bluuebunny/crossref_metadata_2025 huggingface dataset:
FURTHER OCCURRENCES OF SPENCERITES FROM THE MIDDLE PENNSYLVANIAN OF KANSAS AND ILLINOIS
Authors: Leisman Gilbert A. , Stidd Benton M.
Published: January 2018

New specimens of Spencerites moorei add knowledge of its sporophylls and method of sporangial attachment. The sporophyll consists of a slender pedicel which expands at its distal end into a fleshy, peltate, diamond‐shaped head which bears a presumably fleshy lamina. The sporangium is attached through most of its length to the adaxial surface of the pedicel rather than distally as in S. insignis. It is suggested that the distal attachment shown in S. insignis may be derived through a phyletic shift from the pedicellate position. Additional specimens of Spencerites provisionally assigned to S. majusculus are also recorded. The spores are bilateral, monolete, and shaped like quadrants of a sphere. Two prominent wings extend along the two contact faces and the monolete mark is prominently raised, thus imparting a three‐winged appearance to the spore. The axis consists of an exarch protostele and a cylinder of thick‐walled outer cortex.
SOME ASPECTS OF DIFFERENTIATION IN CELLS OF PICEA GLAUCA CULTIVATED IN VITRO
Authors: White Philip R.
Published: January 2018

Microscopic observation of cells of Picea glauca, grown in tissue culture under a variety of cultural conditions, reveals a series of phenomena which are believed to be associated with the development of specific types of cells recognizable in intact plants. Characteristically patterned deposits of resin drops, and strands, furrows, and channels in the cytoplasm appear to be capable of serving as templates around which cellulose and lignin may later be deposited. The cytoplasm is extruded into characteristic papillae, and cell content may be extruded slowly or ejected with force through the cell walls, through multiple pores of characteristic distribution. Material ejected from such cells condenses in characteristic extracellular patterns. All of these processes may contribute to the differentiation of recognizable distinct cell types.
QUINONE DISTRIBUTION IN HORSE‐CHESTNUT CHLOROPLASTS, GLOBULES AND LAMELLAE
Authors: Barr Rita , Magree Lynette , Crane F. L.
Published: January 2018

The quinone content of whole and sonicated horse‐chestnut chloroplasts was studied over a period of 6 months. Whole chloroplasts show a steady increase of plastoquinone A and C concentrations from May to September. By September 1 about 0.5 μmoles PQ A and about 0.3 μmoles PQ C plus D per mg chlorophyll are found in whole chloroplasts. The osmiophilic globule fraction of sonicated chloroplasts contains traces of PQ A but no PQ C in May. By October 5 equal amounts of PQ A and PQ C plus D (0.15 μmoles per mg chlorophyll) are found in horse‐chestnut globules. By Oct. 15 the PQ A content increases at least 20‐fold, the PQ C content at least 7‐fold. The lamellae fraction of sonicated horse‐chestnut chloroplasts contains 0.05 μmoles PQ A and 0.03 μmoles PQ C plus PQ D in May. By October 15 about 0.3 μmoles PQ A and 0 1 μmoles PQ C per mg chlorophyll can be found in lamellae. The total amount of plastoquinones accumulated in the globules accounts for up to 20% of the total accumulation in the chloroplast during the season.
THE MOLECULAR ORGANIZATION OF CHLOROPLAST MEMBRANES
Authors: Weier T. Elliot , Benson Andrew A.
Published: January 2018

The presence of subunits in chloroplast membranes is suggested by polarization, fluorescence, and X‐ray studies. Subunits (quantasomes) may be observed in the electron microscope on dried shadowed membranes and in replicas of membranes produced by the freeze‐etching technique. Regular subunits are also observed with the electron microscope in thin sections of chloroplast membranes. Chemical considerations suggest that many membranes are composed of lipoprotein subunits. Thin sections reveal two types of chloroplast membranes, the fret membranes composed of one layer of subunits, and the partitions composed of two layers of subunits. Chloroplast membranes consist of about 45% protein and 55% lipid. Some 80% of the lipids are the highly surfactant glycolipids. In this paper the subunits are visualized as assymetric lipoproteins, probably having a protein core surrounded by components determined by the nature and environment of the membrane. Since the stroma, fret channels, and loculi contain aqueous materials, it is further postulated that the membranes bordering these spaces bind the highly surfactant glycolipids. The region between the two rows of subunits in the partition appears to be highly hydrophobic, rich in chlorophyll, and low in glycolipids. Some chlorophyll also may occur within the subunits both in the partitions and in the fret membranes. Since four subunits appear to comprise a quantasome, at least two types of forces, inter‐ and intra‐quantasome forces, bind the subunits together in sheets. Chloroplast membranes thus differ from a “unit membrane” in two important respects: (1) they must be an aggregate of globular subunits, and (2) the lipoprotein subunits consist of a protein matrix which binds the chlorophylls and lipids by hydrophobic association with their hydrocarbon moieties.
SYNTHETIC HYBRIDS OF NEW WORLD AND OLD WORLD AGROPYRONS. IV. TETRAPLOID AGROPYRON SPICATUM F. INERME X TETRAPLOID AGROPYRON DESERTORUM
Authors: Dewey Douglas R.
Published: January 2018

Emasculated and unemasculated crosses of tetraploid A. spicatum f. inerme X A. desertorum yielded four hybrids. The hybrids were morphologically intermediate between the parent species but resembled A. desertorum more closely than A. spicatum. Both parents behaved cytologically as autoploids. Mean chromosome associations of 0.04 I, 8.60 II, 0.01 III, and 2.67 IV were observed at diakinesis in the 28‐chromosome A. spicatum. The A. desertorum parent contained 30 chromosomes, 2 of which were likely supernumeraries, and averaged 0.03 I, 9.85 II, and 2.57 IV at diakinesis. Three hybrids contained 30 chromosomes, and one had 29. The most common chromosome association in the 30‐chromosome hybrids was 2 I and 14 II; and the average was 3.00 I, 13.40 II, 0.06 III, and 0.01 IV. A. spicatum and A. desertorum chromosomes were usually distinguishable from each other in the hybrid cell on the basis of size. All pairing in the hybrids was attributed to autosyndesis within parental genomes. A. spicatum, A. desertorum, and their hybrids were represented by genome formulas of SSSS, CCCC, and SSCC, respectively. The hybrids produced 5 to 439 seeds under open pollination. Three controlled crosses between the hybrids yielded 2, 5, and 23 seeds, respectively, on 10 maternal spikes in each cross. The prospects of developing a fertile, cytologically stable allotetraploid species from the hybrids appear favorable.
MICROSCOPICAL OBSERVATIONS OF INITIAL INTERACTIONS IN VARIOUS MATINGS OF SCHIZOPHYLLUM COMMUNE AND OF COPRINUS LAGOPUS
Authors: Sicari Lidia M. , Ellingboe Albert H.
Published: January 2018

In Schizophyllum commune and Coprinus lagopus the frequency of hyaline hyphal tips adjacent to anastomoses reflects the degree of incompatibility between mated strains. The lowest percentage is associated with full compatibility, the highest with full incompatibility. The hyaline hyphal tips appear several hours after an anastomosis has been detected. The data suggest that the factor(s) responsible for a cytoplasmic incompatibility is not constitutive but is induced at the time of mating.
MORPHOGENESIS OF SCHIZOPHYLLUM COMMUNE I. MORPHOLOGICAL VARIATION AND MATING BEHAVIOR OF THE THIN MUTATION
Authors: Schwalb Marvin N. , Miles Philip G.
Published: January 2018

A single gene, recessive mutation of Schizophyllum commune, designated as thin, is characterized by its sparse growth on agar and unusual hyphal morphology. Many hyphae exhibit various degrees of “waviness,” although some branches of these wavy hyphae appear normal. Differences in cell size and branch development between normal and thin strains are also noted. Most of the characteristics attributed to thin vary quantitatively between strains. In addition, considerable variability in hyphal characteristics can be found in a single strain. Thin mutants behave as bilateral maters. In matings where the normal allele is present, genetic complementation occurs and normal clamped cells are produced. Fruit bodies with viable spores are formed on both the thin and normal sides of the mating. Thin X thin matings give a stable dikaryon, but they retain the thin morphology and do not produce fruit bodies. Evidence that there is only one locus for the thin mutation is presented. Certain aspects of the variability of thins, the possible role of extracellular polysaccharide, and the potential uses for thin strains in studies of hyphal and fruit body development are discussed.
COMPARISON OF DIMENSIONS AND FIBRIL ANGLES OF LOBLOLLY PINE TRACHEIDS FORMED IN WET OR DRY GROWING SEASONS
Authors: Hiller Charlotte H. , Brown Rodney S.
Published: January 2018

Diameter and wall thickness of tracheids and the fibrillar angle in their S2 layers were investigated at five relative heights within two increment sheaths of one dominant loblolly pine (Pinus taeda L.). The sheaths investigated were formed during extremes of soil moisture availability. In both increment sheaths the radial and longitudinal trends of the respective anatomical features were similar; however, the sheaths differed in the degree and rate at which their size changed from the apex to the base of the tree. Soil moisture conditions directly affected the width of the annual rings, tracheid diameter, and wall thickness but not the fibril angle of tracheid walls.
CHROMATOGRAPHIC DOCUMENTATION OF INTERSPECIFIC HYBRIDIZATION IN VERNONIA: COMPOSITAE
Authors: Hunter G. E.
Published: January 2018

Chromatographic analysis of the flavonoid compounds in leaf extracts support field and morphological studies which lead to the interpretation of Vernonia guadalupensis Heller as a natural hybrid between V. lindheimeri Engelm. and Gray and V. interior Small. Of 16 major flavonoids found in leaf extracts of the parental species, 8 were found only in V. lindheimeri, 3 were found only in V. interior; 5 were common to both. All 16 were found in leaf extracts of V. guadalupensis.
A SURVEY OF FLORAL ANATOMY IN ARACEAE
Authors: Eyde Richard H. , Nicolson Dan H. , Sherwin Priscilla
Published: January 2018

Flowers of 23 species representing six subfamilies of Araceae were studied by means of serial cross sections, special attention being given to vascular patterns and to taxa of supposed phylogenetic importance. Floral structure is shown to be extremely diverse with no unifying pattern common to all subfamilies. Conclusions include the following: (1) Lysichiton has a specialized gynoecial vascular pattern which differs from others encountered in the survey and which weighs against the primitive position attributed to this genus by Hutchinson. (2) Philodendron, with its multiple stylar canals, cannot have originated from subfamily Pothoideae, as Engler's phylogenetic concept would require of all Araceae; instead, it appears that several syncarpous evolutionary lines have evolved independently from extinct apocarpous members of the family. (3) In Acorus, stamens are introrse and dorsal carpellary bundles are lacking; these characters and others justify the recognition of Acorus as a separate subfamily Acoroideae. In addition, the survey revealed a peculiar deterioration of the inner ovary wall and the septa in several taxa, apparently a normal feature of floral development. Spathiphyllum solomonense Nicolson is described in an appendix.
THE ORIGIN AND DEVELOPMENT OF INDUCED BRANCHES IN HELIANTHUS
Authors: Marr Currie , Blaser H. Weston
Published: January 2018

The development of buds and their vascular connections are described for Helianthus annuus and H. bolanderi. Bud meristems of H. annuus usually become isolated by parenchymatization of the bud traces in the cortical zone. If the buds are induced to grow as a result of decapitation of the terminal meristem, a continuous range between typical primary connections and pseudo‐adventitious connections are made between the main axis and the lateral buds. Considerable growth of the branches occurs within 48 hours after decapitation. Axillary buds of H. bolanderi grow continuously, and both the meristem and vascular system of the buds are derived directly from the apical meristem of the shoots.
THE HYDRATED MEGASPORE OF MARSILEA VESTITA
Authors: Machlis Leonard , Rawitscher‐Kunkel Erika
Published: January 2018

The megaspore of Marsilea has an exospore composed of several layers and is contained within the original megasporangial wall (making it technically a megasporangium). Upon contact with water there is an almost explosive unrolling of the megasporangial wall and expansion of the spore wall layers into a complex structure, part of which has not been previously described. The dynamics of the hydration process and the resultant structures are described.
ELECTRON MICROSCOPY OF WOOD OF CALLIXYLON AND CORDAITES
Authors: Schmid Rudolf
Published: January 2018

Replicas and ultrathin sections of the wood of two Paleozoic genera, Callixylon and Cordaites, were examined with the electron microscope. The pattern of wall layering of Callixylon closely resembles that of extant plants. An electron‐dense compound middle lamella markedly thickened at the corners of cells, a thin, electron‐transparent S1 layer of the secondary wall, and a thick, electron‐dense, partially decayed S2 layer of the secondary wall are evident in transverse sections of tracheids. No S3 layer seems to be present. The structure of the bordered pit‐pairs of Callixylon is described in detail. The slitlike outer pit apertures are conspicuously narrower and shorter than the inner pit apertures. Both sections and replicas of the bordered pit‐pairs display pit membranes lacking tori. Microfibrillar structure is obscure in both sections and replicas of Callixylon wood. Replicas of the bordered pits of Cordaites wood are very similar to those of Callixylon. Pit membranes lack tori, and microfibrillar structure is not very discernible. Knowledge about the evolution of the torus is summarized. It is postulated that the type of pit membrane of Callixylon and Cordaites, which is very homogeneous in structure and lacks a torus, represents a primitive condition among gymnosperms from which structurally more complex pit membranes and the torus later evolved.
STRUCTURAL CHANGES DURING BEAN LEAF ABSCISSION
Authors: Scott Peter C. , Miller Lillian W. , Webster Barbara D. , Leopold A. C.
Published: January 2018

Anatomical changes in the laminar abscission zone of primary leaves of Phaseolus vulgaris L. ‘Red Kidney’ have been examined in conjunction with the regulation of abscission by growth substances. Quantitative measurements were made of the frequency of vascular obstructions (tyloses, callose plugs). The development of abscission was correlated with an increasing frequency of tyloses and other plugging materials in the xylem of the abscission zone coupled with the dissolution of callose from the abscission zone sieve tubes. These changes were accelerated in petiole explants in which abscission was stimulated by either ethylene or auxin and were suppressed in explants in which abscission was inhibited by auxin.
VEGETATIVE NUCLEAR DIVISION IN NEUROSPORA
Authors: Namboodiri A. N. , Lowry R. J.
Published: January 2018

A re‐examination of the mode of vegetative nuclear division in Neurospora crassa was facilitated by the availability of the mutant “clock” which produces definite growth bands. Since the growth rhythm is correlated with nuclear divisions, stained mycelial mats of this mutant prepared at intervals from the beginning of a growth period provided a sequence of stages of division. In a 28‐hour period the following broad features of nuclear behavior were observed: In the early part of the period during rapid mycelial growth, dividing elongated nuclei predominated. At the end of the period the mycelium contained mostly rounded resting nuclei. In the middle of a growth period nuclear forms of various degrees of annularity occurred along with elongated and rounded nuclei. Elongated and rounded nuclei completed division cycles without change in form, although the corresponding stages of the two types were similar. Elongated nuclei assumed a spiral form at the beginning of division. As division proceeded, relaxation of the nuclear gyres was accompanied by a visible duplication of the chromatin thread and the appearance of chromomere‐like bodies on the daughter threads. One of the chromomere‐like bodies became displaced and was interpreted to be a chromosome or a segment of a chromosome that acts as a mitotic center. All the chromosomes were found to be interconnected and to act as a unit throughout the division cycle. Only after the separation of the daughter chromatin threads could seven chromosomes be counted. Electron microscopic studies complemented the observations with the light microscope. On the basis of the evidence it was concluded that the vegetative nuclear division in Neurospora differs from the classical mitotic pattern in the following respects: (1) absence of visible centrioles, (2) the presence of interconnected chromosomes, (3) the comparatively late appearance of countable chromosomes, and (4) the frequent presence of interzonal connections between separating chromatin threads.
TETRAXYLOPTERIS SCHMIDTII: ITS FERTILE PARTS AND ITS RELATIONSHIPS WITHIN THE ANEUROPHYTALES
Authors: Bonamo Patricia M. , Banks Harlan P.
Published: January 2018

The fertile branching system of Tetraxylopteris is composed of successive “nodes” bearing opposite and decussately arranged, upcurved sporangial complexes. By means of the transfer technique the morphology of the sporangial complex was revealed. It consists of a main stalk which dichotomizes twice producing four major branches. Each of the four branches is further subdivided three times, the subdivisions being arranged alternately and pinnately. The ultimate divisions bear the sporangia singly and terminally. The sporangial complexes decrease in size distally and are more tightly curved at the apex. The sporangia are oblong‐oval with an acute apex. The spores are identical to the dispersed spore taxon Rhabdosporites langii, Richardson. They are spherical, trilete and pseudosaccate with a fine granular ornament on the pseudosaccus. They are 75–176 μ in diameter and show developmental stages from young tetrads to separated, fully mature spores depending on the age of the sporangium from which they were obtained. This is the first account of spores in sporangia of Tetraxylopteris. The diagnosis of the genus and species are emended to include the new information and the order Aneurophytales is redefined.
RADIOAUTOGRAPHIC STUDY OF TRANSLOCATION IN BEAN LEAVES
Authors: Nakata S. , Leopold A. C.
Published: January 2018

The movement of the radioactivity from sucrose, indole‐3‐acetic acid (IAA) and phosphate has been examined in excised bean leaves. Preferential translocation of the labelled materials toward the base of leaf and petiole was demonstrated, suggesting a natural mobilization gradient down the leaf and petiole. Establishment of other mobilization centers in the leaf by local application of N6‐benzyladenine diverted the movement of the sucrose label and, to a lesser extent, the phosphate label. There was no apparent mobilization of IAA by benzyladenine. Evidence is provided that there is a continuity of label from the source to the sink regions, and it is suggested that reported instances of noncontinuity of label may be attributable to the refixation of respired C14O2 by tissue treated with benzyladenine. The observations appear to substantiate the concept that the unloading of solutes from the phloem can regulate the direction and intensity of translocation.
THE CHLOROPLAST STRUCTURE OF IOJAP MAIZE
Authors: Shumway L. K. , Weier T. E.
Published: January 2018

The ultrastructure of the plastids from the genetically caused but maternally transmitted mutant iojap of maize was studied at four stages of development. The plastids of green and potentially green tissue were normal at all stages studied. The plastids of the white tissue were aberrant at all stages studied and lacked the normal grana‐fretwork system as well as a normal prolamellar body. DNA‐like fibrils were present in aberrant plastids, but ribosomes were absent. This indicates that chloroplast ribosomes are important in chloroplast membrane formation. Aberrant plastids fail to develop normally and are not a degeneration of normal plastids. Aberrant and normal plastids occur in single cells in green tissue, but only aberrant plastids have been found in white tissue.
POLLEN SUCCESSION, ABSOLUTE POLLEN FREQUENCY, AND RECURRENCE SURFACES IN CENTRAL JAPAN
Authors: Tsukada Matsuo
Published: January 2018

A generalized pollen diagram, associated with three simplified pollen diagrams from Tsubogakure (1,500 m), Nakatashiro (1,400 m) and Yashima‐ga‐hara (1,650 m) bogs in central Japan, represents five pollen zones for the last 12,000 years, i.e., L (before 10,500 B.P., pine‐boreal); R I (10,500–9,500 B.P., boreal‐oak); R II (9,500–4,500 B.P., temperate); R IIIa (4,500–1,500 B.P., temperate‐boreal); and R IIIb (after 1,500 B.P., pino‐nonarboreal). Absolute pollen frequency is high in well‐humified peat, in gyttja (deposited immediately below the first peat formation), and in peat in the part of the R IIIa cooling stage, and it is low in less‐humified peat, since the former sediments have slow and the latter rapid rates of accumulation, respectively. Changes of plant communities should affect the absolute pollen frequency, but changes of sedimentation rates are more critical. After a re‐examination of Nakatashiro bog, it is hardly possible to recognize a recurrence surface in the European sense, nor can the accumulation of thin tephra on the bog surface be responsible for a temporary halt in peat growth. Nakatashiro bog (like Tsubogakure bog) is a low‐moor bog, and true recurrence surfaces would not be expected in it. In a raised Yashima‐ga‐hara bog, however, there are seven recurrence surfaces without a volcanic ash band; the well‐humified horizons correspond to low values of Sphagnum spores and Cyperaceae pollen, and the less‐humified horizons to high values of Sphagnum spores and Cyperaceae pollen. Peaks of these species in the upper core correspond to those Cryptomeria pollen, an indicator of the high precipitation (generally >1,800 mm/yr). Regularly interrelated fluctuations among these species, absolute pollen frequency, and peat horizons suggest that the precipitation was low in well‐humified peat and was high in less‐humified peat.
FINE STRUCTURE OF THE SPERMATOZOID OF ZAMIA WITH SPECIAL REFERENCE TO THE FLAGELLAR APPARATUS
Authors: Norstog Knut
Published: January 2018

The locomotor apparatus of the spermatozoid of Zamia integrifolia consists of numerous flagella having the typical 9 + 2 substructure connected through basal bodies to a spiral band of complex structure. Basal bodies have a fine structure somewhat resembling that found in algae, mosses, and ferns, but they are much longer. They are composed of a circle of 9 double fibers just beneath the plasma membrane, changing to 9 doublets interconnected by fibrils in a star‐pattern, giving over to a centriolar type of 9 triplet fibers embedded in an electron‐dense layer of the spiral band, and ending in a “cartwheel” configuration. A system of microtubules arranged in a spiral, secondary to the flagellated spiral, is thought to underlie the plasma membrane in flagellated regions. It is suggested that this system accounts for “euglenoid” movements of the sperm. Other details of cellular fine structure are described.
CHLOROPLAST DEVELOPMENT IN THE GERMINATING SAFFLOWER (CARTHAMUS TINCTORIUS) COTYLEDON
Authors: Engelbrecht A. H. P. , Weier T. E.
Published: January 2018

Proplastids in the mesophyll cells of the cotyledons of mature seeds of safflower are irregular in shape and compressed in narrow corners between the large inclusion bodies, oil vacuoles and protein bodies. The proplastids contain a few irregular internal membranes. During dark germination, sheets or sac‐like membranes are produced by the activity of the inner component of the proplastid envelope. These continuous membranes become reticulate and aggregate to the center of the proplastid to form after seven days' germination a quasicrystalline prolamellar body. The membranes are at first irregularly arranged and are of two sorts: those found in the interior of the developing prolamellar body, composed of laterally connected spherical profiles, and those on the periphery of the prolamellar body, which are continuous smooth sheets. The prolamellar body in these dark‐germinated proplastids reverts after 3 hr of illumination to the irregularly arranged membranous structure of the 5‐day dark germination stage. After 6 hr of illumination membranes grow from the prolamellar body forming concentric loops which, in cross section, appear as concentric circles. These membranes must be nested semi‐spheroids. Small grana appear immediately on these looped membranes close to the prolamellar body. With further illumination additional grana develop along the looped membranes in close proximity to the slowly disappearing prolamellar body. Grana increase in size and number along the looped intergranal membranes. The prolamellar body disappears after 15 hr of illumination. The interconnecting fret membranes, sparse at the 15‐hr stage, increase and after 24‐hr illumination result in the typical grana fretwork system of the mature chloroplast. Membranes are continuously being produced by the invagination of the inner member of the plastid envelope.
HYBRIDIZATION, POLYPLOIDY AND ADVENTITIOUS GROWTH IN THE GENUS ASPLENIUM
Authors: Morlang Charles
Published: January 2018

Gametophytes of Asplenium platyneuron, A. rhizophyllum and A. monlanum were grown from spores under controlled conditions. Factors inhibiting and promoting germination and growth were determined. Leaves cut from sexually produced sporophytes of A. platyneuron, A. rhizophyllum and A. montanum were cultured under controlled conditions on agar slants. The leaves produced neoplastic growths of two kinds: (1) two‐dimensional growths, (2) three‐dimensional growths. The former developed into normal‐appearing, rhizoid‐ and gametangia‐producing, heart‐shaped gametophytes having a diploid chromosome complement. The formation of two‐dimensional growths was favored by conditions drastically reducing the energy supply of the initiating sporophytic cells and by destroying the correlation of the leaf. Three‐dimensional growths most often developed into sporophytes unless conditions were limiting; in the latter case they transformed into two‐dimensional growths. Both two‐ and three‐dimensional growths developed from fragmented leaves excised from buds growing near the tips of acuminate fronds of A. ebenoides. The high frequency of two‐dimensional adventitious growth leads to the conclusion that apospory may provide a mechanism for the production of fertile allotetraploids, by the fusion of diploid gametes of adventitiously produced diploid gametophytes, in the genus Asplenium and perhaps other fern genera, in contrast to that which has been previously suggested in the literature.
SURFACE AREA RELATIONS OF WOODY PLANTS AND FOREST COMMUNITIES
Authors: Whittaker R. H. , Woodwell G. M.
Published: January 2018

Surface area of wood and bark is an important dimension of forests, with implications for respiration rate, energy exchange, and water and mineral budgets. Surface area of stem wood and bark can be estimated effectively from linear regressions on conic surface (one‐half basal circumference times tree height) or from regressions of the logarithm of area on the logarithm of diameter at breast height. Branch surface can be estimated from a formula using branch basal diameter, length, and number of current twigs, and from logarithmic regressions of branch bark surface on basal diameter of branches and breast‐height diameter of trees. In temperate deciduous forests several square meters of plant surface occur above each square meter of ground surface; these plant surfaces include 0.3–0.6 m2 of stem bark, 1.2–2.2 m2 of branch bark, and 3.0–6.0 m2 of leaf blades. Branch bark surface increases more rapidly than leaf surface with increasing size of branches and trees. Growth and aging of trees, and maturation of forests, imply increasing ratios of bark (and wood) surface to the photosynthetic leaf surface which supports its growth and respiration.
MORPHOLOGICAL AND HISTOLOGICAL EFFECTS OF TRIFLURALIN ON ROOT DEVELOPMENT
Authors: Bayer D. E. , Foy C. L. , Mallory T. E. , Cutter E. G.
Published: January 2018

The most obvious external effect of trifluralin on the primary root was an increase in the amount of radial expansion near the root tip. The initial radial expansion of the treated roots occurred in the region of maximum elongation. With increased duration of treatment there was a gradual decrease in the extent of the meristematic tissue zone because of progressive vacuolation and subsequent differentiation. Although trifluralin disrupted the mitotic process, no one type of mitotic figure prevailed. Mitotic activity was not affected in all of the cells, some of which appeared to be undergoing a perfectly normal mitosis. Rates of trifluralin application sufficient to inhibit lateral root emergence without interfering with development of the primary root affected the pericycle and portions of the endodermis. The pericyclic cells were much enlarged in. the regions opposite the protoxylem and had undergone some of the initial phases of lateral root formation. These enlarged pericyclic cells correspond to what have been called primordiomorphs.
STUDIES IN THE CAPPARIDACEAE. XI: CLEOME AFROSPINA, A TROPICAL AFRICAN ENDEMIC WITH NEOTROPICAL AFFINITIES
Authors: Iltis Hugh H.
Published: January 2018

The Tropical West African‐Congolese spiny Cleome previously referred to the neotropical “C. spinosa” is the indigenous, distinct, here newly described C. afrospina, most closely related to the southern South American C. trachycarpa of the otherwise endemic neotropical Section Tarenaya. Early collections (from 1816) and widespread distribution in wet forests and riversides also indicate it to be indigenous and not adventive. Related also is the widespread Brazilian‐Argentinian C. hassleriana Chod. (“C. spinosa” auct. non Jacq.; “C. pungens” auct. non Willd.?), the commonly cultivated “Spider Flower,” once recently collected in the Congo (cultivated?). As the only indigenous spiny Old World Cleome, C. afrospina is a remarkable neotropical element in the African flora. Historical explanations for such disjunctions (continental drift, land bridges) are rejected. Avian long‐distance dispersal is indicated by semi‐aquatic successional habitats of high ecological receptivity, generally annual habit, other highly disjunct vicariads, and self‐compatibility within the group. Similar disjunctions occur in the distribution patterns of many aquatic birds (e.g., whistling ducks—Dendrocygna) and of various tropical plants of ecologically receptive “open” habitats.
PETRIFIED PLANTS FROM THE UPPER MISSISSIPPIAN OF NORTH AMERICA. I: THE SEED RHYNCHOSPERMA GEN. N.
Authors: Taylor Thomas N. , Eggert Donald A.
Published: January 2018

Petrified seeds of Upper Mississippian age (Chester Series) are described from sediments from northwestern Arkansas. Specimens of Rhynchosperma quinnii gen. et sp. n. are radially symmetrical and range in length from 1.2 to 2.2 cm and 1.0 to 1.3 cm at the greatest diameter. The seeds are ovate with a tapered apex having 8–10 integumentary ribs and a broadly rounded chalaza. The integument is two‐parted, consisting of an outer presumably soft tissue with secretory canals and an inner layer constructed of longitudinally oriented thick‐walled cells. Nucellus and integument are confluent, but they diverge near the seed midlevel with the free portion of the nucellus forming a dome‐shaped pollen‐receiving structure. Additional features such as vasculature and the structure of well‐preserved megagametophytes are described. The petrified specimens are compared with taxa instituted for casts and impressions which include Rhynchogonium and Boroviczia. The ovulate versus cupulate nature of these genera which has remained uncertain until now appears to be settled in favor of an ovular identity.
THE ORIGIN OF CLOSED CIRCLES OF FIVE CHROMOSOMES IN OENOTHERA
Authors: Cleland Ralph E.
Published: January 2018

Circles in Oenothera are normally composed of even numbers of chromosomes. Two cases of trisomic hybrids with closed circles containing an odd number of chromosomes are here reported. The first of these appeared to contain β Trois Pistoles I and hMateo and had a closed circle of 5, an open chain of 8, and a pair; or chains of 9 and 4 plus a pair. The second hybrid seemed to contain α Trois Pistoles II and β Palmer Lake and had a closed circle of 5 and an open chain of 10. It was possible to analyze in considerable detail the situation in the first of these. The chromosome 5·12 or 11·6 of or Trois Pistoles I was present in this trisomic, which arose either through the simple addition of 5·12 or 11·6 to the β Trois Pistoles I complement contributed through the egg, or through double non‐disjunction. If it were a trisomic of the former type it contained only one chromosome of α Trois Pistoles I. If it arose through double non‐disjunction, the minimum it could have had would be the equivalent of two α Trois Pistoles I chromosomes, and it might theoretically have had up to the equivalent of 5 chromosomes. It showed, however, no influence of α Trois Pistoles I in its phenotype, although the two Trois Pistoles I complexes produce very different phenotypes. It is probable, therefore, that the trisomic arose as a result of simple addition of 5·14 or 11·6 of α Trois Pistoles I to the β Trois Pistoles I complex received from the mother.
THE SPHEROSOMES AND THE RESERVE FAT IN PLANT CELLS
Authors: Sorokin Helen P.
Published: January 2018

The deposition of reserve fat is studied in plants with a high, medium, or low lipid content, and is contrasted with the spherosomes of the same cells. In storage tissue with a high lipid content the reserve triglycerides have the form of comparatively large globules which are quite distinct from the spherosomes. In plants with a medium lipid content the reserve fat appears in the form of granules, globules, or oil‐plasm, and as a homogeneous, interstitial deposition between the protein bodies. Plants with a low lipid content contain a very large number of spherosomes and only very few small sudanophil globules. The spherosomes and the reserve fat represent distinctly separate entities.
ASPLENIUM PLENUM: A FERN WHICH SUGGESTS AN UNUSUAL METHOD OF SPECIES FORMATION
Authors: Morzenti Virginia M.
Published: January 2018

Morphological data, chromosome behavior, and occurrence strongly suggest that the Florida fern known as Asplenium plenum arose as a cross (AAB1B2) between a sexual 2x species, A. abscissum (AA), and a “sterile” 3x hybrid, A. curtissii (AB1B2). A mechanism is described whereby such an origin is possible: A. curtissii, among other so‐called “sterile” hybrids, has the ability to produce unreduced spore mother cells capable of becoming spores directly. Such spores are able to form gametophytes with viable sperms and have the potential of producing sporophytes apogamously. It is highly probable that this heretofore overlooked process has operated in the origin of the hybrid fern, A. plenum, and is the first to be reported in the literature.
ANALYSIS OF GENOME AND SPECIES RELATIONSHIPS IN THE POLYPLOID WHEATS BY PROTEIN ELECTROPHORESIS
Authors: Johnson B. Lennart , Barnhart David , Hall Ove
Published: January 2018

Protein spectra from 4n and 6n species of Triticum were obtained by electrophoresis of seed extracts on polyacrylamide gels. Homologies among the species with regard to protein bands were tested by comparing each species with the standard T. dicoccum in a protein mixture spectrum. By reference to two pairs of homologous bands, each spectrum was then adjusted to the migration velocity of the standard by photographic enlargement. The homologies were found to be consistent with evidence from conventional methods regarding genome relationships among the Triticum polyploids. T. dicoccoides and other known AABB tetraploids showed nine fast‐moving albumin homologues, while T. timopheevi and other known AAGG tetraploids showed seven. The two genomic groups had five albumin bands in common. The hexaploid (AABBDD) subspecies showed 12 albumin homologues, 9 of which were also homologous with the 9 of the AABB tetraploids and 3 of which were attributed to the D‐genome donor. Differences among species within each of the tetraploid genomic groups and among the hexaploid subspecies were largely confined to the slow‐moving bands of the gliadin series.
BIOCHEMICAL CHANGES DURING SEXUAL DEVELOPMENT IN MARCHANTIA POLYMORPHA: I. ESTERASES
Authors: Maravolo Nicholas C. , Garber Edward D. , Voth Paul D.
Published: January 2018

Extracts of uninduced thalli, induced thalli, stalks, antheridiophore and archegoniophore disks of Marchantia polymorpha were subjected to starch‐gel zone electrophoresis. Developed gels were treated with appropriate reaction mixtures to detect sites of activity for 12 enzyme systems; only phosphatases, esterases, and peroxidases were observed. Although common sites of phosphatase, peroxidase, and esterase activity were detected in all tested extracts, additional sites of peroxidase and esterase activity were found in extracts from antheridiophore disks. The antheridia provided the additional esterases as determined by the electrophoresis of antheridial extracts and by a histochemical test for esterases in sections of antheridiophores.
ULTRASTRUCTURAL CHANGES DURING ZOOSPORE FORMATION IN PHYTOPHTHORA PARASITICA
Authors: Hohl Hans R. , Hamamoto Susan T.
Published: January 2018

Cleavage of the multinucleate sporangial cytoplasm begins by a rearrangement and subsequent fusion of randomly dispersed cleavage vesicles. The vesicles line up in planes equidistant from neighboring nuclei and along the sporangial wall. In addition, they contribute to the enlargement of the central vacuole. Fusion of these vesicles with themselves and with the central vacuole cleaves the cytoplasm into uninucleate zoospores, each with two flagella. The sporangial wall consists of two layers, an outer thin one which is continuous over the plug of the discharge pore and an inner thick one which tapers off near the plug. The plug consists of fibrillar material and is ejected upon release of the zoospores. A plug‐like structure separating the forming sporangium from the hypha has a homogeneous matrix pervaded with an anastomosing network of fine electron‐dense channels. In addition, glycogen‐like granules occur within mitochondria and paired structures are interpreted as procentrioles.
THE TUBERS, SAPOGENINS, AND VIRUS RESISTANCE OF DIOSCOREA SPECIES HYBRIDS
Authors: Martin Franklin W. , Delfel Norman E.
Published: January 2018

Dioscorea species differ in sapogenin content, tuber size and shape, and virus resistance. The amount and type of sapogenins in tubers of F1 hybrids among four sapogenin‐bearing and one other Dioscorea species were determined chromatographically. Characteristics of the tuber and resistance to a virus were observed and compared to those of the parents. The presence of particular sapogenins appeared to be a dominant trait modified by minor genes from either parent. Other traits appeared to be determined by many genes. Heterosis was expressed in some hybrids by superior yields and excellent virus tolerance. Some of the hybrids could be used as clonal varieties, but none contained the desired keto sapogenins except in mixtures with diosgenin.
PETIOLE VASCULARIZATION OF LUXEMBURGIEAE (OCHNACEAE)
Authors: Decker Jane M.
Published: January 2018

Sections through the petiole and blade midrib and sometimes the node of 20 genera of Luxemburgieae have revealed variations in vascularization which appear significant in determining the phylogeny of the tribe. The most primitive group are the pentacarpellate genera; they are characterized by multilacunar nodes and numerous leaf traces which mostly remain free to the leaf apex; some of these become medullary bundles in the petiole. The more advanced bicarpellate genera have multilacunar or trilacunar nodes, still with many leaf traces in the case of Wallacea. These traces fuse in the blade, resulting in a siphonostele. The most advanced genera are tricarpellate and have trilacunar nodes with only three traces; these traces fuse, forming a siphonostele. There are no medullary bundles present in this last group of genera.
PRELIMINARY INVESTIGATION OF THE DOUBLE‐DIFFUSION TECHNIQUE AS A TOOL IN DETERMINING RELATIONSHIPS AMONG SOME MYXOMYCETES, ORDER PHYSARALES
Authors: Franke Robert G.
Published: January 2018

Double‐diffusion technique was used to investigate myxomycete relationships within the order Physarales. Extracts of plasmodia of 22 slime mold isolates were reacted with five antisera produced to Plasmodia of Didymium nigripes, Physarella oblonga, Physarum polycephalum, Physarum gyrosum and Fuligo septica. Two isolates of Fuligo septica tested alike. Four isolates of Physarum pusillum did not test alike, and no valid conclusion of the relationship of this species was possible. These isolates showed strong serological affinity: (1) Physarum gyrosum, Physarella oblonga, two isolates of Fuligo septica, and possibly two isolates of Physarum pusillum, and Physarum tenerum; (2) Physarum polycephalum and Physarum flavicomum; (3) Fuligo septica and many of the species tested; (4) Didymium nigripes and at least one isolate of Didymium iridis. In most cases serologial relationships among species tested did not coincide with current taxonomy based on morphology of fructification.
GROWTH AND DEVELOPMENT OF THE MYXOMYCETE PERICHAENA VERMICULARIS. II. CHROMOSOME NUMBERS AND NUCLEAR CYCLES
Authors: Ross Ian K.
Published: January 2018

Chromosome counts of dividing nuclei of the myxomycete Perichaena vermicularis indicate a number of 25 ± 2 in the amoebae and 50 ± 4 in the Plasmodia, confirming earlier reports that amoebae are haploid and plasmodia diploid. Chromosome numbers obtained from nuclei during sporangial development indicate a fluctuation in the location of meiosis influenced by environmental conditions. The implications of these observations are discussed in reference to past conflicting evidence of the location of meiosis.
ELEGTROPHORETIC VARIATION IN PROTEINS AND ENZYMES OF THE TUMOR‐FORMING HYBRID NICOTIANA GLAUCA X N. LANGSDORFFII AND ITS PARENT SPECIES
Authors: Bhatia C. R. , Buiatti M. , Smith H. H.
Published: January 2018

Leaf and tumor extracts of the genetically tumor‐conditioned amphiploid Nicotiana glauca X N. langsdorffii, as well as leaf extracts from the parent species and a nontumorous mutant of the amphiploid, were separated on acrylamide gel columns by the method of disc electrophoresis. Gels were stained for general proteins with amido black and specifically for esterases, peroxidases and leucine amino peptidase. The results show characteristic protein and enzyme patterns for leaves of each of the parental species and the amphiploid hybrids. The amphiploids show some bands which are comparable to bands of either one or both of the parental species, while other bands do not have their equivalents in the parental species. Leaf tissue of the tumorous and nontumorous amphiploids were found to differ by a few protein bands, at least two for esterases and at least one for peroxidases. Extracts from tumor tissue show very different patterns from those of the leaves of the same genotype.
EFFECTS OF RADIATION ON FLOWERING OF HYOSCYAMUS NIGER
Authors: Schneider M. J. , Borthwick H. A. , Hendricks S. B.
Published: January 2018

Flowering and stem‐lengthening responses of the long‐day plant Hyoscyamus niger L. were followed under various photo‐ and dark‐period combinations. Phytochrome action was identified by its photoreversibility, spectral region of response, and requisite levels of irradiance. Flowering control was also affected by another photoreaction having an action maximum at 710–720 nm. This reaction, while observable over appropriate short periods, is best displayed by protracted irradiation. The effectiveness of this reaction has a half‐life of the order of 1–4 min. Responses to it can be observed over an intensity range of more than 100‐fold. The two photoreactions interplay in flowering control depending on light quality during photoperiods. The interplay is a prominent factor affecting the adequacy of fluorescent and incandescent‐filament radiation in plant growth experiments.
THE INITIATION AND ELONGATION OF RHIZOID CLUSTERS IN CAULERPA PROLIFERA
Authors: Chen James C. W. , Jacobs William P.
Published: January 2018

Under improved environmental conditions the average rate of elongation of the rhizoid cluster was 5.2 mm/day in the first 3 days. The rate decreases thereafter and is close to zero around 5–6 days after initiation. The elongation, like that of the rhizome, is chiefly by means of “tip‐growth.” The presumptive site of the initiation is 1.3–1.7 mm from the rhizome tip. Under present experimental environment, the presumptive time of the initiation was mainly at 1 to 3 hr after the beginning of the light period. Initiation in the dark period was less frequent, and little or no initiation in the middle and later parts of the light period was observed. The average plastochron of the cluster was 0.91 day. The rate of elongation of the rhizoid cluster was less variable than that of the rhizome. Hence, the slope of calculated regression line from the plot, the cluster length vs. its distance from the rhizome tip, is steeper when the rhizome grows slower (4.9–5.8 mm/day) and less steep when the rhizome grows faster (7.3–8.9 mm/day). In spite of some variation in the slope of the regression line, the intersection between the line and X‐axis remains about the same. The application of information on the presumptive site and presumptive time of the rhizoid cluster initiation to a developmental study of micro‐events taking place prior to the morphological differentiation is proposed.
ASCOCARPIC CENTRUM ONTOGENY OF SPECIES OF HYPODERMATACEAE OF CONIFERS. II
Authors: Gordon C. C.
Published: January 2018

Ascocarpic studies of the ontogeny of Lophodermium nitens disclosed a type of development unlike that of all other species of Hypodermataceae occurring on conifer needles. For this reason the centrum of L. nitens is designated as Type III and is compared with Type I (Gordon, 1966). Because L. nitens produces its ascocarp in several tissues of various species of pine, the ontogeny of ascocarps in different locations is discussed and illustrated. The most significant ontogenetic feature of the ascocarp of L. nitens is a layer of hyaline cells in the primordium; this layer is meristematic and gives rise to all subsequent structures of the centrum.