bluuebunny/crossref_metadata_2025 huggingface dataset:
SOMATIC INSTABILITY IN DERIVATIVES FROM AGROELYMUS TURNERI RESEMBLING AGROPYRON REPENS
Authors: Nielsen E. L. , Nath J.
Published: January 2018

Nielsen, E. L., and J. Nath. (U. Wisconsin, Madison.) Somatic instability in derivatives from Agroelymus turneri resembling Agropyron repens. Amer. Jour. Bot. 48(4): 345–349. Illus. 1961.—Variations in somatic chromosome numbers of 4 to over 80 were observed in root tip cells of Agropyron repens‐like plants derived from Agroelymus turneri. The latter presumably had out‐crossed to Agropyron repens. Split spindles in dividing nuclei and multinucleate cells were observed in the root tip meristem. The nuclear and mitotic behaviors observed can perhaps be attributed to an unbalanced ribonucleoprotein system resulting from the combination of distantly related genomes in the formation of the hybrid.
THE GERMINATION OF ZYGOSPORES OF RHIZOPUS STOLONIFER
Authors: Gauger Wendell L.
Published: January 2018

Gauger, Wendell L. (U. Nebraska, Lincoln.) The germination of zygospores of Rhizopus stolonifer. Amer. Jour. Bot. 48(5): 427–429. Illus. 1961.—Zygospores of R. stolonifer (Ehrenb. ex Fr.) Vuill. germinated in less than 30 days when placed on filter disks kept moist with sterile distilled water. Single germinating zygospores produced germ sporangiospores which, when cultured, reacted as either all plus, all minus or as mixtures of the two.
CONTRIBUTIONS TO OUR KNOWLEDGE OF AMBROSIA FUNGI. I. ASCOIDEA HYLECOETI SP. NOV. (ASCOMYCETES)
Authors: Batra Lekh R. , Francke‐Grosmann Helene
Published: January 2018

Batra, Lekh R. (U. Kansas, Lawrence), and Helene Francke‐Grosmann. Contributions to our knowledge of ambrosia fungi. I. Ascoidea hylecoeti sp. nov. (Ascomycetes). Amer. Jour. Bot. 48(6): 453–456. Illus. 1961.—The genus Ascoidea Bref. & Lindau in Brefeld (1891) belongs to the family Ascoideaceae (Endomycetales, Hemiascomycetidae). Ascoidea differs from all other ascomycetes by its possession of characteristic multispored asci which proliferate, the newer asci being formed through the collar‐like wall remnants of older asci. Ascogenous hyphae are absent. The present fungus differs in many ways from the type and the only species of the genus, A. rubescens Bref. & Lindau. Ascoidea hylecoeti reproduces asexually by chlamydospores. The asci are conical and many spored. They are aggregated in thick clusters of 50–200 individual asci. The number of ascospores per ascus is much larger than that of A. rubescens and their size is much smaller. Ascoidea hylecoeti is known to occur only in association with the genus Hylecoetus, one of the ambrosia beetles.
STUDIES ON THE EFFECT OF CARBON DIOXIDE ON X RAY–INDUCED CHROMOSOME ABERRATIONS IN TRADESCANTIA. II. RELATION TO DOSE RATE AND ENVIRONMENT DURING IRRADIATION
Authors: LaChance Leo E.
Published: January 2018

LaChance, Leo E. (Biology Dept., Brookhaven Nat. Lab., Upton, L. I., N. Y.) Studies on the effect of carbon dioxide on X ray‐induced chromosome aberrations in Tradescantia. II. Relation to dose rate and environment during irradiation. Amer. Jour. Bot. 48(6): 489–492. 1961.—The effect of carbon dioxide on radiation‐induced chromosome aberrations has been investigated to determine the relation of this agent to dose rate and the efficacy of a pretreatment followed by X‐irradiation in nitrogen or in vacuo. Carbon dioxide and air, present during the radiation treatment, significantly increase the frequency of chromosome aberrations induced by 300 r of X rays through a 46‐fold difference in dose rate. Pretreatment with CO2 and air also increases the aberration frequency if the radiation occurs in air. Pretreatment is completely ineffective when the inflorescences are irradiated in vacuo or in nitrogen. Thus it appears that CO2 acts synergistically with oxygen in increasing the frequency of chromosome aberrations induced by X rays.
A REPORT ON THE CULTURE OF SOME SPECIES OF HALOSACCION, RHODYMENIA AND FAUCHEA
Authors: Sparling Shirley R.
Published: January 2018

Sparling, Shirley R. (U. California, Santa Barbara, Goleta.) A report on the culture of some species of Halosaccion, Rhodymenia, and Fauchea. Amer. Jour. Bot. 48(6): 493–499. Illus. 1961.—Cultures of the red algae, Halosaccion glandiforme (Gmelin) Ruprecht, Rhodymenia palmata f. mollis Setchell et Gardner, Fauchea laciniata J. G. Agardh, and F. fryeana Setchell were started from spores and in some instances maintained for about 2½ yr. Culture methods are described and the plants obtained in culture compared to those in nature. Of the plants cultured, only some of F. laciniata became fertile. The use of spores undergoing their first division in germination for observation of mitotic divisions is reported.
A SMALL‐COLONY VARIANT OF CANDIDA ALBICANS
Authors: Bianchi D. E.
Published: January 2018

Bianchi, D. E. (San Fernando Valley State Coll., Northridge, Calif.) A small‐colony variant of Candida albicans. Amer. Jour. Bot. 48(6): 499–503. Illus. 1961.—Normal cultures of Candida albicans give rise to a small‐colony variant similar in many respects to the “petite” of Saccharomyces cerevisiae. The difference in colony size is due to a difference in the rate of cell division. They arise spontaneously from the wild‐type at a frequency of from 1–3%, and the individual cells of both types are the same size. However, unlike the “petite,” they contain the enzymes cytochrome oxidase, cytochrome b, and succinic dehydrogenase, and they respire normally.
MORPHOGENETIC STUDIES ON THE FERN TODEA BARBARA. III. EXPERIMENTAL EMBRYOLOGY
Authors: DeMaggio A. E. , Wetmore R. H.
Published: January 2018

DeMaggio, AugustusE. (Rutgers · The State U., Coll. of Pharmacy, Newark, N. J.), and RalphH. Wetmore.Morphogenetic studies on the fern Todea barbara. III. Experimental embryology. Amer. Jour. Bot. 48(7): 551–565. Illus. 1961.—A study of the various stages in the life history of the fernTodea barbara(L.) Moore has shown that young embryos can be removed from the surrounding prothallial tissue, within which they normally develop, and successfully grown in culture. It was possible, therefore, to investigate the manner in which the embryo develops when it is freed from the restraint of surrounding cells. Embryos excised 20 days after fertilization could be grown to mature sporophytes in a liquid culture containing mineral salts and sugar. Younger embryos, excised 17 days after fertilization, required the addition of whole coconut milk or a mixture of sorbitol and inositol, components of the “neutral” fraction of coconut milk, to complete their development. Embryos excised prior to the appearance of the first division wall, 4–5 days after fertilization, did not develop into the usual, 3‐dimensional, diploid or sporophytic plant. Instead they become irregular, rather 2‐dimensional, thalloid structures, remarkably similar to the early haploid or gametophytic plant. These findings are considered in relation to the environmental conditions of growth with particular reference to nutritional and physical factors.
A BIOSYSTEMATIC STUDY OF TRIDENS (GRAMINEAE)
Authors: Tateoka Tuguo
Published: January 2018

Tateoka, Tuguo. (U. Montréal, Montréal, Canada.) A biosystematic study of Tridens (Gramineae). Amer. Jour. Bot. 48(7): 565–573. Illus. 1961.—The genus Tridens has been studied from cytological, morphological, anatomical and histological points of view. Species of Tridens can be divided into 2 groups according to the characters of caryopses, stigmas, lemmas, paleas and general habit. In accordance with the morphological disparities, the 2 groups have different appearances of the anatomy of leaf margins and midribs and also of the bicellular microhairs on the epidermis of the leaf blade. Further, the 2 groups have different basic chromosome numbers, x=8 and x=10, and some distinction in karyotype. Somatic chromosomes of 8 species have been examined. The evidence given by the combined studies indicates that Tridens should be regarded as a mixture of 2 phylogenetically distant groups. Based on this conclusion, the 5 species representing one of the 2 groups (T. pilosus, T. avenaceus, T. grandiflorus, T. nealleyi and T. pulchellus) are transferred to the genus Erioneuron which is hereby revived. Nomenclatural changes are made for the species of the revived genus.
MEIOTIC CHROMOSOME BEHAVIOR IN SOME INTERGENERIC HYBRIDS OF THE VANDA ALLIANCE
Authors: Tanaka R. , Kamemoto H.
Published: January 2018

Tanaka, R., and H. Kamemoto. (U. Hawaii, Honolulu.) Meiotic chromosome behavior in some intergeneric hybrids of the Vanda alliance. Amer. Jour. Bot. 48(7): 573–582. Illus. 1961.—Meiotic chromosome behavior of 11 groups of diploid intergeneric hybrids (2n=38) of the Vanda alliance was investigated. Vanda Miss Joaquim × Luisia teretifolia and Ascocentrum curvifolium × Vanda lamellata usually produced 19 bivalents at metaphase I, indicating good homology of the parental chromosomes. Vanda tricolor var. sanderae × Vandopsis lissochiloides, Vandopsis lissochiloides × Vanda sanderiana, Vandopsis lissochiloides × Vanda Tatzeri and Arachnis flos‐aeris × Vandopsis lissochiloides showed fair homology of parental genomes with formation of 12–15 bivalents at metaphase I. Trichoglottis brachiata × Vanda sanderiana, Vanda tricolor var. purpurea × Phalaenopsis denevei, Vanda Tatzeri × Aerides lawrenceae, Renanthera monachica × Vanda luzonica, Renanthera storiei × Vanda Clara Shipman Fisher and Aerides lawrenceae × Saccolabium giganteum, formed an average of 2–7 bivalents, thereby indicating poor homology of parental genomes. The hybrids, Renanthera monachica × Phalaenopsis sanderiana and Arachnis hookeriana × Vanda suavis, lacked chromosome pairing. On the basis of chromosome affinity at meiosis, a cytotaxonomic scheme was developed for the several genera of the Vanda alliance studied. Cytotaxonomy, evolution and breeding behavior in the Vanda tribe were briefly discussed.
A STUDY OF THE VITAMIN REQUIREMENTS OF THREE SPECIES OF THE GENUS GELASINOSPORA
Authors: Hackbarth R. D. , Collins R. P.
Published: January 2018

Hackbarth, R. D., and R. P. Collins. (U. Connecticut, Storrs.) A study of the vitamin requirements of three species of the genus Gelasinospora. Amer. Jour. Bot. 48(7): 603–606. Illus. 1961.—The vitamin requirements of 3 species of Gelasinospora (G. tetrasperma, G. retispora, G. cerealis) were determined. Various combinations of the 10 vitamins used in the study were tried and biotin was found to be the factor limiting growth.
THE ULTRAMICRO STRUCTURE OF STARCH‐FREE CHLOROPLASTS OF FULLY EXPANDED LEAVES OF NICOTIANA RUSTICA
Authors: Weier T. Elliot
Published: January 2018

Weier, T. Elliot. (U. California, Davis.)The ultramicro structure of starch‐free chloroplasts of fully expanded leaves of Nicotiana rustica.Amer. Jour. Bot. 48(7): 615–630. Illus. 1961.—The grana of starch‐free chloroplasts of fully expanded leaves ofNicotiana rusticaare distinct, compartmented, subplastid entities. They vary in size, shape, orientation and in the distinctness with which their compartments are delineated. It has not been possible to equate accurately their micro and ultramicro appearances. At the ultramicro level, the grana are connected with each other at irregular intervals by a system of anastomosing channels. The partitions forming the compartments of the grana may be coarse or very fine but are constant in appearance in any given chloroplast. The loculi enclosed by the partitions may vary in size with a granum, depending upon their location or upon the physiological activity of the chloroplast. The stroma does not penetrate the grana; it may be relatively fluid and the grana‐fretwork system may move within it. A double envelope, which may have pores connecting stroma and hyaloplasm, surrounds the chloroplasts. Materials may collect between the surfaces of the envelope. There is considerable variation in the ultramicro details of chloroplast structure ofNicotiana rustica.It is not yet possible to distinguish accurately between those variations which may be of physiological significance and those which may be induced by processing.
A CALAMITEAN SHOOT APEX FROM THE PENNSYLVANIAN OF IOWA
Authors: Melchior Robert C. , Hall John W.
Published: January 2018

Melchior, Robert C., and John W. Hall. (U. Minnesota, Minneapolis.) A calamitean shoot apex from the Pennsylvanian of Iowa. Amer. Jour. Bot. 48(9): 811–815. Illus. 1961.—A shoot apex of a calamitean stem is described from the Des Moines Series, Middle Pennsylvanian. Internodal elongation of the 7 preserved internodes follows a sigmoid curve. A large apical cell has produced derivatives in a fashion apparently comparable to those in Equisetum arvense, except for the number of cells in the first leaf primordium ring and, possibly, the intercalary meristem. Pith meristem developed close to the apical cell. Data from internodal cell elongation of hypodermal cells of the cortex are presented which demonstrate intercalary internodal growth; no intercalary meristems are preserved and the existence of intercalary meristems which might have produced a jointed stem like that of Equisetum is only inferred.
TRISOMIC TRANSMISSION IN CLARKIA UNGUICULATA
Authors: Vasek Frank C.
Published: January 2018

Vasek, F. C. (U. California, Riverside.) Trisomic transmission in Clarkia unguiculata. Amer. Jour. Bot. 48(9): 829–833. 1961.—Seven primary trisomic plants derived from a triploid‐diploid cross were self‐pollinated. The 7 progenies included diploids and trisomics, the latter varying in frequency from 16 to 30%. In addition, 2 of the progenies included tetrasomic plants. Crosses were made between diploids and either trisomics or tetrasomics. The extra chromosome of 1 progeny was readily transmitted through the pollen of trisomic and tetrasomic plants. When a trisomic of the same progeny was used as a seed parent, only diploids and tetrasomics were found among the offspring, indicating a duplication of the extra chromosome. The extra chromosomes of other progenies were not transmitted through either pollen or eggs in controlled diploid‐trisomic crosses but trisomics of these progenies were recovered after self‐pollination. It is suggested that differential pollen‐tube growth precluded transmission to diploid‐trisomic hybrids and that under conditions of reduced pollen competition the extra chromosome normally would be transmitted through pollen. The extra chromosomes generally occur as univalents at metaphase and are ordinarily included in telophase nuclei.
RESPONSE TO WOUNDING OF FLORAL HAIRS OF STAPELIA
Authors: Benda G. T. A.
Published: January 2018

Benda, G. T. A. (U. Notre Dame, Notre Dame, Indiana.) Response to wounding of floral hairs of Stapelia. Amer. Jour. Bot. 48(9): 833–842. Illus. 1961—Wounded single‐celled hairs of the corolla of Stapelia grandiflora were used to investigate: (1) the closure of the wound; and (2) the dynamics of water balance in these cells and their adjoining tissue. The cells were wounded by removing the tip of the cell, and the technique described made it possible to follow small volume changes over 2‐sec intervals for extended periods. The data obtained indicate that the volume of cell content results from a dynamic balance of uptake and loss of water. In cells kept relatively dry, the part of the protoplast nearest the wound was free to move back and forth within the cell wall. A wound does not necessarily result in a plug of coagulated protoplast visible at the microscopic level, but a plug is produced if the wounded cell takes up water rapidly.
OBSERVATIONS ON CHYTRIDIACEOUS PARASITES OF PHANEROGAMS. XI. A PHYSODERMA ON AGROPYRON REPENS
Authors: Sparrow F. K. , Griffin Joyce E. , Johns R. M.
Published: January 2018

Sparrow, Frederick K. (U. Michigan, Ann Arbor), Joyce E. Griffin, and Robert M. Johns. Observations on chytridiaceous parasites of phanerogams. XI. A Physoderma on Agropyron repens. Amer. Jour. Bot. 48(9): 850–858. Illus. 1961.—A Physoderma has been found in Michigan on Agropyron repens, which produces dark‐brown, non‐erumpent streaks up to 20 mm (usually 4–6 mm) in length by 0.5 mm in width and very local discoloration of the leaf blades and sheaths. There is no systemic infection, and plants parasitized are normal in size and bear flowers. Resting spores upon germination produce zoospores which may develop either into the endobiotic, poly‐centric, resting spore‐bearing thallus or into monocentric, epibiotic, ephemeral sporangia. The latter bear either colorless or orange globuled zoospores. These zoospores may give rise to new epibiotic sporangia, or, apparently without fusing in pairs, to the endobiotic system. Comparison with other congeneric fungi reported on Agropyron repens reveals the Michigan fungus to be distinct from them. Whether it can be embraced within Physoderma graminis (Büsgen) de Wild. or other described taxa on grasses awaits the results of future cross‐inoculation studies.
A CHLORELLA MUTANT LACKING NITRATE REDUCTASE
Authors: Shafer John , Baker James E. , Thompson John F.
Published: January 2018

Shafer, John, Jr., James E. Baker and John F. Thompson. (U. S. Plant, Soil and Nutrition Laboratory, U. S. D. A., Ithaca, New York.) A Chlorella mutant lacking nitrate reductase. Amer. Jour. Bot. 48(10): 896–899. 1961.—Following ultraviolet irradiation of Chlorella pyrenoidosa, a mutant was isolated which could not utilize nitrate nitrogen but which could use nitrite, ammonia and some organic nitrogen compounds. This suggested an abnormal nitrate reductase system. Nitrate reductase activity was found in cell‐free extracts of wild‐type cells but not in similar preparations from the mutant. A test for inhibitor in the mutant extract showed that there was none. Therefore, it was concluded that the mutant lacks an active nitrate reductase.
XYLEM ANATOMY OF SOPHORA (LEGUMINOSAE) IN RELATION TO HABIT
Authors: Cumbie B. G. , Mertz Dan
Published: January 2018

Cumbie, B. G., and Dan Mertz. (U. Missouri, Columbia.) Xylem anatomy of Sophora (Leguminosae) in relation to habit. Amer. Jour. Bot. 49(1): 33–40. Illus. 1962.—A comparison of 8 tree, shrub, and herbaceous species of Sophora showed considerable variation in structural organization of the secondary xylem in relation to habit. A reduction in duration of cambial activity has been accompanied by a decrease in conspicuousness of storied structure, more frequent arrangement of vessels in multiples, the formation of narrower rays, and a striking reduction in amount of axial xylem parenchyma. On the other hand, relatively minor changes in size of xylem elements have resulted from decreased cambial activity, as shown by comparing the first‐formed secondary xylem elements of woody and herbaceous species. In many structural features, shrubs were found to be more or less intermediate between the tree and herbaceous species, at least in the early stages of development. These observations indicate that the often repeated generalization that the organization of herbaceous stems resembles that of the first year's growth in closely related woody species is not always applicable.
MORPHOLOGY, FERTILITY, AND CYTOLOGY OF AGROPYRON REPENS × AGROPYRON DESERTORUM F2'S
Authors: Dewey Douglas R.
Published: January 2018

Dewey, Douglas R. (Crops Res. Lab., Agric. Expt. Sta., Logan, Utah.) Morphology, fertility, and cytology of Agropyron repens × Agropyron desertorum F2's. Amer. Jour. Bot. 49(1): 78–86. Illus. 1962.—An 82‐plant population derived from F1 hybrids of A. repens × A. desertorum included morphological types indistinguishable from the parent species as well as many intermediate forms. Most, if not all, of the F2 population were products of backcrossing of F1 hybrids to one of the parent species. Backcrossing of F1 hybrids to A. repens and A. desertorum occurred with equal frequency. Fifty‐four percent of the F2 plants were completely sterile. Fertility in the F2 population was related to the nature of the F1 backcross. F2 plants obtained from backcrossing to A. desertorum were more fertile than equivalent backcrosses to A. repens. Fertility in the F2's was concentrated in a few plants. Nine F2's accounted for 85% of the seed produced in the 82‐plant population. The most fertile plant produced 441 viable seeds. Meiotic chromosome counts of 66 F2's ranged from 30 to 49 and averaged 36. Chromosome number was related to the direction of the backcross. Chromosome associations in all F2 plants at metaphase I included many different combinations of univalents, bivalents and trivalents. Occasional pairing of A. repens and A. desertorum chromosomes were noted in some F2's. On the basis of morphology, fertility and chromosome pairing, genome formulae were assigned to the parent species. The genome formula of A. repens was given as BBBBCC and A. desertorum was designated as AAAA.
THE FINE STRUCTURE OF THE GRASS GUARD CELL
Authors: Brown Walter V. , Johnson Sr. C.
Published: January 2018

Brown, W. V., and Sr. C. Johnson. (U. Texas, Austin.) The fine structure of the grass guard cell. Amer. Jour, Bot. 49 (2): 110–115. Illus. 1962.—An electron microscopic study of 16 species of grasses classified in 10 tribes and 5 subfamilies has revealed some hitherto unknown facts about guard‐cell structure. In species of 3 subfamilies, but not in the Festucoideae, there are membranes on the guard cells overarching the stoma. In the Festucoideae, the membrane is rudimentary or absent and is associated with a different cross‐sectional shape of the guard cell. The central canal through the thick‐walled region of the guard cell is structurally quite complex. The wall between the central canal and the subsidiary cell is thin and lacks plasmodesmata. There are plastids but no developed chloroplasts in grass guard cells. Mitochondria are abundant, but vacuoles are undetectable. At the ends of the guard‐cell pair, the wall between them is incomplete and the protoplasts are confluent.
INTERSPECIFIC HYBRIDIZATION IN HAPLOPAPPUS AND ITS BEARING ON CHROMOSOME EVOLUTION IN THE BLEPHARODON SECTION
Authors: Jackson R. C.
Published: January 2018

Jackson, R. C. (U. Kansas, Lawrence.) Interspecific hybridization in Haplopappus and its bearing on chromosome evolution in the Blepharodon section. Amer. Jour. Bot. 49 (2) : 119–132. Illus. 1962.—Cytological analyses of interspecific hybrids between H. gracilis (n = 2) and H. spinulosus ssp. australis (n = 8) indicate that ssp. australis is a segmental allotetraploid, derived from past hybridization between 2 taxa with chromosome numbers of n = 4. Analysis of hybrids between H. gracilis (n = 2) and H. ravenii (n = 4), a previously undescribed species, has shown that the chromosome segments of these 2 species are almost completely homologous. Differential contraction is suggested as the explanation for the disappearance in late pachytene of presumed non‐homologous segments which were evident in some cells at early pachytene. The pairing relationship of gracilis and ravenii chromosomes at pachytene and later prophase I stages of meiosis indicates that gracilis has evolved from ravenii by an aneuploid reduction process similar to that described for Crepis. The close morphological relationship of the 2 species adds further support to this proposition. Data from the cytological analysis of both interspecific hybrids indicate that x = 4 is the basic chromosome number for the Blepharodon section of Haplopappus.
THE NUTRITION OF CERTAIN SPECIES OF THE GREEN ALGA OEDOGONIUM
Authors: Machlis Leonard
Published: January 2018

Machlis, Leonard. (U. California, Berkeley.) The nutrition of certain species of the green alga Oedogonium. Amer. Jour. Bot. 49 (2) : 171–177. Illus. 1962.—Evidence is presented showing that O. cardiacum and O. geniculatum require vitamin B12 and an unknown growth factor released from soil into water during autoclaving. The unknown growth factor is shown not to be a number of things, to be retained on anion exchange columns, and to be partially purified by fractionation on the polydextran, Sephadex 50. It appears to be an organic substance with acidic properties. Isolates of Oedogonium presently in unialgal and axenic culture are listed and the methods used to obtain the axenic cultures and to grow them for nutritional studies are described.
GROWTH STUDIES OF THE ROOT OF INCENSE CEDAR, LIBOCEDRUS DECURRENS. I. THE ORIGIN AND DEVELOPMENT OF PRIMARY TISSUES
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. I. The origin and development of primary tissues. Amer. Jour. Bot. 49(3): 221–236. Illus. 1962.—The anatomical features of active and dormant roots of incense‐cedar seedlings are described and discussed in relation to various problems of differentiation and morphogenesis. Autoradiographs confirm the presence of a group of relatively inactive cells at the site of the apical initials. During periods of maximum growth activity, the presence of a quiescent center is accentuated by a peak in number of divisions in adjacent tissues. With diminution in growth activity, the peak occurs closer to the quiescent center and the size of the meristem appears to diminish. During dormancy, the configuration of the initial region seems to indicate the existence of apical initial cells which coincide with a minimal constructional center, as determined by studies of cell lineage. Roots whose apical cells retain their meristematic appearance are able to resume growth after a period of dormancy, whereas roots whose apical cells undergo vacuolation are likely to perish. Graphs are presented to show the functional relationships between growth rate and the varying distances from the apical meristem at which the tissues of the root differentiate and mature. Although early differentiation of precursory phloem could be discerned almost as soon as early vacuolation of metaxylem, its recognition was more dependent upon subjective judgment. The functional relationship between differentiation and growth rate was most pronounced in the maturation of protoxylem elements, the development of Casparian strips in the endodermis, the development of suberin lamellae in the endodermis, and by the development of phi layers in the inner cortex.
AMPHIPLOIDY AND INTROGRESSION IN STIPA
Authors: Johnson B. Lennart
Published: January 2018

Johnson, B. Lennart. (U. California, Los Angeles.) Amphiploidy and introgression in Stipa. Amer. Jour. Bot. 49(3): 253–262. Illus. 1962.—Frequent specimens heretofore referred to Stipa californica (2n = 36) were found to be similar to an undescribed polyploid (2n = 68) species of Stipa on the ratio of lemma to palea length. On other individual diagnostic characters, S. californica and the polyploid were not separable. However, on the discriminant function (Z) comprising 5 such attributes, their mean difference was highly significant. The polyploid is given the new species name, Stipa nevadensis. Appropriate tests using the function Z excluded S. californica as a possible parent of the polyploid and pointed to S. lettermani (2n = 32) and the combined species S. occidentalis (2n = 36) and S. elmeri (2n = 36) as the putative parents. The last 2 species were barely separable on multigenic differences measured by the discriminant function, and the mean Z for S. californica fell near the mid point between them and S. columbiana (2n = 36). This fact together with evidence from the frequency distribution of Z suggested a hybrid origin for S. californica and introgression with its putative parents.
STUDIES ON INDUCED VARIATION IN THE RHIZOBIA. III. HOST RANGE MODIFICATION OF RHIZOBIUM TRIFOLII BY SPONTANEOUS AND RADIATION‐INDUCED MUTATION
Authors: Schwinghamer E. A.
Published: January 2018

Schwinghamer, E. A. (Brookhaven Natl. Lab., Upton, New York.) Studies on induced variation in the rhizobia. III. Host range modification of Rhizobium trifolii by spontaneous and radiation‐induced mutation. Amer. Jour. Bot. 49(3): 269–277. Illus. 1962.—Mutant strains capable of nodulating pea seedings ineffectively (incapable of nitrogen fixation) have been obtained from 2 antibiotic‐resistant marked strains of Rhizobium trifolii which normally do not form nodules on this host. Such variant forms apparently occur spontaneously in these strains at a low frequency which can be significantly increased by irradiation with ultraviolet light, X rays, and fast neutrons. Nodulation of vetch, sweet peas and several varieties of peas by the mutant strains suggests a close parallelism of the extended host range with the range of R. leguminosarum, although nitrogen fixation by the mutants on the new hosts is negligible or absent. The mutant nodules on these hosts also differ from those of the pea strains in slightly smaller size, spherical form, and lighter pink color. Nodule morphology on the homologous host, clover. appears unaltered but a slight loss of effectiveness was noted on red clover. This loss may be attributed partly to a reduction in infective ability since the average number of nodules formed per plant of clover or pea is appreciably lower than for comparable inoculation by strains of nonmutant R. trifolii or R. leguminosarum, respectively. Cultural characteristics of mutant strains resemble those of the nonmutant R. trifolii strains.
INVESTIGATIONS ON LICHEN SYNTHESIS
Authors: Ahmadjian Vernon
Published: January 2018

Ahmadjian, V. (Clark U., Worcester, Mass.) Investigations on lichen synthesis. Amer. Jour. Bot. 49(3): 277–283. Illus. 1962.—Separated fungal and algal components of the lichen, Acarospora fuscata (Nyl.) Am., were recombined under controlled laboratory conditions to form structures comparable to those of the naturally occurring lichen thallus. The primary condition for this artificial synthesis was the absence of organic and inorganic supplements to the agar substrate. Thus, in effect, the mycobiont was forced into union with the phycobiont. It was demonstrated that both alga and fungus derived benefit from the lichenized association.
THE INTRACELLULAR DISTRIBUTION OF SOME METALLIC ELEMENTS IN LEAVES
Authors: Stocking C. Ralph , Ongun Alpaslan
Published: January 2018

Stocking, C. Ralph, and AlpaslanOngun. (U. California, Davis.)The intracellular distribution of some metallic elements in leaves.Amer. Jour. Bot. 49(3): 284–289. Illus. 1962.—A comparison of the potassium, sodium, calcium, magnesium, and nitrogen levels of chloroplasts isolated in an aqueous sucrose medium and by the nonaqueous method reveals that large amounts of these elements are lost from the plastids during their isolation in sucrose solution. Nonaqueously isolated chloroplasts of bean and tobacco leaves contained over 40% of the total leaf potassium, magnesium, and calcium. High levels of nitrogen up to 70% of the total leaf nitrogen were found associated with nonaqueously isolated chloroplasts. As much as 40–50% of this nitrogen is lost when chloroplasts are isolated in a sucrose solution. Electron photomicrographs of nonaqueously isolated chloroplasts reveal only a partial disruption of the internal structure and a loss of the plastid membrane during isolation.
THE GENUS PROTOSTELIUM
Authors: Olive Lindsay S.
Published: January 2018

Olive, L. S. (Columbia U., New York, N. Y.) The genus Protostelium. Amer. Jour. Bot. 49(3): 297–303. Illus. 1962.—Two new species of this simplest genus of the cellular slime molds are described: P. fimicola, a species with spherical spores and gelatinizing stalks occurring on dung, and P. arachispora, an elongate‐spored species from dead plant material. The first has been found in North Carolina and the West Indies, while the second species has been found only once in North Carolina. Protostelium mycophaga var. major, from Connecticut, has distinctly larger spores than the original species. Further data on the distribution and development of P. mycophaga are presented. The genus is transferred to a family of its own, the Protosteliaceae.
THE ROLE OF LIGHT IN HISTOGENESIS AND DIFFERENTIATION IN THE SHOOT OF PISUM SATIVUM. I. THE APICAL REGION
Authors: Thomson Betty F. , Miller Pauline Monz
Published: January 2018

Thomson, B. F., and P. M. Miller. (Connecticut Coll., New London.) The role of light in histogenesis and differentiation in the shoot of Pisum sativum. I. The apical region. Amer. Jour. Bot. 49(3): 303–310. Illus. 1962.—Seedlings of Pisum sativum grown under constant conditions and kept in total darkness or exposed daily to red or white light were harvested at the same plastochron age and examined histologically to determine what specific aspects of histogenesis and differentiation are affected by light. The tissue organization of the shoot apex is the same in all light conditions to a point below the 2 youngest leaf primordia. The first detectable difference is a slight thickening of the internode in light due to more and larger cells. The first effect on longitudinal growth appears below the fourth youngest primordium and consists of an increase of internode length in light‐grown plants. This is associated with a greater distance between the apex and the first mature protoxylem. The distance from apex to the first pith, provascular strands, and protophloem and the distances between the 4 youngest leaf primordia are not affected by light.
CELL WALL BREAKDOWN AND GROWTH IN PEA SEEDLING STEMS
Authors: Matchett William H. , Nance James F.
Published: January 2018

Matchett, William H., and J. F. Nance. (U. Illinois, Urbana.) Cell wall breakdown and growth in pea seedling stems. Amer. Jour. Bot. 49(4): 311–319. Illus. 1962.—Carbon‐14 introduced into cell‐wall constituents of pea stems is subject to metabolic turnover. Turnover is increased when test tissues are supplied with growth‐promoting levels of indoleacetic acid and decreased by growth‐inhibiting levels of mannitol and galactose. Studies on uptake of calcium‐45 confirm earlier work by showing that treatment of pea‐stem slices with growth‐promoting levels of indoleacetic acid results in an increased capacity for rapid uptake of calcium ion. Studies on loss of calcium‐45 by previously labeled pea‐stem slices confirm earlier observations by showing that this loss is greatly enhanced by the presence of indoleacetic acid. Experiments designed to test the effects of various exchangeably bound ions upon the extent of carbon‐14 turnover reveal that turnover is increased by the presence of potassium ion or magnesium ion and that in each case calcium ion reverses the effect. Studies on the tip‐burst response exhibited by growing pollen tubes reveal that either anaerobiosis or the presence of potassium ion increases the frequency of bursting. The results of this investigation are discussed with reference to several hypotheses concerning plasticization of the primary cell wall.
RECONSTRUCTIONS OF ARCHAEOPTERIS, AND FURTHER CONSIDERATION OF ITS PHYLOGENETIC POSITION
Authors: Beck Charles B.
Published: January 2018

Beck, C. B. (U. Michigan, Ann Arbor.) Reconstructions of Archaeopteris, and further consideration of its phylogenetic position. Amer. Jour. Bot. 49(4): 373–382. Illus. 1962.—Two reconstructions, one of a branch bearing the basal part of 3 leaves and the other of the habit, are presented with the evidence upon which they are based. An analysis is made of some features which characterize the ferns. These, and characters of Archaeopteris, are considered in the light of present knowledge of evolutionary trends, and the conclusion is reached that Archaeopteris was neither a primitive fern nor a fern ancestor. Additional evidence is discussed which supports the view that the plant was a progymnosperm.
CHANGES IN SENSITIVITY OF MAIZE CHROMOSOMES TO X RAYS DURING SEED GERMINATION
Authors: Latterell Richard L. , Steffensen Dale M.
Published: January 2018

Latterell, Richard L., and Dale M. Steffensen. (Brookhaven Natl. Lab., Upton, L. I.. N. Y.) Changes in sensitivity of maize chromosomes to X rays during seed germination. Amer. Jour. Bot. 49(5): 472–478. Illus. 1962.—Changes in the radiosensitivity of maize seeds during early stages of germination were studied by means of somatic‐mutation techniques. Seeds heterozygous for the yg2 (yellow‐green) locus were irradiated with 800 r of X rays after soaking in running tap water up to 42 hr. Yellow‐green sectors, representing mutations affecting the dominant yg2 locuss in leaves 4 and 5 of seedling plants were used as a criterion of radiosensitivity. The frequency of somatic sectors was virtually nil for dry seed and for seeds soaked up to 16 hr. Sector frequencies underwent a marked (9‐ to 15‐fold) rise from 16 to 28 hr, reached a plateau of sensitivity and subsequently declined. Manometric studies were conducted on seeds soaked under the same conditions as those irradiated. The rate of oxygen consumption rose rapidly from 0 to 7 hr, remained essentially constant from 7 to 16 hr, then underwent an approximately 2‐fold increase from 16 to 24 hr, after which the rate of progressive increase was retarded. The fact that the marked rise in frequency of X‐ray‐induced somatic sectors coincided with the major increase in oxygen consumption suggests that radiosensitivity of soaked seeds is conditioned by metabolic changes during seed development. Changes in radiosensitivity that followed attainment of peak sector frequencies were apparently governed by factors that influenced the rate of seed development.
FURTHER STUDIES IN THE GENUS DRYOPTERIS: THE ORIGIN OF D. CLINTONIANA, D. CELSA AND RELATED TAXA
Authors: Walker S.
Published: January 2018

Walker, S. (Liverpool Univ., England.) Further studies in the genus Dryopteris: the origin of D. clintoniana, D. celsa and related taxa. Amer. Jour. Bot. 49(5): 497–503. Illus. 1962.—Cytogenetic studies of 5 Dryopteris species, from North America, together with wild and synthesized hybrids between some of them, show that D. clintoniana and D. celsa are allohexaploid and allotetraploid respectively. Cytological and morphological evidence points to D. cristata and D. goldiana being parental to D. clintoniana, whilst D. goldiana and D. ludoviciana are parental to D. celsa. The taxon D. X australis is triploid and has been synthesized; it is the backcross between D. celsa and D. ludoviciana.
USE OF GROWTH CHARACTERISTICS IN STUDIES OF MORPHOLOGIC RELATIONS. I. SIMILARITIES BETWEEN EPIBLAST AND COLEORHIZA
Authors: Foard Donald E. , Haber Alan H.
Published: January 2018

Foard, Donald E., and Alan H. Haber. (Oak Ridge Natl. Lab., Oak Ridge, Tenn.) Use of growth characteristics in studies of morphologic relations. I. Similarities between epiblast and coleorhiza. Amer. Jour. Bot. 49(5): 520–523. Illus. 1962.—We compared the characteristics of wheat epiblast, coleorhiza, and leaves during germination and seedling growth. Although the epiblast and coleorhiza grow without cell division during germination, they sometimes produce hairs that resemble root hairs but are different in form and mode of origin from leaf hairs. Despite the similar orientation of the epiblast and leaves with respect to the main axis of the plant, during growth the epiblast changes shape such that the axis of greater linear extension per millimeter is perpendicular to the main axis of the plant, whereas leaves change shape such that the greater rate of linear extension per millimeter is parallel to the main axis of the plant. Indoleacetic acid treatment produces excessive and disorganized growth of both the epiblast and coleorhiza but retards leaf growth. Gibberellic acid stimulates, whereas (2‐chloroethyl)trimethylammonium chloride retards leaf growth. Neither substance significantly affects epiblast or coleorhiza. We conclude that the epiblast is not leaf‐like, but together with the coleorhiza forms a single, continuous structure. This paper illustrates how a wide variety of growth characteristics may be used to complement classical anatomic approaches in studies of morphologic relations.
“MULTIPLE SPINDLE”—A MEIOTIC IRREGULARITY IN CLARKIA EXILIS
Authors: Vasek Frank C.
Published: January 2018

Vasek, F. C. (U. California, Riverside.) “Multiple spindle”—a meiotic irregularity in Clarkia exilis. Amer. Jour. Bot. 49(5): 536–539. Illus. 1962.—“Multiple spindle” is a meiotic irregularity in which more than one spindle occurs in a high proportion of first‐metaphase cells. Abnormal telophase segregations, the occurrence of micronuclei with the microspore nuclei, and reduced pollen fertility are further manifestations of this irregularity. Reciprocal hybrids between normal and multiple spindle are normal. Segregation data from F2 and F3 progenies indicate that multiple spindle is inherited as a single recessive gene, m. The mm genotype has persisted at a high frequency (about 15%) for at least 7 years in the natural population from which cultures were derived.
TEMPERATURE‐INDEPENDENT RIBOFLAVINELESS MUTANTS OF ASPERGILLUS NIDULANS
Authors: Panicker Radha K. , Shanmugasundaram E. R. B.
Published: January 2018

Panicker, Radha K., and E. R. B. Shanmugasundaram. (U. Madras, India.) Temperature‐independent riboflavineless mutants of Aspergillus nidulans. Amer. Jour. Bot. 49(6): 555–559. Illus. 1962.—Studies on the biosynthesis of riboflavine using 5 non‐allelic, riboflavineless mutants of Aspergillus nidulans show that: (1) all of them are temperature‐independent; (2) optimal amounts of the vitamin required for maximal growth vary from one mutant to the other; (3) the riboflavine activity of purines and pyrimidines on the mutants are none too different from the earlier observations on Neurospora crassa, Eremothecium ashbyii and Ashbya gossypii; and (4) the isoalloxazine and alloxazine derivatives are not only devoid of vitamin activity but also slightly inhibit the growth of the mutants in presence of the vitamin.
ONTOGENY AND PHYLLOTAXIS OF THE TERMINAL VEGETATIVE SHOOTS OF MICHELIA FUSCATA
Authors: Tucker Shirley C.
Published: January 2018

Tucker Shirley C. (Northwestern U., Evanston, Ill.) Ontogeny and phyllotaxis of the terminal vegetative shoots of Michelia fuscata. Amer. Jour. Bot. 49(7): 722–737. Illus. 1962.—Two patterns of symmetry occur in Michelia fuscata In the lead shoots, leaves arise in a 2/5 spiral arrangement which may be either clockwise or counterclockwise. Other shoots are dorsiventrally organized; these shoots produce leaves in a modified ½ phyllotaxis in which the angle between the 2 files of leaves lies between 100° and 150°, according to the particular branch. Both types of shoot have a zonate apical meristem with a biseriate tunica a central initial zone, and a peripheral zone. The apical configuration of cells does not change appreciably during the plastochron. The flat to low‐convex outline of the shoot apex is maintained by initiation of the leaves close to the summit of the apex; the diameter of the meristem diminishes greatly after such an initiation. Leaf inception in the subsurface tunica layer is followed by precocious activity of the marginal meristems which extend the stipular flanges completely around the base of the apical meristem. The stipular margins then fuse laterally and form a hood over the apex. A subapical initial meanwhile is active in the leaf blade, where it persists up to the time the leaf is 2 mm high. The most recent primordium is 300 μ high before another leaf is initiated. The vascular system of the stem is a cylindrical network of leaf traces, with 6–12 traces per leaf. The procambium develops acropetally from preexisting vascular strands in the stem below. Elements of the diverse sclereid system differ in shape in different tissues, according to the availability of intercellular space. Goebel's term “Pendelsymmetrie” is discussed with reference to apical activity in Michelia.
GENOME RELATIONSHIPS IN INTERSPECIFIC AND INTERGENERIC HYBRIDS OF RENANTHERA
Authors: Kamemoto H. , Shindo K.
Published: January 2018

Kamemoto, H., and K. Shindo. (U. Hawaii, Honolulu.) Genome relationships in interspecific and intergeneric hybrids of Renanthera. Amer. Jour. Bot. 49(7): 737–748. Illus. 1962.—Chromosome numbers and meiotic behavior of species and hybrids of Renanthera (Orchidaceae) were investigated. Renanthera elongata, R. histrionica, R. matutina, R. monachica, and R. storiei were diploid (2n = 38). The race of R. coccinea commonly grown in Hawaii was found to be hexaploid (2n = 114), while a recently introduced clone from Thailand was diploid (2n = 38). Diploid interspecific hybrids formed about 18 bivalents at M‐I, indicating a relatively strong homology of parental chromosomes. The tetraploid hybrid of diploid R. monachica and hexaploid R. coccinea showed predominantly 37 or 38 bivalents, indicating good homology of genomes of the 2 parental species, and autosyndetic pairing in the 2 additional genomes of R. coccinea. Intergeneric hybrids involving Renanthera spp. could be classified into 2 distinct groups: those with 14–11 bivalents that are generally oriented at the metaphase plate and eventually lead to a preponderance of tetrads or tetrads with microcytes, and those with fewer bivalents (9–5) many of which are unoriented pseudobivalents and which ultimately give rise to dyads and dyads with microcytes. Relationships of parental species on a taxonomic basis are closer in the former than the latter group.
AN ATTEMPT TO DETECT UTILIZATION OF DNA BREAKDOWN PRODUCTS FROM THE TAPETUM FOR DNA SYNTHESIS IN THE MICROSPORES OF LILIUM LONGIFLORUM
Authors: Takats Stephen T.
Published: January 2018

Takats, Stephen T. (Brookhaven Natl. Lab., Upton, N. Y.) An attempt to detect utilization of DNA breakdown products from the tapetum for DNA synthesis in the microspores of Lilium longiflorum. Amer. Jour. Bot. 49(7): 748–758. Illus. 1962.—The tapetum in anthers of Lilium longiflorum encloses the developing microspores and when it degenerates is a possible source of precursor material for DNA4 synthesis in the microspores. To check this, time‐course experiments were carried out tracing the fate of label introduced into the tapetal DNA. H3‐thymidine was given in vivo to anthers during late pachytene of meiosis, when the tapetum can be selectively labelled. Growth was then followed by sampling anthers until the tapetum degenerated and the microspores synthesized DNA and divided. Autoradiographs indicated that the label in tapetal nuclei was lost shortly before DNA synthesis in the microspores. The microspore walls were transiently labelled, but the microspore nuclei did not incorporate a detectable amount of label. The results are discussed in the light of related biochemical findings, and are explained on the basis of: (1) complete catabolism of tapetal DNA (or tapetal thymine); and (2) the existence of a non‐tapetal pool of precursors.
EFFECT OF NITROGEN, SULFUR AND OTHER FACTORS ON ZOOSPORE PRODUCTION BY PROTOSIPHON BOTRYOIDES
Authors: O'Kelley Joseph C. , Deason Temd R.
Published: January 2018

O'Kelley, J. C., and T. R. Deason. (U. Alabama, University.) Effect of nitrogen, sulfur and other factors on zoospore production by Protosiphon botryoides. Amer. Jour. Bot. 49(7): 771–777. Illus. 1962.—Nutrient‐medium pH, osmotic pressure, staling products, and mineral depletion were studied in relation to zoospore production by Protosiphon botryoides in liquid media. In an intermediate range (pH 5.1–7.7), pH has little or no influence specifically on zoospore production. Although distilled water is an unsuitable medium for zoospore production, if a balanced nutrient medium is supplied, osmotic pressure is without pronounced influence over a wide range. Staling products in old cultures exert a minor inhibitory effect. Deficiencies of nitrate, sulfate, or calcium in liquid media can decrease drastically zoospore production or release, and nitrate or calcium depletion appears to be mainly responsible for loss of the capacity of Protosiphon to produce and release zoospores in aged liquid cultures.
AXENIC CULTURE OF UTRICULARIA
Authors: Pringsheim Ernest G. , Pringsheim Olga
Published: January 2018

Pringsheim, Ernest G., and Olga Pringsheim. (Pflanzenphysiologisches Inst., Göttingen, Bundesrepublik Deutschland.) Axenic culture of Utricularia. Amer. Jour. Bot. 49(8): 898–901. Illus. 1962.—Utricularia exoleta, a small tropical floating carnivorous plant, was freed of other organisms by hypochlorite treatment. An inorganic nutrient solution was composed which produced good vegetative growth but flowering only if organic compounds, as contained in beef‐extract, were added aseptically.