bluuebunny/crossref_metadata_2025 huggingface dataset:
SYNTHETIC AGROPYRON‐ELYMUS HYBRIDS: II. ELYMUS CANADENSIS X AGROPYRON DASYSTACHYUM
Authors: Dewey Douglas R.
Published: January 2018

Pollination of 40 emasculated E. canadensis florets with A. dasystachyum pollen gave rise to 12 shriveled seeds, one of which was viable. The hybrid seedling developed into a vigorous plant whose vegetative and spike characteristics were for the most part intermediate between those of the parents. Both parents behaved cytologically as allotetraploids, 2n = 28, and formed 14 bivalents regularly at metaphase I. Chromosome associations in the hybrid, 2n = 28, averaged 0.42 I, 13.70 II, 0.02 III, and 0.03 IV in 142 metaphase‐I cells interpreted. The hybrid produced 165 seeds under open‐pollination during its second year in the field. E. canadensis and A. dasystachyum apparently contain closely homologous genomes whose major structural differences consist of several inverted segments and possibly a small reciprocal translocation. The close homology between the E. canadensis and A. dasystachyum genomes was unexpected in view of the wide morphological, ecological, and reproductive differences that separate the two species.
AUXIN‐CYTOKININ CONTROL OF SECONDARY VASCULAR TISSUE FORMATION IN ISOLATED ROOTS OF RAPHANUS
Authors: Torrey John G. , Loomis Robert S.
Published: January 2018

A comparative study was made of the effectiveness of various hormone and metabolite mixtures in inducing vascular cambium initiation and secondary vascular tissue formation in isolated first‐transfer roots of the radish, Raphanus sativus L. ‘White Icicle,‘ when provided to the cut basal end of the root grown in sterile culture. An auxin, such as indoleacetic acid (IAA) at 10–5 m, a cytokinin, such as 6‐benzylamino purine at 5 × 10–6 m, a cyclitol, such as myo‐inositol at 5 × 10–4 M and sucrose at 8% were all required for maximum response. Requirements for auxin and cytokinin were absolute; in their absence no cambium was formed. The addition of cyclitol, while not an absolute requirement for cambium initiation, increased the magnitude of the response markedly. Alternative auxins such as α‐naphthaleneaeetic acid and 2,4‐dichlorophenoxyacetic acid were equally as effective as IAA. Alternative effective cytokinins included 6‐furfurylaminopurine, 6‐phenylaminopurine and 6‐(γ,γ‐dimethylallylamino)purine. Alternative cyclitols equivalent to myo‐inositol were seyllitol and pinitol. Other related cyclitols tested were much less effective or totally inactive.
ANATOMY OF BORON‐DEFICIENT THUJA PLICATA
Authors: Blaser H. Weston , Marr Currie , Takahashi David
Published: January 2018

Seedling trees were grown in complete nutrient solution and in one without added boron for a period of 5 years. Roots and shoots of boron‐deficient plants showed a variety of symptoms which were involved in the disruption of normal cellular differentiation. Abnormalities in structure, cell shape, wall conformation and rigidity are described for both primary and secondary tissues. The persistence of the trees in spite of the death of apical meristems and local or seasonal variations are discussed.
RECOVERY FROM CURLY‐TOP DISEASE IN TOMATO SEEDLINGS
Authors: Benda G. T. A. , Bennett C. W.
Published: January 2018

Plants of commercial varieties of tomato cease to grow normally and usually die, when infected by curly‐top virus by means of the beet leafhopper. Only rarely does an infected plant resume and maintain growth, i.e., recover. However, when tomato seedlings were infected with curly‐top virus by means of the beet leafhopper, some plants of six of seven commercial varieties recovered. The best recovery of plants in a single trial was 20% in ‘Penn Orange’ infected with the Paso Robles strain of virus. The per cent and degree of recovery of infected seedlings were influenced by the variety of tomato, severity of the virus strain on the seedlings, and probably by factors affecting rate of development of both plant and virus.
ANATOMICAL FEATURES OF METAPHLOEM IN STEMS OF SABAL, COCOS AND TWO OTHER PALMS
Authors: Parthasarathy M. V. , Tomlinson P. B.
Published: January 2018

Sieve tubes in metaphloem of palm stems function throughout the life of the plant and merit close investigation. A stem of Sabal palmetto estimated to be 50 years old was sampled extensively. Variation in length of sieve‐tube elements throughout this stem was measured and is discussed. In the metaphloem of individual vascular bundles companion cells are not sharply differentiated from other phloem parenchyma cells. Definitive callose deposits and slime are normally absent from mature sieve tubes, even in fixed material. Otherwise no conspicuous structural features which might account for the longevity of sieve tubes can be discerned. Occlusion of phloem strands after leaf fall is initially by callose deposition on sieve plates followed immediately by tylosoid formation. Similar sampling of Cocos nucifera, Washingtonia robusta and to a lesser extent Archontophoenix alexandrae confirmed these results except for quantitative differences.
ANTHOCYANIN SYNTHESIS IN SALPIGLOSSIS SINUATA
Authors: Miller John H. , Miller Pauline M. , Deal Robert H.
Published: January 2018

Measurements were made of the growth and pigment content of developing flower buds of Salpiglossis sinuata. From the time the buds were approximately 10 mm long they grew in length exponentially until they reached their final length. The logarithm of bud length increased linearly with time and served as a convenient morphological index on which to relate the progress of anthocyanin synthesis. Buds shorter than about 42 mm had no anthocyanin, but when buds reached this length, anthocyanin production was initiated and proceeded rapidly. The maximum relative pigment concentration (pigment/mg fresh weight) was attained by the buds about 17 hr after the initiation of pigment synthesis. In the mahogany‐colored variety used in these studies, two anthocyanidins were found and identified as cyanidin and delphinidin. Buds excised from the plants could be cultured in vitro. Buds started in culture at a length of 30–35 mm when they contained no anthocyanins developed pigment during their growth. The amount of pigment formed increased with increasing light intensity, while only small amounts of pigment could be formed in buds cultured in darkness. The anthocyanidins of these cultured buds were the same as those of the intact flowers, but the ratio of delphinidin to cyanidin decreased with decreasing light intensity. Brief daily irradiation of dark‐grown buds with red, far‐red or blue light did not increase pigment synthesis nor change the anthocyanidin ratio. If buds were placed in culture at 20–25 mm and grown in darkness, they developed a third anthocyanidin, identified as malvidin, which was not present in intact flowers, light‐grown buds or 30–35‐mm buds cultured in darkness.
NEW MARINE ALGAE FROM THE CENTRAL TROPICAL PACIFIC OCEAN
Authors: Hollenberg George J.
Published: January 2018

Three new taxa are described: Dolyella hawaiiensis var. clavata var. nov., Cottoniella triseriata sp. nov., and Taenioma dotyi sp. nov. A modified characterization of the genus Cottoniella is given, and certain critical distinctions between the species are presented. Taenioma dotyi is distinctive in the increased width of the determinate branches resulting from division of the flanking cells.
EFFECTS OF BALSAM WOOLLY APHID (ADELGES PICEAE) INFESTATION ON CAMBIAL ACTIVITY IN ABIES GRANDIS
Authors: Smith Frank H.
Published: January 2018

Salivary secretions injected into the cortex or outer phloem by Adelges piceae (balsam woolly aphid) feeding on Abies grandis induce the production of wood that is in some respects similar to compression wood. Cambial activity was analyzed by examination of serial tangential sections through an annual ring in the xylem produced before infestation occurred and compared with similar sections from a ring produced after infestation. Growth after infestation was characterized by increased periclinal and anticlinal divisions of fusiform initials, increased production of new ray initials from fusiform initials and from anticlinal divisions of existing ray initials, and decline of numerous fusiform initials and termination of many tiers by maturation. This results in increased frequency of ray fusion and separation by decline or intrusion of adjacent fusiform initials. There was a marked increase in size and number of rays and number of parenchyma strands both of which also distinguish aphid‐affected wood from compression wood with which it frequently has been compared.
ONTOGENY AND ANATOMY OF THE FLOWER OF LIMNOCHARIS FLAVA (BUTOMACEAE)
Authors: Kaul Robert B.
Published: January 2018

The flowers of Limnocharis flava (L.) Buch. are borne in an indeterminate umbel and each consists of three sepals, three yellow petals, and about 18 carpels surrounded by numerous stamens and staminodia. The androecium is centrifugally developed, and the last‐formed members are staminodial; it is supplied by branching vascular systems. Carpels arise almost simultaneously, and a prominent residual floral apex remains. The carpels are partially conduplicately closed and are also primitive in possessing laminar placentation and in lacking differentiation of a style. The gynoecium is essentially apocarpous, but there are slight fusions of adjacent carpels near their ventral margins where they are attached to the receptacle. It is suggested that the Limnocharis flower is the most primitive in the family.
INITIATION AND ONTOGENY OF THE MICROSPORANGIATE CONE IN CUPRESSUS ARIZONICA IN RESPONSE TO GIBBERELLIN
Authors: Owens John N. , Pharis Richard P.
Published: January 2018

Cupressus arizonica, a member of the Cupressaceae, was induced to produce pollen cones in response to gibberellin treatment. All apices remained vegetative during the first 17 days of treatment. At this time many lateral vegetative apices began to undergo a transition to the reproductive state. The transition was marked by changes in apical zonation characterized by increased mitotic activity primarily in the subapical mother‐cell and peripheral zones. Also, precocious initiation of branch meristems occurred much higher on the shoot apex than before the transition period. About 22 days after the initial treatment, most apices became distinctly reproductive. The reproductive apex has a zonation pattern similar to the branching apex but is shorter and wider and quite distinct from the vegetative apex. The small subapical mother cells and cells of the peripheral zone form a continuous mantle of mitotically active cells with prominent nucleoli. This mantle encloses a very broad pith region which differentiates nearly to the summit of the apex. Microsporophyll and leaf initiation are similar and the protoderm of the apex remains discrete and does not contribute to deeper tissues. Sporangia do not originate from superficial cells of the microsporophyll. After all microsporophylls are initiated the reproductive apex becomes inactive. A discussion concerns the morphological implication in the origin of the foliar structures and of the similarity of C. arizonica to many angiosperms in the transition of the apex from vegetative to reproductive.
MITOSIS AND ANEUPLOIDY IN THE VEGETATIVE HYPHAE OF MACROPHOMINA PHASEOLI
Authors: Knox‐Davies P. S.
Published: January 2018

Giemsa and aceto‐orcein staining and an improved squash technique were used to study nuclear behavior in the vegetative hyphae of Macrophomina phaseoli. Stages in nuclear division were similar to those previously recorded in the developing pyenospores except that no spindle was revealed. Mitotic irregularities were common. The commonest chromosome number was six, but higher counts suggested a continual reassortment of chromosomes, with haploid, diploid, aneuploid and possibly polyploid nuclei occurring in the same mycelium. The nature of the division and the occurrence and possible role of aneuploidy in both saprophytic and plant pathogenic fungi are discussed.
VARIATION IN APPLE CYTOCHIMERAS
Authors: Pratt Charlotte , Ourecky D. K. , Einset J.
Published: January 2018

Diploid‐tetraploid cytochimeras of apple were investigated by cytological examination of buds from branches selected by the characteristics of the fruits, flowers or pollen. Eight types of cytochimeras were identified on the basis of relative size of cells, nuclei and metaphase mitoses in the apical meristem (protomeristem) and mitoses in meristematic primary tissues. There appeared to be five apical layers which contributed to the stem and four which contributed to the leaves and flower parts. Buds of various cytochimeral patterns (designated by a formula giving the ploidy of the apical layers) were found on some bearing trees propagated from known cytochimeral sources. The most frequently associated types were (a) 2–4–2–2–2 and 2–4–4–4–4 (and 2–4–2–4–4 in one cultivar), or (b) 2–2–2–4–4 and 2x. Some sports were uniformly 2–4–4–4–4. The stability of apple cytochimeras under normal conditions appeared greater in some eultivars than in others. Sprouts from severely pruned 2–2–4–4–4 trees were more variable than unpruned branches. Buds of shoots which grew from radiation‐damaged buds were more variable than those from non‐irradiated buds and included types not yet found by branch selection. Cytochimeral variation was interpreted to be due to layer replacement resulting from infrequent periclinal divisions in apical or axillary meristems, or from wounding of meristems by ionizing radiation.
CULTURE STUDIES ON THE MARINE GREEN ALGA HALICYSTIS PARVULA—DERBESIA TENUISSIMA. II. SYNCHRONY AND PERIODICITY IN GAMETE FORMATION AND RELEASE
Authors: Page Joanna Ziegler , Kingsbury John M.
Published: January 2018

Unialgal cultures of the macroscopic, vesicular, coenocytic gametophyte (Halicystis parvula Schmitz) of Derbesia tenuissima (DeNotaris) Crouan fr. were grown under various environmental regimes to elucidate the cytology of gamete formation and the factors controlling synchronous gamete formation and release. No synchrony of nuclear division was observed in vegetative plants or during the early stages of gamete formation. In the later stages of gamete formation in plants in a light‐dark cycle, nuclear divisions within any gametangium were synchronous, and the stages of gamete formation were synchronous for the population. This synchrony was not as great for plants in continuous light. Gametes of plants in a light‐dark cycle were released explosively immediately following the dark‐to‐light transition. Release was random and much less forceful for plants in continuous light. After a certain stage of gamete formation, gamete release was timed to occur after a particular interval of darkness, but release could be triggered by light during the last portion of this interval. The length of the dark interval was shorter for male plants than for females, but the period of light sensitivity was longer for females. Formation of gametangia by series of isolated plants was also synchronous and sometimes periodic under certain conditions. Intervals between gametangia on the same plant varied from 2 to 14 days but were usually 4 or 5 days (unlike plants in nature, which show a bi‐ or tri‐weekly periodicity). Male and female plants did not differ in synchrony or periodicity. Different media affected the number of gametangia formed over a period of time but not the synchrony of formation. Under some conditions changing the medium had a stimulating or synchronizing effect. Non‐repeated temperature changes also synchronized gamete formation. Optimum temperature for continued gamete formation was about 21 C. Regular daily light and temperature variation together maintained synchronous and periodic gamete formation in populations of isolated plants. Reproduction diminished and became less synchronous at constant temperature either in continuous light or under a light‐dark schedule, although in the light‐dark regime steps in the formation of any given gametangium remained synchronous with the light‐dark cycle. Length of times between gametangial formation on individual plants showed a tendency to occur in multiples of the usual period lengths; e.g., plants sometimes tend to “skip” intervals, thus maintaining the synchrony of the population. These results suggest that interaction between daily environmental cycles and an endogenous physiological cycle may maintain periodic reproduction.
SEED DORMANCY AND GERMINATION IN MELAMPYRUM LINEARE
Authors: Curtis E. J. C. , Cantlon J. E.
Published: January 2018

Immature seeds of Melampyrum lineare Desr. have very high germination percentages and dormancy is induced in a variable fraction of the seed crop during ripening. Correlated with this is the endogenous gibberellin‐like activity which is found in considerable amounts in immature seeds, less in batches of ripe seeds, and is not detectable in batches containing only dormant seeds. For germination dormant seeds require activation followed by cold storage. In the laboratory activation is produced by allowing moist, dormant seeds to respire freely for several weeks at 20 C, or by treatment with exogenous GA3. Dormancy appears to be most directly related to inability of the embryo to hydrolyze the thickened, mannan‐containing endosperm cell walls. Embryos excised from dormant seed can be grown on agar enriched with whole macerated dormant seeds or with the ethanol‐extractable materials from these (mostly sucrose and a glycoside). However, dormant seed material does not support growth when extracted to remove benzene‐ and ethanol‐soluble materials.
THE LEPIDOPHYTIC AFFINITIES OF THE GENUS CHINLEA AND OSMUNDITES WALKERI
Authors: Miller Charles N.
Published: January 2018

Chinlea campii Daugherty and Osmundites walkeri Daugherty are species of petrified stems from the Upper Triassic Chinle Formation of Arizona that were described as members of the fern family Osmundaceae. Investigation of additional material indicates that the two species are conspecific and belong to the Lepidophyta. The stems are radially symmetric and have an ectophloic siphonostele in which the xylem cylinder is thick and deeply furrowed. Internal pressure against the xylem cylinder caused by the lateral expansion of the pith in some stems produces what appears in transverse section to be a ring of up to 60 separate xylem strands. Leaf traces are small, terete, collateral and have exarch xylem. They are arranged in a tight spiral. Adventitious roots, secondary xylem, and secondary cortex are lacking. The stems are classified under the binomial Chinlea campii, and other axes that have similar cortical anatomy but in which all vascular tissues have decayed are treated as Chinlea sp. Both types of stems are interpreted as ephemeral aerial shoots of an herbaceous plant. Of the known fossil Lepidophyta, Chinlea is most similar to Pleuromeia and Nathorstiana, but it differs from each of these genera in a number of respects and is therefore included in Lepidophyta incertae sedis.
INTRAPLANT MORPHOLOGICAL VARIATIONS IN GRASSES
Authors: Nielsen Etlar L.
Published: January 2018

Clonal progenies were developed from individual nodal segments of bromegrass, cormlets of timothy, and secondary basal buds of sorghum. The parent plants were morphologically unstable or chimeral and occurred in either hybrid or inbred populations. Intraplant clonal progenies usually continued to be unstable through the second clonal generation. Marked deviating types occurred within clonal rows. Intraplant comparisons were made of inflorescence characters and seed‐set following open‐pollination of unstable plants from inbred lines of smooth bromegrass. Significant differences occurred between characters in panicles from different parts of the same plant.
THE PHOTOPERIODIC RESPONSE OF AMERICAN PROSOPIS AND ACACIA FROM A BROAD LATITUDINAL DISTRIBUTION
Authors: Peacock J. Talmer , McMillan Calvin
Published: January 2018

Prosopis and Acacia from North and South America were studied in the laboratory under constant and increasing night length under two temperature regimes. The Prosopis juliflora (Sw.) DC. complex showed strong populational differentiation; Acacia farnesiana (L.) Willd. showed minimal populational differentiation. In Prosopis a population from Oklahoma (36° N) showed the greatest inhibition of stem height under increasing night length. A population from Peru (6° S) showed least control of stem height by night length. In Acacia the response of the latitudinal series was relatively uniform within each of the 6 sets of light period‐temperature conditions. In general the height increase for Acacia was two to three times greater under the warmer regime than under the cooler regime at a given night length. Since Acacia farnesiana occurs sympatrically with the Prosopis juliflora complex over a broad range of latitudes, it is of interest to find that the distributional mechanisms of these two leguminous trees are basically different.
FLORAL DEVELOPMENT AND VASCULATURE IN HYDROCLEIS NYMPHOIDES (BUTOMACEAE)
Authors: Kaul Robert B.
Published: January 2018

The flower of Hydrocleis nymphoides consists of three sepals which arise in spiral succession, three simultaneously arising petals, numerous stamens and staminodia which arise in centrifugal order, and six carpels. A residual apex remains at maturity. The first‐formed members of the androecium are stamens and the later‐formed members are staminodia which develop below the stamens and which become outwardly displaced during expansion of the receptacle. The androecium is supplied by branching vascular trunk bundles. The carpels are completely open but the ventral margins are slightly conduplicately appressed basally. A single dorsal bundle provides the stigmatic area with vascular tissue, and a network of small placental bundles supplies the numerous laminar ovules. There are no clearly defined ventral bundles. It is suggested that Hydrocleis nymphoides is neither the most primitive nor the most advanced member of the family. A pattern of phylogenetic reduction in the androecium and receptacle is suggested for the entire family.
MORPHOLOGICAL STUDIES OF THE ROOT OF RED PINE, PINUS RESINOSA I. GROWTH CHARACTERISTICS AND PATTERNS OF BRANCHING
Authors: Wilcox Hugh E.
Published: January 2018

Observations were made of the seasonal root growth behavior under natural conditions and under controlled conditions in plant observation boxes. Under natural conditions root growth conformed to the commonly reported pattern of a surge of growth in the spring, a mid‐summer low, and a renewed burst in the fall. Growth of individual roots was cyclic. Growth patterns ordinarily varied according to root diameter and branching and in the plantations were modified by soil moisture conditions. Observations of roots during periods of constant elongation showed that the distance from the root apex to the first lateral root primordium varied directly with growth rate. Laterals did not arise in strict acropetal succession, and lateral root abortion was common, particularly in large‐diameter, fast‐growing roots. Observations of root initiation in relation to seasonal growth increments and to dormancy structures showed an increase in numbers of laterals on both the proximal and distal portions of a seasonal increment.
INDUCTION OF XYLEM ELEMENTS IN ISOLATED COLEUS PITH
Authors: Earle Elizabeth D.
Published: January 2018

Small pith explants from the fifth internode of Coleus blumei were placed on a defined medium supplemented with different concentrations of indoleacetic acid (IAA). With all levels of IAA tissue growth was slight; however, when the medium contained more than 10‐7 m IAA, xylem elements developed after 11‐14 days. Omission of sucrose from the medium prevented this differentiation of xylem elements. Isolated xylem cells or small nodules were most common, but long strands were also seen. The merits of the Coleus system for study of plant‐cell differentiation are discussed.
SYSTEMATIC STUDIES IN THE COREOPSIDINAE: CYTOTAXONOMY OF MEXICAN AND GUATEMALAN COSMOS
Authors: Melchert Thomas E.
Published: January 2018

Correlated chromosomal and morphological data are presented for 25 Mexic n and Guatemalan species of Cosmos. A major evolutionary dichotomy is demonstrated among the perennial species. The rhizome‐producing species become suffrutescent and have a base chromosome number of n = 11, while the species with fascicled, tuberous roots and strictly herbaceous habit all have a base number of n = 12. Several independently derived polyploid complexes are demonstrated within each of these series, and their taxonomic implications are discussed. Hybridization between C. carvifolius and C. linearifolius var. magnifolius is documented, and the taxonomic problems resulting from interspecific hybridization at both the diploid and tetraploid levels are pointed out.
ORIGIN AND EARLY DEVELOPMENT OF NONARTICULATED LATICIFERS IN EMBRYOS OF EUPHORBIA MARGINATA
Authors: Mahlberg Paul G. , Sabharwal Pritam S.
Published: January 2018

In E. marginata 12 nonarticulated laticifer initials arise in the cotyledonary node of the young embryo during the early heart stage. The initials arise progressively in the developing embryo, the first laticifers differentiating simultaneously with or shortly before the elements of the pro‐cambium. The laticifers occupy a position lateral to the six procambial strands which are formed in the embryo. Upon subsequent growth each laticifer becomes vacuolated and nuclear division unaccompanied by cytokinesis results in the formation of a coenocytic protoplast. The enlarging laticifer produces several branches, one growing into the cotyledon, another growing down along the hypocotyl penetrating toward the root meristem, and one or several growing along intercellular spaces of adjacent cells. No fusion of these branches with one another or adjoining parenchyma cells was observed.
ENDOGENOUS BETA IRRADIATION AND TUMOR PRODUCTION IN AN AMPHIPLOID NICOTIAN A HYBRID
Authors: Conklin Marie E. , Smith Harold H.
Published: January 2018

The amphiploid Nicotiana suaveolens × N. langsdorffii, which is genetically constituted to produce tumors spontaneously late in development, can be induced to form them in the early seedling stage by treatment of the apical meristem with kinetin and indoleacetic acid. Application of H3‐or C14‐labeled plant‐growth regulators resulted in most plants and notably with C14‐labeled indoleacetic acid in a significant increase in the rate of tumor production over growth‐regulator treatment alone. Endogenous radiation alone was shown to be tumefacient since radioactive nucleosides, tritiated water, and C14‐sodium carbonate also enhance tumorization.
QUANTITATIVE CHANGES IN GIBBERELLIN AND RNA CORRELATED WITH SENESCENCE OF THE SHOOT APEX IN THE ‘ALASKA’ PEA
Authors: Ecklund Paul R. , Moore Thomas C.
Published: January 2018

Senescence of shoot apices of Pisum sativum L. ‘Alaska’ as measured by cessation of stem elongation was delayed by removal of flowers and by treatment with gibberellin A3 and was hastened by treatment with AMO‐1618 (2 isopropyl‐4‐dimethylamino‐5‐methylphenyl‐1‐piperi‐dinecarboxylate methyl chloride). Ontogenetic changes in relative endogenous gibberellin levels and in capability of gibberellin biosynthesis in deflowered and control plants were determined indirectly by studying time‐course changes in the sensitivity, as indicated by the growth response, of these plants to applied gibberellin and AMO‐1618. The results of these experiments suggest that the endogenous gibberellin level varies directly with the growth rate. Analyses of total RNA and protein in shoot tips of deflowered and control plants revealed that the levels of these substances also vary directly with growth rate throughout ontogeny. It is concluded that decreases in endogenous gibberellin, RNA and protein are factors correlated with senescence of the shoot apex.
THE OCCURRENCE AND DISTRIBUTION OF ACRASIEAE IN FORESTS OF SUBTROPICAL AND TROPICAL AMERICA
Authors: Cavender James C. , Raper Kenneth B.
Published: January 2018

Forests of the subtropical and tropical regions of North America harbor cellular slime molds not found in the soils of temperate deciduous forests investigated previously. However, most species found in the temperate forest are common in the tropics. Although the diversity of forms is greater in the soils of tropical forests the numbers of Acrasieae per unit of soil are comparable. Characteristic of tropical and subtropical forest soils are Acrasieae bearing crampon bases, of which four new species of Dictyostelium are presently known. Also present, but less frequently isolated, are two other new species of the genus Dictyostelium and two still undescribed species of the Guttulinaceae. Occasional isolates of D. purpureum and D. discoideum were found that produce macrocysts, which seem, also, to be confined to tropical and subtropical areas. Macro‐cysts were previously known only in D. mucoroides and D. minutum isolated from temperate forest soils. The occurrence and distribution of Acrasieae in warm temperate desert and mesquite‐scrub, in subtropical hammock, and in tropical thorn, deciduous, seasonal evergreen, rain, and cloud forests were investigated. Acrasieae were well represented in all of these forests except desert. The number of species and the total populations were largest in seasonal evergreen forests. The composition of the cellular slime mold populations and the dominant species within these populations could be related to the soil environment as expressed by the dominant vegetation.
PRIMARY STEM VASCULAR PATTERNS IN THREE SUBFAMILIES OF THE CRASSULACEAE
Authors: Jensen Lawrence C. W.
Published: January 2018

Primary stem vasculature was investigated in seven genera and 69 species of the Cotyledonoideae, Kalanchoideae and Sedoideae. Vascular patterns in whole cleared stems were determined by number of leaf traces per leaf, number of leaf‐trace sympodia per stem, and connections between traces and sympodia. Four patterns were found in the Cotyledonoideae, eight in the Kalanchoideae and four in the Sedoideae. Similarities and differences among the patterns are discussed and possible phylogenetic trends are suggested. Changes in vasculature during ontogeny were observed in the Kalanchoideae and related to patterns found in mature stems. Many species in all three subfamilies reveal a relationship between phyllotaxy, number of sympodia per stem, and the intervals at which leaf traces are connected to each sympodium. Patterns of vasculature were found to support many of the intergeneric relationships suggested by other studies of this family.
NUTRITION OF THE GREEN ALGA GOLENKINIA
Authors: Ellis Richard J. , Machlis Leonard
Published: January 2018

Defined media were established for four strains of Golenkinia. Strains 929 and 930 require thiamine and vitamin B12, strain 931 requires the latter and is stimulated by thiamine; only strain 320 and a mutant of strain 931 are capable of completely autotrophic growth. The optimal nitrogen concentration is 0.025 m except for strain 931 where it is 0.015 m and the requirement may be met by nitrate, ammonium, or urea. Optimal levels of the other components are: 0.0025 m KH2PO4, 0.0005 to 0.001 m MgSO4, and 50 ml of a stock trace‐element solution per liter. Only strain 931 required calcium; however, its addition stimulates the growth of strains 929 and 930. The optimal pH before autoclaving is 6.8. Maximal growth rates of two to three cell doublings per day and yields of 26 to 30 (log2) cells per ml were obtained. These growth data compare favorably with those for other unicellular green algae.
A REVISION OF THE GENUS GYMNODERMA
Authors: Yoshimura Isao , Sharp Aaron J.
Published: January 2018

Gymnoderma, which has been considered a monotypic genus, is composed of three species. G. insulare is described from Japan and differs from G. coccocarpum of southeastern Asia in being smaller and having a thicker cortex with didymic acid present. G. lineare from the Southern Appalachians is transferred from Cladonia because the podetia lack symbiotic algae, are solid, and are located on the marginal lower side of the thallus. Gymnoderma, including three species and possibly representing an ancestral form of Cladonia, is disjunctively distributed in eastern Asia and the Southern Appalachians. G. coccocarpum is reported from Thailand and Borneo for the first time.
FLOWERING OF DICHONDRA IN RESPONSE TO TEMPERATURE AND DAYLENGTH
Authors: Youngner V. B. , Nudge F. J. , Spaulding S.
Published: January 2018

Experiments using controlled environment facilities showed that flowering of Dichondra repens was promoted by chilling plants at 10 C or below. Optimum length of the chilling period was 5–6 weeks. Unchilled plants did not flower. The flowering stimulus resulting from chilling was destroyed by temperatures above 21 C. Rate of flowering was increased by short days during chilling, but short days could not substitute for the chilling requirement. Optimum daylength for flower initiation following chilling was approximately 14 hr and the optimum temperature was approximately 15 C. Flower buds developed in leaf axils of primary stems and laterals, but stem apices remained vegetative. When the chilling requirement was met flowering continued indefinitely as the plants grew.
ACTINOXYLON BANKSII GEN. ET SP. NOV.: A PROGYMNOSPERM FROM THE MIDDLE DEVONIAN OF NEW YORK
Authors: Matten Lawrence C.
Published: January 2018

A new genus from a Middle Devonian locality near Cairo, N. Y., is described. Actinoxylon gen. nov. is based upon pyritic petrifactions. Three orders of branching are present: penultimate branch, ultimate branch, and leaf. The penultimate branch bears spirally arranged ultimate branches and leaves, the leaves apparently replacing the branches in the spiral. The ultimate branches bear opposite to subopposite and decussate leaves. The leaves are non‐planated, unwebbed structures which show at least three dichotomies. Each segment of the leaf is terete as are all other axes. Internally the penultimate branch has a six‐lobed actinostele with mesarch protoxylem areas, one or two per lobe. Secondary xylem is visible in the oldest parts of several specimens. The xylem has helical‐reticulate, reticulate, scalariform and circular‐pitted elements. The presumptive areas of phloem are occupied by cells with dark contents. The cortex is composed of a parenchymatous inner region and a sclerenchymatous outer region. The ultimate branch traces are at first three‐lobed protosteles, later becoming four‐lobed. Several ultimate branch traces also possess secondary xylem while within the cortex of the penultimate branch. The leaf traces are terete strands. Below each forking of a leaf segment there is a corresponding forking of the vascular strand. Actinoxylon is compared with the progymnosperms Actinopodium, Svalbardia, Archaeopteris, Siderella, and Tetraxylopteris. The anatomy of the penultimate branch of Actinoxylon is similar to that of Actinopodium, Archaeopteris macilenta, and Siderella. The ultimate branch traces of Archaeopteris and Actinoxylon are similar. The ultimate branch stele and pattern of trace formation in Actinoxylon is similar to the stelar configuration and trace formation in the r + 2 axes of Tetraxylopteris schmidtii. The unwebbed leaves are similar to those of Archaeopteris fissilis, Svalbardia, and the terminal units of the Aneurophytales.
FINE STRUCTURAL DEVELOPMENT OF THE MEGAGAMETOPHYTE OF ZEA MAYS FOLLOWING FERTILIZATION
Authors: Diboll Alfred G.
Published: January 2018

The changes in cytoplasmic fine structure during the interval between pollination and zygotic division in the megagametophyte of Zea mays are reported. The rate of membrane synthesis appears to be low in the mature unfertilized megagametophyte. This megagametophyte is suggested to be in a state of relative metabolic inhibition. The rate of membrane synthesis is high in the zygote and free nuclear endosperm. After fertilization the swelling of the mitochondria in all cytoplasms is interpreted to reflect a presumed increase in metabolic rate relative to growth. In the zygote and endosperm, endoplasmic reticulum (ER) production is associated with the nuclear envelope. In all of the material the ribosomes not associated with the ER are helical polysomes which increase in length after fertilization. On the basis of permanganate staining, the ribonucleoprotein of the endosperm is suggested to be different from that of the other cytoplasms. The specific plastid form of each cell type does not change during the first few hours after fertilization. Dictyosomes are most numerous and active in the antipodals. They are least numerous in the egg and zygote. The smallest dictyosome vesicles are in the synergids. Dictyosome number and vesicle size increase in the egg and central cell after fertilization. Similarities among the megagametophytes of several angiosperms are enumerated.
CAPSELLA EMBRYOGENESIS: THE EGG, ZYGOTE, AND YOUNG EMBRYO
Authors: Schulz Richardis , Jensen William A.
Published: January 2018

The ultrastructure and composition of the egg, zygote, and young embryo of Capsella bursa‐pastoris were examined. The egg is a highly polarized cell; one‐half to one‐third of the micropylar end is filled with a large vacuole while the chalazal end contains the nucleus and much of the cytoplasm of the cell. The wall which surrounds the cell is incomplete at the chalazal end. Ribosomes fill the cytoplasm and show little or no aggregation into polysomes. The structure of the nucleolus suggests that ribosomes are not being produced. Following fertilization and the formation of the zygote, the cell decreases slightly in volume as the large central vacuole becomes smaller. The zygote soon increases in size as the small chalazal vacuoles present before fertilization begin to enlarge. The dictyosomes become active and a continuous wall forms around the zygote. Aggregation of the ribosomes begins and numerous polysomes are formed. Before division of the zygote all plasmodesmata between the zygote and the surrounding cells are lost. The first division of the zygote is unequal as a result of its marked polarity. A large basal cell and a small terminal cell are produced. The basal cell appears to contain more protein, RNA, carbohydrate, and cell organelles than the terminal cell. Ribosomal aggregation is even more pronounced at this stage. Starch accumulates in the plastids. Numerous plasmodesmata are present between the terminal and basal cells but there are no connections between the endosperm or other cells. The basal cell divides next to give rise to a three‐celled linear embryo consisting of the basal cell, the suspensor cell, and the terminal cell. The terminal cell stains more intensely for protein and RNA as a result of increased numbers of ribosomes. Starch in all the cells is about equal and reaches a maximum in the embryo at this stage.
STUDIES OF THE MOTILE CELLS OF CHYTRIDS. V. FLAGELLAR RETRACTION IN POSTERIORLY UNIFLAGELLATE FUNGI
Authors: Koch William J.
Published: January 2018

Presented are observations of 17 species in the following 14 genera. Blastocladiales: Allomyces and Blastocladiella. Chytridiales: Asterophlyctis, Catenochytridium, Chytridium, Chytriomyces, Cladochytrium, Entophlyctis, Phlyctochytrium, Rhizophlyctis, Rozella, Septochytrium, and two undescribed cladochytriaceous genera. Encystment without flagellar retraction is briefly considered. Recognized and described are four basic developmental patterns or methods of flagellar retraction: lash‐around, body‐twist, straight‐in, and vesicular. Variations in and combinations of the four basic methods are described. Observations, most of which are illustrated with brightfield, darkfield, phase‐contrast, and electron microscopy, along with what is known from the literature, are discussed and serve as the basis for generalized, summary diagrams or two‐dimensional models of patterns of flagellar retraction in posteriorly uniflagellate fungi. An endeavor is made to put the findings reported on in this paper in historical, morphogenetic, and phylogenetic perspective.
RHABDOXYLON AMERICANUM SP. N., A STRUCTURALLY SIMPLE FERN‐LIKE PLANT FROM THE UPPER PENNSYLVANIAN OF ILLINOIS
Authors: Dennis Robert L.
Published: January 2018

A new species of the genus Rhabdoxylon Holden (1960), an anatomically simple plant of presumed fern or fern‐like affinities, is described from a coal ball petrifaction found in the Upper Pennsylvanian of southern Illinois. The new species, R. americanum, is based upon five specimens consisting of stems bearing spirally arranged leaves and numerous randomly distributed adventitious roots. The haplostelic stems branch by equal dichotomies and bear foliar traces which arise as unequal dichotomies of the stele. Leaf traces possess a circular outline in cross section and one adaxial protoxylem strand. The characteristics of exclusively primary tissues, diarch adventitious roots, centrarch haplosteles with simple scalariform pitting, and the nature and arrangement of the leaf traces, suggest that Rhabdoxylon represents a fern or fern‐like plant rather than a representative of the Rhyniophytina or Trimerophytina. At present it is not possible to determine whether the simple structure of Rhabdoxylon has come about through phyletic reduction or represents a primitively simple condition.
STUDIES IN THE VISCACEAE. II. A REINVESTIGATION OF THE FEMALE GAMETOPHYTE OF ARCEUTHOBIUM DOUGLASII
Authors: Bhandari N. N. , Nanda Kanan
Published: January 2018

A reinvestigation of the female gametophyte of Arceuthobium douglasii showed that the development conforms to the Allium type (bisporic), and the report of tetrasporic development is erroneous.
DEVELOPMENT OF EXCISED FLORAL BUDS OF AQUILEGIA: THE COCONUT‐MILK PROBLEM
Authors: Bilderback David E. , Karpoff Arnold J. , Tepfer Sanford S.
Published: January 2018

In an attempt to define a medium and to investigate the effects of glycine, floral buds of Aquilegia were grown in culture on coconut milk and defined media containing either White's minerals or a new mineral formula, with and without glycine. Development obtained on the best defined medium was 66 to 76% of that achieved on the equivalent coconut‐milk medium. The inability of buds to achieve development equal to that on the coconut‐milk medium may be partially explained by the existence of a barrier to carpel formation and development. The effect of glycine on floral buds grown on a defined medium was dependent not only upon the minerals used but also on the stage of development of the bud. With White's minerals, glycine inhibited the development of buds in early and intermediate stages but was slightly promotive with buds in later stages. With the new minerals, glycine was slightly promotive with early and intermediate stages of development but was inhibitory with later stages. Further work is necessary before development on a defined medium will equal or exceed development on the coconut‐milk medium.
CYTOGENETIC STUDIES IN CLARKIA, SECTION PRIMIGENIA. IV. A CYTOLOGICAL SURVEY OF CLARKIA GRACILIS
Authors: Abdel‐Hameed Fathi , Snow Richard
Published: January 2018

Clarkia gracilis (2n = 28) is an allotetraploid which combines genomes from two subsections of section Primigenia. Natural populations consist of plants homozygous for a single chromosome arrangement, which may differ from the arrangements in other populations by one or more reciprocal translocations. One arrangement, the “standard,” was widespread. Cytological observations on plants derived from crosses between populations of C. gracilis, and on triploid plants derived from crosses with C. amoena subsp. huntiana, one of the parents of the tetraploid, were used to determine the end arrangements present. Ten arrangements were identified, and it was found that the standard amoena subgenome of C. gracilis is identical in end arrangement to the previously defined standard arrangement of the diploid C. amoena. Hence a race of C. amoena with this arrangement was involved in the hybridization which gave rise to C. gracilis. Evidence was found that other arrangements of C. amoena have probably been introduced into C. gracilis by subsequent introgressive hybridization. Cytological differences, coupled with differences in morphology, ecology, and distribution indicate that C. gracilis should be subdivided into four subspecies instead of the three presently recognized.
A LIGHT‐ AND ELECTRON‐MICROSCOPIC STUDY OF PRIMARY HETEROGENEITY IN THE EGGS OF TWO BROWN ALGAE
Authors: Neushul M. , Liddle L.
Published: January 2018

The mature eggs of Zonaria farlowii and Dictyota binghamiae exhibit a distinctively symmetrical arrangement of organelles. In mature oogonia plastids occur in two groups in the central region of the cell and vacuoles of several types are arranged in peripheral layers. Before the mature egg is released, an amorphous “mucilage layer” developes inside the wall of the oogonium. After fertilization the plastids become uniformly distributed. When the eggs of Zonaria develop parthenogenetically the primary heterogeneity is retained. The symmetrical arrangement of membranes seen in the oocytes of these plants may represent an organizing system that influences cytodifferentiation and perhaps subsequent embryology.
PALYNOLOGY AND SYSTEMATICS OF CUPHEA (LYTHRACEAE). I. MORPHOLOGY AND ULTRASTRUCTURE OF THE POLLEN WALL
Authors: Geaham Alan , Graham Shirley A. , Geer Donald
Published: January 2018

A survey of pollen from 153 species of Cuphea has revealed a remarkable array of morphological forms. The survey involved light and electron microscope investigations of C. crassiflora, jorullensis, and koehneana to determine details of exine morphology, and a more general study of pollen from an additional 150 species. Comparison of pollen types within a single morphological category and within taxonomic groups (i.e., sections or subsections) indicates considerable variation at subgeneric levels. The genus is distinctly eurypalynous, and the extent to which pollen varies among the sections, subsections, species and varieties is probably exceeded by few genera of comparable size. The pollen is also variable within each taxon, but size studies of single‐anther lactic acid preparations demonstrate the genus is not polymorphic, as in Lythrum, where pollen polymorphism is associated with heterostyly. The latter phenomenon is as yet unknown in Cuphea. These results reveal that pollen morphology constitutes an important and useful character for taxonomic studies of Cuphea.
OBSERVATIONS ON METAPHLOEM IN THE VEGETATIVE PARTS OF PALMS
Authors: Parthasarathy M. V.
Published: January 2018

Metaphloem was studied in available vegetative parts of 374 species in 164 genera of palms. Sieve elements usually have compound sieve plates except in the subfamilies Lepidocaryoideae and Nypoideae. Sieve elements in roots usually have oblique to very oblique end walls, whereas in stems and leaves they have transverse to oblique walls. Within a phloem strand the degree of compounding of a sieve plate is directly correlated with element diameter. Plastids are normally present in functioning, enucleate sieve elements. Small quantities of “slime” substances have been detected in young sieve elements in stems and petioles of a few species. Many sieve plates in functioning sieve elements lacked callose in materials quick‐killed in liquid nitrogen or chilled acetic‐alcohol. Definitive callose is confined to sieve elements just before their obliteration. Sieve tubes in leaf and stem are usually ensheathed by contiguous parenchyma cells while those in root have very few contiguous parenchyma cells. Two types of contiguous parenchyma cells can be distinguished by difference in cytoplasmic density, especially with the electron microscope. Cells with denser cytoplasm are interpreted as companion cells. Lignified contiguous parenchyma cells are occasionally present in metaphloem of petioles. The possible diagnostic and taxonomic features of metaphloem are discussed.