators as a source of supposedly synchronous cells for studying genetic, chromosomal and molecular events of meiotic prophase I. Because of questions raised by the literature as to the reliability of such synchrony, new baseline data were obtained for L. longiflorum ‘Croft’ in preparation for experiments requiring homogeneity or synchrony. Homogeneity was found to be reliable at the same level of locules of the same anther and of anthers from the same bud up to the onset of diplotene. Synchrony deteriorates rapidly from diplotene on. Less than half the anthers examined had PMC's at the same stage from apex to base. Hence experiments requiring complete homogeneity within anthers would call for rigorous monitoring of each anther included in the sample. Synchrony between buds of the same length was insufficient to allow bud length to be used as a reliable index of meiotic stage.
CHROMOSOME COUNTS OF COMPOSITAE FROM THE UNITED STATES AND MEXICO
Authors: Pinkava Donald J. , Keil David J.
Published: January 2018

Chromosome counts are reported for 126 taxa representing 122 species and 61 genera of Compositae. First reports include two genera, Stylocline (n = 14) and Chromolepis (n = 19), 17 species, two infraspecific taxa, and one interspecific hybrid. Five additional taxa have chromosome numbers differing from previously published accounts. Carminatia is reinstated to generic status.
GLAND DISTRIBUTION AND CANNABINOID CONTENT IN CLONES OF CANNABIS SATIVA L.
Authors: Turner Jocelyn C. , Hemphill John K. , Mahlberg Paul G.
Published: January 2018

The relationship between glandular trichomes and cannabinoid content in Cannabis sativa L. was investigated. Three strains of Cannabis, which are annuals, were selected for either a drug, a non‐drug, or a fiber trait and then cloned to provide genetically uniform material for analyses over several years. The distribution of the number and type of glands was determined for several organs of different ages including the bract and its subtending monoleaflet leaf and the compound leaf on pistillate plants. Quantitation of glands on these structures was integrated with gas chromatographic analyses of organ cannabinoid profiles. A negative correlation was found between cannabinoid content and gland number for each of the three clones. Isolated heads of the capitate‐stalked glands also were analyzed for cannabinoid content and found to vary in relation to clone and gland age. These studies indicate that cannabinoids may occur in plant cells other than glandular trichomes. The results of these studies emphasize the need for stringent sampling procedures in micromorphological studies on trichome distribution and analytical determinations of cannabinoid content in Cannabis.
REPRODUCTIVE BIOLOGY OF THE CERRO CUADRADO (JURASSIC) FOSSIL CONIFERS: PARARAUCARIA PATAGONICA
Authors: Stockey Ruth A.
Published: January 2018

Seventy‐two silicified cone specimens of Pararaucaria patagonica Wieland from the Cerro Cuadrado (Jurassic) petrified forest in Patagonia were studied by use of thin sections and reflected light. Traces from the cone axis stele to the bract and ovuliferous scale are separate at their origins. In cross section the abaxially concave ovuliferous scale trace and massive circular bract trace branch half‐way out into the cone‐scale complex. Two triangular‐shaped bundles of fibers follow the scale trace into the laminar part of the ovuliferous scale. Both surfaces of the ovuliferous scale possess hairs which may have assisted in cone closure. Cones typically contain one flattened, winged seed per ovuliferous scale. Multi‐layered seed integuments are represented by an inner fleshy layer of large cells filled with a black amorphous material, a sclerotesta consisting of wedges or fan‐shaped groups of sclereids oriented at right angles to the seed surface, and a thin, often crushed fleshy layer. Seed wings consist of anastomosing, branched cells resembling glandular hairs and containing many intercellular spaces. Well‐preserved polycotyledonous embryos containing up to eight cotyledons are present in several cones. Tissues of the embryo including the shoot apex, calyptroperiblem, hypocotyl, and cotyledons are described. On the basis of anatomical and morphological features, specimens of P. patagonica are compared to members of both extant and extinct families of conifers including the Araucariaceae, Taxodiaceae, Pinaceae, Cupressaceae, and Cheirolepidaceae.
A COMPARATIVE LIGHT‐ AND ELECTRON‐MICROSCOPIC STUDY OF MICROSPOROGENESIS IN MALE‐FERTILE AND CYTOPLASMIC MALE‐STERILE SUNFLOWER (HELIANTHUS ANNUUS)
Authors: Horner Harry T.
Published: January 2018

Cytoplasmic male sterility (CMS) in sunflower anthers is compared with its normal (N) line by using light and electron microscopy. Degeneration and disintegration of CMS tapetum and microspore tetrads occur after meiosis II, resulting in sterility. At the onset of meiosis, the CMS tapetum enlarges radially and shows signs of disorganization of organelles and walls. The developing CMS meiocytes and tetrads of microspores do not show these abnormalities when compared with their N counterparts. The CMS microspore tetrads remain viable until a rudimentary exine forms around each microspore. At this time, the radially enlarged tapetum disintegrates, followed by disintegration of the tetrads. In N‐line microsporogenesis, a peripheral, dense tapetum is present at the tetrad stage, and as each locule enlarges, free spaces occur around the tetrads. After a rudimentary exine with associated spines and colpi is formed around each microspore, the callose holding each tetrad together dissolves, freeing the microspores for further development. Eventually the binucleate tapetum becomes plasmodial, persisting until the vacuolate pollen stage.
THE DEVELOPMENT AND POSSIBLE RELATIONSHIPS OF A NEW ATKINSIELLA PARASITIC IN INSECT EGGS
Authors: Martin W. Wallace
Published: January 2018

Atkinsiella entomophaga is a holocarpic parasite in eggs of various midges and caddis flies. Primary zoospores escape through long discharge tubes and assume an abbreviated period of motility before encysting. Laterally biflagellate secondary zoospores subsequently emerge from the cysts. Coincident with discharge tube formation, the thallus undergoes strong vacuolization giving the protoplast a reticulate aspect with nuclei situated between the vacuoles and connected to one another by protoplasmic threads. Stages in zoosporogenesis resemble those of members of the Lagenidiales. It is proposed that Atkinsiella be included in the Eurychasmaceae along with Eurychasma and Eurychasmidium and that the family be transferred to the Lagenidiales. All members of this family have diplanetic zoospores.
ANATOMICALLY PRESERVED SEED CONES OF THE PINACEAE FROM THE EARLY CRETACEOUS OF VIRGINIA
Authors: Robison Coleman R. , Miller Charles N.
Published: January 2018

A collection of anatomically preserved conifer cones from the Early Cretaceous of Virginia contains two new species of the extinct pinaceous genus Pityostrobus. Superficially, the fossil cones resemble those of modern species of Picea. However, the fossils reveal such a peculiar mixture of anatomical features that they cannot be assigned to any extant genus of the Pinaceae. One of the new species, Pityostrobus hueberi, is most comparable with Pityostrobus corneti Alvin from the Early Cretaceous of Belgium. Pityostrobus virginiana, the other new species, differs from all other members of the genus in only slight—but nonetheless significant—attributes. Pityostrobus hueberi and P. virginiana are the first species of this genus to be reported from Early Cretaceous sediments of the North American Atlantic Coastal Plain. As such, they increase our knowledge of the structural variation exhibited by ancient members of the Pinaceae.
COTYLEDON PHOTOSYNTHESIS DURING SEEDLING GROWTH OF COTTON, GOSSYPIUM HIRSUTUM L.
Authors: Lane H. C. , Hesketh J. D.
Published: January 2018

Respiration and net photosynthetic O2 production by cotton cotyledons were determined from an early age through the senescent stage. Various treatments were applied to cotyledons to assess the importance of current photosynthesis as compared to translocation of reserves to seedling development. Rates of respiration and net photosynthesis per cm2 were high on 1‐day‐old cotyledons, but the rates decreased sharply with rapid expansion to reach a fairly stable rate. Respiration per cotyledon decreased linearly with age until the onset of senescence, then exhibited a distinct climacteric rise followed by a sharp decrease. Net photosynthesis per cotyledon increased until expansion was completed and then decreased linearly and steeply with age. Excision of cotyledons, inhibition of photosynthesis either chemically or by covering, and removal of the terminal bud indicated that current photosynthesis is a potent force behind early epicotyl growth.
CHROMOSOME COUNTS OF COMPOSITAE FROM MEXICO AND THE UNITED STATES
Authors: Keil David J. , Stuessy Tod F.
Published: January 2018

Chromosome counts of Compositae are reported from Mexico and the United States. First generic counts are from Egletes (n = 27), Hydropectis (n = 9), and Pippenalia (2n = ca. 60). First counts also are reported for 22 specific and infraspecific taxa in Baccharis, Erigeron, Flaveria, Gnaphalium, Grindelia, Helenium, Heterotheca, Melampodium, Montanoa, Perymenium, Piqueria, Senecio, Stevia, Verbesina, Xanthocephalum, and Zaluzania. Additional counts also are provided for 123 populations of taxa counted previously, of which eight are new numbers. Taxonomic implications of certain counts are discussed.
THE ULTRASTRUCTURE OF CARPOSPOROGENESIS IN CALOGLOSSA LEPRIEURII (DELESSERIACEAE, CERAMIALES)
Authors: Triemer Richard E. , Vasconcelos Aurea C.
Published: January 2018

Carposporogenesis in Caloglossa leprieurii is divided into three cytological stages. At stage I, the young spores have few plastids and little starch. Abundant dictyosomes secrete a gelatinous wall layer in scale‐like units. At stage II, dictyosomes produce a second fibrillar wall component in addition to the gelatinous constituent. Large fibrillar vesicles accumulate in the cytoplasm. Production of gelatinous material decreases in this stage. By stage III, starch grains and fully developed plastids are abundant. Rough endoplasmic reticulum occupies much of the peripheral cytoplasm. A dense, granular proteinaceous component appears in the wall in association with the fibrillar layer. Arrays of randomly oriented tubules are scattered in the cytoplasm. The mature carpospore is surrounded by an outer gelatinous wall layer and an inner fibrillar layer. Few dictyosomes persist in the mature spore. Carposporogenesis in Caloglossa is compared with that in other red algae.
AXILLARY BUD DEVELOPMENT IN POPULUS DELTOIDES. II. LATE ONTOGENY AND VASCULARIZATION
Authors: Pizzolato Thompson D. , Larson Philip R.
Published: January 2018

A nearly mature axillary bud of Populus deltoides was embedded in epoxy and serially sectioned at 6 μm. Sectioning extended from the cataphyll tips to a level in the subtending internode about 6 mm below the bud base. Vascular development was followed through the serial microsections and the vascular system was mapped in its entirety from initiation of the original bud traces to termination of the last recognizable leaf trace beneath the bud apex. Each vascular trace was identified as to its origin, its termination within a foliar organ, and its relation to other traces comprising the bud vascular cylinder. Analysis of these data confirmed the procambial patterns found in Part I of this study. Two original bud traces that diverged from the central trace of the axillant leaf gave rise to two pairs of scale traces in quick succession, and these scale traces become the progenitors of all subsequent vascular traces that were perpetuated within the bud. Just before the bud vascular system separated from that of the stem, a third pair of scale traces diverged from the original bud traces; the latter then receded toward the stem to eventually merge with its vasculature. The third pair of scale traces produced a horizontal vascular connection between stem and bud before terminating in the adaxial cataphyll. The vascular system at first conformed with a ½ vascular phyllotaxy when the original bud traces were initiated, progressed through a ⅓ vascular phyllotaxy in the scale trace system, and terminated at the time of sampling with a ⅖ vascular phyllotaxy in the foliage leaf primordia.
LEAF SURFACE AND HISTOLOGICAL PERTURBATIONS OF LEAVES OF PHASEOLUS VULGARIS AND HELIANTHUS ANNUUS AFTER EXPOSURE TO SIMULATED ACID RAIN
Authors: Evans Lance S. , Gmur Nicholas F. , Costa Filomena Da
Published: January 2018

Initial injury to adaxial leaf surfaces of Phaseolus vulgaris and Helianthus annuus occurred near trichomes and stomata after exposure to simulated sulfate acid rain. Lesion frequency was not correlated with density of either stomata or trichomes but was correlated with degree of leaf expansion. The number of lesions per unit area increased with total leaf area. Results suggest that characteristics of the leaf indumentum such as development of trichomes and guard cells and/or cuticle thickness near these structures may be involved in lesion development. Adaxial epidermal cell collapse was the first event in lesion development. Palisade cells and eventually spongy mesophyll cells collapsed after continued, daily exposure to simulated rain of low pH. Lesion development on Phaseolus vulgaris followed a specific course of events after exposure to simulated rain of known composition, application rate, drop size frequency, drop velocities, and frequency of exposures. These results allow development of further experiments to observe accurately other parameters, such as nutrient inputs and nutrient leaching from foliage, after exposure to simulated sulfate acid rain.
ULTRASTRUCTURE OF THE MATURE UNGERMINATED RICE (ORYZA SATIVA) CARYOPSIS. THE CARYOPSIS COAT AND THE ALEURONE CELLS
Authors: Bechtel Donald B. , Pomeranz Yeshajahu
Published: January 2018

The results of a light and electron microscopic study of the caryopsis coat and aleurone cells in ungerminated, unimbibed rice (Oryza sativa) caryopses are presented. Surrounding the rice grain is the caryopsis coat composed of the pericarp, seed coat and nucellar layers. The outermost layer, the pericarp, consists of crushed cells and is about 10 μm thick. The seed coat, interior to the pericarp, is one cell thick and has a thick cuticle. Between the seed coat cuticle and endosperm are the remains of the nucellus. The nucellus is about 2.5 μm thick and has a thick cuticle adjacent to the seed coat cuticle. Interior to the caryopsis coat is the aleurone layer of the endosperm. The aleurone completely surrounds the rice grain and is composed of two cell types—aleurone cells that surround the starchy endosperm and modified aleurone cells that surround the germ. The aleurone cells of the starchy endosperm contain many aleurone grains and lipid bodies around a centrally located nucleus. The modified aleurone cells lack aleurone grains, have fewer lipid bodies than the other aleurone cells, and contain filament bundles (fibrils). Plastids of aleurone cells exhibit a unique morphology in which the outer membranes invaginate to form tubules and vesicles within the plastid. Transfer aleurone cells are not observed in the mature rice caryopsis.