bluuebunny/crossref_metadata_2025 huggingface dataset:
A SURVEY OF THE VEGETATIVE SHOOT APICES IN THE FAMILY MALVACEAE
Authors: Tolbert Robert J. , Johnson Marion A.
Published: January 2018

The present study compares the structure of the vegetative shoot apex in 40 species of the Malvaceae. There is a wide range of size, shape, and zonation within the apices of the family. Although many of the apices are domed, some are flat‐topped and do not extend above the axil of the youngest leaf primordium. Also, most of the species investigated are recorded as having a more or less marked cytohistological zonation superimposed on the tunica‐corpus configuration. The tunica is single‐layered in a majority of species, but stratification of the upper corpus is common. In an effort to give a more accurate concept of apical structure and activity, the apex is described as the metrameristem and its derivatives: the flanking meristem, and the pith rib meristem or pith mother cells. The metrameristem, consisting of the tunica initials and the co pus initials, is the focal point of the study of the zoned apices. Data are presented for the measurements of the metrameristem, measurements of the apical dome, type of flanking meristem, origin of the pith, and growth habit of the plant. There appears to be a correlation between growth habit and the distinctness with which the metrameristem is marked off from the surrounding tissue. Most of the herbaceous species have an indistinctly marked metrameristem, whereas the shrubby trees and trees have a distinctly marked metrameristem. Zonation in shrubs and suffrutescent plants may be of either type.
CHEMO‐DEMES OF DIPLOID AND TETRAPLOID THELESPERMA SIMPLICIFOLIUM (HELIANTHEAE, COREOPSIDINEAE)
Authors: Melchert Thomas E.
Published: January 2018

Selected secondary biochemical constituents (mainly flavanoids) contained in methanol leaf extracts of 11 taxa in the genus Thelesperma were analyzed via two‐dimensional paper chromatography. With but one exception all produce an essentially identical array of these compounds. Since this common or “generic” biochemical profile is present regardless of the morphological, ecological, and cytological differences among and within the various species, it is impossible to make accurate specific identifications on the basis of chromatographic data alone. Recently, however, morphologically identical, but allopatric, diploid and tetraploid races of T. simplicifolium were discovered which differ radically in respect to these secondary biochemical components. Their infraspecific biochemical differences are so absolute that it is possible to predict accurately the ploidy level and geographic source of any given individual from its chromatographic profile. The evolutionary implications of these biochemical differences are also discussed briefly.
SOME ASPECTS OF SIEVE CELL ULTRASTRUCTURE IN PINUS STROBUS
Authors: Murmanis Lidija , Evert Ray F.
Published: January 2018

The immature sieve cell of Pinus strobus contains all of the protoplasmic components commonly encountered in young cell types. In addition, it contains slime bodies with distinct double‐layered limiting membranes. The mature sieve cell is lined by a narrow layer of cytoplasm consisting of a plasmalemma, one or more layers of anastomosing tubules of endoplasmic reticulum, numerous mitochondria, starch granules and crystal‐like bodies. Each mature cell contains a necrotic nucleus. Ribosomes and dictyosomes are lacking. Strands derived ontogenetically from the slime bodies of the immature cell traverse the central cavity and are continuous with those of neighboring sieve cells through the plasmalemma‐lined pores of the sieve areas. Sieve‐area pores are also traversed by numerous endoplasmic membranes. A membrane was not found separating the parietal layer of cytoplasm from the large central cavity.
SEED DISPERSAL OF DENDROMECON: ITS ECOLOGIC, EVOLUTIONARY, AND TAXONOMIC SIGNIFICANCE
Authors: Berg Rolf Y.
Published: January 2018

Both species of Dendromecon are diplochorous, that is, the seeds are first scattered from the mother plant by violently dehiscing capsules and then transported further away by ants, which are strongly attracted to the elaiosome at the micropylar end of the seed. The tensions that cause the capsule to explode develop between the two carpels and also between lateral and central fiber strands in the capsular valves. The elaiosome is unusual in that it contains large quntities of starch in addition to the commonly present fatty oils and that it is more drought resistant than most known elaiosomes. Seed dispersal is very efficient over short distances, but migration barriers a few hundred meters or more cannot be crossed except by chance dispersal. Dendromecon differs strikingly from most ant‐dispersed plants in being woody and xerophytic; so far, D. rigida is the only chaparral plant known to be habitually dispersed by ants. The presence of an auto‐chorous‐myrmecochorous type of seed dispersal in D. rigida may partly explain the polymorphism of this species, since this type of seed dispersal tends to keep local populations isolated. The nearly complete correspondence, anatomically, morphologically, and functionally, between the fruit of Dendromecon and that of Eschscholzia strongly supports the idea of a close taxonomic relationship between these two genera. The seed appendage is believed to be a “recent” specialization in Dendromecon, phylogenetically independent from seed appendages facilitating dispersal by ants in other genera of the Papaveraceae.
EFFECTS OF INDOLE‐3‐ACETIC ACID AND PARACHLOROPHENOXY‐ISOBUTYRIC ACID ON ABSCISSION IN PETIOLES OF DEBLADED LEAVES OF PHASEOLUS VULGARIS
Authors: Devlin Robert M. , Hayat M. Arif
Published: January 2018

The effects of indole‐3‐acetic acid (IAA) and p‐chlorophenoxyisobutyric acid (PCIB) on rates of abscission layer formation and abscission were investigated. The primary leaves of Phaseolus vulgaris were used as test material. Treatment at the distal end of one petiole of the pair from debladed primary leaves with 1% IAA inhibited the abscission of that petiole and accelerated the abscission of its opposite untreated partner. PCIB applied simultaneously with IAA counteracted the accelerating effect of IAA on the opposite untreated petiole. This influence increased with increasing concentrations of PCIB. Anatomical studies revealed that PCIB, although it counteracted the effect of IAA on the rate of abscission, had no effect on abscission layer formation. In other words abscission layer formation takes place under the influence of the auxin despite the presence of the antiauxin. The centripetal sequence of abscission layer formation was found in all cases.
CHROMATOGRAPHIC EVIDENCE OF HYBRIDIZATION AND EVOLUTION IN PHLOX MACULATA
Authors: Levin Donald A.
Published: January 2018

Representatives of P. maculata ssp. maculata and P. glaberrima ssp. interior and 36 putative hybrids were collected from a population in central Indiana. Chromatographic analysis revealed the presence of nine diagnostic components in P. maculata ssp. maculata and eight such components in P. glaberrima ssp. interior. Putative F1 hybrids contained all or most of the parental marker components; markers of the non‐recurrent parent were absent in the two classes of putative backcross progeny. The characters of P. maculata ssp. pyramidalis are a composite of those present in P. maculata ssp. maculata and P. glaberrima ssp. interior, and the former is virtually identical to certain hybrids from the population in question. The contention that P. maculata ssp. pyramidalis is a stabilized derivative of natural hybridization between these taxa is substantiated by the presence of all of the diagnostic constituents of the putative parents on its chromatograms. It is the author's opinion that the definitive data which chromatography affords will be invaluable in elucidating the complex pathways of evolution in Phlox.
EVIDENCE OF A ROLE OF HETEROCYSTS IN THE SPORULATION OF A BLUE‐GREEN ALGA
Authors: Wolk C. Peter
Published: January 2018

Sporulation of vegetative cells adjacent to heterocysts is prevented by detachment of the two cell types, probably without impairment of the capacity of those vegetative cells to sporulate. Apparently, therefore, heterocysts are in part responsible for the sporulation of vegetative cells attached to them.
HYBRIDS AND GENOME RELATIONS OF HIBISCUS SABDARIFFA, H. MEEUSEI, H. RADIATUS AND H. ACETOSELLA
Authors: Menzel Margaret Y. , Wilson F. D.
Published: January 2018

Chromosome pairing was studied in the following hybrids: Hibiscus radiatus‐meeusei (tetraploid F1), H. sabdariffa‐meeusei (tetraploid F1 and spontaneous allooctoploid F2), and hexaploid H. acetosella‐(sabdariffa‐meeusei). Genome constitutions of the species adduced from these data are symbolized as follows: H. radiatus and H. acetosella, AABB; H. meeusei, AAXX; H.sabdariffa, XXYY or AAYY.
PALEOZOIC LYCOPSID FRUCTIFICATIONS. II. LEPIDOSTROBUS TAKHTAJANII IN NORTH AMERICA AND GREAT BRITAIN
Authors: Balbach Margaret Kain
Published: January 2018

A study was made of 50 detached lycopsid megasporophylls in coal balls of middle Pennsylvanian age from Illinois. Direct comparison of these specimens with those reported from Great Britain by D. H. Scott in 1901 and considered by him as the immature stage of Lepidocarpon lomaxi Scott shows no difference between them. Furthermore, the study shows that these sporophylls and those of Scott are not the immature stage of L. lomaxi but represent a different taxon. Comparison of the British and American material with the descriptions and illustrations of Russian specimens assigned by Snigirevskaya in 1964 to Lepidostrobus takhtajanii reveals that all represent the same taxon. Accordingly, the British and American specimens are assigned to L. takhtajanii. An emended description of L. takhtajanii Snig. is given based on additional information obtained in this study. Relationships of lycopsid megasporophylls are discussed.
THE F1 HYBRIDS OF SOME SAPOGENIN‐BEARING DIOSCOREA SPECIES
Authors: Martin Franklin W. , Cabanillas Eugenio
Published: January 2018

Fifteen species of Dioscorea and one of Rajania were cross‐pollinated in 60 different combinations. Crosses among New World species were partially successful, whereas crosses between New and Old World or among Old World species usually failed entirely. Viable hybrids were obtained from 13 combinations, including all 12 possible combinations among 4 sapogenin‐bearing species. Hybrids were intermediate to their parents with respect to vegetative characteristics, but exhibited wider variation or poor physiological control of critical growth phases, including length of the juvenile phase, dry season dormancy, and season of flowering. The flowers of hybrids were also intermediate to those of parents with no clear expressions of dominance. Chromosomal behavior of hybrids was essentially normal but reduction in fertility was manifested by high percentages of abnormal pollen, low crossability and poor seed germination. The significance of these findings with reference to speciation, reproductive barriers, and improvement by breeding is discussed.
TAXIMETRICS AS APPLIED TO THE GENUS LITHOPHRAGMA (SAXIFRAGACEAE)
Authors: Taylor Roy L.
Published: January 2018

A taximetric analysis of Lithophragma, a genus endemic to North America containing 10 taxa, reveals a close similarity to the taxonomy proposed by the author in a recent monograph using the traditional intuitive approach. The taximetric method is based on a neo‐Adansonian approach utilizing the same characters used in the intuitive study, but arbitrarily giving equal weight to all unit characters. A total of 29 unit characters was employed and although this is fewer than is considered necessary by most taximetrists to ensure reproducible results, the analysis is restricted to but a single small genus. The number of unit characters could be greatly increased by the inclusion of generic characters; however, such characters would be merely redundant and positive. A rearranged similarity matrix and dendogram are included. The conclusion is reached that taximetrics may help place plant taxonomy on an objective basis as is classification in such disciplines as physics and chemistry. Its application, however, must await extensive documentation of plant taxa on a broad basis.
SEED DORMANCY IN UNIOLA PANICULATA
Authors: Westra Raymond N. , Loomis Walter E.
Published: January 2018

Seeds of Uniola paniculata L., a sand‐dune grass of the Southeast coast, showed an increasing dormancy under laboratory germination conditions that reached 98–100% six months after maturity. The embryos were viable and nondormant and the seeds absorbed water readily. Chemical treatments were only moderately effective, but leaching the seeds after cutting into the endosperm gave 100% germination. The presence of a diffusible growth inhibitor was demonstrated by this response and by tests of endosperm leachate. Temperature, particularly sand temperature above 30 C, appears to be the major factor in normal germination of the seed.
MEIOTIC IRREGULARITY IN SPECIES AND INTERSPECIFIC HYBRIDS OF PINUS
Authors: Saylor LeRoy C. , Smith Ben W.
Published: January 2018

This paper describes a comparative analysis of meiotic conditions in 61 individual trees representing 21 species and 22 interspecific hybrid combinations of the genus Pinus. Material was collected during three successive growing seasons at the Eddy Arboretum of the Institute of Forest Genetics at Placerville, California. Meiotic irregularity occurred in all species and hybrids examined; mean irregularity frequencies of individual trees ranged from 0 to 47.2 percent. Abnormalities in chromosome movement and their consequences, (1) precocious disjunction associated with the occurrence of univalents and (2) the failure of chiasma terminalization leading to lagging chromosomes and to chromosome breakage and fragments, account for most of the observed irregularity. The same kinds of irregularity occur both in the species and in the hybrids, but they were considerably more frequent in certain of the hybrids than in the related species. These abnormalities in chromosome movement seem to be characteristic of Pinus and are attributed primarily to rrechanical difficulties which attend the large pine chromosomes in meiosis. The most spectacular meiotic irregularities were the characteristic bridge‐fragment configurations considered to be the result of crossing‐over in heterozygous paracentric inversions. Inversion bridges were observed in 59 of the 61 trees and were as frequent in the species as in the hybrids. They apparently do not result from interspecific differentiation in chromosome structure but from spontaneous intra‐specific rearrangements. The literature and work now in progress provide increasing evidence that introgression has been an important factor in the evolution of pine populations. The cytological study of pine chromosomes has failed to produce qualitative evidence of introgression, but the quantitative measurement of meiotic irregularity may serve as a useful criterion for recognizing the results of past hybridization.
THE ONSET OF MITOSIS AND DNA SYNTHESIS IN ROOTS OF GERMINATING BEANS
Authors: Davidson D.
Published: January 2018

The time of onset of mitosis and DNA synthesis has been determined in roots of germinating seeds of Vicia faba. Mitosis is not initiated in all roots simultaneously. Dividing cells are seen 36 hr from the beginning of germination, but they are present in low frequency (0.02%). Dividing cells do not become frequent, i.e., occurring as 5% or more of all cells, until 56 hr, and it is not until 66–68 hr that all roots in a sample of 10 are mitotically active. DNA synthesis shows a similar sporadic beginning. It occurs in a few cells by 28 hr, and by 40 hr all roots exposed to 3H–thymidine show active incorporation. For most cells in these germinating roots DNA synthesis precedes mitosis. In one root in 10, however, some cells are unlabeled when they enter mitosis, indicating that they had spent the dormant period in the G2 phase of the mitotic cycle. The presence of these cells determines whether or not roots show chromatid and chromosome aberrations following irradiation during germination.
GEOTROPISM IN SIMULATED LOW‐GRAVITY ENVIRONMENTS
Authors: Dedolph R. R. , Gordon S. A. , Oemick D. A.
Published: January 2018

The assumption that changes in growth associated with horizontal clinostat rotation are caused by the nullification of the directional component of the gravity‐force vector has not been rigorously tested. It was found that geotropic response is dependent upon the calculated degree of nullification of the directional component of the gravity‐force vector. This relationship increases the probability that clinostat rotation at appropriate rates produces conditions simulating low gravity. Using oat seedlings and clinostat techniques that cancel only a portion of the gravity‐force vector, there is no threshold of gravity perception. The geotropic curvature response increases with the force imposed. Forces of 0.06 and 0.08 × g were sufficient for maximum response of oat roots and coleoptiles, respectively.
CHROMOSOME NUMBERS IN PURE AND GROSS CULTURES OF MYXOMYCETES
Authors: Ross Ian K.
Published: January 2018

Certain strains of Myxomycetes grown in pure culture in liquid media display widely varying chromosome numbers which indicate the presence of polyploid series of amoebae and plasmodia. The implications of these chromosome number variations on existing controversies concerning Myxomycete life cycles and cytology are discussed.
ARCHAEOPTERIS MACILENTA, ANATOMY AND MORPHOLOGY OF ITS FROND
Authors: Carluccio Leeds M. , Hueber Francis M. , Banks Harlan P.
Published: January 2018

The stem, rachides, and pinnae of Archaeopteris macilenta, formerly considered to be a fern of Devonian age, comprise a branch system in which the ultimate divisions heretofore referred to as pinnules are the leaves. The primary vascular system of the “frond” is a lobed siphonostele from which leaf traces arise in a spiral sequence. The anatomy of the “rachis” and of the “pinnae” is shown to be similar to that of the stem, Callixylon, which bore these “fronds.” Branching, epidermal pattern and stomates are described for the spirally arranged leaves (fertile pinnules). Attachment and dehiscence of sporangia as well as their stomates are reported. Archaeopteris is retained in the Class Progymnospermopsida which includes plants with gymnospermous anatomy and pteridophytic reproduction. It is suggested that Actinopodium, Svalbardia and Siderella are related closely to Archaeopteris and that this group of genera shows evolutionary stages in webbing of leaves and planation of branch systems. The opportunities for ontogenetic studies of the arborescent genus Archaeopteris are pointed out.
SOME ASPECTS OF MORPHOGENESIS IN CUSCUTA GRONOVII
Authors: Truscott F. H.
Published: January 2018

More than 100 primary root segments from dormant seeds, 100 radicular segments from immature embryos, 450 whole immature embryos, and a number of whole seedlings of C. gronovii were studied under in vitro cultivation in the presence of such growth‐regulating factors as: coconut milk, casein hydrolysate, auxins, kinetin, adenine, gibberellic acid, and additional B vitamins as supplements to White's medium. In normal embryogeny early swelling of the basal pole of the embryo and profuse production of epidermal hairs upon germination are superficial characteristics of Cuscuta which resemble seedling root growth in other plants. At no time is there evidence of a primary‐root meristem, nor at any time do cotyledons develop. It was not possible to induce root formation experimentally from any of the starting embryonic materials, nor from stems which were cultured to maturity culminating in the production of flowers after 6 months of in vitro cultivation, nor from callus derived from the radicular pole of the embryo. The undifferentiated radicular pole frequently gave rise to rapidly growing callus from which new shoots were formed spontaneously, although some immature embryos completed normal embryogeny. Embryo size and subsequent type of development were not strictly correlated but there was a tendency toward the following patterns. Embryos less than 0.4 mm in length lost their original form, callused evenly throughout and became masked by development of buds over the entire surface. Embryos 0.4–1.2 mm were most apt to retain their original form; callus developed at the radicular pole but not at the shoot pole. Embryos 1.5 mm and larger frequently gave rise to radicular callus but also grew normal shoots. Embryo inoculants which had begun to coil were most apt to complete normal embryogenesis. No correlation could be drawn between the addition of specific growth regulators or combinations of regulators and specific patterns of development. It is suggested that in the evolution of Cuscuta from autotrophic ancestors, the loss of both cotyledons and roots was a single embryonic event and so complete that even under the influence of a highly modified biochemical environment it would be impossible to derive roots from dodder tissue. The usual interpretation of the dodder haustorium as a highly modified adventitious root in all probability is not valid. Is is further suggested, however, that this loss of root and cotyledon is not a necessary consequence of the evolution of the parasitic mode of nutrition, nor of the gross adult growth form.
ABSCISIN, AUXIN, AND GIBBERELLIN EFFECTS ON THE DEVELOPMENTAL ASPECTS OF ABSCISSION IN COTTON (GOSSYPIUM HIRSUTUM)
Authors: Bornman C. H. , Spurr A. R. , Addicott F. T.
Published: January 2018

The effects of accelerating and retarding amounts of abscisin (Ab II), auxin (IAA), and gibberellin (GA3) on abscission in explants of 14‐day‐old cotton (Gossypium hirsutum L.) seedlings were studied. Applications of Ab II, a potent accelerant (0.025 μg/abscission zone), resulted in a lysigenous breakdown of cells in a weakly defined separation layer in contrast to GA3, an accelerant (0.01 μg/abscission zone), and IAA, a retardant (0.125 μg/abscission zone), which resulted in a schizogenous type of breakdown of cells in a well‐defined separation layer, three or more rows of cells wide. Separation usually commenced adaxially with GA3, abaxially with IAA and in the controls, and either ad‐ or abaxially with Ab II. Cell division preceded abscission, the number of cells increasing greatly within 24 hr after GA3 treatment. Tyloses formed in vessel elements throughout the explant, both distal and proximal to the plane of separation in all treatments and in the controls. The retardant, IAA, appeared to stimulate tyloses formation. Tylosis development was not causal but was secondarily related to abscission.
APICAL DOMINANCE AND FORM IN WOODY PLANTS: A REAPPRAISAL
Authors: Brown Claud L. , McAlpine Robert G. , Kormanik Paul P.
Published: January 2018

The form of woody plants is commonly interpreted in terms of apical dominance. Trees with the decurrent or deliquescent branching habit are said to have weak apical dominance, whereas excurrent branching is associated with strong apical dominance. A close examination of many decurrent species such as the oaks, hickories, and maples reveals that almost all of the lateral buds on the current year's twigs are completely inhibited. This complete inhibition of lateral buds by definition and common usage of the term is an expression of strong apical dominance. In trees possessing the excurrent branching habit, such as most conifers and some angiosperms, many of the lateral buds on the current year's twigs elongate to varying degrees. This is usually interpreted as an expression of weak apical dominance. The relationship between bud inhibition and form in woody perennials is much more complex than bud inhibition in herbaceous plants because of the time sequence in the formation and release of lateral buds. For example, it is only after a period of rest or dormancy in the decurrent forms that one or more of the uppermost lateral buds are released, and these may outgrow the currently elongating terminal shoot resulting in forking. Conversely, in the excurrent forms, it seems that the initial expression of weak apical dominance enables the terminal leader to outgrow the currently elongating lateral branches so that it exerts complete control over their subsequent growth and development in later years. An examination of the levels of diffusible auxin at different points along the twigs of excurrent and decurrent species indicates that the balance of growth factors at any given locus, and not the absolute quantity of auxin, exerts primary control over bud inhibition and shoot elongation.
POLYOLS IN SCHIZOPHYLLUM COMMUNE
Authors: Niederpruem Donald J. , Hunt Stephen
Published: January 2018

Sugars and sugar alcohols present in extracts of the wood‐rotting mushroom Schizophyllum commune were identified by paper chromatography during fruiting, basidiospore germination, and growth of vegetative mycelium. Homokaryotic fruitbodies and dikaryotic fruits derived from several compatible matings of S. commune contained mannitol and arabitol. Basidiospores shed from dikaryotic fruits also contained mannitol and arabitol while the latter disappeared during spore germination. Vegetative mycelium (strain 699) contained glucose, fructose, mannitol and glycerol while these compounds as well as arabitol occurred in mycelium of strain 845. Polyols are not, therefore, associated exclusively with the sporulation process in S. commune.
FLORAL PIGMENTATION STUDIES IN THE GENUS GOSSYPIUM. III. QUALITATIVE ANALYSIS OF TOTAL FLAVONOL CONTENT FOR TAXONOMIC STUDIES
Authors: Parks Clifford R.
Published: January 2018

Despite the potential contribution suggested from chromatographic studies of many groups, taxonomic conclusions based on paper chromatography alone may carry some inherent errors. In many instances chemical differences between taxa cannot be characterized by two‐dimensional chromatography of crude extracts. Pigment diversity may go unnoticed in such a study, and conclusions based on simple chromatographic results may show too much similarity between the taxa being compared. The resolution of chromatographic separations of the often very complex mixtures encountered in crude plant extracts can be greatly improved by a preliminary column separation, and in this study a method of pigment analysis employing both preliminary column and subsequent paper chromatography is used. While it is usually impractical to identify all of the components of a flavonoid complex, each member should be characterized to the degree that it can be distinguished from all others. Here, the characterization of a component includes its rate of movement in the column, relative position and color under ultraviolet light on the chromatogram, the absorption spectrum in ethanol and the change in the absorption spectrum when a reagent is added to the ethanol which has a particular effect on the spectral properties of that flavonoid. With very few exceptions no one criterion of characterization is definitive for any component. More than 20 flavonoid pigments have been observed in the two tetraploid Gossypium species, G. barbadense and G. hirsutum. Only 10 of the constituents were common to the two species. The results of a previous study based on two‐way paper chromatography of crude extracts makes the two species appear much more similar in flavonoid composition than is indicated by the more detailed column‐paper chromatography presented here. The degree of difference between G. hirsutum and G. barbadense is surprisingly large in light of the generally accepted theory of their common origin. The value of chromatographic‐chemotaxonomic studies is greatly increased if the chemical systems involved are characterized.
KARYOTYPES OF EASTERN NORTH AMERICAN PHLOX
Authors: Smith Dale M. , Levin Donald A.
Published: January 2018

The karyotypes of 32 Phlox taxa were studied in many plants representative of populations found throughout eastern North America. Most plants were diploid with 2n = 14, but a few tetraploids and plants with B‐chromosomes were also observed. Some species were virtually indistinguishable karyotypically, while others differed. Within and between the Subsections Speciosae, Divaricatae, and Subulatae, strikingly similar karyotypes were observed. Other Subsections differed significantly, with the Ovatae showing strong intrasubsectional variation. Increased karyotype asymmetry is correlated with morphological specialization. Where polyploidy was observed, discordant chromosome sets indicated allopolyploidy.
A NEW SPECIES OF DICTYOSTELIUM FROM HAWAII
Authors: Nelson Nancy , Olive L. S. , Stoianovitch Carmen
Published: January 2018

A new species of Dictyostelium, isolated from a decaying ear of corn in Hawaii, is described. Because of the numerous irregularities in its developmental morphology and general appearance, it is being named D. irregularis. Aggregation is by amoebal streaming, and the aggregation mass commonly segments into several pseudoplasmodia, each of which produces a sorocarp in situ or after migration. During migration stalk material is laid down behind the pseudoplasmodium. The mature sorocarps, which do not exceed 1 mm in height, have very irregular stalks and globular‐to‐elongate sori with elliptical spores that measure 3.5‐7 × 4.8‐9.8μ. Cyst formation was not observed. The new species is of particular interest from the standpoint of its probable primitive position in the genus.
CHEMICAL CONTROL OF ADVENTITIOUS ORGAN FORMATION IN LACTUCA SATIVA EXPLANTS
Authors: Doerschug Marcia R. , Miller Carlos O.
Published: January 2018

Both kinetin and adenine promote bud initiation in excised cotyledons of Lactuca sativa. Controls lacking these substances form abundant roots but have never formed buds. Indoleacetic acid and certain mineral salts are also necessary for regeneration of shoots. Although bud growth from cotyledons is extensive on a medium containing both indoleacetic acid and kinetin, excised roots display a low propensity toward bud formation and typically develop callus tissue with roots. Growth of hypocotyl sections is intermediate with respect to bud formation. Shoot initiation in lettuce thus varies with the region of the seedling as well as with the culture medium.
DEVELOPMENTAL CHANGES IN THE VASCULAR CAMBIUM IN LEITNERIA FLORIDANA
Authors: Cumbie B. G.
Published: January 2018

Developmental changes in the vascular cambium of Leitneria floridana, a shrub, were determined primarily by an analysis of the secondary xylem. During the production of the first growth ring of secondary xylem, 37% of the anticlinal divisions in the fusiform initials were lateral, the remaining were oblique. The oblique partition averaged ½ of the length of the dividing initials during this period of growth. Following their origin in anticlinal division, daughter cells elongated at a rapid rate until they were about as long as the mean for all cells, and then most cells elongated at a slow rate. Almost all initials survived during the formation of the inner secondary xylem (growth rings 1–10), and few new rays were formed from fusiform initials. During the production of the outer secondary xylem (growth rings 22–26), lateral divisions accounted for less than 5% of all anticlinal divisions. The oblique partition averaged only ¼ of the length of the dividing cells during this period, although the mean length of dividing initials was relatively constant throughout secondary growth. About 20% of the initials studied during the deposition of the outer secondary xylem disappeared from the cambium, and many others were transformed into ray initials. The findings are discussed in relation to the developmental changes in the vascular cambium in plants of different habits.
ANGIOSPERM WOOD FROM THE UPPER CRETACEOUS OF CENTRAL CALIFORNIA: PART I
Authors: Page Virginia M.
Published: January 2018

This paper is the first in a series about a collection of 40 Upper Cretaceous woods from central California. The wood is in the form of fragments of stems and roots embedded in nodules of collophane rich in microorganisms, pollen, and spores. Two new species are described: Ulminium pattersonensis and Ulminium mulleri. Evidence presented indicates that these two specimens are similar to woods of the Lauraceae and fall well within the range of variation of woods of that family. Because the taxonomy of the Lauraceae is in need of revision, meaningful comparisons of fossil plant parts with modern taxa were found to be unfeasible.
THE EFFECTS OF COLCHICINE ON CELLULAR ORGANIZATION IN CHLAMYDOMONAS. II. ULTRASTRUCTURE
Authors: Walne Patricia L.
Published: January 2018

Comparative ultrastructural investigations of the effects of 0.005 m colchicine on the organization of cellular components in Chlamydomonas eugametos were made at intervals during and after treatment. Periodic observation of colchicine‐treated cells revealed curling of the Golgi cisternae and increased vesicle production by the Golgi apparatus, followed by a continuous increase in number of that organelle. Elongated mitochondria were observed to bo an early, but transitory, response, as was a marked proliferation of the nuclear envelope and endoplasmic reticulum; the latter was followed by an increase in nuclear size and convolution. Colchicine‐treated cells also manifested stratification of cell walls and replication of many cellular components. Nuclear anomalies, cytoplasmic compartmentalization, and unusual associations of several organelles were also observed. Initial manifestations of recovery were reorganization of the stigma granules and alignment of cytoplasmic vacuoles. Electron microscopy of apparently recovered cells indicated their organization to be similar to that of the controls.
A TEMPERATURE‐SENSITIVE MALE‐STERILE MUTANT OF THE TOMATO
Authors: Rick Charles M. , Boynton John E.
Published: January 2018

Variable male sterility was encountered in a spontaneous mutant of Lycopersicon esculentum Mill. ‘San Marzano.‘ The trait, conditioned by a single recessive gene vms, was proved by trisomic and linkage tests to lie on chromosome 8, probably in the longer arm between the markers bu and dl. Under field conditions, from June to October in the interior valleys of California, vms develops severely reduced, deformed stamens and defective corolla, being otherwise physiologically and morphologically normal. Despite the production of a limited amount of stainable pollen under these conditions, it is effectively male‐sterile. Earlier in the season in the field and throughout the entire year under normal greenhouse conditions, the flowers are normal except for a slight reduction in the width of corolla segments. Differences in temperature account for the varied response of vms to the environment, minimal temperatures of 30 C in the field and of 32 C in the greenhouse being required to evoke the sterile phenotype. Application of high temperatures to a single branch of vms elicits a response only in the subsequently developed flowers of that branch. The approximate minimal requirements for the greenhouse environment are temperatures of 35 C or higher applied (1) for 4 hr/day for 2 weeks, (2) for 8 hr/day for 1 week, or (3) continuously for 48 hr. The vms response was also elicited by 29.5 C applied continuously for 96 hr and by 40.5 C for 12 hr. Depending upon the rate of growth, the response first appears 3–5 weeks after the start of treatment and continues for approximately the same length of time as that of the treatment. In the light of these findings and of the observed rate of development under the same environment, the sensitive stage is estimated to be flower primordia of 0.075 mm or smaller diam. Buds of this size appear very close to the shoot meristem, are still highly mitotic, and precede meiosis in PMC by at least 10 days—a relationship that is in keeping with the deformity observed in anthers of all dissectable sizes.
KLEINODENDRON AND XYLEM ANATOMY OF CLUYTIEAE (EUPHORBIACEAE)
Authors: Stern William L.
Published: January 2018

Kleinodendron, a new genus of Euphorbiaceae, was assigned by Smith and Downs to the tribe Cluytieae. A xylem anatomical survey indicates that there are no objections to this placement. Woods of Cluytieae are diverse but may be characterized generally by having pores which average less than 80 μ in diameter and which are well divided between solitary and radial multiple distributions in the same species; simple vessel perforations; alternate intervascular pitting; fiber‐tracheids and libriform wood fibers; exclusively uniseriate, or uniseriate and biseriate heterocellular vascular rays in the same species; uniseriate “bridges” linking superposed biseriate ray segments; diffuse, diffuse‐in‐aggregates, and scanty vasicentric axial parenchyma, sometimes in the same species; and crystal rhomboids. That Microdesmis and Pogonophora diverge sharply from these generalizations in having scalariform vessel perforations and broad vascular rays, is an indication that they may not be closely related to other genera in Cluytieae.
SOME OBSERVATIONS ON THE MECHANISM OF ORIENTATION MOVEMENT OF WOODY STEMS
Authors: Hejnowicz Z.
Published: January 2018

The force that induces orientation movement of inclined or bent woody stems is generated in reaction wood even in young terminal stems with a large proportion of soft tissues to secondary xylem. Compression wood formed in pine as a response to inclination expands longitudinally after the stresses are released by sawing it from the stem. The increment of length of compression wood when sawed is equal to the decrement of its length which occurs during drying. This suggests that stresses developed by compression wood in the stem are related to imbibition of water by its cell walls. Not all compression wood develops tensile forces in the stem. Neutral compression wood was observed in the lower portion of inclined stems of pine. Tension wood in poplar develops contractile forces in the stem during its aestival maturation. However, when harvested before developing contractile forces in situ, it develops such forces during drying. This suggests that in poplar the mechanism which produces forces responsible for orientation bending also involves changes in cell wall hydration.
FLAVONOID PIGMENTS IN MIMULUS CARDINALIS AND ITS RELATED SPECIES. I. ANTHOCYANINS
Authors: Pollock H. Gail , Jr. Robert K. Vickery , Wilson Kenneth G.
Published: January 2018

Chromatographic and spectrophotometric techniques were used to identify the anthocyanin pigments present in Mimulus cardinalis and its related species of section Erythranthe of the genus Mimulus (Scrophulariaceae). On the basis of rigorous tests, the flowers of M. cardinalis were found to contain pelargonidin‐3‐glucoside, pelargonidin‐3‐rhamnoglucoside, the caffeoyl ester of pelargonidin‐3‐glucoside, cyanidin‐3‐glucoside, cyanidin‐3‐rhamnoglucoside, and the caffeoyl ester of cyanidin‐3‐glucoside. Qualitatively all members of the group contain these six anthocyanins except M. lewisii. All of its populations lack the pelargonidin glycosides and some lack, in addition, the cyanidin‐3‐rhamnoglucoside. The striking differences in flower color and intensity appear to be due to quantitative differences not here analyzed.
DEVELOPMENTAL PATTERNS IN STEM PRIMARY XYLEM OF WOODY RANALES. I. SPECIES WITH UNILACUNAR NODES
Authors: Benzing David H.
Published: January 2018

Patterns of protoxylem strands in vegetative stems of 11 species representing eight families of woody Ranales are illustrated and discussed. Primary vascular systems of many species examined tend to be pseudosiphonostelic. Protoxylem tissue, however, is discontinuous and consists of discrete strands which develop basipetally. The author assumes that data pertaining to the morphology of these protoxylem strand patterns can be significant in determining phylogenetic relationships among ranalean families and between these and higher angiosperms. The value of the primary vascular system in past taxonomic investigations is also considered. Results of this study indicate that the protoxylem strand patterns of 11 woody ranalean species are diverse even though the species are characterized by identical phyllotaxis and nodal structure.
THE EFFECT OF LIGHT ON THE CELLULAR COMPONENTS OF POLARIZED GROWTH IN BEAN INTERNODES
Authors: LeNoir William C.
Published: January 2018

First internodes of light‐grown bean seedlings exposed to supplementary red and far‐red light and those of dark‐grown seedlings were sectioned and studied to determine the effects of irradiation on the cellular components of polarized growth. Cell counts and measurements of epidermis, cortex, and pith are given. Increased length of internodes of far‐red‐treated plants was caused by both increased rate and increased duration of cell elongation. The effect of far‐red light is interpreted as a reversal of the accelerating effect of light upon cell maturation. It is suggested that investigations of the mechanism of the red, far‐red response of stems be concerned with the processes involved in cell elongation. In darkness, rate and duration of cell division as well as rate and duration of cell elongation were greater than in any of the irradiated plants, indicating that only part of the photocontrol of stem elongation is mediated through the red, far‐red system.
PLANTS OF THE NEW ALBANY SHALE. III: CHAPELIA CAMPBELLII GEN. N.
Authors: Beck Charles B. , Bailey Robert E.
Published: January 2018

The single specimen from the Falling Run Member of the Sanderson Formation is interpreted as a segment of a petiole from a region just proximal to a major branching of the frond. The specimen is characterized, basally, by a four‐lobed primary xylem strand. Following stelar branching there are two outer papilionoid strands that produce alternate traces bilaterally and two inner clepsydroid strands, oriented at right angles to the plane of the frond. The frond, which appears to be a morphologically flattened and modified lateral branch system, is probably of calamopityean or pteridosperm affinity.
EVOLUTIONARY SORTING OF CHARACTERS IN A HYBRID SWARM. I: DIRECTION OF SLOPE
Authors: Benson Lyman , Phillips Edwin A. , Wilder Patricia Ann
Published: January 2018

Quercus Douglasii and Quercus turbinella subsp. californica intergrade in California in a belt about 250 miles long. In the area of each parental taxon and near Lebec, in the middle of the zone where hybrids are common and where the gene pool is about evenly divided as to origin, the phenotypes were scored on a six‐point scale to establish hybrid indices. At Lebec populations on slopes facing at intervals of one‐eighth the distance around the compass were scored. The composition of each population was heterogeneous but restricted markedly according to exposure to the sun. Plants on northeast‐facing slopes approached but did not equal the high score of Quercus Douglasii in Madera County; those on southwest‐facing slopes approached but did not equal the extreme low score of subsp. californica near Victorville. Evolutionary sorting must be very rapid, for it is correlated with slopes of the same hills, and the hybrid swarm must be very sensitive to the environment.
THE CYTOTAXONOMY OF FILIPENDULA (ROSACEAE) AND ITS IMPLICATIONS
Authors: Baker Herbert G. , Baker Irene
Published: January 2018

The genus Filipendula Mill. is generally separated from Spiraea L. in systematic keys on the basis of a single fruit character. In some taxonomic treatments of the Rosaceae, where subfamilies are used, this places the genera in separate subfamilies. Karyological studies can be useful in assaying the justifiability of such treatment and are needed because of serious discrepancies between previous reports of chromosome numbers and the recent textbook designation, on dubious grounds, of F. vulgaris as an example of a “permanent chromosome hybrid.” The results given in this paper show that x = 7 in this genus (compared with x = 9 in Spiraea) and the reasons for rejecting previous counts of 2n = 15 for F. vulgaris are presented. “Permanent chromosome hybridity” for this species is also rejected. The possibility that a cytotype with 2n = 16 may exist in the northern part of the range of F. ulmaria cannot be completely discounted, but positive evidence is presented for 2n = 14 in this species (even though 2n = 16 has been reported most frequently recently). The basic number 7 for Filipendula is in agreement with the placing of this genus in the subfamily Rosoideae even though the hereditary peculiarities (apomixis and permanent chromosome hybridity) shown by some other members of this subfamily are apparently not now needed to explain the cytological situation in Filipendula.
EFFECT OF CARBON AND NITROGEN NUTRITION ON REPRODUCTION IN LEPTOSPHAERULINA BRIOSIANA
Authors: Pandey M. C. , Wilcoxson Roy D.
Published: January 2018

Reproduction of Leptosphaerulina briosiana was studied on modified Richard's medium supplemented with seven carbon compounds, six amino acids, five inorganic nitrogen compounds or with urea. The fungus grew on each of the media, but it did not reproduce on all. Ascostromata formed on each of the carbon sources, but the formation of asci and ascospores and the ejection of ascospores varied with the carbon source and the isolate of the fungus. Ascostromata formed on all the nitrogen sources except arginine and ammonium sulfate. Formation of asci and ascospores and ejection of the ascospores varied with the nitrogen source and the isolate of the fungus. The fungus grew and produced ascostromata on Richard's medium supplemented with each of six vitamins, but asci and ascospores were not formed.
NUCLEAR BEHAVIOR IN THE BASIDIUM OF FOMES ANNOSUS
Authors: Wilson Charles L. , Miller Josephine C. , Griffin Billy R.
Published: January 2018

Meiotic division in Fomes annosus is similar to that reported for other higher fungi. Nuclei in dikaryotic cells prior to fusion in the basidia are long, thin, and double‐stranded with paired heterochromatic areas. Various stages of prophase are similar to those in higher plants. At metaphase I and II seven pairs of chromosomes are aligned in a circle and the chromatids migrate to opposite poles established by two centrioles. The centrioles function in the movement of the nuclei in the basidium, nuclear alignment prior to fusion, establishment of poles for division, and the migration of the nuclei into the basidiospore. After nuclei migrate into the basidiospore, they soon divide, producing a binucleate spore.
A COMPARISON OF ROOT CAP CELLS OF EPIPHYTIC, TERRESTRIAL AND AQUATIC PLANTS
Authors: Mollenhauer Hilton H.
Published: January 2018

Outer cells from the root cap of Cattleya orchids are characterized by their secretory activity. They are arranged in layers intercalated with layers of secretory product and form a protective mantle over the root tip. The ultrastructure of these cells is similar to those of terrestrial roots (for example Zea mays) in that they are characterized by copious quantities of endoplasmic reticulum and numerous dense‐staining prevacuolar bodies. In contrast, most root cap cells of water hyacinth and duckweed are highly vacuolate with no dense‐staining prevacuolar bodies. The endoplasmic reticulum is sparse and dictyosomes are small and without secretory activity.
OBSERVATIONS OF SEEDLING DEVELOPMENT IN POLYGONUM BISTORTOIDES
Authors: Allessio Mary L.
Published: January 2018

Observations of the development of Polygonum bistortoides Pursh from achenes collected in the Colorado alpine show an unusual seedling. Photosynthetic cotyledons are supported by coalesced petioles which form a hollow sheath. The first true leaf, which usually passes through the sheath and emerges between the cotyledons, gives the appearance of a typical dicotyledonous seedling. For the second and subsequent leaves there is not space in the cotyledonary sheath. The sheath splits near its base and leaves grow from the swollen base where the apical bud is located. Since the apex is at the soil surface, and the swelling, early evidence of the rhizomatous habit, begins to develop when the seedling is less than 2 weeks old, it is suggested that the seedling structure may aid in rapid establishment during the short alpine growing season.