bluuebunny/crossref_metadata_2025 huggingface dataset:
HISTOLOGICAL STUDIES ON THE COLEOPTILE. II. COMPARATIVE VASCULAR ANATOMY OF COLEOPTILES OF AVENA AND TRITICUM
Authors: Thimann Kenneth V. , O'Brien Terence P.
Published: January 2018

The vascular bundles in the uppermost 1‐4 mm of the coleoptiles of 9 varieties of Avena sativa, and also of Avena fatua L., all terminate essentially vertically with a small “cap” of tracheary elements. In Triticum vulgare Vill., by contrast, they terminate with a horizontal or downward‐pointing section. This brings the two bundles more or less together and may result in their complete fusion, usually with a short vascular extension. In both genera the bundles contain one or more series of apparently active, undifferentiated cells. In the mature embryos the bundles are entirely procambial in nature, but xylem differentiation begins rapidly upon germination and proceeds towards the tip, which is reached by the time the coleoptile is 1.5 mm long; thereafter it proceeds basipetally and it may continue at the base after elongation has ceased there. The differentiation of stomata also appears to proceed basipetally. It may be deduced that the coleoptile cannot form lignin while in the embryo but begins to do so upon germination. Parallels are brought out between auxin production first by the endosperm and then by the tip, on the one hand, and lignification in the xylem and in the stomata, on the other.
THE CHROMATOGRAPHIC CHARACTERIZATION OF ARTEMISIA, SECTION TRIDENTATAE
Authors: Holbo H. R. , Mozingo H. N.
Published: January 2018

Acid methanol leaf extracts of all of the eleven species assigned to the Section Tridentalae of Artemisia by Beetle were chromatographed using a descending two‐dimensional method. Analysis of the resultant chromatographs showed that the presence or absence of any or all of three spots, in particular, blue (84/53), orange (80/50), and green (81/58), was consistently the same for any species or variety. These spots have been designated as species‐specific. Certain relationships on the basis of this evidence are postulated. Three additional spots which appeared on the chromatograms, blue (55/65), orange (51/70), and blue (53/79), seem to be characteristic of the Section Tridentatae. It is proposed that the three species which do not show these spots do not properly belong in this section. Preliminary evidence indicates that the species diagnostic spots are aglycones or free phenolics while the section‐diagnostic spots are possibly phenolic glycosides.
A PLUCHEA HYBRID FROM THE PACIFIC
Authors: Cooperrider Tom S. , Galang Marilyn M.
Published: January 2018

Two species of Pluchea have been introduced into the Hawaiian Islands in the present century. These are P. indica, native to southeastern Asia, and P. odorata, native to the western hemisphere. Both are erect shrubs. Within the past 30 years a third Pluchea taxon, a sprawling shrub morphologically distinct from the two species, has appeared in the Hawaiian Islands and on other islands in the tropical Pacific. On the basis of morphology, fertility, meiotic behavior, and other evidence, it is concluded that the third taxon is a hybrid between the two species. The hybrid is highly sterile; it has a limited capacity for asexual reproduction. Metaphase I configurations for both species were found to be 10II; the most frequent configuration in the hybrid was 8II + 4I. The hybrid is given a binomial.
CHEMOTAXONOMY AS AN AID IN DIFFERENTIATING WOOD OF EASTERN AND WESTERN WHITE PINE
Authors: Seikel Margaret K. , Hall Stan S. , Feldman Linda C. , Koeppen Robert C.
Published: January 2018

Heartwoods from Pinus strobus (eastern white pine) and Pinus monticola (western white pine), which are difficult to distinguish anatomically, can be separated, with about 95% accuracy, by subjecting their acetone extracts to simple paper chromatography. Basically, this differentiation is possible because the relative proportions of certain flavanones vary in the two species, and when these are treated with the chromogenic spray, distinguishing colors are produced at different rates of speed. With P. strobus, the characteristic yellowish‐orange spot results from higher percentages of cryptostrobin and strobobanksin, while the pinkish‐red spot, typical of P. monticola extract, is due to a preponderance of pinocembrin.
CYTOLOGY OF DIFFERENTIATING TRACHEARY ELEMENTS II. STRUCTURES ASSOCIATED WITH CELL SURFACES
Authors: Esau K. , Cheadle V. I. , Gill R. H.
Published: January 2018

During the differentiation of helical secondary walls in tracheary elements of Beta vulgaris L. and Cucurbita maxima Duchesne special structures were recognized on both sides of the plasmalemma in variously fixed material. Microtubules oriented parallel with the expected orientation of microfibrils in the cell wall occur near the inner side of the plasmalemma. Inclusions in the form of vesicles and tubules occur between the plasmalemma and the wall in pockets apparently formed by invaginations or infoldings of the plasmalemma into the cell interior. The concepts on possible relation of these structures to the growth of the wall are reviewed.
CALAMOPHYTON IN THE MIDDLE DEVONIAN OF NEW YORK STATE
Authors: Bonamo Patricia M. , Banks Harlan P.
Published: January 2018

Specimens of Calamophyton from the Middle Devonian Ashokan Sandstone near Kingston, Ulster County, N.Y., are shown to belong to C. bicephalum Leclercq and Andrews, a Belgian species. Steel needles and a stereoscopic binocular microscope were used to follow the path of the forking leaves and branching sporangiophores of the specimens through the matrix. The terete leaves dichotomized two to three times in more than one plane. Sporangiophores dichotomized once. Each branch bore three recurved lateral branches which in turn bore two sporangia. Each branch terminated in an elongate, filiform projection. Sporangia apparently dehisced longitudinally. Their walls were composed of elongate cells. Their spherical spores ranged from 86 to 166 μ in diameter and bore a trilete mark. Ornamentation consisted of coni and spinae up to 4.5 μ long. They resembled dispersed spores of Dibolisporites gibberosus var. major Richardson. This is the second occurrence of Calamophyton bicephalum and the first account of its spores. It is the second report of the genus in North America.
EFFECTS OF IONIZING RADIATION AND FIRE ON GAYLUSSACIA BACCATA AND VACCINIUM VACILLANS
Authors: Brayton R. D. , Woodwell G. M.
Published: January 2018

Fire and ionizing radiation have parallel effects on survival of natural populations of Gaylussacia baccata and Vaccinium vacillans. Vaccinium is substantially more resistant to both. The differences in survival are due to differences in regenerative capacity; buds of Vaccinium are more resistant to damage, occur at greater depths in the soil, and are better protected from both radiation and heat. This pattern of radiation and fire resistance lends further support to the general observation that in plants radiation resistance is related to ecological hardiness.
VARIATIONS OF MORPHOGENETIC BEHAVIOR IN PLANT TISSUE CULTURES I. CICHORIUM ENDIVIA
Authors: Vasil I. K. , Hildebrandt A. C.
Published: January 2018

Several‐years‐old callus tissue derived from mature embryos of endive (Cichorium endivia Linn., Compositae) was grown on synthetic liquid and/or agar nutrient media. Incorporation of yeast extract or high concentrations of inositol, kinetin, casein hydrolysates (pancreatic and acid hydrolysates), etc., improved growth and organ formation. Rosettes of leaves, shoots and roots were differentiated on synthetic media. On agar media shoots arose first and were from marginal meristematic areas, while the roots arose later and were from pockets of meristematic tissue located in the deeper regions of the callus. In liquid media embryoids from single cells were formed which first developed roots and then shoots.
BISCALITHECA KANSANA SP. N. (COENOPTERIDALES, ZYGOPTERIDACEAE), A COMPRESSION FROM THE LAWRENCE SHALE (UPPER PENNSYLVANIAN), KANSAS, U. S. A.
Authors: Cridland Arthur A.
Published: January 2018

The organ bearing the sporangia of Biscalitheca kansana is a laminate rachis with subopposite fertile appendages, a structure previously unknown for Biscalitheca. The sporangia differ from those of the petrified Biscalitheca musata only by lacking nests of sclerotic cells. They contain spores which are called Convolutispora when found dispersed. Speculations are made that Monoscalitheca fasciculata will ultimately be regarded as a synonym of Biscalitheca musala and that some fossils called Aphlebia and Brittsia problematica may be the sterile foliage of zygopterids.
A STUDY OF WALL ORNAMENTATION IN CULTURES OF SCENEDESMUS
Authors: Trainor Francis R.
Published: January 2018

In a comparative study, six strains of Scenedesmus isolated from one small pond were examined in culture. Three of the isolates, S. denticulatus, S. dispar, and S. abundans, proved to be morphologically quite stable when studied in the laboratory. In an axenic culture of any one of the three pleomorphic strains one could find coenobia which resemble S. longispina or S. armatus. High percentages of four‐celled coenobia with several ridges but with only two spines (the S. semipulcher type) were found typically in older cultures of two of the pleomorphic cultures. Long, delicate appendages (bristles) were easily detected on most coenobia in desiccated preparations of all but the S. dispar culture. The use of cultures in identifying Scenedesmus coenobia is discussed.
THE QUESTION OF POST‐REDUCTION IN SPHAGNUM
Authors: Bryan Virginia S.
Published: January 2018

The 19 spatially distinct chromosomal units at first meiotic metaphase in sporophytically diploid species of Sphagnum have usually been considered to be bivalents, but one investigator (Sorsa, 1956) has interpreted them as chromosomes from dissociated bivalents and meiosis as post‐reductional. The present studies on diploid S. squarrosum (Pers.) Crome establish the chromosome number on the basis of the following evidence: there are in addition to m‐chromosomes, 19 pairs of chromosomes in early prophase, 19 bivalents at diakinesis, 19 chromosomes in each of the two sets at second metaphase, 19 daughter chromosomes in each of the four sets at late second anaphase, and 19 chromosomes in gametophytic mitoses. The 19 bodies at first meiotic metaphase in diploid species are true bivalents in loose secondary association, which has led to their erroneous interpretation as chromosomes of dissociated bivalents. The gametic chromosome number in sporophytically diploid Sphagnum is therefore, without doubt, n = 19, and this evidence negates the claim for post‐reduction in Sphagnum.
PAURODENDRON, A RHIZOMORPHIC LYCOPOD
Authors: Phillips Tom L. , Leisman Gilbert A.
Published: January 2018

From middle Pennsylvanian coal balls collected in Kansas and Illinois the ligules and rhizomorph of Paurodendron have been illustrated. Assignment of Paurodendron to the Lycopsida is corroborated. Discovery of the root‐bearing portion of this Carboniferous lycopod establishes a diminutive, phyletic line in the Paleozoic with rhizomorphs smaller than many species of Isoeles. Paurodendron resembles the selaginelloid line more closely than other rhizomorphic types. Anatomical comparisons of Paurodendron with roots and root‐bearing structures of lycopods are made; the root‐bearing and a representative leaf‐bearing portion of Paurodendron fraiponti have been reconstructed. The specific diagnosis has been emended, and the three species described by Fry have been reduced to one.
STUDIES OF CYTOCHEMICAL LOCALIZATION OF SPECIFIC DEHYDROGENASES IN FROZEN, DISEASED TISSUES OF PINUS
Authors: Koenigs Jerome W.
Published: January 2018

Intracellular activity of individual dehydrogenases in frozen tissues of Pinus monticola and Cronartium ribicola was demonstrated by supplying a specific substrate and the appropriate pyridine‐nucleotide‐linked coenzyme. Freezing broke cell permeability barriers releasing endogenous coenzymes and substrates which had produced nonspecific enzymatic reduction of nitro blue tetrazolium by miscellaneous dehydrogenases throughout fresh tissues. Freezing enhanced specificity by accentuating the differences between control and treatment sections. Succinic, ethanol, glutamic, α‐glycerophosphate, isocitric, lactic, malic, glucose‐6‐phosphate, and 6‐phos‐phogluconate dehydrogenases and NAD and NADP diaphorases were localized within cells of the blister rust fungus and its western white pine host. NAD‐ and NADP‐linked forms of glutamic, isocitric, and malic dehydrogenases were also detected. The distribution and activity of the enzymes are described for cell types of host and pathogen. β‐Hydroxybutyric and pyruvic dehydrogenases were not detected. Calcium and magnesium (5 × 10−3 m final conen) and zinc (1.5 × 10−5 m final concn) had little or no effect on localization. Amytal increased reduction by 6‐phosphogluconate, glutamic, and ethanol dehydrogenases while azide depressed the reaction for the last enzyme. Cyanide augmented diformazan formation with succinate. Transhydrogenase was eliminated as a likely contributor to spurious localization in these frozen tissues. Enzymatically produced diformazan appeared on the surface of lipid droplets in cells of both organisms in fresh and frozen sections. The use and interpretation of data from frozen and fresh tissues in tetrazolium cytochemistry are discussed.
FINE STRUCTURAL STUDIES OF ZEA MAYS POLLEN I: CELL MEMBRANES AND EXINE ONTOGENY
Authors: Skvarla John J. , Larson Donald A.
Published: January 2018

Electron microscopy was used to study pollen wall ontogeny in Zea mays. The initial stage of development consisted of compartmentalization of microspores within callose special walls. Microspore plasma membranes retracted and tubular elements of the endoplasmic reticulum became perpendicularly oriented to the plasma membranes. Evaginations of the endoplasmic reticulum into the microspore plasma membrane resulted in the establishment of a template or blueprint of the mature pollen wall. Sporopollenin deposition upon the template began immediately after dissolution of the callose special walls and release of the microspores into the anther locule. The columellae were the first pollen wall units to be formed; the tectum and foot layer became established shortly thereafter. The granular endexine was the last‐formed unit. The relationships of membrane systems to the ontogeny of the pollen wall units and the mode of pollen wall growth are discussed.
EVIDENCE FOR DIVERSE CELL TYPES IN THE APICAL REGION OF THE ROOT EPIDERMIS OF PANICUM VIRGATUM
Authors: Rothwell Norman V.
Published: January 2018

All epidermal cells in root tips of panicoid grasses have been considered to be capable of hair formation. Observations made in this investigation suggested that cells of two maturation potentials may be present in the root‐tip epidermis of Panicum virgatum. Protein bodies which swell and fuse in the region of elongation were revealed in the meristem of this grass by different staining procedures. In many roots not all cells seemed to receive the same amount of these bodies or of the protein‐positive material which appeared to arise from them. Only deeply stained cells with large nucleoli were seen to form hairs. Epidermal cells of very hairy roots contained uniform nucleoli and exhibited similar distributions of protein material. The protein positive inclusions were never found in the cortex, a region of cells with one maturation potential. Following chloramphenicol treatment, root tips were found to contain epidermal cells with nucleoli of similar size, a reduced amount of protein bodies, and a reduction in the number of root hairs. RNase treatment did not appear to affect the integrity of the inclusions. The significance of such protein bodies is discussed in relation to differentiation of epidermal cells in P. virgatum.
EFFECTS OF RED AND FAR‐RED RADIATION ON CELL DIVISION AND ELONGATION IN THE STEM OF PINTO BEAN SEEDLINGS
Authors: Nakata Shigeru , Lockhart James A.
Published: January 2018

Nine‐day‐old Pinto bean seedlings, Phaseolus vulgaris L., were treated daily for 12 days with supplementary red or far‐red radiation following daily exposure to 8 hr of daylight. Stem elongation was nearly exponential from the 4th to the 12th day of treatment and was about 2.9 times greater under far‐red radiation. Cell division and cell elongation were promoted essentially equally by far‐red radiation. There was virtually no difference in either the rate of leaf initiation or the duration of growth of internodes under the supplementary radiation.
MORPHOLOGY OF THE COMPILOSPECIES BOTHRIOCHLOA INTERMEDIA
Authors: De Wet J. M. J. , Harlan J. R.
Published: January 2018

The widely distributed and morphologically variable grass species Bothriochloa intermedia (R. Br.) A. Camus was studied in detail. Morphological and cytogenetical observations indicated that variation is due to interspecific and intergeneric hybridization. The species B. grahamii (Haines) Bor and B. glabra (Roxb.) A. Camus represent intergeneric hybrid derivatives between B. intermedia and Dichanthium annulatum (Forssk.) Stapf, and between B. intermedia and Capillipedium parviflorum (R. Br.) Stapf, respectively. These intergeneric hybrids, and also the apomictic hybrid derivatives of both B. grahamii and B. intermedia with the related B. ischaemum (L.) Keng, are included in the compilospecies. Morphological and cytogenetical studies suggested that the apomictic B. odorata (Lisboa) A. Camus and B. haenkei (Presl) Ohwi are biotypes of B. glabra. The genera involved, Bothriochloa O. Kuntze, Capillipedium Stapf and Dichanthium Willemet, behave phylogenetically like sections of a single genus, with the last‐mentioned generic name taking priority.
EFFECT OF FLORAL AGING ON THE GROWTH OF COMPATIBLE AND INCOMPATIBLE POLLEN TUBES IN LILIUM LONGIFLORUM
Authors: Ascher Peter D. , Peloquin S. J.
Published: January 2018

Compatible and incompatible pollen tube growth in detached styles of three Lilium longiflorum cultivare varies with the physiological age of the style. Before anthesis both compatible and incompatible pollen tubes grow, in 48 hr, only a fraction of the distance compatible tubes grow after anthesis. Incompatible pollen tubes are restricted to about half the distance of compatible tubes in the four days postanthesis, but thereafter increase up to or three‐fourths or more the length of compatible tubes at the time of floral senescence. About 10 days after anthesis, growth of both types of pollen tubes decreases. The detached style method of pollen‐tube cultivation is validated in the cultivar ‘Ace’ by seed set obtained following self‐pollination in the 6‐ to 9‐day interval and failure of seed set after either self‐ or cross‐pollination after 9 days following anthesis. Also, in agreement with detached style data, self‐pollination fails to produce seeds when attempted in bud stages or the five days following anthesis. Cross‐pollinations are successful in this period. This material and technique appear well suited for study of the nature of the self‐incompatibility reaction.
AN EXPERIMENTAL ASSOCIATION BETWEEN CHLORELLA XANTHELLA AND A STREPTOMYCES
Authors: Lazo Waldo R.
Published: January 2018

An association in the form of a lichen‐like crust (“actinolichen”) was obtained by seeding Chlorella xanthella cells and spores of a Streptomyces sp. isolated from soil on the surface of potato sections partially immersed in water at temperatures with a diurnal fluctuation of 9–19 C or 14–25 C, and with illumination continuous or during the hours of the higher temperatures. Sections of the crust showed a lichen‐like organized tissue with layers of Streptomyces sp. spores, hyphae alone and associated hyphae and algae.
THE MORPHOLOGICAL EFFECTS OF PROTEIN SYNTHESIS INHIBITION IN MARSILEA
Authors: White Richard A.
Published: January 2018

Marsilea vestita and M. drummondii were grown in sterile cultures to which concentrations of the protein synthesis inhibitors, 2‐thiouracil (10 mg/liter) and 5‐fluorouracil (1 mg/liter) had been added. When young sporelings are grown in a solution of thiouracil at optimum concentration, there is an inhibition of the rate of leaf formation, a retardation of the leaf heteroblastic series, and all leaves develop as land forms. When thiouracil is added to plants which are already producing typical adult, quadrifid leaves, the effects depend on whether the treated plants are water or land forms. Plants which are typically water forms convert to land forms. After treatment successive leaves develop typical sunken stomata on both leaf surfaces. The tissues of the rhizome, root and petiole are more compact and, in general, the cells of the plant have thicker walls. Vascular patterns are not changed, though the size of the rhizome, root and petiole may be reduced. Plants which are typically land forms are less affected than the water forms, but they show a small reduction in apex volume and an apparent reversion of the leaflet number from the typical quadrifid leaf to a trifid, bifid, or single lamina condition. In both land and water forms apical dominance may be broken by treatment with 10 mg/liter thiouracil or 1 mg/liter fluorouracil and numerous lateral branches develop. Higher concentrations (15–25 mg/liter of thiouracil) may result in abnormal development of lateral axillary buds, petiole bases and leaflets. The meristems of the plant are differentially sensitive to thiouracil; leaflet meristems are most sensitive, the root meristems are the least sensitive. It appears that a true reversion to juvenile leaf development need not occur even though protein synthesis and the volume of the apex are reduced. The development of the land or water form in Marsilea appears to depend on rate of growth. Hence inhibition of the growth of typical water forms, through inhibition of protein synthesis, causes a shift in development toward the morphology typical of land forms.
THE ULTRASTRUCTURE OF GRANA IN MESOPHYLL PLASTIDS OF ZEA MAYS
Authors: Paolillo Dominick J. , Falk Richard H.
Published: January 2018

The compartments of the grana of mesophyll plastids of Zea mays are extensively interconnected. In median sections of grana, 16.5% of compartment margins were involved in a Y‐shaped conjunction of the loculi of two consecutive compartments with the loculus of an attached fret. Various configurations accounted for the remainder of the compartment margins seen in median sections of grana. Tangential views of grana and serial sections revealed an oblique relationship between the frets and the grana. Analysis of serial sections allows the conclusion that the components of the fretwork are helically wound around a granum.
CYTOTAXONOMIC STUDIES IN CHRYSOTHAMNUS (ASTEREAE, COMPOSITAE)
Authors: Anderson Loran C.
Published: January 2018

The basic chromosome number for Chrysothamnus is x = 9 as determined by 234 original counts representing all species. Polyploidy is frequent only in C. viscidiflorus where diploids, tetraploids, and hexaploids are found. Pollen size in the genus is basically correlated with style length rather than ploidy level. Most aspects of meiosis appear normal except for the tendency for nucleolar fragmentation. To reduce chromosome clumping during meiosis, an ice‐water pretreatment was utilized. Karyotypes in Chrysothamnus reflect similar trends of specialization noted in chromosome structure for other Compositae. The taxa are predominantly self‐fertilized; however, one instance of interspecific hybridization is noted. Taxonomic significance of the chromosome numbers, karyotypes, and breeding system in Chrysothamnus is discussed.
ROLE OF DICTYOSOMES IN WALL FORMATION DURING CELL DIVISION OF CHLORELLA VULGARIS
Authors: Bisalputra T. , Ashton F. M. , Weier T. E.
Published: January 2018

The behavior of dictyosomes in wall formation during cell division of Chlorella vulgaris follows a definite pattern. During formation of the partition membrane they migrate into the equatorial plane and pair. There is a close spatial relationship between the dictyosomes and the partition membrane which, itself, may be derived from the fusion of dictyosomal vesicles. Dictyosomes also may participate significantly in the deposition of new wall material.
NUTRITIONAL REQUIREMENTS OF FRAXINUS CALLUS CULTURES
Authors: Wolter Karl E. , Skoog Folke
Published: January 2018

A satisfactory synthetic medium has been developed for continuous growth of Fraxinus pennsylvanica Marsh. callus cultures. The medium contains modified Reinert and White (1956) inorganic nutrient solution with 5 mg/liter Fe as NaFe‐EDTA and supplemented with myoinositol 10 mg/liter, pyridoxine HCl 0.1 mg/liter, 2,4‐dichlorophenoxyacetic acid 0.04 mg/liter, kinetin 1 mg/liter, sucrose 20 g/liter, and agar 10 g/liter. myo‐Inositol, pyridoxine and an auxin are essential. α‐Naphthaleneacetic acid is an effective alternate auxin. Kinetin and to some extent gibberellic acid improve the yields. Thiamine has no effect.
CYTOLOGICAL EXPRESSIONS OF A CYTOPLASMIC MALE STERILITY IN SOLANUM
Authors: Grun Paul , Aubertin Mary
Published: January 2018

Anther contents of plants expressing the cytoplasm‐gene interaction that results in anther indehiscence were studied under the light microscope. Plants could be classified in four groups on the basis of anther content: (1) A blockage resulted from cessation of development principally during the stages of meiosis of apparently normal sporocytes. This produced anthers in open flowers that usually contained monads or dyads. (2) Disorganization of sporocytes during first meiotic prophase resulted in irregularity of disjunction during the two meiotic divisions. Sporocytes produced quartet‐stage clumps having more than four cells. Microspores failed to grow beyond early stages of exine development. (3) Abnormal small pollen having a very thick exine. (4) Normal pollen present in anthers that lacked terminal pores. The variety of anther content types resulted from presence of modifying genes rather than from differing actions of genes that conditioned indehiscence itself. Expression was not modified by environmental fluctuations, and plants did not show chimeral sectors having changed anther contents or dehiscent anthers.
FORAGING BEHAVIOR OF BOMBUS (HYMENOPTERA: APIDAE) IN RELATION TO AQUILEGIA POLLINATION
Authors: Macior Lazarus Walter
Published: January 2018

Observations on native and cultivated plants indicated that the ruby‐throated hummingbird (Archilochus colubris L.) and at least four species of Bombus are probably effective pollinators of Aquilegia canadensis L. in southeastern Wisconsin. Bombus affinis Cresson perforated more than 90% of 2173 nectar spurs of flowers at full anthesis on wild plants. Cinematographic and stereo‐photographic records of insects revealed a general behavioral pattern of mandibular perforation following exploration by antennae, maxillae, and tongue. Pollen‐foraging behavior on 19 cultivated Aquilegia species and varieties was uniform, but nectar‐foraging behavior varied with flower form and position and not with color variation within one flower form. Observations on marked insects showed that workers tended to forage in one manner on one plant variety, while queens foraging in one or more ways visited up to five different flower forms on one flight. Initial observations on neonate workers from a cultivated B. affinis colony suggested that a probably innate mandibular perforation behavior is not instinctively directed toward nectar‐bearing floral parts, and that foraging behavior is capable of rapid establishment and considerable versatility.
THE CYTOLOGY AND PHYLOGENETICS OF THE DIPLOID SPECIES OF GOSSYPIUM
Authors: Phillips Lyle L.
Published: January 2018

Meiotic chromosome behavior of 11 inter‐genomic hybrids of Gossypium (2n = 26) were investigated. Per cell univalent frequencies at meiotic metaphase I in these hybrids were: A genome × Cgenome—G. herbaceum × sturtianum, 10.53; G. herbaceum × australe, 18.05. A genome × E genome—G. smnalense × arboreum, 21.82. B genome × C genome—G. anomalum × sturtianum, 9.23; G. anomalum × australe, 13.11. B genome × D genome—G. anomalum × klotzschianum, 17.45; G. anomalum × raimondii, 18.83. C genome × D genome—G. robinsonii × davidsonii, 12.77; G. sturtianum (armourianum × thurberi), 8.63. C genome × E genome—G. somalense × australe, 23.78; G. somalense × bickii, 25.58. Trivalent and quadrivalent frequencies were relatively high for those hybrids involving a C genome species, indicating that a reciprocal translocation differentiates the C genome from the A, B, D, and E genomes. The results of this study and the data of similar studies cited from the literature on Gossypium cytogenetics are discussed relative to the phylogenetics and evolution of the major (genome) groups of Gossypium and their constituent taxa.
MITOTIC ACTIVITY IN THE CAMBIAL ZONE OF PINUS STROBUS
Authors: Wilson Brayton F.
Published: January 2018

Mitotic activity in the cambial zone of 20‐year‐old Pinus strobus L. trees was determined quantitatively, using mitotic counts from serial tangential sections of sample pieces. Counts from nine cores 1.6 mm in diameter from each sample piece were averaged and expressed as the number of mitoses per core with the sampling error. Estimation of the number of cambial zone cells per core permitted calculation of mitotic indices. In the fourth internode from the ground the first mitoses were observed on April 15 and the last on September 15. The number of mitoses per sample piece was comparable throughout each internode at any one sampling, but the number was higher in internodes within the crown than in those below it. Mitotic index was not appreciably higher within the crown, but it decreased from 3.7 in spring to 2.0 in fall. An internode in the crown sampled May 11–13 showed afternoon peaks in mitotic activity, but an internode below the crown showed no peaks, nor did other internodes sampled later in the season.
STRUCTURE OF THE SHOOT APEX IN LACTUCA SATIVA
Authors: Constantin M. J. , Mullenax R. H.
Published: January 2018

Histological observations of the leaf lettuce ‘Black Seeded Simpson’ showed the dormant embryo to possess two visible leaves and a flkat to slightly depressed plumular apex. Observations conducted over a 12‐day period of germination and growth showed the development of L1 and L2, emergence of L3 and L4, and periodic changes in size of the apex which were associated with leaf emergence. Thus the dormant embryo of Lactuca appears to be considerably more advanced in development than was previously believed. The shoot apex appeared flat to slightly depressed at all developmental stages studied.
CHROMOSOME NUMBERS IN UMBELLIFERAE. III
Authors: Bell C. Ritchie , Constance Lincoln
Published: January 2018

Chromosome numbers are reported for 156 collections representing 100 taxa of Umbelliferae. Approximately two thirds of the collections are from Mexico, Central and South America and indicate a high percentage of polyploid species in certain genera found in this area. Chromosome numbers for plants belonging to 78 taxa are published here for the first time, previously published chromosome numbers are verified for 18 taxa and chromosome numbers differing from those previously published are reported in seven instances. No chromosome counts have been previously published for nine of the genera included here. Further aneuploidy and polyploidy were found in Eryngium, and Lomatium columbianum has been found to be a high polyploid with 2n = 14x. Every chromosome count is referable to a cited herbarium specimen.
CARPEL DEVELOPMENT IN DRIMYS LANCEOLATA
Authors: Tucker Shirley C. , Gifford Ernest M.
Published: January 2018

The dissimilar carpels of representatives of the Tasmannia and Wintera sections of the genus Drimys have been investigated developmentally with particular attention to the presence of peltation. In Drimys winteri of the Wintera section peltation results from an active adaxial meristem, but in D. lanceolata of the Tasmannia section the adaxial “cross‐zone” meristem is weakly developed and contributes little to the carpel. The form of the carpels also shows contrasts; the carpel of D. lanceolata begins growth as paired ridges separated by a cleft extending over the summit. Allometric growth reorients the cleft and it eventually extends from the ventral base of the carpel up over the summit. The cleft elongates greatly, together with the main part of the carpel. In D. winteri, growth is concentrated below the level of the cleft, and the carpel grows as an elongating cylinder. The cleft remains short, not extending with the carpel. In both species, early growth involves subsurface initials: subapical, adaxial (although weak in D. lanceolata), and submarginal. The presence of a disc encircling the base of the solitary carpel is reported for the first time for D. lanceolata.
THE ANATOMY OF INTERNAL TIPBURN OF CABBAGE
Authors: Struckmeyer B. Esther , Walker J. C.
Published: January 2018

Leaves of resistant and susceptible breeding lines of two closely related varieties of cabbage, ‘Glory’ and ‘Globe,’ showing internal tipburn were examined anatomically. Since both resistant and susceptible lines developed tipburn, the type of injury rather than the amount was considered. Regardless of the degree of resistance, cellular disorders in the tipburned areas were the same. Early symptoms showed small gray areas at the lobes of the leaves. The outer parenchymatous cells of these areas remained normal. Some of the xylem vessels became occluded with a granular substance; surrounding cells, including the idioblasts, enlarged. The idioblasts, reported to contain the enzyme myrosin, contained a particulate substance. Some idioblasts hypertrophied and also divided resulting in the distribution of the particles to additional cells. The conditions causing tipburn also affected cell walls, causing thickening and the production of pectic warts between cells and on walls facing the intercellular spaces. As more xylem vessels became occluded, and as the number of idioblasts with particles increased, the cells at the periphery of the leaf collapsed.
ENVIRONMENTAL FACTORS AND THE GROWTH OF NATIVE ORCHIDS
Authors: Stuckey Irene H.
Published: January 2018

The environments in which native orchids grow were examined in terms of factors which might determine the survival and reproduction of the various species. Soil tests were made for 34 species now known to be growing in Rhode Island. Soil reaction appears to be related to growth of orchids, but other factors in the environment were found to be of equal if not greater importance. These include light, moisture, temperature and destruction by animals. Fertility was not found to be limiting under the conditions observed.
GIBBERELLIN RELATIONSHIPS IN THE ‘ALASKA’ PEA (PISUM SATIVUM)
Authors: Moore Thomas C.
Published: January 2018

'Alaska’ peas (Pisum sativum L.) grown under a 16‐hr photoperiod at 20 ± 1 C and an 8‐hr dark period at 16 ± 1 C in their ontogeny exhibit two periods of sensitivity to applied gibberellin (GA), namely, prior to and subsequent to but not during the linear phase of stem elongation. This paper describes experiments conducted primarily with seedlings. Growth‐saturating doses of GA, applied to dry seeds before planting (10−3 m) and to the shoot tips of 3‐day‐old seedlings (10 μg), evoked growth rates equal to the growth rate of etiolated seedlings. Sensitivity of seedlings to applied GA decreased with age through the first 2 to 3 weeks of development; by the time seedlings were about 14 days of age and had four elongating internodes they no longer responded to applied GA. As endogenous growth rate diminished late in ontogeny, the plants again became sensitive to applied GA. Growth response was used as a criterion for determining apparent translocation of applied GA. ‘Alaska’ pea seedlings appeared to transport GA, both acropetally from the cotyledons and basipetally from the shoot tip, to all internodes with remaining extension potential. Excision of both cotyledons at any time during the first 9 days of development caused a significant reduction of growth rate, and applied GA did not restore normal growth rate. No evidence was found that the cotyledons supply endogenous GA to the shoot axis in normal seedling development. It is suggested that the normal growth rate of light‐grown ‘Alaska’ peas is correlated with the rate of synthesis of GA and that GA is rate‐limiting for stem elongation during early seedling development and during the period of decreasing growth rate and onset of apex senescence.
CYTOLOGICAL STUDIES OF OEDOGONIUM. II. CHROMOSOME NUMBERS IN TWELVE SPECIES OF OEDOGONIUM
Authors: Hoffman Larry R.
Published: January 2018

Mitotic chromosome counts are reported for 12 species of Oedogonium with the following distribution: two species with 13 chromosomes, two species with 16 chromosomes, five species with 17 chromosomes one species with 19 chromosomes, one species with 32 chromosomes, and one species with 38 + 1 chromosomes. Diploid strains of two species are illustrated and discussed. Cytological comparison of species establishes that there is great diversity in Oedogonium with relation to chromosome number, size, and morphology.
ON THE STRUCTURE OF CALAMOSTACHYS BINNEYANA FROM THE LOWER PENNSYLVANIAN OF NORTH AMERICA
Authors: Taylor Thomas N.
Published: January 2018

The discovery of specimens of Calamostachys binneyana in Lower Pennsylvanan petrifaction material in North America has provided additional information about the structure of this calamitean fructification. The cones consist of regularly spaced alternating whorls of bracts and sporangiophores. Bracts are fused in a disc except at the margin where the individual units become free. Sporangiophores are inserted at right angles to the cone axis and bear four axially directed sporangia. The vascular system of the North American specimens differs from that in other reports of the taxon in the presence of twelve vascular bundles in the cone axis. Each sporangiophore is supplied by a single vascular trace that departs from one axial bundle. There appears to be no constant relationship between the number of vascular bundles and the number of bracts. Spores are spherical, thin‐walled, and of the Calamospora type. Relationships with other structurally preserved members in the genus are discussed in light of the diversity in structure demonstrated by the new specimens.
A QUANTITATIVE STUDY OF SIEVE‐TUBE DIFFERENTIATION IN VEGETATIVE SHOOT APICES OF COLEUS
Authors: Jacobs William P. , Morrow Ielene B.
Published: January 2018

Quantitative methods, with round‐the‐clock collecting of large samples in successive years, have uncovered several new phenomena of sieve‐tube differentiation in young leaves of Coleus vegetative shoots. In small leaves (1–350 μ), there are no sieve tubes in the leaf itself, but they differentiate acropetally in the two traces to each leaf. Regression lines fitted to the data for leaf length vs. most distal position of sieve tubes in the traces support the view that differentiation is steady and acropetal, but they also reveal that differentiation in the traces falls steadily farther behind elongation of the leaf. Leaves more than 500 μ long have sieve tubes close to their tips. An intensive search of leaves of intermediate lengths revealed an isolated locus of sieve‐tube differentiation. These relationships were reproducible year after year. Every plant with discontinuous strands of sieve tubes in the second leaf pair had discontinuous xylem in the third. This isolated locus was not seen before, probably because of small samples and daytime collections; most of our cases were from night collections.
ANALYSIS OF THE OILS OF WESTERN NORTH AMERICAN JUNIPERS BY GAS‐LIQUID CHROMATOGRAPHY
Authors: Vasek Frank C. , Scora Rainer W.
Published: January 2018

Oil samples from six species of Juniperus include 37 detected components, of which most are quantitatively highly variable. Nine chromatographic patterns were identified, including one for each of two subspecies of J. occidentalis and, surprisingly, two different patterns in both J. californica and J. monosperma. The chemical evidence supports earlier taxonomic conclusions based on morphology and natural history that J. occidentalis subsp. occidentalis and J. occidentalis subsp. australis are indeed subspecies, that the former is intermediate between the latter and J. osteosperma, and that J. californica and J. osteosperma are closely related but distinct species. It is concluded that the techniques of gas chromatography have considerable potential as a taxonomic tool.
CRYSTALLINE SILICA IN PLANTS
Authors: Sterling Clarence
Published: January 2018

Crystalline silica has been found in Fragaria leaves, Equisetum shoots, diatomite, and tabaschir. Differing proportions of amorphous silica (opal) also occur in each of these. The crystalline X‐ray reflections of α‐quartz, low tridymite, or α‐cristobalite have been found in virtually all specimens. However, unidentified crystalline reflections are noted, particulary in the silica isolated from Fragaria leaves and diatomite.
PALEOZOIC LYCOPSID FRUCTIFICATIONS. III. CONSPECIFICITY OF BRITISH AND NORTH AMERICAN LEPIDOSTROBUS PETRIFACTIONS
Authors: Balbach Margaret Kain
Published: January 2018

A study was made of 30 apparently similar microsporangiate cone specimens of the lycopsid fructification Lepidostrobus found in coal balls of Middle Pennsylvanian age from Illinois and Kansas. None of these specimens was a complete cone, but at least 19 were large enough and well enough preserved to provide information regarding variation both within one cone and among several specimens. The data obtained substantiated the original assumption that all 30 specimens represented one species. Attempts to equate this one species with any of the similar, previously described North American taxa, Lepidostrobus coulteri, L. pulvinatus and Lepidocarpon magnificum‐microsporangiate form, and the British taxon Lepidostrobus oldhamius, including the forms (α), (β), (γ) and pilosus, revealed that no significant differences existed among any of these taxa. Furthermore, all characteristics described for these taxa were referable to, and well within the range of variation of, the one species here analyzed. Differences among the taxa were found to represent only differences in maturation or normal variation. All these taxa are, therefore, conspecific and are assigned to one species which by priority is named Lepidostrobus oldhamius. The common association of the megasporangiate Lepidocarpon lomaxi with all these miorosporangiate cones, now recognized as representing the single taxon Lepidostrobus oldhamius, is strong evidence for the probability that Lepidocarpon lomaxi and Lepidostrobus oldhamius were produced by the same parent plant species.
A STUDY OF THE PROPOSED GENUS OBREGONIA (CACTACEAE)
Authors: Anderson Edward F.
Published: January 2018

The monotypic genus Obregonia Frič was compared with Ariocarpus, Lophophora, Strombocactus, and certain other cactus genera. Obregonia and Ariocarpus are similar in characters of seeds, seedlings, habitat, fruits, and general habit. They differ in time of flowering, point of flower origin, areole structure, presence or absence of druses and a mucilage system, and presence or absence of spines. Obregonia and Lophophora are similar in characters of seeds, habitat, basic areole structure, and fruits. They differ in seedling form, habit of adult plants, presence or absence of spines, and chemical analysis. Strombocactus resembles Obregonia in few ways except in basic areole structure and some aspects of anatomy. The author concludes that Obregonia is an intermediate form between Ariocarpus and Lophophora and deserves generic rank. A formal taxonomic treatment of the genus follows the conclusions.
INFLUENCE OF ULTRAVIOLET RADIATION ON AUXIN‐CONTROLLED PLANT GROWTH
Authors: Klein Richard M.
Published: January 2018

Ultraviolet irradiation (254 mμ) of plant test systems results in alterations in growth capacity which can be ascribed to UV‐induced modifications of the ability of plant cells to respond to auxin. This conclusion was reached following study of auxin‐requiring, auxin‐sufficient, and auxin‐surfeit test systems representing cell division, cell enlargement, and cell differentiation. The UV effect was usually reversible by subsequently presented near‐visible or visible radiation.
POLAR TRANSPORT OF GROWTH‐REGULATORS IN PITH AND VASCULAR TISSUES OF COLEUS STEMS
Authors: Jacobs W. P. , McCready C. C.
Published: January 2018

Movement of IAA‐C14 and 2,4‐D‐C14 through cylinders of known size and histology was compared using liquid scintillation counting. Both auxins showed strongly polar movement, even through pith parenchyma cut from Coleus internode #5, the youngest internode to have ceased elongation. The polar movement was correlated with sizable elongation of the excised cylinders. Velocities of basipetal movement for a given auxin, as determined by the intercept method, showed small or negligible differences between pith and “corner” cylinders. (Corner cylinders comprised mostly vascular tissue, plus some cortical, pith, and epidermal cells.) For IAA, basipetal velocities ranged from 2.1 to 3.3 mm per hr; for 2,4‐D, they were 0.6–0.8. For both auxins there was much more net loss into corner than into pith cylinders, a difference associated with the fact that corner cylinders showed 10 times as many cells in transection. More 2,4‐D moved basipetally through corner than through pith cylinders and the reverse was true of IAA. By chromatographic evidence, all the radioactivity in the basal receiving blocks was still associated with the auxin molecules.
ECOTYPIC VARIATION IN LARREA DIVARICATA
Authors: Yang T. W.
Published: January 2018

Data on rate of germination, rate of growth, and temperature and moisture responses of croosotebush (Larrea divaricata Cav.) seedlings from the Sonoran Desert and Chihuahuan Desert suggest that the species as it occurs in North America is comprised of at least two major genetic population systems or ecotypes. Compared to the Chihuahuan Desert ecotype, that of the Sonoran Desert is characterized by a taller, more erect and more open growth form, more slender and less incurved leaflets, slower germination rate, slower initial growth rate of the seedling, less tolerance for low temperature, and greater tolerance for low moisture.
THE DISTRIBUTION AND PHYLOGENETIC SIGNIFICANCE OF BINUCLEATE AND TRINUCLEATE POLLEN GRAINS IN THE ANGIOSPERMS
Authors: Brewbaker James L.
Published: January 2018

Studies of the cytology of angiosperm pollen which extend our knowledge of the distribution of binucleate and trinucleate pollen to almost 2,000 species of flowering plants are summarized. Approximately 70% of the species studied release pollen in a binucleate stage, and none of them shed both types of pollen as a constant varietal trait. All phylogenetically primitive taxa are binucleate. The trinucleate trait evidently has originated independently at many times during angiosperm evolution. In no instance must one infer the origin of binucleate taxa from trinucleate ancestors. Most genera are monotypic with respect to pollen cytology, and only 10 genera are known to include both binucleate and trinucleate species. Among the 265 families studied, 179 include only binucleate genera and 54 include only trinucleate genera, while 32 include both types. Nearly all aquatic species with submersed flowers shed pollen in a trinucleate stage. A group of physiological differences which distinguish binucleate and trinucleate pollen is reviewed in relation to the survival and possible selective advantage of trinucleate mutants, and the significance of the binucleate pollen grain in the origin and evolution of flowering plants is discussed.