Showing papers in "Botanical Gazette in 1957"
TL;DR: Experiments with bean internode elongation show that this pigment is present and functioning in the plant at all times; no period of preliminary light or darkness is required for its generation.
Abstract: 1. Internodes of young seedlings of Pinto bean (Phaseolus vulgaris L.), grown under fluorescent lights, elongated to about three or more times their normal length in response to low radiant energies of unfiltered incandescent-filament light applied at the close of daily high-energy fluorescent-light periods. The lengthening response was due to the far-red radiant energy of the supplemental light and was completely and repeatedly reversible with red. Maximum lengthening occurred when the plants received cycles of about 4 hours of light and 20 hours of dark. Plants that received no daily high-energy period of light did not elongate in response to far-red treatments unless given sugar solution through their severed hypocotyls. 2. The lengthening response was found to result from the action of a photoreversible pigment which also controls flowering, seed germination, and certain other photoregulated phenomena. Experiments with bean internode elongation show that this pigment is present and functioning in the ...
219 citations
TL;DR: An attempt to work out the origin of the genus Saccharum from phytogeographical data, corroborated by morphological, cytological, and breeding evidences shows that Erianthus has the highest number of species, twenty-eight, and is most widely distributed in Asia, Europe, and America.
Abstract: 1. The present paper reports an attempt to work out the origin of the genus Saccharum from phytogeographical data, corroborated by morphological, cytological, and breeding evidences. 2. The distribution of Saccharum and its congeners shows that Erianthus has the highest number of species, twenty-eight, and is most widely distributed in Asia, Europe, and America. The majority of the species of Erianthus occur in India, particularly on the slopes and foothills of the Himalayas in eastern India and in America. Saccharum has in all five species occurring in India, Malaysia, and China, of which four occur in India. Sclerostachya has three species, two of which are found in India, and Narenga has two species, distributed in India, Indochina, and China. Hence the maximum concentration of species belonging to these four genera is in India. 3. It is suggested that the Saccharum complex originated in the Indo-Burma-Chinese region and spread to adjoining areas. It is quite likely that Saccharum, Sclerostachya, and N...
166 citations
TL;DR: The principal roles of the velamen in free aerial roots are mechanical protection and the prevention of excess loss of water from the cortex, as shown by studies on photosynthesis and respiration of detached roots.
Abstract: 1. The number of cell layers and the volume of cells in the velamen of the aerial roots of the several species of orchids studied are not constant but may be affected by the relative humidity in which the roots are growing. 2. In the plants studied, the pneumathodes do not have modified tissue, as reported by Haberlandt. The pneumathode cells are not wetted by water but are rendered wettable by addition of a detergent. Cell walls of the pneumathode and of the exodermis are more heavily lignified than are those of other velamen cells. The lignin of the pneumathode cells may differ in composition from that of the other cells. 3. The intact mature velamen and exodermis of the aerial roots of certain orchids seem to be nearly impermeable to water and certain solutes. Though the velamen may absorb both, little of either seems to penetrate into the living cortex within. Radioactive phosphorus could not be detected in leaves of orchids even after aerial roots had been immersed in a solution containing it for as ...
106 citations
TL;DR: How light acts in controlling flowering of several varieties of chrysanthemums was studied with greenhouse-grown plants from rooted cuttings and transferred to plant-growth rooms for the duration of the experiments, finding results to agree very closely with macroscopic observations made on other branches of the same plants after the plants had developed for several weeks after the light treatments.
Abstract: 1. How light acts in controlling flowering of several varieties of chrysanthemums was studied with greenhouse-grown plants from rooted cuttings and transferred to plant-growth rooms for the duration of the experiments. The radiation treatments, which were of 8 days' duration, were preceded and followed by non-inductive photoperiodic conditions. In most experiments the treatments consisted of brief irradiations with red or far red or both near the middle of the dark period, and the plants were dissected 2 weeks later to observe the flowering conditions. The stage of floral initiation was designated by numbers from 0 to 10; 0 represents a vegetative condition of the terminal meristem, and 10 the most advanced condition, in which perianth primordia were present on all florets. Dissection results were found to agree very closely with macroscopic observations made on other branches of the same plants after the plants had developed for several weeks after the light treatments. 2. Floral initiation was markedly ...
71 citations
TL;DR: It was shown that adenine and various related compounds can stimulate bud formation and kinetin is especially effective in promoting cell division in buds but not in the protonemata; a growth-inhibitory material is built up in the medium during the growth of the moss.
Abstract: 1. The effect of various factors leading up to development of the gametophore of Tortella caespitosa was investigated with special interest centered on auxins and nucleic acid derivatives. 2. Earlier work showing the inhibition of budding by high concentrations of auxins and the stimulatory effect of low concentrations was confirmed. 3. It was shown that (a) adenine and various related compounds can stimulate bud formation; (b) kinetin is especially effective in promoting cell division in buds but not in the protonemata; (c) a growth-inhibitory material is built up in the medium during the growth of the moss. 4. A mechanism is suggested for the formation of the gametophore.
69 citations
TL;DR: Cytological studies of hybrids between the 20-chromosome species revealed only bivalent pairing and normal meiosis, except for an infrequent bridge and fragment at anaphase I of two of the hybrids, and pairing of chromosomes in the analyzed hybrids supports the assumption that S. almum is a segregate from a cross between S. vulgare and S. halepense.
Abstract: 1. Cytological analysis of chromosome association at metaphase I was made in the parents and the hybrids of Sorghum vulgare x S. halepense, S. vulgare x S. almum, S. almum x S. halepense, S vulgare x S. arundinaceum, and S. vulgare x S. verticilliflorum. S. halepense and S. almum have 2n = 40, and the others have 2n = 20. 2. Heterosis was apparent in all hybrids with the exception of S. almum x S. halepense, which showed very little hybrid vigor. The chromosome number was determined for eleven of the seventeen hybrids of S. vulgare x S. halepense; one hybrid had 2n = 30, and ten had 2n = 40. Association of chromosomes at metaphase I was studied in three of these hybrids, and it was concluded from the type of pairing in the hybrids and the parents that one genome in S. halepense is similar to the genome in S. vulgare. Data also indicate that S. halepense arose as a segmental allopolyploid with only two genomes and that its chromosomal complement now consists predominantly of one genome, which is similar to...
65 citations
TL;DR: Chromosome numbers in various interspecific Saccharum hybrids are reported and a relatively large number of S. robustum hybrids have been studied, and all have n + n chromosome numbers.
Abstract: 1. Chromosome numbers in various interspecific Saccharum hybrids are reported. Aneuploid chromosome numbers which deviate greatly from any possible "expected" numbers are found only in false or doubtful hybrids. Otherwise, the results of earlier studies are generally supported. For the first time a relatively large number of S. officinarum x S. robustum hybrids have been studied, and all have n + n chromosome numbers. 2. Chromosome numbers are given for the following hybrid types not previously recorded in the literature: S. officinarum x 96-chromosome S. spontaneum n + n and 2n + n S. officinarum x 128-chromosome S. spontaneum 2n + n S. sinense (Pansahi group) x S. officinarum n + n and n + 2n S. sinense (Sunnabile group) x S. spontaneum n + n 3. Literature dealing with chromosome numbers in interspecific and intergeneric hybrids of Saccharum is reviewed and discussed.
59 citations
TL;DR: In the 1956-57 tests the Rubra and Azapa varieties were able to produce substantial numbers of inflorescences under the minimum amount of chilling given, indicating that they might be adaptable to regions of relatively high winter temperatures.
Abstract: 1. Inflorescence and subsequent fruit production in eight varieties of olives was, in general, directly proportional to the amount of winter chilling received. Trees of each variety maintained in a warm greenhouse throughout the winter failed to produce a single inflorescence. 2. The number of flowers per inflorescence or the percentage of perfect flowers produced was not affected by the amount of winter chilling 3. The varieties Ascolano and Sevillano required the maximum amount of winter chilling encountered at Davis, California, during each of two winters before appreciable amounts of inflorescences were produced 4. The varieties Mission, Criolla, Barouni, and Manzanillo produced some inflorescences with intermediate amounts of chilling, although considerably more developed with the full amount of chilling 5. In the 1956-57 tests the Rubra and Azapa varieties were able to produce substantial numbers of inflorescences under the minimum amount of chilling given, indicating that they might be adaptable to...
58 citations
TL;DR: The flowering response in Biloxi soybean is apparently influenced to a marked degree by some endogenous rhythm of 24 hours' duration, which might explain the results obtained with cycles of different durations at both normal and low temperatures.
Abstract: 1. Experiments with Biloxi soybean (Glycine max [L.] Merr.) showed that length of photoperiod as well as length of dark period influenced the degree of flower initiation. With effective dark periods there were lower-critical, optimum, and- upper-critical lengths of photoperiods. With effective photoperiods there were lower-critical, optimum, and upper-critical lengths of dark periods when cycles were shorter than 36 hours long. 2. These critical and optimum lengths of photoperiod became shorter when accompanied by longer dark periods; the converse was also true for critical and optimum lengths of dark period in relation to the length of the accompanying photoperiod. 3. Cycles with photoperiods 8 hours long and cycle lengths ranging from 18 to 56 hours showed two distinct optimum lengths of dark periods. These optima differed in duration by about 24 hours. With relatively short dark periods there was a lower-critical duration below which, and with very long dark periods there was an upper-critical duration...
44 citations
TL;DR: It appears that the root is the primary if not the sole site of atropine synthesis, when synthesis ofAtropine is considered on an organismal level, and that at least the final and most important rate-limiting steps of atopine synthesis occur in the root.
Abstract: 1. Isolated roots, root callus, and stem and leaf callus of Atropa belladonna L. were grown in vitro to determine the site of synthesis of atropine. Gautheret's medium plus various supplements were used. 2. The root callus possessed the capacity for unlimited growth in vitro and for development of an entire plant in that roots, stems, and leaves were formed. 3. Atropine in measurable amounts was obtained from the isolated roots and root callus grown in darkness, in absence of stems and leaves. The nutrient material in the medium apparently contained the necessary precursors of atropine. 4. Atropine was not detected in excised stem-and-leaf-callus tissues which had been grown in vitro for at least 4 months and which had not produced macroscopic adventitious roots. 5. The medium in which the isolated roots were grown contained 25-50 mg. of atropine which was detected chromatographically. 6. It appears that the root is the primary if not the sole site of atropine synthesis, when synthesis of atropine is cons...
44 citations
TL;DR: By use of certain characteristics frequently associated with apomictic species, that is, a series of polyploid forms, a disturbed meiotic behavior in division figures, a polymorphic species structure, and so forth, the authors have been able to select probable apomic species with considerable accuracy.
Abstract: 1. By use of certain characteristics frequently associated with apomictic species, that is, a series of polyploid forms, a disturbed meiotic behavior in division figures, a polymorphic species structure, and so forth, the authors have been able to select probable apomictic species with considerable accuracy. 2. Themeda triandra Forsk. and Bothriochloa ischaemum (L.) Keng., two perennial species of the tribe Andropogoneae important in warm and temperate grasslands throughout extensive areas of the Old World, have been shown to be aposporous apomicts with probable pseudogamous development of embryos. B. ischaemum is in all probability an obligately apomictic species, whereas in T. triandra there are probably diploid sexual forms. 3. The apomictic mechanism is essentially the same in both species and usually involves (a) degeneration of the egg mother cell; (b) initiation of one to several aposporous embryo-sac initials; and (c) following two nuclear divisions in each sac, the organization of 4-nucleate apos...
TL;DR: Ammonium and ethanolammonium ions, supplied either as salts of 2,4-D or as buffer cations, in alkaline solutions induced responses approaching those observed with acid solutions, while sodium and potassium ions did not manifest this property.
Abstract: The influence of several cations and anions on penetration of 2,4-D into leaves of bean plants was studied by measurement of growth responses. In the absence of other cations, the rate of absorption was dependent upon the hydrogen-ion concentration, in accord with the findings of earlier investigators. However, at neutral or alkaline pH values, the response was found to be influenced markedly by certain cations. Thus, ammonium and ethanolammonium ions, supplied either as salts of 2,4-D or as buffer cations, in alkaline solutions induced responses approaching those observed with acid solutions. On the other hand, sodium and potassium ions did not manifest this property. The cation effect was influenced to some extent also by certain anions and surfactants.
TL;DR: The soil fungi of two grassland plots in central Oklahoma were compared during 1952 and some definite differences were found between the fungous populations of the two plots on a monthly or seasonal basis.
Abstract: 1. The soil fungi of two grassland plots in central Oklahoma were compared during 1952. Species numbers were determined for each of 9 months in an abandoned field and a prairie. 2. The average number of fungi per gram (based on the total number of colonies per plate) was greater in the field plot throughout the year. The difference in numbers between plots was greatest in early summer and winter and least in spring and late summer. Numbers in both plots were lowest in summer and highest in spring. 3. Usually a greater number of species was found in the abandoned field. The average percentage of species common to both plots was 35.2. A greater number of species was found in the abandoned field only (average 37.4%) than in the prairie only (average 27.9%). 4. Although a few species appeared with a high frequency throughout the year, most species were of seasonal or sporadic occurrence. This means that the species composition of each plot changes from season to season and, to a lesser degree, from month to m...
TL;DR: The mean number of seeds per capsule was considerably lower for plants with, than for plants without, a heterozygous reciprocal translocation, and this number proved to be a reliable criterion for positive identification of the two types.
Abstract: 1. At least one plant with a heterozygous reciprocal translocation was found in the progeny of each of sixteen of thirty plants of Collinsia heterophylla Buist (n = 7) treated by three different methods of application. 2. The interchange complex in the eighteen reciprocal translocations occurred either as a ring or chain of four chromosomes and as bivalents at metaphase I; the frequencies of each configuration were not constant for all the reciprocal translocations. 3. The orientation of ring and chain interchange complexes at metaphase I to give either an adjacent or an alternate orientation was not directed, since the two types of orientation occurred with approximately equal frequencies. 4. Although plants with a heterozygous reciprocal translocation usually had a lower percentage of stainable pollen grains, this criterion was not reliable for their positive identification. The mean number of seeds per capsule, however, was considerably lower for plants with, than for plants without, a heterozygous rec...
TL;DR: Embryos grown without GA exceeded the initial values for nitrogen per embryo, suggesting a capacity for protein synthesis and a dilution of protoplasm in this group as a result of the apparent inhibition by GA of nitrate uptake or of protein synthesis.
Abstract: 1. Embryos of upland cotton (Gossypium hirsutum) at two ages, having fresh weights of 37 and 64 mg., were cultured for 10 days in four different media: (a) Cultured control, complete medium containing inorganic salts and sucrose. (b) IAA, complete medium plus indoleacetic acid 10-5 M. (c) IAA/GA, complete medium plus indoleacetic acid 10-5 M and gibberellic acid 10-5 M. (d) GA, complete medium plus gibberellic acid 10-5 M. 2. Fresh and dry weights of the embryos and cell numbers of the cotyledons and axes individually were obtained for the various groups of each culture. After freeze-drying, biochemical determinations for total nitrogen and total carbohydrate were found and calculated on a per embryo and per cell basis. Starch and aleurone protein were identified by microscopic examination of sectioned material. These determinations were made on samples both of the initial embryos and after 10 days of culturing. 3. The embryos of the 37-mg. culture showed no capacity for cell division or elongation, nor c...
TL;DR: The rate of decline in transpiration of an excised leaf or twig from an oak or pine in the first 6 minutes after severing was found to be quite variable, depending on the species and the time of day.
Abstract: 1. The rate of decline in transpiration of an excised leaf or twig from an oak (Quercus coccinea Muenchh.) or pine (Pinus strobus L.) in the first 6 minutes after severing was found to be quite variable, depending on the species and the time of day. Oak leaves showed especially rapid decline in the afternoon, with definite decreases within 1 minute of severing; on similar days pine leaves were less responsive to cutting from the tree, whether twigs or fascicles were used, and transpiration declined only slightly after severing in the subsequent 6 minutes. 2. Night rates for oak often showed a slight increase after severing and then a decline about 3 minutes after severing, but the pine leaf transpiration was quite steady at night for the same 6-minute period. 3. Diurnal trends for either oak or pine transpiration showed that cloudy and clear days had about the same effect on total rates. Likewise, occasional periods of cloudiness during the day had no apparent effect in depressing the rate in either oak o...
TL;DR: The phenotypes were arbitrarily divided into six groups: five groups are based on the organ or organs affected, and a sixth group includes genes affecting growth and developmental characters.
Abstract: 1. Forty-eight loci were identified in Collinsia heterophylla Buist (n = 7). 2. The phenotypes were arbitrarily divided into six groups: five groups are based on the organ or organs affected, and a sixth group includes genes affecting growth and developmental characters. 3. The type of division and the number of divided leaves were controlled by two closely linked genes of which one has two dominant allels. 4. The intensity of the color of the upper and lower lips of the flower was influenced by genic interactions. 5. Two linkage groups were established with eight genes in group I and nine genes in group III. Two genes had already been placed in group II by Hiorth.
TL;DR: A survey is given of the developmental history of certain leaves, based upon both earlier publications and further unpublished observations by the author, and a dorsal meristem is now known which may give rise to strongly protruding midribs, dorsal keels, or ligulae (Thalictrum).
Abstract: 1. A survey is given of the developmental history of certain leaves, based upon both earlier publications and further unpublished observations by the author. 2. The arrangement of the vascular bundles in plant organs depends on the prevailing morphological and physiological conditions. For example, a circular arrangement of vascular bundles in cylindrical organs is insufficient proof of their unifaciality. Such a conclusion can be reached only by ontogenetic methods. 3. Some instances were observed in which the leaf petiole is derived from the leaf-base (Unterblatt) instead of from the upper-leaf (Oberblatt) as usual. 4. Apical growth of angiosperm leaves generally ceases early; certain leaves, however, are capable of producing a second growing point on the abaxial surface of the primordium, from which "precursory apices" (Hemerocallis), complete swordlike blades (Iris), and even pitcher-like leaves (Sarracenia) may arise. 5. In many instances no sharp line exists between apical and marginal growth in the...
TL;DR: The morphology and vascular anatomy of the inflorescence shows that the so-called umbel of Samadera indica is a condensed thyrsoid inflorescence and the floral parts are considered to be lateral organs, and the bundles fusing with the ventrals are interpreted as belonging to a third whorl of carpels.
Abstract: 1. The morphology and vascular anatomy of the inflorescence shows that the so-called umbel of Samadera indica is a condensed thyrsoid inflorescence. 2. The flowers of S. indica and S. lucida are pedicellate, bracteate, actinomorphic, dichlamydous, bisexual, hypogynous, and tetramerous. The vascular anatomy of the two species is similar. Each sepal has a gland on the dorsal side. The sepal laterals arise commissurally. The petal is a single-trace organ. 3. The stamens are in two whorls of four each. Anatomically there is no indication of obdiplostemony. Each stamen has a bilobed scale at the base of the filament which is interpreted to be stipular in nature. A single trace enters the filament of each stamen and becomes siphonostelic. The filament is considered to correspond to a petiole. 4. The vascular supply to the disk occurs on radii alternating with the carpellary supply. The disk breaks up into four lobes, each lobe alternating with the antepetalous free carpels. The disk is considered to be a modifi...
TL;DR: Parenchyma and epidermal cell lengths and their relationship to culm internode length and plant height were studied in eight varieties of winter wheat grown in a field nursery at Lincoln, Nebraska, in 1954.
Abstract: 1. Parenchyma and epidermal cell lengths and their relationship to culm internode length and plant height were studied in eight varieties of winter wheat (Triticum aestivum L.) grown in a field nursery at Lincoln, Nebraska, in 1954. 2. Both cell types differed significantly in length in the different internodes. Generally close agreement in cell length was observed for the two cell types in corresponding internodes. 3. An inverse relationship was found to exist between lengths of parenchyma cells and of culm internodes. The longest parenchyma cells occurred in the shortest (lowest) internode, and parenchyma cell length was less in each successively higher and longer internode. 4. Epidermal cell length followed somewhat the same pattern as parenchyma cell length but was less consistent. The shortest epidermal cells were always in the peduncle or longest internode, but the longest ones occurred variously in the first, second, or third internodes. 5. Significant varietal differences in cell length were found...
TL;DR: Results from seeds planted in soil in greenhouse flats and stratified outdoors during the winter for various periods indicated that 1 or 2 months of stratification sufficed for the breaking of dormancy, and after-ripening occurred only at low temperatures and when the seeds were moist.
Abstract: 1. Seeds obtained from selfing Hemerocallis minor and from intercrossing hybrid Hemerocallis plants of complex origin were used in a series of experiments in 1953, 1954, and 1955 to determine the nature of seed dormancy in this genus. 2. Freshly harvested seeds germinate to a limited extent but only within a narrow temperature range. Minimum, optimum, and maximum temperatures for non-stratified seeds were found to be above 16⚬, 22⚬-25⚬, and below 33⚬ C., respectively. 3. Differential peeling experiments demonstrated that an endosperm membrane one cell thick, which covers the protruding tip of the hypocotyl, was responsible for delayed germination at 22⚬ C., while at 16⚬ C., in addition to the membrane, endosperm storage tissue restricts gaseous diffusion. Complete germination was brought about at 16⚬ C. either by removing a wedge of storage tissue to expose about one-fourth of the embryo axis or by completely excising the embryo, as compared with little or no germination of intact seeds. Sealing of the hy...
TL;DR: In this paper, a statistical analysis of available data on the types of endosperm and vessel perforation in dicotyledonous taxa indicates that (a) nuclear-type Endosperm is positively associated with porous perforations and (b) Cellular-type EUs are negatively associated with vessel perfusion.
Abstract: 1. Statistical analysis of available data on the types of endosperm and of vessel perforation in dicotyledonous taxa indicates that (a) Nuclear-type endosperm is positively associated with porous perforation and that (b) Cellular-type endosperm is negatively associated with such perforation. 2. As it has been well established that porous perforation of the vessel member represents a high degree of phylogenetic specialization, it follows that Nuclear-type endosperm is in all probability more advanced than Cellular-type endosperm.
TL;DR: Cocklebur plants (Xanthium pensylvanicum Wallr.) exhibiting iron-deficiency symptoms during photoinductive treatment either did not flower subsequently or flowered abnormally when maintained on complete nutrient solution.
Abstract: 1. Cocklebur plants (Xanthium pensylvanicum Wallr.) exhibiting iron-deficiency symptoms during photoinductive treatment either did not flower subsequently or flowered abnormally when maintained on complete nutrient solution. 2. The abnormal flowering was characterized by (a) the delayed appearance and slower development of terminal staminate inflorescence primordia, (b) the development of pistillate inflorescences, which were surrounded by "rosettes" of many leaves, and (c) the failure of pistillate inflorescences to produce mature burs. 3. Plants which had recovered from iron deficiency and were then subjected to photoinductive treatment flowered normally. 4. A low carbohydrate level in - Fe plants during induction is apparently not responsible for their abnormal flowering, since - Fe plants supplied with 10% sucrose solution during photoinductive treatment also flowered abnormally. The - Fe plants supplied with sucrose soon exhibited more vigorous stem elongation than did - Fe plants not given sucrose, ...
TL;DR: The phloroglucin-hydrochloric acid test indicated that the cells immediately outside the primary vascular tissue was designated as pericycle, and the next layer of cells as endodermis become lignified at the same time and to the same degree as the protoxylem elements.
Abstract: 1. Differentiation in the apple root proceeds in an acropetal direction. Although vacuolation occurs in the metaxylem region first, this tissue is the last to mature. Sieve tubes are the first vascular elements to mature, followed by xylem. 2. Thickenings occur on the radial and transverse walls of the cortical cells just outside the endodermis. These thickenings develop simultaneously with the first protoxylem elements. The phloroglucin-hydrochloric acid test indicated that they become lignified at the same time and to the same degree as the protoxylem elements. 3. The layer of cells immediately outside the primary vascular tissue was designated as pericycle, and the next layer of cells as endodermis. 4. Suberin lamellas develop on the walls of the cells of the endodermis. The deposition takes place at first in the cells outside the primary phloem poles and then proceeds toward the primary xylem poles. 5. The number of xylem arcs which develop is not constant but appears to be correlated with the diamete...
TL;DR: Ontogenetic evidence indicates that the mesocotyl is an internode, the lowermost of the shoot, and its transitional character is made evident by the presence of endodermis, pericycle, and a cylindrical, bilaterally symmetrical arrangement of vascular bundles.
Abstract: 1. The ontogeny of the mesocotyl in Zea mays seedlings grown in darkness is described for the first 10 days of growth. The vascular system is evident in the embryo and is mainly procambial. In cells of all the tissues (protoderm, procambium, and ground meristem) elongation occurs first near the base of the mesocotyl adjacent to the scutellar plate. Elongation gradually progresses upward to the coleoptilar node. All the bundles within the mesocotyl are leaf traces or fusion products of several leaf traces. There is no regular pattern of fusion between leaf traces. 2. The various bundles of the mesocotyl differentiate in a regular order: the two coleoptilar sympodia, leaf 1 sympodium, the lateral compound bundles adjacent to the leaf 1 sympodium, and, last, the two lateral sympodia next to the coleoptilar bundles. 3. There is a continuous acropetal pattern of differentiation and maturation of cells of the procambium, protophloem, metaxylem, and metaphloem of each strand and in the pericycle and endodermis. ...
TL;DR: It is proposed that physiological studies of weedy species may reveal means of altering the environment in ways disadvantageous to the weed and suggest additional methods of control.
Abstract: 1. Evidence was obtained demonstrating that soil temperature may determine which weedy plants emerge in competition with seeded grass. A comparison of species was made by subjecting seeded grasses and weeds to several levels of soil heat in a controlled temperature chamber. The relative differences in heat tolerance so obtained agreed with the seasonal emergence pattern of these weeds in the field. 2. The winter annual grasses possess a lower pre-emergence temperature tolerance than do several perennial grasses used in range reseeding, while certain forbs possess a higher pre-emergence temperature tolerance. 3. A degree of regulation of the weedy competition resulting from seed resident in the soil may be attained by timing preparatory tillage operations and the date of seeding with regard to prevailing temperatures. 4. It is proposed that physiological studies of weedy species may reveal means of altering the environment in ways disadvantageous to the weed and suggest additional methods of control.
TL;DR: Combustion analyses indicate that the amount of deuterium incorporated into fixed positions in the mycelia is only about half the deuterum level in the corresponding medium.
Abstract: 1. Differences in the growth rate and morphology of Penicillium notatum Westling and Aspergillus fonsecaeus Thom and Raper grown in Czapek media containing 0, 10, 25, 33, 50, 66, and 99 atom % deuterium were studied over a period of 3 months. 2. The growth rate of both fungi was inversely proportional to the deuterium content of the medium. The total amount of growth made over a 3-month period showed reduction first at the 50 atom % D level with P. notatum and at the 66 atom % D level with A. fonsecaeus. 3. In both fungi the type of growth varied from a "floating-mat type" in 0 atom % D media to a "submerged floccose type" in 99 atom % D media. The production of pigment and aromatic substances was succeedingly lower in each medium of higher deuterium concentration. 4. Sporulation was inhibited in both fungi: P. notatum sporulated only in media containing 0, 10, and 25 atom % D; A. fonsecaeus sporulated in all media except the one containing 99 atom % D. 5. Among the cultures grown at different deuterium c...
TL;DR: It is concluded, therefore, that GA and auxin did not interact to cause GA-induced cell elongation in zinnia seedlings.
Abstract: Spraying zinnia seedlings (Zinnia elegans var. Scarlet Flame) with triiodobenzoic acid and thus upsetting the polarity did not interfere with cell elongation stimulated by GA spray. It is concluded, therefore, that GA and auxin did not interact to cause GA-induced cell elongation.
TL;DR: The inflorescence in Prosopis spicigera L. is an axillary or a terminal spike containing fifty to sixty flowers, and that in Desmanthus virgatus Willd.
Abstract: 1. The inflorescence in Prosopis spicigera L. is an axillary or a terminal spike containing fifty to sixty flowers, and that in Desmanthus virgatus Willd. is a solitary, axillary, globose head of fifteen to twenty flowers. The number of fruits formed per inflorescence is two to four in the former, and four to six in the latter, plant. 2. The cyclic floral parts arise in acropetal succession. 3. The parietal tissue of the anther is composed of an endothecium, and one or two middle layers and a tapetum which disintegrate. The tapetum is of the secretory type, and its cells remain uninucleate. 4. The microsporangial archesporium differentiates rather late. The microspore mother cells produce tetrahedral tetrads following the meiotic divisions, and cytokinesis takes place by furrowing. Some isobilateral tetrads are also produced in P. spicigera. 5. The pollen grains are simple and belong to the Prosopis glandulosa type. They are two-celled at the time of shedding. 6. The ovules are anatropous and bitegmic. Th...
TL;DR: Yellow lupine (Lupinus luteus L.) infected with common pea-mosaic virus showed two types of reaction: almost complete sterility of flowers and continuous growth or a highly stimulated pod-setting and no continuous growth.
Abstract: 1. Yellow lupine (Lupinus luteus L.) infected with common pea-mosaic virus showed two types of reaction: (a) almost complete sterility of flowers and continuous growth or (b) a highly stimulated pod-setting and no continuous growth. 2. Since both reaction types were due to the same virus, experiments were designed to determine whether there was possible genetic difference in reaction in the two types of host plants, and to study the effects of infection at different stages of development of the plants. 3. Apart from a slight varietal difference in reaction between varieties Weiko III, on the one hand, and Weiko II and New Zealand Sweet Yellow, on the other, no genetic difference in reaction was found. 4. Early infection, before appearance of the main inflorescence, caused plants to produce an increased number of flowers per inflorescence, but these flowers were usually sterile, and growth continued through development of lateral shoots. 5. Plants infected later, when inflorescences appeared, produced almo...