bluuebunny/crossref_metadata_2025 huggingface dataset:
STEEREELLA, A NEW GENUS OF HEPATICAE FROM THE WEST INDIES
Authors: Kuwahara Yukinobu
Published: January 2018

In addition to the complete lack of the usual spiral bands of thickenings in the elaters, the new genus Steereella is unique among the Hepaticae for the resemblance of its cellular organization in the thalloid gametophyte to that of some moss leaves. The taxon recognized is one genus, Steereella, gen. n., and one species S. linearis (Swartz) Kuwah. comb. nov., in which the variable nature of the gametophyte is particularly noted. The genus appears to be restricted to the West Indies.
RING‐POSITION AND FREQUENCY OF ADJACENT DISTRIBUTION OF MEIOTIC CHROMOSOMES IN RHOEO SPATHACEA
Authors: Lin Yue Jee , Paddock Elton F.
Published: January 2018

The morphological sequence of the twelve chromosomes around the ring as worked out by Sax is reaffirmed with slight corrections of the centromere position on three chromosomes: Aa, fA, and Dd. Adjacent distribution was found in 53/120 MI PMC (44.2%). Ring‐position analysis was achieved in 34 of the 53. There were 127 chromosomes and 66 arm‐pairs involved in adjacent distribution in these 34 MI PMC. Adjacent distributions occurred at random among the twelve chromosome positions and among the twelve arm‐pair positions. There were eleven instances among the 66 arm‐pairs (16.7%) of adjacent distribution despite free ends due to chiasma failure. Up to four consecutive chromosomes may pass to the same pole. Not all cells with 6–6 distribution are genetically balanced. Distribution of 7–5 occurred in 24/120 AI PMC (20.0%). Another nine (7.5%) in the same sample had one or more lagging chromosomes. At MI, three PMC had 8–4 distribution, but none such were seen at AI.
TRANSLOCATION OF 14C METABOLITES IN CARROT ROOT
Authors: Caplin Samuel M.
Published: January 2018

Four‐month‐old carrot plants exposed to 14CO2 for 1 hr in light were harvested successively at 1, 5, 10, 26, and 78 hr after initial exposure. Half‐mm thick transverse slices from 3 and 10 cm below the crown were frozen quickly, freeze‐dried, and autoradiographed on film. Radioactivity was first localized in a ring surrounding the cambium. The radioactive region extended centrifugally along radii as discrete loci to half the phloem thickness in 10 hr, in a pattern similar to radial rows of callose‐stained sieve elements. Median longitudinal sections stained for callose demonstrated the presence of anastomosing sieve tube strands between the more vertical sieve tubes of differing age. Radioactive materials did not move across the cambium for 5–10 hr. These data fit with the decreased growth, in earlier studies, of uniform phloem explants removed from increasing distances from the cambium and of the lesser growth than phloem of similar xylem explants.
ADDITIONS TO THE MIOCENE SUCKER CREEK FLORA OF OREGON AND IDAHO
Authors: Taggart Ralph E.
Published: January 2018

Study of plant microfossils and additional macrofossils collected from sediments in the vicinity of Sucker Creek along the Oregon‐Idaho boundary has provided additional data on the composition of this fossil flora. A total of seven taxa new to the flora have been recognized. These include colonies of Botryococcus; pollen of Podocarpus, Pachysandra, and the Onagraceae; and leaves of Cephalotaxus californica and Vaccinium sophoroides. The occurrence of Podocarpus in this mid‐Miocene flora is particularly significant in view of the limited number of records of this genus in the Tertiary of North America. In addition to these new records, the presence of three additional taxa—Castanea, Nyssa, and Ilex—previously recognized on the basis of leaf remains, is further substantiated by the occurrence of fossil pollen in the sediments.
STARCH IN FUNGI. II. INDUCTION OF AMYLOIDITY IN MEMBERS OF DIVERSE GENERA
Authors: McCracken D. A. , Nadakavukaren M. J. , Dodd J. D.
Published: January 2018

Nonamyloid hyphae from fungal fruit bodies which normally produce amyloid structures can be induced to produce starch molecules when incubated in glucose‐1‐phosphate solution. Hyphae from fruit bodies without natural amyloid structures could not be induced to produce starch. The genes for the starch‐synthesizing enzymes are apparently activated when fruit body formation is initiated.
ABNORMAL REDUCTIONAL AND NONREDUCTIONAL MEIOSIS IN CERATOPTERIS: ALTERNATIVES TO HOMOZYGOSITY AND HYBRID STERILITY IN HOMOSPOROUS FERNS
Authors: Hickok Leslie G. , Klekowski Edward J.
Published: January 2018

Natural and synthesized hybrids of Ceratopteris were investigated to determine the effect of hybridization on the genetic system. Studies indicated that the hybrids exhibited massive spore abortion and pairing abnormalities at meiotic prophase, characteristic of “sterile diploids and triploids” reported in hybridization studies of other fern genera. However, a small percentage of viable spores also was produced by the hybrids. Cytological investigations indicated the presence of previously unreported meiotic adaptations that allowed the production of unreduced spores and reduced spores exhibiting chromatid heterozygosity. The reduced spores allow haploid gametophytes to form heterozygous zygotes in spite of intragametophytic selfing. The unreduced spores were shown to be responsible for the fertility of the “sterile” hybrid and allowed the subsequent production of up to three generations of sporophytes. The literature suggests that these meiotic adaptations are present in other fern genera and may play a significant role in evolution through hybridization.
THE EFFECT OF LIGHT ON THE USE OF THE NITROGEN RESERVES OF GERMINATING SOYBEAN SEEDS
Authors: Hurst Clyde J. , Sudia T. W.
Published: January 2018

Light affects the mobilization and distribution of several of the storage components of the cotyledons of germinating soybean seeds. The nitrogen content of the cotyledons began to decrease during the first day of germination, continued through day 12 for plants in the light, and day 14 for those in the dark. Cotyledons from both treatments had lost about the same amount of nitrogen by day 14. Plants from both treatments lost about the same amount of dry weight by day 8, but those in the light had taken up nitrogen from the nutrient solution; while those in the dark showed no increase. The plants in the light had higher concentrations of soluble amino nitrogen in the cotyledons than did those in the dark, but the opposite was true for the seedling axis. Aspartate and its amide accounted for half or more of the total free amino acids in all parts of dark‐grown plants at 6 and 14 days. In the light‐grown plants aspartate and asparagine usually accounted for less than half of the total free amino acids in all plant parts except the cotyledons at 6 and 14 days. Total soluble amino acids were much lower in these plants than those in the dark, excepting the cotyledons.
THE REGULATION OF ABSCISSION AND IAA BY SENESCENCE FACTOR AND ABSCISIC ACID
Authors: Chang Yaw‐Pan , Jacobs W. P.
Published: January 2018

The effects of the endogenous “senescence factor” (SF) and synthetic (±)‐abscisic acid (ABA) on basipetal transport of indoleacetic acid (IAA) in Coleus blumei Benth. were studied. When used to pretreat explant petioles, both SF and ABA accelerated abscission and decreased basipetal movement of IAA through petiolar sections but had no effect on acropetal movement, which was negligible in all experiments. SF decreased the intensity but not the velocity of the basipetal movement of IAA. Pretreatment with either SF or ABA decreased the free IAA and increased the IAA‐aspartate extractable from the sections. The results support the hypothesis that SF and ABA hasten abscission by lowering the amounts of IAA transport in the tissue. Known properties of SF are similar to those of ABA. Efforts are under way to elucidate the chemical identity of SF.
SCIADOPITOPHYLLUM CANADENSE GEN. ET SP. NOV.: A NEW CONIFER FROM WESTERN ALBERTA
Authors: Christophel Dave C.
Published: January 2018

A new Sciadopitys‐like conifer is described on the basis of compression fossils of shoots and leaves found at the Smokey Tower locality in western Alberta. The specimens consist of long, strap‐like leaves attached in apparent whorls and subtended by groups of scale leaves. Other scale leaves are borne in loose spirals on the shoots between whorls. These specimens represent the first record of Sciadopitys‐like foliage from western North America. Comparisons are made with extant and extinct species of the genus Sciadopitys (Siebold and Zuccarini, 1841) and with the widely distributed fossil genus Sciadopitytes (Goeppert and Menge, 1883).
PLASMODESMATA AND AN ASSOCIATED CELL WALL COMPONENT IN BARLEY ALEURONE TISSUE
Authors: Taiz Lincoln , Jones Russell L.
Published: January 2018

A unique cell wall component has been observed in the aleurone layer of barley (Hordeum vulgare L. cv. Himalaya). This wall component has been shown to be localized adjacent to the plasmalemma. Unlike the surrounding cell wall matrix it is resistant to “Onozuka” cellulase and remains intact during gibberellic acid‐stimulated hydrolase release. After treatment of the tissue with gibberellic acid followed by digestion with “Onozuka” cellulase this resistant wall component can be isolated free of protoplast. Study of its surface features revealed the presence of numerous tubular extensions, 120 nm wide, connecting adjacent resistant walls. These tubes resembled light microscope images of plasmodesmata in size and appearance. E.M. sections of resistant walls showed the presence of unit membrane lining the inner surface of the wall tubes. It was concluded that the resistant wall constitutes a modified wall layer that is secreted uniformly across all plasmalemma surfaces, including those in the wall (plasmodesmata). The presence of wall tubes surrounding plasmodesmata enhances the apparent size of the plasmodesmata in the light microscope. This may account for previous inconsistencies in the literature between light and electron microscope determinations of plasmodesmata diameters.
FLORAL DEVELOPMENT AND STAMEN FILAMENT ELONGATION IN CLEOME HASSLERIANA
Authors: Koevenig James L.
Published: January 2018

Floral development in Cleome hassleriana is briefly described. Experimental evidence is presented supporting the hypothesis that the anthers control stamen filament elongation by supplying IAA rather than kinetin or gibberellic acid. This control depends upon the developmental stage of the bud and does not exclude the effect of other floral organs on stamen filament elongation at early developmental stages. Evidence that the anthers also partially control stamen filament and floral abscission by supplying IAA is given.
THE EFFECTS OF PLANT GROWTH SUBSTANCES ON IN VITRO FIBER DEVELOPMENT FROM FERTILIZED COTTON OVULES
Authors: Beasley C. A. , Ting Irwin P.
Published: January 2018

Cotton ovules were aseptically removed from ovaries 48 hr after anthesis and floated on the surface of liquid medium. Plant growth substances were filter sterilized and added to the medium in which glucose was the principal source of carbohydrate and KNO3 the sole source of nitrogen. The amount of total fiber produced from the ovule surface was determined colorimetrically from the intensity of a destaining solution to which the ovules had been transferred following their 15‐second emersion in a solution of toluidine blue O. Gibberellic acid induced a marked stimulation and kinetin and abscisic acid a marked inhibition of fiber production from fertilized cotton ovules. Indoleacetic acid afforded only a trend of stimulation of fiber production. Gibberellic acid overcame the inhibition of total fiber production induced by both kinetin and abscisic acid. Indoleacetic acid did not overcome the inhibition of total fiber production induced by kinetin but did, to a great extent, overcome the inhibition due to abscisic acid.
THE NINETY‐YEAR PERIOD FOR DR. BEAL'S SEED VIABILITY EXPERIMENT
Authors: Kivilaan A. , Bandurski Robert S.
Published: January 2018

In 1879 Dr. W. J. Beal selected seeds of 23 different species of locally common plants, mixed 50 seeds of each species with moist sand in unstoppered one‐pint bottles, and buried the bottles in a sandy knoll to be unearthed and the viability of the seeds tested periodically. The year 1970 marked the ninetieth year the seed had been buried, and the thirteenth bottle was recovered to test for seed viability. Of the three species which had germinated in the 1960 test (curly dock, Rumex crispus; evening primrose, Oenothera biennis; and moth mullein, Verbascum blattaria), only V. blattaria had viable seed with 20% germination. No other species germinated. All ten seedlings of V. blattaria were grown to maturity, and seeds were then harvested to study the possible deviations from normality and the requirements for seed germination. All seedlings emerging from the first progeny seed appeared normal. The most prominent requirement for germination was light, and this is a possible explanation of why the seeds had remained viable but dormant for so long a period. One‐third of the freshly harvested seed germinated in darkness and, furthermore, redrying of dark‐moistened seed in the absence of light induced additional germination. Germination of dark‐moistened seed was not completely restored when the still moist seeds were subsequently exposed to light. However, when dark‐moistened seeds were dried and then remoistened in the light, germination was about 95 %. About 5 % of the seed did not germinate under the conditions used. We find that 5 % of the population of V. blattaria seeds are dormant for unknown reasons, that 30 % will germinate if supplied only with moisture, and that 65 % are inhibited and require light and moisture simultaneously for germination. Supplying this 65 % of the population with moisture in darkness results in the development of a second type of inhibition which is no longer light reversible. It appears that the simultaneous requirement for light and moisture is an important factor in permitting V. blattaria seeds to remain dormant during prolonged burial.
ANATOMICAL CHANGES DURING LEAF ONTOGENY IN POPULUS DELTOIDES
Authors: Isebrands J. G. , Larson Philip R.
Published: January 2018

The leaf plastochron index (LPI) was used to interpret the anatomical changes during leaf ontogeny in the developing leaf zone of young cottonwood trees and to relate leaf anatomical structure to physiological function. The lamina tip matured precociously with respect to both structure and function. Below the lamina tip the intercellular spaces, stomates, and minor veins matured basipetally, while the major veins developed acropetally. Ontogenetically, maturation progressed from LPI –1.0, which was anatomically immature except for its lamina tip, to the first fully expanded leaf at LPI 6.0, which was anatomically mature. Physiological maturity also occurred at LPI 6.0, thus signifying a transition with respect to both structure and function. By evaluating the anatomical observations in conjunction with physiological data collected at comparable LPI's in other experiments, it could be demonstrated that anatomical development was a limiting factor in photosynthesis and translocation of assimilates.
MOVEMENT OF IAA IN SECTIONS FROM SPIDER FLOWER (CLEOME HASSLERIANA) STAMEN FILAMENTS
Authors: Koevenig J. L. , Sillix Dale
Published: January 2018

Movement of IAA in spider flower (Cleome hassleriana Chod.) stamen filaments was studied by placing 2‐mm sections horizontally between donor agar blocks containing 14C‐labeled IAA and plain agar receiver blocks and measuring radioactivity in the donor and receiver blocks and filament sections by scintillation counting after the desired transport time. Movement was strictly polar and basipetal at all stages of floral development, except in open flowers just before stamen abscission when the amounts moving acropetally and basipetally were equal. The amount of IAA moved depended upon the stage of development. As buds aged more IAA was moved, until the buds opened and the stamen filaments reached maximum elongation; then the amount of IAA moving basipetally dropped drastically. There was an insignificant amount of acropetal IAA movement except just before stamen abscission. This change in IAA movement is not due to a change in filament diameter. In time‐course studies the amount of IAA moved basipetally increased with time up to 5 hr and then declined slightly. The amount of radioactivity retained by sections increased until 8 hr. The amount of IAA moved in tip sections was less than that in mid or base sections; however, this can be partially explained by differences in uptake area of these sections. The relationship of these results to the hypothesis that changes in IAA movement are important in the control of stamen filament elongation and abscission is discussed.
TRIDENS X OKLAHOMENSIS (T. FLAVUS X T. STRICTUS), AN INTERSPECIFIC STERILE HYBRID IN THE ERAGROSTEAE (GRAMINEAE)
Authors: Crooks Patti , Kucera C. L.
Published: January 2018

The incidence of Tridens oklahomensis Feath. with T. flavus (L.) Hitchc. and T. strictus (Nutt.) Nash together with its morphological intermediacy between the latter two species suggests a hybrid origin. Field and laboratory studies conducted over several years provide substantial evidence of an interspecific cross. Tridens oklahomensis appears in generally disturbed habitats, such as roadsides and cleared areas, where the adventive (for this region) T. strictus occurs as overlapping populations with the ubiquitous T. flavus. At no time has the supposed hybrid been recorded solely with one or the other of the two species. On a moisture gradient, T. strictus is found mainly in swales and ditches while T. flavus occurs on the drier and more general upland. The hybrid occurs toward the moist end of gradient, near T. strictus. On this basis it is reasoned that the latter is the pistillate parent. The hybrid is sterile and has no vegetative means of spreading. Under these conditions its presence is limited to chance fertilization in those situations where T. strictus has invaded the range of the more widespread T. flavus.
OBSERVATIONS ON CHYTRIDIACEOUS PARASITES OF PHANEROGAMS. XIX. A PHYSODERMA ON EURASIAN WATER MILFOIL (MYRIOPYLLUM SPICATUM)
Authors: Sparrow Frederick K.
Published: January 2018

A Physoderma was found on Myriophyllum spicatum in Michigan. This is the first recorded on this host from this hemisphere. It differs from the Danish P. myriophylli Rostrup in not producing galls on the host and in several aspects of its endobiotic stage. It more closely resembles a Swedish fungus attributed to Physoderma hippuridis by Lagerheim occurring on the same species of host.
EFFECTS OF PLANT GROWTH SUBSTANCES ON IN VITRO FIBER DEVELOPMENT FROM UNFERTILIZED COTTON OVULES
Authors: Beasley C. A. , Ting Irwin P.
Published: January 2018

Fertilization of cotton ovules was prevented by removal of styles and stamens on the morning of anthesis. Forty‐eight hr later ovaries were harvested and ovules were aseptically transferred to liquid culture medium supplemented with various plant growth substances. In the absence of phytohormones, ovules browned and failed to increase in size or produce fibers. Indoleacetic acid and gibberellic acid provided for ovule growth and fiber development. Kinetin provided for ovule growth only. The ovule's capacity for indoleacetic acid‐ or gibberellic acid‐stimulation of fiber development was reduced by high concentrations of kinetin or abscisic acid. Low concentrations of kinetin partially reversed the inhibitory effect of abscisic acid.
OBSERVATIONS ON CHYTRIDIACEOUS PARASITES OF PHANEROGAMS. XX. RESTING SPORE GERMINATION AND EPIBIOTIC STAGE OF PHYSODERMA BUTOMI SCHROETER
Authors: Sparrow F. K.
Published: January 2018

The development and morphology of Physoderma butomi Schroeter on Butomus umbellalus L., found in Michigan, is followed from germination of the resting spore through formation of epibiotic and endobiotic stages, to resting spore. No evidence for sexuality was found.
STRUCTURAL DIMORPHISM OF STIGMATIC PAPILLAE IN DISTYLOUS LINUM SPECIES
Authors: Dulberger Rivka
Published: January 2018

Intermorph differences in the wall structure and constituents of stigmatic papillae are described for distylous Linum pubescens and L. grandiflorum. In the long‐styled morph of both species the wall portion around the apex of the papilla has a thickened cellulose‐pectin layer. In the short‐styled morph of L. pubescens a cap zone is interposed between the cuticle and apical portion of the papilla wall. The subcuticular cap space contains pectins and lipid particles. Similar particles are also present in deposits on the cuticle surface. Papillae of the short‐styled morph in L. grandiflorum lack a cap zone and have only epicuticular lipid deposits. Other distylous Linum species in which the two morphs differ in wall structure of the papillae are L. mucronatum, L. flavum, L. perenne, L. austriacum, and L. maritimum. Studies of stigma dimorphism can help to elucidate evolutionary relations between dimorphic and monomorphic Linum species.
EXTERNAL SPORE MORPHOLOGY AND TAXONOMIC AFFINITIES OF PHYLLOGLOSSUM DRUMMONDII KUNZE (LYCOPODIACEAE)
Authors: Breckon Gary J. , Falk Richard H.
Published: January 2018

The external spore morphology of Phylloglossum drummondii was studied with the scanning electron microscope and shown to share a number of features with spores in the subgenus Urostachys in Lycopodium. Within Urostachys the affinities of P. drummondii were less evident: the foramino‐fossulate distal face, pyramidal proximal surface, and subcircular outline of its spores are similar to spores in the section Phlegmaria while the weakly foveolate proximal surface and raised laesurae are characteristic of spores in the section Selago.
THE FINE STRUCTURE OF OOGENESIS IN MARCHANTIA POLYMORPHA
Authors: Zinsmeister Dorothy D. , Carothers Zane B.
Published: January 2018

Archegonium development, beginning with the archegonial initial and culminating in the mature egg, was studied with the electron microscope. The ultrastructural features of the beginning stages in development of the archegonium are relatively similar to one another. Plasmodesmata occur between all adjacent cells at this time. After the secondary central cell is formed these protoplasmic connections are lost, and both axial and parietal cell lineages begin to show signs of ultrastructural differentiation. The mature egg is characterized by cytoplasm rich in ribosomes and larger organelles. Mitochondria and simplified plastids commonly display a juxtaposed association. As far as could be ascertained the numerous plastids and mitochondria in the egg of Marchantia arise through division of preexisting organelles and are not formed anew from evaginations of the nucleus. Blebbing of the nucleus produces polymorphic organelles which appear to be pinched off into the cytoplasm. The mature egg also contains vacuoles and lipid bodies toward its periphery, while dictyosomes and extensive endoplasmic reticulum occur throughout. The space between the wall cells and the mature egg appears to contain an amorphous substance. No extra membrane was observed around the mature egg.
ANATOMY AND FINE STRUCTURE OF THE MISTLETOE HAUSTORIUM (PHTHIRUSA PYRIFOLIA). II. PENETRATION ATTEMPTS AND FORMATION OF THE GLAND
Authors: Dobbins David R. , Kuijt Job
Published: January 2018

The earliest attempts at host penetration by the primary haustorium of Phthirusa pyrifolia (H.B.K.) Eichl. were studied utilizing the techniques of light and electron microscopy. Cells located in the central portion of the haustorial core form a lens‐shaped structure, the gland. Gland cells are of two kinds, possessing either a dense‐staining cytoplasm or a light‐staining one. The ultrastructural features of these unique cells are described. A cavity forms at the base of the gland and fills with a fibrillar substance, which appears morphologically similar to that characterizing the core parenchyma, and the contents of some disintegrated gland cells. The gland cavity extends through the contact zone, where its contents exude onto the host's surface. The primordial endophyte is initiated above the gland and grows through it to the host's surface. If not successful in penetrating the host, this organ may spread laterally between the host and the old contact layer. A new contact layer is subsequently formed. Several successive penetration attempts may be made until one is successful. Strands of vessel members may be followed from the hypocotyl to the gland. Along these strands the pitting pattern changes from scalariform to reticulate, respectively.
SYMMETRY AND DEVELOPMENT OF BUTOMUS UMBELLATUS (BUTOMACEAE) AND LIMNOCHARIS FLAVA (LIMNOCHARITACEAE)
Authors: Wilder George J.
Published: January 2018

The prostrate rhizome of Butomus umbellatus produces branch primordia of two sorts, inflorescence primordia and nonprecocious vegetative lateral buds. The inflorescence primordia form precociously by the bifurcation of the apical meristem of the rhizome, whereas the non‐precocious vegetative buds are formed away from the apical meristem. The rhizome normally produces a branch in the axial of each foliage leaf. However, it is unclear whether the rhizome is a monopodial or a sympodial structure. Lateral buds are produced on the inflorescence of B. umbellatus either by the bifurcation or trifurcation of apical meristems. The inflorescence consists of monochasial units as well as units of greater complexity, and certain of the flower buds lack subtending bracts. The upright vegetative axis of Limnocharis flava has sympodial growth and produces evicted branch primordia solely by meristematic bifurcation. Only certain leaves of the axis are associated with evicted branch primordia and each such primordium gives rise to an inflorescence. The flowers of L. flava are borne in a cincinnus and, although the inflorescence is simpler than that of Butomus umbellatus, the two inflorescences appear to conform to a fundamental body plan. The ultimate bud on the inflorescence of Limnocharis flava always forms a vegetative shoot, and the inflorescence may also produce supernumerary vegetative buds. Butomus umbellatus and Limnocharis flava exhibit a high degree of mirror image symmetry.
TAXONOMIC POSITION OF TERMITARIA AND MATTIROLELLA (ENTOMOGENOUS DEUTEROMYCETES)
Authors: Khan Saeed R. , Kimbrough James W.
Published: January 2018

Termitaria snyderi Thaxter is found in and around Gainesville, Florida, infecting the subterranean termites Reticulitermes virginicus (Banks) and R. flavipes (Kollar). The fungus forms sporodochia‐like structures on the exoskeleton of the termites. These structures have a subhymenium of tightly held phialides. The phialides cut off phialoconidia apically in basipetal succession into the collarettes at conidiogenous loci. The basal layer of the thallus has certain thick‐walled cells that send haustoria into the integument of the host termite. Termitaria appears to be closely related to another cuticle‐infecting parasite of termites, Mattirolella Colla. A new species of the latter, M. crustosa, is described here. The relationships of the two genera are discussed and a new order of Deuteromycetes, Termitariales is proposed for them.
ULTRASTRUCTURE OF THE NACREOUS LEPTOIDS (SIEVE ELEMENTS) IN THE POLYTRICHACEOUS MOSS ATRICHUM UNDULATUM
Authors: Stevenson Dennis Wm.
Published: January 2018

The physiological phloem equivalents, leptoids, of the polytrichaceous moss Atrichum undulatum appear to be similar to the nacreous sieve elements that occur in many higher plants. These leptoids are elongated cells with nacreous thickenings on their radial and tangential walls. Their oblique end walls, which lack such thickenings, are traversed by numerous pores through which the plasmalemma, endoplasmic reticulum, and cytoplasm are continuous between adjacent leptoids of a longitudinal file. These end walls closely resemble the simple sieve areas of the sieve elements found in Polypodium vulgare. The leptoid sieve pores have a median expanded area and frequently are occluded by small amorphous protein plugs at each end. Also, callose was observed as electron‐luscent areas both on the faces of the end walls and as a thin cylinder surrounding the lateral area of each pore. Amorphous and granular cytoplasmic contents of the leptoids appear to be morphologically similar to the slime (P‐protein) found in the sieve‐tube elements of many angiosperms. Differentiating leptoids are characterized by the formation of numerous membrane‐bound protein bodies in close association with polysomes and endoplasmic reticulum. As the leptoid matures, the contents of the protein bodies become dispersed in the cytoplasm. Ultrastructurally and ontogenetically the leptoids in the gametophores of A. undulatum appear almost identical to the sieve elements of P. vulgare and therefore should be considered sieve elements rather than phloem‐like equivalents.
THE FLAVONOIDS OF LASTHENIA (COMPOSITAE)
Authors: Bohm B. A. , Saleh N. A. M. , Ornduff Robert
Published: January 2018

Lasthenia (Compositae: Helenieae), a western North American‐Chilean genus of 16 species, produces 22 flavonoid glycosides. Flavonoids are the chalcones butein and okanin, the aurones maritimetin and sulfuretin, the flavone luteolin, and the flavonols kaempferol, quercetin, and patuletin. The presence or absence of various of these classes of compounds in general follows sectional alignments in the genus, confirms affinities based on morphological and cytological evidence, and suggests relationships of problematical species. Intraspecific variation in flavonoid constituents occurs in several species, and in one taxon intrapopulation variation seems to exist as well. Evolution within Lasthenia has been associated with a loss of the ability to produce or accumulate luteolin, chalcones, and aurones; an increase in diversity of quercetin glycosides; acquisition of the ability to produce patuletin; and an elaboration of glycosylation patterns of patuletin.
OZONE SENSITIVITY OF LEAVES: RELATIONSHIP TO LEAF WATER CONTENT, GAS TRANSFER RESISTANCE, AND ANATOMICAL CHARACTERISTICS
Authors: Evans Lance S. , Ting Irwin P.
Published: January 2018

Relative water content, resistance to gas transfer, stomatal spacing, and other characteristics of primary bean leaves were studied in relation to ozone sensitivity and injury. Cells of primary bean leaves are maximally sensitive to ozone exposure 9–10 days after germination under our experimental conditions. The stage of maximum sensitivity was not correlated with changes in stomatal number or resistance on either adaxial or abaxial leaf surfaces. It was deduced that bean leaf sensitivity was a function of more internal circumstances, and gas exchange was never the limiting factor through the developmental period studied. Changes in resistance were not significantly altered by ozone levels that produced no visible injury. After exposure to high ozone doses, a decrease in adaxial resistance occurred apparently as a result of palisade and epidermal cell lysis. Normally most gas exchange occurs through the adaxial surface. A 10 % decrease in relative water content accompanying a 60‐min ozone exposure of 0.55 ppm could not be explained physiologically on the basis of cell injury as no visible leaf injury occurred.
CYTOPLASMIC INCOMPATIBILITY STUDIES IN THE MYXOMYCETE DIDYMIUM IRIDIS: RECOVERY AND NUCLEAR SURVIVAL IN HETEROKARYONS
Authors: Ling Hubert , Upadhyaya Kailash C.
Published: January 2018

At least eleven somatic compatibility loci exist in the myxomycete Didymium iridis. Cell fusion is controlled by at least seven fusion loci (Fus1–Fus7). Cytoplasmic compatibility is controlled by at least four clear‐zone loci (Cz1–Cz4). Plasmodia with identical phenotypes at all seven fusion loci, but different phenotypes at the clear‐zone loci, will fuse temporarily, but fusion is soon blocked by cytoplasmic reactions which prevent complete mixing. Areas which contain cytoplasm from two incompatible Plasmodia become clearly delineated from healthy cytoplasm. Such areas, termed clear zones, have been isolated and found to recover. If clear zones are sectioned into several small pieces, not all pieces will recover, indicating that toxic cytoplasmic reactions have occurred. Plasmodial fusion studies and F1 studies of recovered clear zones indicate that the clear‐zone loci may also control nuclear survival in heterokaryons.
POSTPOLLINATION PHENOMENA IN ORCHID FLOWERS. V. PARTICIPATION BY THE ROSTELLUM AND GYNOSTEMIUM TIP
Authors: Arditti Joseph , Flick Brigitta H.
Published: January 2018

Removal of the rostellum following pollination does not prevent stigmatic closure in Cymbidium flowers and has a minimal effect on straightening of the gynostemium (column). However, this treatment does depress anthocyanin levels in both gynostemia and labella. Excision of the rostellum 30 or 60 min after pollination has a more pronounced effect than removal after 150 min. Stigmatic closure is not inhibited by removal of the gynostemium tip, but column swelling is reduced. These findings are discussed relative to rostellar functions and theories regarding their origin.
MOVEMENT AND DISTRIBUTION OF 14C WITHIN PETIOLES OF INTACT COLEUS BLUMEI (LABIATAE) AFTER APPLICATION OF INDOLE‐3‐(ACETIC ACID‐2‐14C) TO THE LEAF SURFACE
Authors: Kaldewey Harald , Jacobs William P.
Published: January 2018

Auxin transport and immobilization were followed in the petioles of intact plants of Coleus blumei Benth. after application of IAA‐2‐14C at a physiological concentration as droplets to the upper surface near the base of the blades of leaves #3 and #5. After 14 hr transportable and immobilized radiocarbon was found all along the petioles. Moreover, about half the total amount of 14C detected within the plant (= uptake) had moved beyond the petioles. This was true for leaves of both ages although the younger #3 petioles were only about half as long as the older #5 petioles. Because the uptake of radiocarbon by the #3 petioles was roughly half that of the #5 petioles, the absolute amounts immobilized per unit length of section were essentially uniform in the two petioles. On the contrary, the fractions remaining transportable within the #3 petiole sections averaged half those of the #5 petiole sections. The distribution of the transportable and the immobilized radioactive fractions along the petioles was characterized by high values near the apical application point, a decrease toward the middle of the petioles, and an increase to the level of the apical part toward the base of the petioles, which includes the abscission layer. The results have been discussed in connection with measurements of the cross sectional areas and the lengths of the epidermal and subepidermal cells along the petioles. An auxin transport and immobilization model, which assumes there are two different immobilization systems of different strength in the differently aged tissues, is outlined to explain the observations.
THE TRANSITION FROM FILAMENTOUS TO TWO‐DIMENSIONAL GROWTH IN FERN GAMETOPHYTES. IV. INITIAL EVENTS
Authors: Davis Bill D. , Chen James C. W. , Philpott Mary
Published: January 2018

Time‐lapse photomicrography and autoradiography were used to study the initial events leading to the first cell division following transfer from red to white light. The first responses to white light, an apical swelling and a reduced rate of elongation, were often observed within the first 1–2 hr after the transfer; these two changes were not always initiated at the same time. Only the dome region of the cell participated in the elongation in red, as demonstrated by the displacement of anion exchange resin markers. The dome region as well as the region proximal to the dome was associated with the apical swelling, including regions formed in red. The average duration of the G1, S, G2, and M phases was found to be approximately 4, 3, 3.5, and 1 hr, respectively.
FOUR NEW SPECIES OF THRAUSTOCHYTRIUM FROM ANTARCTIC REGIONS, WITH NOTES ON THE DISTRIBUTION OF ZOOSPORIC FUNGI IN THE ANTARCTIC MARINE ECOSYSTEMS
Authors: Bahnweg Günther , Sparrow Frederick K.
Published: January 2018

New species of the obligately marine Thraustochytriaceae Sparrow were discovered in subantarctic and antarctic waters of the southeastern Indian Ocean, the southwestern Pacific Ocean, and the antarctic Ross Sea during two cruises of the research vessel USNS ELTANIN. The life cycles of four species of Thraustochytrium in seawater‐pollen and/or seawater‐brine shrimp larvae cultures are described. Thraustochytrium antarcticum sp. nov. develops sporangia that may proliferate from a single basal rudiment. Flagellated zoospores are liberated from the sporangium upon complete disintegration of the sporangial wall at maturity. Thraustochytrium rossii sp. nov. and T. kerguelensis sp. nov. are both similar in that they develop sporangia that may proliferate from more than one basal rudiment. The latter species releases flagellated zoospores upon complete disintegration of the sporangial wall, but the former species liberates a mass of individually immobile zoospores from the sporangium. These remain quiescent for several hours before they swim away one after another. The protoplast of Thraustochytrium amoeboidum sp. nov. leaves the sporangium through a pore as an amoeboid body which then gives rise to nonflagellated amoebospores by successive bipartitioning. Laterally biflagellate thraustochytrioid zoospores were also observed, but the way in which they are formed remains to be determined. Zoosporic and aplanosporic phycomycetes were recovered from water samples collected in the Subtropical, Subantarctic, and Antarctic Zones of the Southern Ocean. Highest numbers of phycomycete propagules were found in antarctic waters near the Antarctic Convergence during ELTANIN's Cruise 51. In the Subtropical and Subantarctic (but not in the Antarctic) Zones fungal population densities increased with proximity to continents or islands. At each station where phycomycetes were recovered, highest numbers of propagules were generally found in the surface layers (25–250 m) of the ocean below the photic zone (lower limit 30–60 m). This peculiar distribution may indicate that phycomycetes are engaged in decomposing substances derived from the photic zone.
A CYTOCHEMICAL INVESTIGATION OF A CHLOROPLAST INCLUSION
Authors: Ames Ira H. , Pivorun Joan P.
Published: January 2018

The chemical composition of a membrane‐bound plastid inclusion observed in genetic tumor cells of the amphiploid Nicotiana suaveolens X N. langsdorffii was studied by means of electron microscope cytochemistry. Treatment with the following enzymes had no effect on the ultrastructure of the inclusion: α‐amylase, DNase, lipase, papain, pronase, protease, RNase, and trypsin. The only enzyme to alter the fine structure of the inclusion was pepsin, which decreased the electron density of the granular component of the structure. These results indicate that protein is the major chemical constituent of this membrane‐bound plastid inclusion. This finding is discussed in relation to the possible role of the inclusion in plastid ontogeny.
ABSCISSION AND THE AXILLARY FROND IN SPIRODELA OLIGORHIZA (LEMNACEAE)
Authors: Witztum Allan
Published: January 2018

Two abscission zones are present in fronds of Spirodela oligorhiza. In one zone the abscission layer separates the daughter frond and its connecting stalk from the mother frond. The second abscission layer separates the daughter frond from the connecting stalk. An axillary frond is asymmetrically positioned at the base of each daughter frond where it joins the mother frond. In right‐handed physiological clones the axillary frond is to the right of the connecting stalk and in left‐handed clones, to the left of the stalk. When a daughter frond abscises it leaves behind its axillary frond in the pocket of the mother frond. Histological features of abscission and treatments that induce abscission in Spirodela oligorhiza are described.
FORMATION OF CALLOSE AND LIGNIN DURING LEAF ABSCISSION
Authors: Poovaiah B. W.
Published: January 2018

Deblading of bean leaves promoted the formation of callose and lignin in the abscission zone. The abscission layer became evident three days after deblading. The greatest increase in callose occurred in about two layers of cells during the development of the abscission layer. Four days after deblading, only a few layers of cells on the distal side of the abscission layer showed an increase in lignin. Lignification continued to expand to 8–10 layers of cells at the time of separation. After separation, the lignified cells remained with the petiole. Sieve elements in the abscission zone were covered with callose plugs and the vessels were occluded with tyloses.
NITROGEN FIXATION IN THE BAYBERRY (MYRICA PENSYLVANICA) AND ITS ROLE IN COASTAL SUCCESSION
Authors: Morris M. , Eveleigh D. E. , Riggs S. C. , Tiffney W. N.
Published: January 2018

The nodules on roots of Myrica pensylvanica (bayberry) contain a bacterial endophyte. By using the acetylene reduction technique these plant endophyte associations were shown to be capable of fixing nitrogen. As nodulation was plentiful and fixation vigorous, it is proposed that the success of M. pensylvanica as an early successional plant of dunes and impoverished coastal soils is due in part to the nitrogen‐fixing capacity of its nodular association.
THE LOCOMOTOR BEHAVIOR OF LYGODIUM AND MARSILEA SPERM
Authors: Bilderback Diane E. , Bilderback D. E. , Jahn T. L. , Fonseca J. R.
Published: January 2018

Flagella of living sperm of the ferns, Lygodium japonicum (Thunb.) Sw. and Marsilea vestita Hook, and Grev., beat three dimensionally with a continuous traveling helical wave. The wave is propagated from base to tip of the flagellum. Flagella of Lygodium and Marsilea complete 65 and 30 beat cycles per sec, respectively. Each flagellum circumscribes an open conicoid oriented in a latero‐posterior direction. Only dead sperm have anteriorly directed flagella as illustrated in plant morphology textbooks.
EVOLUTION OF EXINE STRUCTURE IN THE POLLEN OF PRIMITIVE ANGIOSPERMS
Authors: Walker James W.
Published: January 2018

Diversity in the structure of the exine in 35 families of the ranalean complex is compared through a series of representative scanning electronmicrographs, and evolutionary trends in exine structure of primitive angiosperms are outlined, along with discussion of the significance of these data for understanding the evolution of exine structure in flowering plants as a whole. In order to reduce ambiguity in the palynological literature, it is suggested that persons undertaking light microscope studies of unstained, acetolyzed pollen grains adopt the morphological terms sexine‐nexine in describing pollen wall layers while restricting their use of the chemically defined terms ektexine‐endexine largely to pollen studies carried out with the transmission electron microscope. This study emphasizes that a clear understanding of the palynological concept of structure versus sculpturing is a necessary prerequisite for the taxonomic/ phylogenetic use of pollen wall morphology. Finally, data from investigation of a number of ranalean families of primitive angiosperms support the conclusion that the direction of a recurrent and major evolutionary trend in exine structure of flowering plants proceeds from pollen that is tectate‐imperforate to tectate‐perforate pollen to semitectate pollen, and more rarely, to pollen grains that are intectate.
MORPHOLOGY AND CYTOLOGY OF TILLETIA CARIES AND T. CONTROVERSA IN AXENIC CULTURE
Authors: Trione E. J.
Published: January 2018

On a wheat‐based medium, the pathogenic phase of the common and dwarf bunt fungi grew slowly at 15–18 C and continued to produce massive quantities of teliospores in all subcultures for over 2 years. At warmer temperatures or on a chemically defined medium, the teliosporogenic colonies reverted to haploid mononucleate colonies. The hyphae of the teliosporogenic colonies were stained with a modified Giemsa technique and found to be thick, contorted, highly branched and short celled with usually one or two nuclei per cell. In contrast, the haploid mononucleate hyphae were thinner, straighter, and longer and never contained more than one nucleus per cell. The vegetative hyphae of T. caries and T. controversa were indistinguishable. Teliospores, formed at the terminal end of binucleate hyphae, were initially binucleate but became mononucleate before the mature cell wall formed.
THE GROWTH PATTERN OF THE FLOWERING SHOOT OF URGINEA MARITIMA L. (LILIACEAE)
Authors: Mitrakos K. , Price L. , Tzanni H.
Published: January 2018

The flowering shoot of Urginea maritima constitutes an interesting one‐dimensional growth system. Stalk emergence from the bulb is completed in a few days and is followed by a characteristic very rapid pattern of subapical elongation, with stalk growth rates approaching 3 mm/hr. This elongation system, similar to root tips and other biological materials, has characteristics that may prove it to be a valuable tool for biological studies, as well as for investigating chemical aspects of biological elongation phenomena.
GROWTH INHIBITION IN GAMETOPHYTES AND OAT COLEOPTILES BY THELYPTERIN A AND B RELEASED FROM ROOTS OF THE FERN THELYPTERIS NORMALIS
Authors: Davidonis Gayle H. , Ruddat M.
Published: January 2018

Gametophytes, when grown in the immediate vicinity of a Thelypteris normalis sporophyte—in soil or in sterile culture on agar—showed a reduced number of cells and an altered gross morphology. This is attributed to the action of the thelypterins, which are inhibitors released from T. normalis sporophytes. Growth inhibition of the gametophytes was greatest when thelypterins were added during early stages of gametophyte development. Removal of thelypterin A permitted resumption of growth. Thelypterin A noncompetitively inhibited auxin‐enhanced elongation of A vena coleoptiles. The growth of T. normalis root segments was not affected by thelypterins. The growth of young sporophytes of T. normalis was inhibited by mature sporophytes.
MICROGAMETOPHYTE DEVELOPMENT IN THE PALEOZOIC SEED FERN FAMILY CALLISTOPHYTACEAE
Authors: Millay M. A. , Eggert D. A.
Published: January 2018

Well‐preserved stages of microgametophyte development are described from pollen produced by the Paleozoic seed fern family Callistophytaceae. Microgametophyte development in both the Middle Pennsylvanian pollen organ Idanothekion and Upper Pennsylvanian Callandrium involved the initial production of an axial row of at least three small prothallial cells proximally and a large embryonal cell distally. The arrangement and form of these cells is like that present in some extant genera of the Pinaceae. The prothallial cells were relatively large in comparison with extant gymnosperms, occupying the entire region of the cap‐pus, and were apparently all primary. Evidence is presented that in Callandrium further development involved an anticlinal division of the large distal cell (antheridial initial) into a small generative cell contained within a larger tube cell. Previously described microgametophytes of the late Paleozoic order Cordaitales are reinterpreted and are shown to consist of an embryonal cell and three to four discoidal prothallial cells in an axial row like that of the Callistophytaceae. Microgametophytes thus far described from the Paleozoic are remarkably modern in appearance and provide no evidence to support the generally held view that the seed plant microgametophyte is an extremely reduced sexual phase that has arisen through the loss of almost all of the vegetative cells and the sterile outer cells of the antheridium. Evidence to support or refute this view will depend upon the discovery of microgametophytes from older groups of seed plants than those for which they are now known.