bluuebunny/crossref_metadata_2025 huggingface dataset:
GROWTH STUDIES OF THE ROOT OF INCENSE CEDAR, LIBOCEDRUS DECURRENS. II. MORPHOLOGICAL FEATURES OF THE ROOT SYSTEM AND GROWTH BEHAVIOR
Authors: Wilcox Hugh
Published: January 2018

Wilcox, Hugh. (State U. Coll. of Forestry, Syracuse, New York.) Growth studies of the root of incense cedar, Libocedrus decurrens. II. Morphological features of the root system and growth behavior. Amer. Jour. Bot. 49(3): 237–245. Illus. 1962.—The common pattern of root growth in incense cedar involves a rush of growth in the spring, a midsummer low, and a renewed surge in the fall. Not all of the roots of a seedling grow at any one time, but some roots are growing while others are dormant. The cycle of growth of an individual root varies from 3 to 9 weeks or more; the large‐diameter roots and the principal laterals grow more rapidly and for longer periods than the smaller‐diameter roots or those of higher order. Roots of various growth rates were treated with different concentrations of indoleacetic acid and with extracts from growing and dormant roots. Roots show adaptation to the lower concentrations of IAA, with subsequent stimulation of elongation occurring in solutions of concentrations 10‐6 through 10‐9 moles/liter of IAA. Roots which have been growing slowly at the time of treatment are more strongly stimulated than those which have been growing rapidly. Roots do not become adapted to root extracts but remain inhibited by all such treatments. A study of the anatomical features of dormant and actively growing roots provides indirect evidence that a number of hormonal factors are operating to control the various physiological activities associated with the growth of the root.
A CYTOTAXOXOMIC SURVEY OF MELAMPODIUM (COMPOSITAE‐HELIANTHEAE)
Authors: Turner B. L. , King R. M.
Published: January 2018

Turner, B. L.. and R. M. King. (U. Texas, Austin.) A cytotaxonomic survey of Melampodium (Compositae‐Heliantheae). Amer. Jour. Bot. 49(3): 233–26. Illus. 1962.—Chromosome counts are reported for individuals from 89 populations of Melampodium representing 26 species The genus is multibasic with x = 9, 10, 11, 12, 16 and 23. Chromosome numbers on a base of x = 10 characterize the section Melampodium while basic numbers of x = 23, 16, 12, 11 and 9 occur in the section Zarabellia. Melampodium camphoratum (n = 16) differs from all other species examined in having relatively small meiotic chromosomes. Only 6 of the 23 species are polyploid or have polyploid races. Melampodium leucanthum and M. cinereum have both diploid and tetraploid populations; the latter occur without any apparent morphological or geographical correlation and are probably autoploid in origin. A survey of the basic chromosome numbers known for other genera of the subtribe Melampodinae (12 of 22 genera) is presented. and it is suggested that x = 10 is the most probable basic number of the genus and subtribe.
MORPHOLOGY OF THE CURD OF CAULIFLOWER
Authors: Sadik Sidki
Published: January 2018

Sadik, Sidki. (U. California, Davis.) Morphology of the curd of cauliflower. Amer. Jour. Bot. 49(3): 290–297. Illus. 1962.—The development of the curd and inflorescence of cauliflower, Brassica oleracea Linn., var. botrytis D.C., is described. The cultivars ‘Snowball M’ and ‘February‐Early‐March’ were studied. The curd has a nonfasciated and monopodial type of branching. Curd initiation of ‘Snowball M’ is not dependent on vernalization, but the curd of ‘February‐Early‐March’ and the floral primordia of both cultivars are initiated only after vernalization. Associated with flowering is the disruption of the curd by the elongation of some of the inflorescence branches. The initiation of leaves, branches, and floral primordia follows a 5 + 8 phyllotaxy throughout all stages of development. This system of phyllotaxy changes at the time of initiation of floral parts.
THE EMERGENCE AND DEVELOPMENT OF BRANCHES IN CROTALARIA JUNCEA AND THEIR RELATIONSHIP TO FLOWERING
Authors: Nanda K. K.
Published: January 2018

Nanda, K. K. (Forest Res. Inst., Dehra Dun, India.) The emergence and development of branches in Crotalaria juncea and their relationship to flowering. Amer. Jour. Bot. 49(4): 334–341. Illus. 1962.—Seeds of Crotalaria juncea L. were sown in pots on March 23, 1959, and records were kept of the dates of emergence of individual branches and the appearance of flower buds on them. Periodical observations were also made of the height of the main shoot as well as its branches and the number of nodes and leaves borne by them throughout the year. The main shoot elongates rapidly and terminates in an inflorescence. Development of lateral buds remains completely arrested during the period of rapid elongation and is initiated only after the appearance of the floral buds when it takes place in basipetal sequence. The flowering of the branches also takes place in a basipetal manner. This mode of emergence of branches and their flowering are exhibited even by secondary and tertiary branches. The length attained by these branches is very small as the flower buds appear soon after their emergence. In contrast, the branches formed towards the middle of May continue to elongate for a considerable period and become many times longer than the main shoot or the branches produced earlier in the season. The vegetative period of these branches is also very much prolonged. These differences in the height attained by branches produced at different times of the year and the basipetal sequence in the emergence of branches and their flowering appear to be under the control of some physio‐chemical changes which cause the transformation of the growing apex from the vegetative to the reproductive state. This holds good irrespective of whether these changes are brought about as a result of a favorable environmental complex, as is the case with the main shoot and late‐formed, much elongated branches, or are due to the favorable internal conditions produced within the plant as a result of the completion of the developmental process of the main shoot, as happens in the case of branches produced earlier in the season.
POLYGONAL ASPECTS OF CELL FACES. II. QUADRILATERALS AS THE PREVAILING TYPE
Authors: Wheeler George E.
Published: January 2018

Wheeler, George E. (Brooklyn Coll., Brooklyn, New York.) Polygonal aspects of cell faces. II. Quadrilaterals as the prevailing type. Amer. Jour. Bot. 49(4): 355–362. Illus. 1962.—Quadrilateral faces are abundant and even predominant among the faces of certain types of cells. Data taken from the literature and several original samples were studied to define the conditions which foster large numbers of quadrilaterals. The presence of free faces (cells on air spaces) profoundly affects cell‐face distributions. There is a great excess of quadrilaterals on cells with 2 free faces on opposite sides (cells of single layers). Among cells with 1 free face (cells of epidermises), pentagonal faces usually surpass quadrilateral faces, although they are just about equal in a few samples. Intermediate ratios of the 2 face types occur in samples which include cells having faces touching 1 free face, mixed with cells having faces between 2 free faces. The “competition” for numerical superiority shifts to pentagons vs. hexagons, among cells comprising internal tissues (cells in contact on all sides with other cells). With respect to epidermises, the relative size of epidermal and of subepidermal cells strongly influences the relative numbers of quadrilaterals and pentagons. A marked trend toward quadrilaterals may also be found in connection with a quite different set of cell relationships: if 2 layers of elongated cells occur together, and if their long axes are mutually perpendicular, then a “checkerboard” pattern may result. This arrangement favors large numbers of quadrilateral faces; in some samples, they may even dominate. It is suggested that certain modifications of this pattern may generate large numbers of triangular and of lenticular (lens‐shaped) faces. Varying patterns of cell division are considered to be primarily responsible for changes in cell‐face distributions and for changes in predominating face types.
THE USE OF POLLEN MORPHOLOGY IN THE TAXONOMY OF DICENTRA
Authors: Stern Kingsley R.
Published: January 2018

Stern, Kingsley R. (Chico State Coll., Chico, Calif.) The use of pollen morphology in the taxonomy of Dicentra. Amer. Jour. Bot. 49(4): 362–368. Illus. 1962.—The pollen morphology of Dicentra has proved to be of great interest because of interspecific differences in surface character istics of pollen grains in all but 2 instances within the genus. Descriptions of the pollen of the 19 species and a key based on pollen morphology are given. Correlations between pollen morphology and gross morphology and anatomy are discussed, and phylogenetic trends are indicated.
THE ROLE OF LIGHT IN HISTOGENESIS AND DIFFERENTIATION IN THE SHOOT OF PISUM SATIVUM. II. THE LEAF
Authors: Thomson Betty F. , Miller Pauline Monz
Published: January 2018

Thomson, Betty F., and Pauline Monz Miller. (Connecticut Coll., New London.) The role of light in histogenesis and differentiation in the shoot of Pisum sativum, II. The leaf. Amer. Jour. Bot. 49(4): 383–387. Illus. 1962.—Development of the form and anatomy of leaves was studied in plants of Pisum sativum grown in vermiculite under constant conditions and exposed daily to red or white light or kept in continuous darkness. The red light used had an intensity in the morphogenetically active red region of the spectrum of 70–75% that of the white light. Light had no effect on the manner of initiation or early development of leaf primordia. Quantitative data from older leaves showed that light has no effect on the pattern of later development but does affect the rate and extent of development. Under all light conditions, the length of the leaflet is closely correlated with the state of its internal anatomy. “Mature” etiolated leaves duplicate young stages of light‐grown leaves. Mature leaves grown in red light duplicate not‐quite‐mature leaves grown in white light. The difference between white‐light and red‐light leaves is attributed here to light intensity and resembles that between sun and shade leaves.
THE TIME AND SITE OF THE SEMIDOMINANT LETHAL ACTION OF “Wo” IN LYCOPERSICON ESCULENTUM
Authors: Huang P. C. , Paddock E. F.
Published: January 2018

Huang, P. C. (California Inst. Technol., Pasadena), and E. F. Paddock. The time and site of the semidominant lethal action of “Wo” in Lycopersicon esculentum. Amer. Jour. Bot. 49(4): 388–393. Illus. 1962.—The semidominant lethal gene, Wo (Woolly), in Lycopersicon esculentum has been investigated with specific attention to its lethal action. The primary lethal action is believed to occur prior to the torpedo stage of embryonic development (approximately 22 days after anthesis). The presumed WoWo embryos cease to grow before any cambial differentiation or organogenesis can be recognized. Their accompanying endospermous cells, however, continue to divide, this resulting in full‐sized seeds. The death of these embryos probably occurs near the time of maturation of the seeds (approximately 52 days after anthesis or when the ovulary turns orange‐red). The mechanism of death of the embryo apparently lies in and is specific to the embryo; hence, this is a case of autogenously determined embryonic lethality.
SOMATIC MITOSIS IN NEUROSPORA CRASSA
Authors: Ward E. W. B. , Ciurysek K. W.
Published: January 2018

Ward, E. W. B., and K. W. Ciurysek. (Canada Department of Agriculture, Edmonton, Alberta.) Somatic mitosis in Neurospora crassa. Amer. Jour. Bot. 49(4): 393–399. Illus. 1962.—The process of nuclear division in the vegetative mycelium of Neurospora crassa was studied with the aid of the HCl‐Giemsa staining technique. Division followed the conventional mitotic sequence and 7 morphologically distinct chromosomes were demonstrated at metaphase. The findings are discussed in relation to other proposed schemes of nuclear division in the fungi.
THE DEVELOPMENTAL MORPHOLOGY OF NICOTIANA TABACUM ‘WHITE BURLEY’ AS INFLUENCED BY VIRUS INFECTION AND GIBBERELLIC ACID
Authors: Stein Diana B.
Published: January 2018

Stein, Diana B. (U. Montana, Missoula.) The developmental morphology of Nicotiana tabacum ‘White Burley’ as influenced by virus infection and gibberellic acid. Amer. Jour. Bot. 49(5): 437–443. Illus. 1962.—‘White Burley’ tobacco with Severe Etch Virus (SEV) displayed a reduction of plant height which was overcome to a limited degree by spraying with gibberellic acid (GA). Spraying with GA, while hastening maturity in terms of earlier elongation and flowering, also prolonged the life of treated plants. Infection with SEV caused an increased rate of leaf production, and since flowering was also delayed, the greater number of leaves is produced by infected plants. Spraying with GA also increased the rate of leaf production but did not increase the final number of leaves produced. All groups except the unsprayed virus‐infected plants showed a spurt in leaf production just prior to flowering. The pattern of internode elongation was obtained by the periodic measurement of individual internodes. In general, this pattern reflected the stunting properties of the virus and the growth‐promoting properties of the GA. Internodes which were mature at time of spraying with GA were not affected. Infection with virus generally delayed elongation and shifted the internode pattern. Infection with SEV tended to reduce the size of leaves already present prior to inoculation, but some leaves produced after infection were actually 1arger than the same leaves on the controls. Spraying a healthy plant with GA made older leaves longer and wider, while less mature leaves at time of treatment tended to be longer and narrower. Spraying with GA reversed the reduction in size caused by the virus only if the leaf was a very young primordium or was formed during the course of treatment with GA.
THE EFFECTS OF AUXINS AND KINETIN ON XYLEM DIFFERENTIATION IN THE PEA EPICOTYL
Authors: Sorokin Helen P. , Mathur S. N. , Thimann Kenneth V.
Published: January 2018

Sorokin, Helen P., S. N. Mathur, and Kenneth V. Thimann. (Harvard U., Cambridge, Mass.) The effects of auxins and kinetin on xylem differentiation in the pea epicotyl. Amer. Jour. Bot. 49(5): 444–454. Illus. 1962.—Treatment of isolated segments from the second internode of etiolated ‘Alaska’ pea epicotyls with indoleacetic acid or 2,4‐D results in: (1) activation of fascicular cambium, and initiation of some interfascicular cambium, resulting in abundant production of secondary xylem, and in formation of hyperplastic tissue; (2) partial or even total occlusion of proto‐ and metaxylem. The secondary xylem formed consists of short vessel members with scalariformly reticulate or pitted walls, which often lack vertical connection with each other, being interrupted by unlignified cells. When IAA is used, the hyperplastic growth mainly takes the form of root primordia, whereas 2,4‐D initiates the formation of callus, but not of root primordia. The growth of this callus causes a characteristic split at the base of the internode. Treatment with kinetin, alone or in combination with the auxin, changes the above structure markedly. It leads to the initiation, over the entire circumference of the core of the internode, of a still more active cambium, which forms several layers of secondary xylem; this consists mainly of long vessel members with pitted walls. Hyperplastic growth is completely absent, and the xylem does not become occluded. Thus the effect of kinetin is to make the xylem more normal and to alter the epicotyl structure from herbaceous to more‐or‐less woody.
CALCIUM AND THE CONTROL OF LIGNIFICATION IN TISSUE CULTURES
Authors: Lipetz Jacques
Published: January 2018

Lipetz, Jacques. (Rockefeller Inst., New York, N. Y.) Calcium and the control of lignification in tissue cultures. Amer. Jour. Bot. 49(5): 460–464. Illus. 1962.—Crown‐gall tissues of Helianthus, Parthenocissus, Nicotiana, habituated Nicotiana, normal carrot, and Parthenocissus tissues grown in vitro on media low in calcium show an increase in lignification. The lignin is deposited not only on the walls of tracheids but on the walls of parenchymatous cells as well. Transferring the tissues to media containing higher calcium concentrations inhibits this excess lignification. Neither strontium nor magnesium could be substituted for calcium. These studies indicate that the availability and concentration of inorganic ions play a role in the control of lignification.
RESTING CELLS OF PEDIASTRUM
Authors: Davis Joseph S.
Published: January 2018

Davis, Joseph S. (Southern Illinois U., Edwardsville.) Resting cells of Pediastrum. Amer. Jour. Bot. 49(5): 478–481. Illus. 1962.—After approximately 10 weeks in a partially defined mineral medium, cells of vegetative colonies of Pediastrum boryanum lost their chlorophyll and became orange resting cells. The resting cells were colored orange by carotenoid pigment dissolved in fat droplets within the cells. No cell wall thickening occurred during or after resting‐cell formation. Starch was abundant in the resting cells. Dried resting cells remained viable for at least 4 years. When placed in the culture medium, 4‐year‐old dried resting cells became green and reproduced like vegetative cells.
THE POLLEN‐TUBE CHEMOTROPIC FACTOR FROM ANTIRRHINUM MAJUS: BIOASSAY, EXTRACTION, AND PARTIAL PURIFICATION
Authors: Mascarenhas Joseph P. , Machlis Leonard
Published: January 2018

Mascarenhas, J. P., and L. Machlis. (U. California, Berkeley.) The pollen‐tube chemotropic factor from Antirrhinum majus: bioassay, extraction, and partial purification. Amer. Jour. Bot. 49(5): 482–489. Illus. 1962.—A new method for quantitatively detecting pollen‐tube chemotropism is described. Extracts from the gynoecial tissues of snapdragon were prepared. Fractionation by paper chromatographic methods as well as by passage through Sephadex 25 indicated that the active moiety is associated with large molecules and can be partially dissociated by treatment with methanol. The active material was not found among a large number of common metabolites and plant growth hormones. It was shown that chemotropic activity was also present in nongynoecial tissues of snapdragon as well as in one other plant. This demonstration depended on using a membrane to prevent interference by pollen‐tube growth inhibitors.
FOLIAR VENATION PATTERNS IN THE RUTACEAE
Authors: Dede Roland A.
Published: January 2018

Dede, Roland A. (California Concordia Coll., Oakland.) Foliar venation patterns in the Rutaceae. Amer. Jour. Bot. 49(5): 490–497. Illus. 1962.—A study of herbarium specimens selected from 80 genera of the Rutaceae revealed a series of 7 venation types. The series is based on the spatial relationship of the venation system to the secretory cavities. The hypothesis is advanced that the uncorrelated venation pattern is primitive and that the more complex types represent end products involving a branching pattern of phylogenetic sequences. A key to the illustrated representatives of the 7 types is included.
SEED GERMINATION STUDIES IN MUSA. I. SCARIFICATION AND ASEPTIC GERMINATION OF MUSA BALBISIANA
Authors: Stotzky G. , Cox Elsie A. , Goos Roger D.
Published: January 2018

Stotzky, G., Elsie A. Cox, and Roger D. Goos. (Central Research Labs., United Fruit Co., Norwood, Mass.) Seed germination studies in Musa. I. Scarification and aseptic germination of Musa balbisiana. Amer. Jour. Bot. 49(5): 515–520. Illus. 1962.—Methods for germinating seeds of Musa balbisiana Colla under aseptic conditions have been developed. Scarification was required for germination under these conditions, and mechanical was superior to chemical scarification. Various methods of mechanical scarification and cultural procedures were developed which facilitated the operation when large numbers of aseptic seedlings were required. Removing a chip from the lateral portion of the seed coat to expose the endosperm was the most effective method of scarification: germination percentages averaged 80%, and the time required for germination in sterile culture was shortened from the 3–6 weeks required for intact seeds in soil to 6–10 days. However, scarification did not shorten the time required for germination in soil, and seeds treated with some methods of mechanical scarification failed to germinate, as a result of their decomposition by microorganisms. The effectiveness of scarification in causing germination in aseptic culture is not presently understood, but, as the excised embryo exhibits no dormancy, the factors delaying germination apparently reside in other portions of the seed.
NATURAL HYBRIDS BETWEEN ORYZOPSIS AND STIPA. II. ORYZOPSIS HYMENOIDES x STIPA NEVADENSIS
Authors: Johnson B. Lennart
Published: January 2018

Johnson, B. Lennart. (U. California, Los Angeles.) Natural hybrids between Oryzopsis and Stipa. II. Oryzopsis hymenoides X Stipa nevadensis. Amer. Jour. Bot. 49(5): 540–546. Illus. 1962.—The amphiploid Stipa nevadensis and one of its parents, S. elmeri, cross with Oryzopsis hymenoides to give nearly identical sterile hybrids heretofore referred to O. bloomeri. Tenuous differences between them proved reliable when verified cytologically. They were distinguished by chromosome counts of 2n = 58 for O. hymenoides X S. nevadensis and 2n = 42 for O. hymenoides X S. elmeri, which counts were expected on the basis of 2n = 68 for S. nevadensis, 2n = 36 for S. elmeri and 2n = 48 for O. hymenoides The parents showed regular bivalent formation and the hybrids mostly univalents. A suggestion that bivalent formation in polyploid species of Stipa may be genically controlled is based on the assumption of homology between different genomes of the amphiploid, S. nevadensis.
THE INFLUENCE OF PRESSURE ON THE DIFFERENTIATION OF SECONDARY TISSUES
Authors: Brown Claud L. , Sax Karl
Published: January 2018

Brown, Claud L. (U. Georgia, Athens), and Karl Sax. The influence of pressure on the differentiation of secondary tissues. Amer. Jour. Bot. 49(7): 683–691. Illus. 1962.—When longitudinal bark strips of Populus trichocarpa and Pinus strobus are separated from the bole wood during early spring and maintained in a humid environment while attached to the parent tree, the cambial zone along the inner surface of the segments rapidly proliferates producing an extensive parenchymatous callus. Subsequently, a new phellogen and cambium differentiate and extend tangentially around the outer periphery of the callus pad, this resulting in the formation of a new stem‐like structure. Whenever bark strips are separated from the bole wood by a layer of polyethylene plastic film and held firmly against the tree by externally applied pressure, the cambium continues to function normally, setting aside derivatives which differentiate and mature into normal, elongate xylary and phloic elements. The importance of mutual pressures and spatial relationships in controlling patterns of differentiation in secondary tissues is clearly demonstrated.
HISTOCHEMICAL AND AUTORADIOGRAPHIC STUDIES OF FLORAL INDUCTION IN CHENOPODIUM ALBUM
Authors: Gifford Ernest M. , Tepper Herbert B.
Published: January 2018

Gifford, Ernest M., Jr., and Herbert B. Tepper. (U. California, Davis.) Histochemical and autoradiographic studies of floral induction in Chenopodium album. Amer. Jour. Bot. 49(7): 706–714. Illus. 1962.—Chenopodium album was induced to flower using short‐day photoperiods. Changes in the chondriome, starch, total protein, ribonucleic acid (RNA), deoxyribonucleic acid (DNA), and histone distribution in cells of vegetative and inflorescence shoot apices were studied. The distal cells of the vegetative apex (especially the axial tunica cells) possess larger nucleoli and vacuoles, less granular mitochondria, and more differentiated plastids than do other cells of the apex; the distal cells stain lightly with dyes that indicate the presence of DNA and histone. RNA is distributed relatively uniformly in the shoot apex; the cells at sites of leaf initiation and young leaf primordia contain slightly higher concentrations of RNA than the axial cells of the shoot apex. Protein is uniformly distributed throughout the vegetative as well as the inflorescence apex. Upon induction, the chemical and morphological differences between cells in the shoot apex gradually disappear. RNA concentration of cells in the apex increases, reaching a maximum after 4 inductive cycles. Protein concentration of cells also increases, but this increase lags behind that of RNA.
THE INHERITANCE AND PHYSIOLOGY OF BORON RESPONSE IN THE TOMATO
Authors: Wall J. R. , Andrus C. F.
Published: January 2018

Wall, J. R., and C. F. Andrus. (U.S.D.A., U. S. Vegetable Breeding Laboratory, Charleston, S. C.) The inheritance and physiology of boron response in the tomato. Amer. Jour. Bot. 49(7): 758–762. Illus. 1962.—Brittle stem (btl), an abnormal sublethal phenotype in the tomato caused by boron deficiency, was found to be controlled by a single recessive gene. The threshold of boron concentration for brittle‐stem expression is not constant but fluctuates and is intimately associated with a number of interrelated environmental factors. Light duration and intensity are especially significant, while temperature and nitrogen, phosphorus, and calcium availability probably contribute to btl expression. It is suggested that when boron supply is limiting, brittle‐stem (boron deficiency) symptoms are intensified by any environmental factor or factors which enhance plant growth. Plants of btl/btl genotype contain much less boron in their leaves than do those of the control variety ‘Rutgers’; conversely, these plants contain more boron in their roots when grown in nutrient cultures of high boron content. This finding is discussed in relation to possible modes of gene action.
SEED GERMINATION STUDIES IN MUSA. II. ALTERNATING TEMPERATURE REQUIREMENT FOR THE GERMINATION OF MUSA BALBISIANA
Authors: Stotzky G. , Cox Elsie A.
Published: January 2018

Stotzky, G., and Elsie A. Cox. (Central Research Labs., United Fruit Co., Norwood, Mass.) Seed germination studies in Musa. II. Alternating temperature requirement for the germination of Musa balbisiana. Amer. Jour. Bot. 49(7): 763–770. Illus. 1962.—Alternating temperatures were found to be required for the germination of seeds of Musa balbisiana. The temperature differentials optimal for germination in soil are dependent upon both the high and low temperatures, and range from 8–23 C. Germination is maximal when the seeds are held 6–12 hr at the high (27–35 C) and 12–18 hr at the low (12–18 C) temperatures. Some germination can be induced by short exposures to alternating temperatures followed by constant high temperatures, but continuous exposure to alternating temperatures is necessary for maximum germination. Excised embryos develop better at constant than at alternating temperatures, showing that the mechanisms affected by alternating temperatures reside elsewhere in the seed. Alternating temperatures are also required for germination of mechanically scarified seeds, although the temperature differentials are less than those necessary for intact seeds, indicating that the action of alternating temperatures is not on the permeability of the integuments.
MEGASPOROGENESIS AND GAMETOPHYTE SELECTION IN PAEONIA CALIFORNICA
Authors: Walters James L.
Published: January 2018

Walters, James L. (U. California, Goleta.) Megasporogenesis and gametophyte selection in Paeonia californica. Amer. Jour. Bot. 49(7): 787–794. Illus. 1962.—In the ovules of Paeonia californica, a massive archesporium produces numerous (estimated at 30–40) megasporocytes, many of which complete meiosis. Several continue into gametophyte development, which is of the Polygonum type, and at the time of fertilization there are from 1 to 4 gametophytes per ovule. Rarely does more than 1 seedling per seed appear in germination. This species is characterized by extensive translocation heterozygosity, and other meiotic irregularities, in its natural populations. It shows a complete range from plants forming only pairs to those with all their chromosomes in rings at meiosis. The latter types have as high as 90% bad pollen. The course of events in the ovules is compared with the “Renner‐effect” found in Oenothera. The multiple megasporocytes and subsequent events are seen as a mechanism which insures each ovule a high probability of containing a viable egg in spite of meiotic behavior which can produce 90% sterility, and thus insures high seed set in the translocation heterozygotes.
STUDIES ON SUBMICROSCOPIC ASPECTS OF MINERAL DEFICIENCIES. I. CALCIUM DEFICIENCY IN THE SHOOT APEX OF BARLEY
Authors: Marinos Nicos G.
Published: January 2018

Marinos, Nicos G. (Waite Agric. Res. Inst., Adelaide, S.A., Australia.) Studies on submicroscopic aspects of mineral deficiencies. I. Calcium deficiency in the shoot apex of barley. Amer Jour. Bot. 49(8): 834–841. Illus. 1962.—The apical dome of the shoot apex of barley, or other cereals, is suitable for the study of submicroscopic cytological changes induced by specific mineral deficiencies because of the many uniform cells available. Also, the well‐defined stages of development of the entire apex make possible, in certain cases, the correlation between growth responses and changes in cell structure. The ultrastructure of shoot apex meristematic cells, after KMnO4 fixation, is fundamentally similar to that of root meristems. The effects of Ca deficiency on cell ultrastructure appear rather suddenly and it has not been possible to reveal unequivocably the initial sequence of events. The first indisputable signs of structural abnormalities appear when the nuclear envelope and the plasma and vacuolar membranes break up and “structureless areas” appear in the cells, followed by the disorganization of other structures like mitochondria and Golgi apparatus, while plastids are more persistent although eventually they also disintegrate. With the progress of Ca deficiency, the cell walls stain darker and gaps may appear, indicating a weakening of their structure. This evidence suggests that Ca is essential for the maintenance and probably for the formation of cell‐membrane systems on which the functional integrity of cell metabolism is dependent; Ca effects on cell walls are probably secondary to those changes already described.
MORPHOLOGICAL STUDIES IN A NEW SPECIES OF ACROSYMPHYTON (RHODOPHYCEAE)
Authors: Abbott Isabella A.
Published: January 2018

Abbott, Isabella A. (Hopkins Marine Sta. of Stanford U., Pacific Grove, Calif.) Morphological studies in a new species of Acrosymphyton (Rhodophyceae). Amer. Jour. Bot. 49(8): 845–849. Illus. 1962.—Acrosymphyton taylori sp. nov. (Dumontiaceae, Cryptonemiales, Rhodophyceae) is shown to have a sexual cycle essentially similar to that of the 2 other species in the genus, but differs in some details of the sexual structures and the vegetative structure. Acrosymphyton taylori, from the Hawaiian Islands, is the only member of the genus from the Pacific. Acrosymphyton is only one of several genera of red algae possessing soft, gelatinous, uniaxial thalli. A study of specimens from various herbaria showed that specimens of Dudresnaya and Calosiphonia have been confused with Acrosymphyton.
THE ISOCITRIC ACID CONTENT OF CRASSULACEAN PLANTS AND A FEW SUCCULENT SPECIES FROM OTHER FAMILIES
Authors: Soderstrom Thomas R.
Published: January 2018

Soderstrom, Thomas R. (Smithsonian Institution, Washington, D.C.) The isocitric acid content of crassulacean plants and a few succulent species from other families. Amer. Jour. Bot. 49(8): 850–855. 1962.—The leaves of 58 species of plants were assayed for isocitric acid content by the highly specific enzymatic method of Grafflin and Ochoa (1950). These species included 39 from the family Urassulaceae in addition to 19 species of succulents representing 8 families and 12 genera. With but one exception (Echeveria derenbergii), isocitric acid was found in relatively large concentrations in the leaves of all crassulacean species examined, and was recorded for the first time in 5 genera of this family. Isocitric acid was found in 2 genera of the Liliaceae and in 1 genus of the Piperaceae, families in which it previously had not been known to occur. The presence of substantial concentrations of isocitric acid in the leaves appears to be characteristic of the family Crassulaceae and of certain genera in other widely unrelated families. There is no indication, however, that the concentrations of this acid in the leaves of species and genera of the Crassulaceae is correlated with their affinities based on morphology.
PHYLOGENETIC STUDY OF HEDYOTIS (RUBIACEAE) IN NORTH AMERICA
Authors: Lewis Walter H.
Published: January 2018

Lewis, Walter H. (Stephen F. Austin State Coll., Nacogdoches, Texas.) Phylogenetic study of Hedyotis (Rubiaceae) in North America. Amer. Jour. Bot. 49(8): 855–865. Illus. 1962.—Chromosome numbers for 39 taxa of Hedyotis separable into the subgenera Edrisia (Raf.) Lewis and Oldenlandia (L.) T. & G. are reported. The occurrence of basic numbers of x = 6, 7, 8, 9(10), 11, and 13, including infraspecific aneuploidy in H. nigricans (Lam.) Fosb., illustrates the importance of aneuploidy in the speciation of Hedyotis in contrast to most rubiaceous genera. In the North American subg. Edrisia, 25 species are ranked according to primitive and advanced expressions for 13 characters. It is postulated on the basis of these, ecologic, geographic, and chromosomal data that the x = 11 group gave rise to the x = 13 line by the gain of chromosomes and to the x = (10)9, 8, and 7 groups by reduction. Those species with a basic number of 6 are thought to have an Asian origin. Although aneuploidy has been dominant in the evolution of subg. Edrisia, only 12% of the species are polyploids. The development of polyploid races in 3 species, H. caerulea (L.) Hook., H. polypremoides (Gray) Shinners, and H. purpurea (L.) T. & G., however, suggests a greater role of polyploidy in the current evolution of Hedyotis.
INTERSPECIFIC INCOMPATIBILITY IN SOLANUM SPECIES
Authors: Pandey K. K.
Published: January 2018

Pandey, K.K. (Crop Res. Div., D.S. & I.R., Lincoln, Christchurch, New Zealand.) Interspecific incompatibility in Solanum species. Amer. Jour. Bot. 49(8): 874–882. Illus. 1962.—A diallel cross involving 11 self‐incompatible and 3 self‐compatible species of Solanum was made to study the genetic basis of interspecific incompatibility. Interspecific incompatibility was not limited to crosses in which a self‐compatible species was used as the male parent onto a self‐incompatible species (unilateral incompatibility). A number of crosses between self‐incompatible species were incompatible. In one cross, Q vernei X verrucosum, a self‐compatible species was successful as a pollen parent with a self‐incompatible species. Unlike other hybrids between self‐compatible and self‐incompatible species, which are self‐incompatible, these F1 hybrids were self‐fertile, and cross‐fertile among themselves and with both parents. The self‐fertile S. polyadenium was cross‐incompatible as a female as well as a male parent with all other species. It is suggested that the unilateral incompatibility is a property of the allele SC which originated as a consequence of one kind of breakdown of the SI gene; the SC allele produces “bare” pollen growth substances which are inactivated in an incompatible style. It is proposed that the failure of the principle of unilateral interspecific incompatibility in solanaceous species may be due to the action of alleles at the second incompatibility locus revealed in certain Mexican species. It is assumed that the South American species are selected intraspecifically only for the action of S alleles but that in certain interspecific crosses and rarely in intraspecific crosses the alleles at the second locus may be expressed, thus interfering with the usual action of S alleles. The F1 hybrids Q verrucosum (self‐fertile) X simplicifolium (self‐sterile) were self‐incompatible at the tetraploid as well as the diploid level, and their cross‐compatibility behavior was consistent with the expected activity of the SC and SI alleles of the 2 parents respectively.
BIOSYSTEMATIC STUDIES IN THE BOUTELOUA CURTIPENDULA COMPLEX. I. THE ANEUPLOID RHIZOMATOUS B. CURTIPENDULA OF TEXAS
Authors: Gould F. W. , Kapadia Z. J.
Published: January 2018

Gould, F. W., and Z. J. Kapadia. (A. & M. College of Texas, College Station.) Biosystematic studies in the Bouteloua curtipendula complex. I. The aneuploid rhizomatous B. curtipendula of Texas. Amer. Jour. Bot. 49(8): 887–891. Illus. 1962.—Widespread throughout central U.S. is a rhizomatous form of B. curtipendula that basically is tetraploid (2n = 40). In the southwest the predominant type is a caespitose aneuploid with a high chromosome number (2n = ca. 80 to 2n = ca. 102). The present study has shown the presence of an extensive series of rhizomatous aneuploids in central Texas, with chromosome numbers ranging from 2n = 41 to 2n = 64. The distribution of these plants is centered about the region of overlap in the ranges of the 2 previously mentioned types. Available evidence indicates that the rhizomatous aneuploids have arisen through hybridization of the caespitose aneuploids and the rhizomatous tetraploids.
COMPARATIVE EFFECTS OF GIBBERELLIN AND INDOLE COMPOUNDS ON THE INDUCTION OF PARTHENOCARPY IN SEXUALLY INCOMPATIBLE PERESKIA ACULEATA
Authors: Sachar R. C.
Published: January 2018

Sachar, R. C. (U. Delhi, India.) Comparative effects of gibberellin and indole compounds on the induction of parthenocarpy in sexually incompatible Pereskia aculeata. Amer. Jour. Bot. 49(9): 913–917. Illus. 1962.—The effects of indoleacetic acid (IAA), indolebutyric acid (IBA), gibberellin (G) and gibberellic acid (GA) were studied on the fruit growth of the sexually incompatible Pereskia. Under natural conditions, this plant did not produce any fruits and seeds, and the flowers abscised a week after anthesis. IAA (50–500 ppm) delayed the formation of an abscission layer by another 2 weeks, but it was ineffective in inducing parthenocarpy. IBA (50–500 ppm) induced fruit‐set in only 15% of the flowers. Best response was achieved by G (100–500 ppm), or GA (100–500 ppm), which gave 100% fruit‐set. The effect of GA in inducing parthenocarpy was not inhibited when used in conjunction with IAA. Maximum size of the fruits was obtained with 2 sprayings of GA, and subsequent sprays were of no consequence. Further, fruit size was the largest when GA or G was sprayed at anthesis, or on old flower buds, but it was much less when the chemicals were sprayed on young flower buds. There was no stimulation of the growth of ovules; instead, a translucent mucilaginous placental tissue developed within the cavity of the fruit wall. Attempts were made to culture ovules and the placental tissue on artificial nutrient medium, but without success.
THE PROBLEM OF DRYOPTERIS LEEDSII
Authors: Walker S.
Published: January 2018

Walker, S. (U. Liverpool, England.) The problem of Dryopteris leedsii. Amer. Jour. Bot. 49(9): 971–974. Illus. 1962.—Investigation of 12 plants of ‘Dryopteris leedsii‘ from the type locality in Harford County, Maryland, has revealed 3 cytological entities, diploid, triploid and tetraploid. The diploid and triploid types exhibit hybrid characters and are sterile, while the tetraploid is a fertile species. The relationship between the 3 entities remains a problem, but the possibilities are discussed.
BRANCHED PISTILLATE INFLORESCENCES IN JUGLANS AND CARYA
Authors: Manning Wayne E.
Published: January 2018

Manning, Wayne E. (Bucknell U., Lewisburg, Pa.) Branched pistillate inflorescences in Juglans and Carya. Amer. Jour. Bot. 49(9): 975–977. Illus. 1962.—One or 2 clusters of abortive pistillate flowers or of short, slender branches of abortive perfect flowers are occasionally found at the base of the terminal pistillate spike in certain species of Juglans and Carya. These make the pistillate inflorescence a branched one, essentially a small panicle. These flower clusters and special branches are considered to be due to the retention of a primitive condition, probably a pre‐juglandaceous one.
PARTHENOGENESIS IN TETRAPLOID LILIUM LONGIFLORUM
Authors: Emsweller S. L. , Uhring Joseph
Published: January 2018

Emsweller, S. L., and Joseph Uhring. (U.S.D.A., Beltsville, Md.) Parthenogenesis in tetraploid Lilium longiflorum. Amer. Jour. Bot. 49(9): 978–984. Illus. 1962.—Nine maternal polyhaploids from 1 capsule and 1 tetraploid from another were produced following pollination of 2 tetraploid Lilium longiflorum plants with pollen from diploids of the same species. One of the 9 plants had 25 chromosomes; the extra chromosome was identified as a modified D. Two other plants had 2 new chromosomes each and the remaining 6 had 24 unmodified chromosomes. Translocations in meiosis of the tetraploid produced the new chromosomes. One plant obtained from a second capsule had 48 chromosomes. The 9 plants were smaller than diploids and the 48‐chromosome plant was considered a diploid until mitosis was observed. The 9 plants originated from unfertilized eggs of the tetraploid, and the 48‐chromosome plant presumably from chromosome doubling of an egg cell.
POLLEN MORPHOLOGY OF THE LENNOACEAE
Authors: Drugg Warren S.
Published: January 2018

Drugg, Warren S. (California Res. Corp., La Habra.) Pollen morphology of the Lennoaceae. Amer. Jour. Bot. 49(10): 1027–1032. Illus. 1962.—The family Lennoaceae contains 3 genera: Pholisma, Lennoa, and Ammobroma. The pollen of Pholisma is 4‐colporate with less common 3‐ and 5‐colporate grains. Lennoa pollen is 3‐colporate with rare 4‐colporate examples. All Ammobroma pollen is 3‐colporate. Pollen of both Lennoa and Ammobroma exhibits sexine thinning in the mesocolpia with resultant depressions. This feature is lacking in Pholisma. Sculpture is reticulate‐simplibaculate on pollen of Lennoa and Pholisma, and reticulate‐duplibaculate on pollen of Ammobroma. Pollen morphology supports placement of Lennoaceae in the Polemoniales near the Boraginaceae and Hydrophyllaceae.
CYTOTAXONOMY OF CESPITOSE ZINNIAS
Authors: Torres Andrew M.
Published: January 2018

Torres, Andrew M. (U. Wisconsin, Milwaukee.) Cytotaxonomy of cespitose zinnias. Amer. Jour. Bot. 49(10): 1033–1037. Illus. 1962.—The results of hybridization studies among 5 of the 6 cespitose species of Zinnia are reported. Analyses of meiosis in the F1 hybrids suggest there are 2 genomes, A and B, in the polyploid taxa. The A genome apparently exists in the diploid state in 2 species, but the B genome is known only from polyploid taxa. The chromosome number of Z. oligantha (2n = 20) is reported for the first time.
SOME ASPECTS OF VASCULAR DIFFERENTIATION IN ROOTS OF CASSIA
Authors: Hayat Mohammed Arif , Heimsch Charles
Published: January 2018

Hayat, Mohammed Arif (North Dakota State U., Fargo), and Charles Heimsch. Some aspects of vascular differentiation in roots of Cassia. Amer. Jour. Bot. 50(10): 965–971. Illus. 1963.—Vascular development, with emphasis on the differentiation of the protophloem, was studied in tips of primary roots of 18 species of Cassia. Variations in levels of protophloem sieve tube maturation were observed among roots of different species as well as among those of different length in the same species. In general, protophloem matured at greater distances from the apex in roots with the larger diameters. Compared with woody species, herbaceous species exhibited greater uniformity in levels of protophloem maturation, and this was correlated with greater uniformity in root diameter. Roots were either triarch or tetrarch. In some species with tetrarch roots, a change to a triarch pattern occurred during early growth. Structural changes in the differentiating root tip which involve the loss of a xylem arm and subsequent fusion of phloem strands are described.
HYBRIDIZATION AND FLORAL VASCULARIZATION
Authors: Hillson Charles J.
Published: January 2018

Hillson, Charles J. (Pennsylvania State U., University Park.) Hybridization and floral vascularization. Amer. Jour. Bot. 50(10): 971–978. Illus. 1963.—The floral steles of 6 synthetic hybrid mints, representing the F1 generation of a cross between Mentha spicata strain 199 and Mentha aquatica, were compared with each other and with the steles of the parents. Comparisons of the level of trace divergence, ovary wall vascularization, presence or absence of a nectary, and the nature of the gaps associated with dorsal carpellary bundles show that floral vascularization is an inherited character. Although slight male dominance is indicated in the hybrid steles, anatomical features of both parents are evident. Thus, while vascular tissue may be conservative when phylogenetic reduction of floral parts takes place through adnation and/or connation, stelar modification through hybridization is documented.
CELL WALL FORMATION IN PEDIASTRUM BIRADIATUM AS REVEALED BY THE ELECTRON MICROSCOPE
Authors: Moner J. G. , Chapman G. B.
Published: January 2018

Moner, J. G. (U. Massachusetts, Amherst), and G. B. Chapman. Cell wall formation in Pediastrum biradiatum as revealed by the electron microscope. Amer. Jour. Bot. 50(10): 992–998. Illus. 1963.‐An electron microscopic study of cell wall development in P. birudiatum is described. Micrographs were taken of thin sections of cells from several stages involved in the transformation of the motile zoospore into the 4‐pronged adult cell type during asexual reproduction. The cell wall begins as a thin membrane which does not change noticeably during the transformation of the zoospore to the adult cell type. In a subsequent period of not more than 6 hr, a definitive cell wall arises accompanied or followed shortly by the appearance of a globular network on the underside of the cell wall proper. During all of the developmental stages osmiophilic globuli are found in the cytoplasm, frequently at the cell surface. Similar, though smaller, globuli are found in the chloroplasts of Pediastrum and other plants, indicating that these bodies may have a plastid origin. It is suggested that whole osmiophilic globuli, or parts thereof, may be transferred to the cell wall proper, giving rise, ultimately, to the globular network.
STUDIES ON SUBMICROSCOPIC ASPECTS OF MINERAL DEFICIENCIES. II. NITROGEN, POTASSIUM, SULFUR, PHOSPHORUS, AND MAGNESIUM DEFICIENCIES IN THE SHOOT APEX OF BARLEY
Authors: Marinos Nicos G.
Published: January 2018

Marinos, Nicos G. (Waite Agric. Res. Inst., Adelaide, S.A., Australia.) Studies on submicroscopic aspects of mineral deficiencies. II. Nitrogen, potassium, sulfur, phosphorus, and magnesium deficiencies in the shoot apex of barley. Amer. Jour. Bot. 50(10): 998–1005. Illus. 1903.—The elongation of the shoot apex of barley was retarded in the absence of N, P, or Mg, while the lack of S or K did not affect its growth as compared with the controls. Ultrastructural changes in cells of the terminal 100μ of the apical dome either appeared concurrently with, or preceded, measurable effects on apical elongation. These changes included: (1) formation of many dense intramitochondrial granules and a statistically significant reduction of the length of mitochondrial tubules; (2) accumulation in the cytoplasm of dense manganophilic inclusions which appeared to be formed by the Golgi bodies (dictyosomes); (3) starch accumulation, only in P‐dcficient plants, in a region of the apex that is normally free of starch. The similarities in the symptoms induced by N, P, and Mg deficiencies reflect the metabolic interrelationships between these elements. On the basis of the time of appearance of these symptoms and their distribution in the longitudinal axis of the apical dome, it is concluded that altered mitochondrial function is an early response of cells to the lack of certain essential elements.