bluuebunny/crossref_metadata_2025 huggingface dataset:
FLORAL MORPHOLOGY, ORGANOGENESIS AND INTERPRETATION OF THE INFERIOR OVARY IN DOWNINGIA BACIGALUPII
Authors: Kaplan Donald R.
Published: January 2018

The inflorescence of Downingia bacigalupii (Campanulaceae; Lobelioideae) is an indeterminate spike. Axillary flowers have a long, linear, inferior ovary with parietal placentation, a pentamerous synsepalous calyx, zygomorphic sympetalous corolla, syngenesious stamens, and a bicarpellate, syncarpous gynoecium. On the basis of floral vascular anatomy the inferior ovary is interpreted as appendicular, representing adnation of outer floral whorls to the gynoecium. Floral ontogeny shows that sepals are initiated in an adaxial to abaxial sequence rather than the 2/5 phyllotaxis reported for other members of Lobelioideae. Growth of the common bases of sepal lobes forms a floral cup and initiation of the following floral whorls occurs along the inner margins of the cup. Continued basal growth of the cup‐shaped bud results in the formation of the elongated inferior ovary. Earlier evidence for the interpretation of a cup‐shaped receptacle during development of epigynous flowers is reexamined and it is concluded that the concave floral bud of D. bacigalupii can also be interpreted as common growth of connate floral whorls, supporting interpretations based on vascular anatomy. Comparison of floral development between Downingia bacigalupii and Pereskia aculeata (Cactaceae) reveals ontogenetic differences between flowers with appendicular and receptacular cups.
VEGETATIVE DISPERSAL IN OXALIS CERNUA
Authors: Galil J.
Published: January 2018

Vegetative propagation and vegetative dispersal of Oxalis cernua were studied. O. cernua is a bulbous dicotyledonous plant. The shoot of a grown plant is divided into two distinct parts: a vertical stem growing upwards and bearing the feeding roots, and a rootless horizontal thin stem. This last is pulled by means of a large contractile root and carries along with it a series of small buds, which form new bulbs at the end of the season. Several new bulbs are formed along the vertical shoot as well. Thus, the propagation bulbs of O. cernua disperse along two axes, which are at right angles to each other.
THE EFFECTS OF LIGHT ON THE DEVELOPMENT OF THE CELLULAR SLIME MOLD ACRASIS ROSEA
Authors: Reinhardt Donald J.
Published: January 2018

No fruiting of the NC‐18 isolate of Acrasis rosea occurs in cultures maintained in continuous light or in continuous dark. The use of different food organisms does not alter the aforementioned behavior. The time at which fruiting occurs in this isolate can be regulated by administering stimulatory light followed by a dark period. Mature sorocarps are formed approximately 14 hr after the termination of light and the start of darkness. Within this 14‐hr interval aggregation and sorocarp development occur. After about 6 hr of dark incubation, NC‐18 amebae, previously stimulated by light, form a few weak aggregation centers. After 8 hr of dark incubation there are numerous aggregation areas, large in size and deep rose in color. By 10 hr the aggregations are quite compact and firm in appearance, and between 12 and 14 hr late aggregations, sorogens and, finally, mature sorocarps are formed. The minimum dark period, i.e., the minimum time that is required in darkness (for cultures previously stimulated with light) to obtain at least some fruiting within the 14‐hr developmental period, is 7–8 hr for NC‐18 and 5–6 hr for Tu‐26. Maximum numbers of sorocarps form when cultures are given 10–11 hr of uninterrupted dark. Light‐stimulated cultures of NC‐18 placed in darkness and interrupted by a 10‐ or 30‐min exposure to wide‐spectrum blue or cool white fluorescent light an hour prior to the minimal dark period exhibit a 4–5 hr‐delay in fruiting when returned to darkness and inspected at intervals following the second irradiation. Growth and fruiting of NC‐18 occurred with purified food sources of each of five different species of Chlorella and with the alga Stichococcus bacillaris. This is apparently the first report of the utilization of algae as food sources by a cellular slime mold. Fruiting of NC‐18 was readily arrested by lowering the relative humidity to 40–45%. This change in the moisture content of the surrounding air induced microcyst formation. Growth on buffered medium occurred in the entire pH range tested, 3.5–7.6, but fruiting occurred only between pH 5.0 and 6.6.
DEVELOPMENT OF THE STAMINATE FLOWER IN THE DWARF MISTLETOE, ARCEUTHOBIUM
Authors: Cohen L. I.
Published: January 2018

A study of the staminate flower of Arceuthobium provided information on the development of the central cushion and the archesporial cells of the anther. From this study it was not possible to substantiate claims that the central cushion of the flower represents a rudimentary pistil. The archesporium of the anther was found to be unilocular from the very beginning and not derived by a breakdown of partitions and subsequent fusion of several locules as previously reported.
HYBRIDIZATION OF PANUS TIGRINUS AND LENTODIUM SQUAMULOSUM
Authors: Rosinski Martin A. , Robinson Albert D.
Published: January 2018

Crosses between monokaryotic isolates of two strains of Lentodium squamulosum and one strain of Panus tigrinus showed complete intercompatibility. Hybrid fruits from crosses between monokaryotic isolates of L. squamulosum and P. tigrinus were uniformly like the P. tigrinus parent. Though both isolates of L. squamulosum showed considerable variability in form, merging toward P. tigrinus, L. squamulosum could always be distinguished from P. tigrinus from hand sections of the hymenophore. The significance of these results as they bear on the problem of inter‐relationships between hymenomycetes and gasteromycetes is discussed. L. squamulosum is recognized as variety squamulosus of P. tigrinus.
CHANGES IN WALL AND INTERNAL STRUCTURE OF ALLOMYCES‐RESISTANT SPORANGIA DURING GERMINATION
Authors: Skucas Gina Purelis
Published: January 2018

The electron microscope was used to examine changes which take place in wall, as well as in internal, structure during germination of mature resistant sporangia of Allomyces neo‐moniliformis. When the resistant sporangia are first placed in water to initiate germination, nuclei, mitochondria, and endoplasmic reticulum are not evident, though after the sporangia have been in water for more than 30 min all of these structures become visible. At this time no cracks are evident in the resistant sporangial wall and the cell membrane appears highly convoluted. Within the next 30 min the outer wall splits and the inner wall expands considerably as the protoplast increases in volume. At the same time the cell membrane straightens out, apparently in response to the protoplasmic expansion. The “cementing substances” begin to dissolve about this time so that 1 1/2 hr after placement in water the outer wall is completely separated from the inner wall which now acts as the cell wall. Cleavage appears to be initiated by the invagination of the cell membrane and by the appearance of segments of endoplasmic reticulum with filled vesicles at one end. Between 2 1/2 and 3 hr after placement in water zoospores are released.
QUANTITATIVE MEASUREMENTS OF INTERACTIONS BETWEEN CROWN‐GALL TUMORS AND THE PINTO BEAN HOST
Authors: Khalifa M. D. El , Lippincott James A.
Published: January 2018

Interactions between crown‐gall tumors on the primary pinto bean leaf and the pinto bean seedling (Phaseolus vulgaris L. ‘Pinto‘) were estimated by quantitative measurements of tumor initiation and growth as affected by certain modifications of the host. Effects of the tumors on the host were estimated by measurements of host growth and correlation responses. The presence of crown‐gall tumors was found to reduce the growth of the leaf in area but to nearly double the weight of the leaf 9 days after inoculation with Agrobacterium tumefaciens (Smith and Town.) Conn, strain B6. The presence of tumors on only one of the two primary leaves resulted in a decrease in the weight of the leaf without tumors, showing the tumors to be effective mobilization centers. Tumors also delayed the abscission of petiole explants and delayed the growth of the epicotyl bud, both reminiscent of auxin effects. The excision of the cotyledons, the epicotyl bud, or one of the pair of primary leaves at the time of inoculation increased the number of tumors initiated per leaf. Removing the epicotyl bud or one of the primary leaves, or placing a cytokinin on one of the leaves, altered leaf growth but failed to alter tumor growth, indicating that tumor growth is not affected by the changes responsible for the compensatory growth effects induced by these treatments. Tumor growth was shown to be generally correlated with leaf growth from day 2 through 8 after inoculation, suggesting that the factors normally limiting leaf growth in a determinate type leaf are also active in limiting tumor growth. The changes in the plant cell responsible for the enhanced rate of growth seen in crown‐gall tumor cells, therefore, appear to occur in regulatory systems other than those normally limiting leaf growth. The regulatory systems that are affected may be identical with those activated in compensatory host growth effects.
A MUCILAGINOUS ROOT SHEATH IN ERICACEAE
Authors: Leiser Andrew T.
Published: January 2018

A prominent mucilaginous sheath surrounding the root tips of plants in the family Ericaceae is described. The sheath was ubiquitous in all species examined. These included representatives of both subfamilies and all tribes of the family. Anatomical studies indicated that the sheath was not the breakdown product of root cap cells but rather that it was formed exterior to a thickened cell wall or cellular layer at the root tip. Although the mucilaginous sheath stained readily with ruthenium red (a specific test for pectins), it was not possible to show it to be one of the common pectins by microchemical tests. Relationships between the soil environment and the extent and condition of the sheath are discussed. Possible significance or functions of the sheath are suggested.
RADIOAUTOGRAPHIC STUDIES IN SYNCHRONIZED CULTURES OF OEDOGONIUM CARDIACUM
Authors: Banerjee S. N. , Horsley R. J.
Published: January 2018

Synthesis of deoxyribonucleic acid (DNA) in synchronized cultures of Oedogonium cardiacum has been studied by radioautography. The germinated zoospores are pulse‐labelled for 15 min with thymidine‐2‐C14. Use of penicillin in the medium reduces the background in the radioautographs by suppressing the growth of bacteria on Oedogonium cells. Incorporation of labelled precursor is greatly enhanced by growing the cells in a conditioned inorganic medium. The length of the DNA synthesis period (S), as estimated from the curve of percentage of labelled cells versus age during the first cell cycle is about 5‐7 hr. The rate of labelling in the nucleus is non‐uniform showing a dip during the mid S period. Concomitant with the doubling of DNA in the nucleus a fourfold increase in the nuclear volume is observed.
CAPSELLA EMBRYOGENESIS: THE SYNERGIDS BEFORE AND AFTER FERTILIZATION
Authors: Schulz Richardis , Jensen William A.
Published: January 2018

The ultrastructure and composition of the synergids of Capsella bursa‐pastoris were studied before and after fertilization. The synergids in the mature embryo sac contain numerous plastids, mitochondria, dictyosomes and masses of ER and associated ribosomes. Each synergid contains a large chalazal vacuole, a nucleus with a single nucleolus and is surrounded by a wall. This wall is thickest at the micropyle end of the cell where it proliferates into the filiform apparatus. At the chalazal end of the cell the wall thins and may be absent for small distances. The pollen tube grows into one of the two synergids through the filiform apparatus and extends one‐third the length of the cell before it discharges. Following discharge of the pollen tube, mitochondria and plastids of the tube can be identified in the synergid as can hundreds of 0.5 μ polysaccharide spheres liberated by the tube. The method by which the sperm or sperm nuclei enter the egg or central cell is not known although an apparent rupture was found in the wall of the egg near the tip of the pollen tube. The second synergid changes at the time the pollen tube enters the first synergid. These changes result in the disorganization of the nucleus and loss of the chalazal wall and plasma membrane. Eventually this synergid loses its identity as its cytoplasm merges with that of the central cell.
THE OPEN CONDUPLICATE CARPEL OF AKEBIA QUINATA (BERBERIDALES: LARDIZABALACEAE)
Authors: Payne Willard W. , Seago James L.
Published: January 2018

Anatomical studies of the carpel of Akebia quinata Decaisne show that it is open at the apex. This carpel is interpreted in this study as a primitively unsealed, conduplicate megasporophyll of the type that is well known among such primitive ranalean genera as Drimys, Bubbia, Degeneria, Schisandra, etc. This interpretation is complemented by other primitive character states of the Akebia flower and carpel, including free organs, laminar stamens, an only slightly modified stigmatic crest, laminal placentation of the many ovules, suture‐like closure of the ovary wall below the stigmatic crest, and maturation of the carpel to produce a moist, dehiscent follicle. These features indicate relative primitiveness of the Lardizabalaceae among the families of the Berberidales.
THE PROBABLE ORIGIN OF ORYZOPSIS CONTRACTA
Authors: Shechter Yaakov , Johnson B. Lennart
Published: January 2018

Oryzopsis contracta is found only in the Big Hollow area of southern Wyoming where it exists sympatrically with the widely distributed species O. hymenoides and O. micrantha. The three species are probably reproductively isolated from each other. Oryzopsis contracta is very similar to O. hymenoides; however, they can be separated on several characters. It also resembles O. micrantha in several characters. This suggests that O. contracta may have evolved through hybridization between the other two species. A quantitative analysis shows that O. contracta occupies an intermediate and central position between the other two species with regard to most characters analyzed. Scatter diagrams reveal a correlated deviation of O. contracta individuals from O. hymenoides toward O. micrantha with respect to several characters. Meiosis in occasional sterile O. hymenoides × O. contracta hybrids shows multivalent associations, suggesting that an appreciable part of the presumed micrantha contribution to the contracta genome was in the form of relatively large chromosome segments. The data suggest that O. contracta evolved as a result of chromosomal translocations in a chance hybrid between O. hymenoides and O. micrantha followed by backcrossing to O. hymenoides and subsequent self‐fertilization of the hybrid.
FUNGUS‐ALGA ULTRASTRUCTURE IN THE LICHEN, CORNICULARIA NORMOERICA
Authors: Walker Alma Toevs
Published: January 2018

Ultrastructure in the symbiotic association in Cornicularia normoerica, fixed in glutaraldehyde, was demonstrated by staining either with potassium permanganate or osmium tetroxide‐thiocarbohydrazide‐osmium tetroxide (OTO) procedures modified for lichen tissues. Channels were observed to originate within the chloroplast, cross the algal cell wall and flare to open space shared with fungal and other algal cells. Tubules within the channels were extensions of chloroplast vesicles. Deeply staining channel walls, tubule elements, spherical bodies within the chloroplast, and organelles of the fungal cytoplasm suggested lipoid substances. The OTO procedure delineated zones in the thick cell walls of both symbionts. Their exterior boundaries were without discernible cellular membranes. The inner zone of the fungal cell wall was finely layered and particulate. No invasive fungal haustoria or zones of dissolution between fungus and alga were seen in any preparation.
ACTINOMYCIN D‐INDUCED CHANGES IN GROWTH AND RIBONUCLEIC ACID METABOLISM IN THE GAMETOPHYTES OF BRACKEN FERN
Authors: Raghavan V.
Published: January 2018

Actinomycin D affected the morphological type of growth in the gametophytes of Pteridium aquilinum and the distribution of RNA and protein in their particulate fractions. Increasing concentrations of the drug progressively inhibited two‐dimensional growth at the end of a period during which controls had formed typical two‐dimensional plants. RNA was lost maximally from the nuclei‐rich and ribosome‐rich fractions of plants growing in a concentration of actinomycin D which inhibited two‐dimensional growth. The magnitude of changes in protein content of the plants was less striking. Presence of actinomycin D in the medium also suppressed incorporation of uridine‐H3 into cytoplasmic fractions of gametophytes. The possibility that two‐dimensional growth in the gametophytes is under control of a newly synthesized messenger RNA, which is sensitive to actinomycin D, is discussed.
CHROMOSOME NUMBERS IN PERITYLE AND RELATED GENERA (PERITYLANAE‐COMPOSITAE)
Authors: Powell A. Michael
Published: January 2018

Chromosome numbers are presented for 28 species of the genus Perityle, one putative inter‐sectional hybrid, two species of Amauria, one species of Eutetras, and one species of Pericome. For Perityle, initial counts are recorded for 12 species of sect. Laphamia (n = 16, 17, 18, 36, ca. 102) and 11 species of sect. Perityle (n = 11, 12, 13, 16, 17, 18, 19, 34, 51). Chromosome numbers for the two species of Amauria (n = 18) are first reports for the genus. Including the current information, chromosome numbers have been recorded for 37 of the approximately 50 species recognized for Perityle. At least 24 taxa have numbers of n = 17, suggesting a base chromosome number of x = 17 for Perityle.
THE RELATION OF AGE AND BUD BREAK TO THE DETERMINATION OF PHYLLOTAXY IN CATALPA SPECIOSA
Authors: Fosket Elizabeth B.
Published: January 2018

Catalpa speciosa is interesting in that the phyllotaxy of the lateral shoots can be either decussate or whorled. The pattern appears to be correlated with the number of buds which emerge. The arrangement is not related to dormancy; nor does the stage of development of the bud at the time of bud break influence the phyllotaxy. The control of bud break appears to be related to the position of the bud on the stem. Possible mechanisms controlling the lateral shoot pattern are discussed.
SPHEROSOMES AND MITOCHONDRIA IN THE LIVING FUNGAL CELL
Authors: Armentrout Vivienne N. , Smith George G. , Wilson Charles L.
Published: January 2018

Study of living hyphae of Fusarium oxysporum Schlect., Fomes annosus (Fries) Cooke, Ceratocystis fagacearum (Bretz) Hunt, Basidiobolus ranarum Eidam, and Mycotypha microspora Fenner with phase contrast revealed that these fungi have spherosomes similar to those in vascular plants. The spherosomes are conspicuous in the hyphal tip, suggesting some function other than fat synthesis. It may be that the Woronin bodies reported by other workers are spherosomes. Mitochondria in these fungi are highly pleomorphic and exhibit saltatory movement. They often interact with nuclei in a manner suggesting close membrane contact.
INTERSPECIFIC CROSSES IN KALMIA
Authors: Jaynes Richard A.
Published: January 2018

Interspecific crosses among Kalmia species are reported for the first time. All possible crosses between K. angustifolia, K. cuneata, K. latifolia, K. hirsuta, K. polifolia var. rosmarinifolia and K. p. var. microphylla were attempted. Several crosses yielded no hybrids, many produced albino or yellow‐green inviable seedlings, and six combinations produced at least a few seedlings with near‐normal growth habit. Stylar inhibition of pollen tube growth prevented some species from hybridizing; reciprocal differences in crossability and pollen tube growth were noted. Kalmia species are highly heterozygous, but no evidence was found within a species for geographic variation of combining ability except for the two varieties of K. polifolia which had different crossing patterns with the other species. The anthocyaninless form of K. angustifolia, in contrast to the normal, has unique combining ability with K. latifolia. No genetic evidence was found to support the placement of K. hirsuta in another genus (Kalmiella) or to designate K. angustifolia var. caroliniana as a distinct species. Use of all the species to breed improved ornamentals is limited by genetic barriers and sterility of F1 hybrids.
DIFFERENT SPECIES, SUCROSE, AND LIGHT IN PLANT SECTION ELONGATION TESTS
Authors: Michel Burlyn E.
Published: January 2018

Sections from both dark‐ and light‐grown seedlings of 11 species were used to test responses to IAA (indoleacetic acid), sucrose, and an inhibitor prepared from cabbage seedlings. Variability among species was great; however, results indicate that many species, light‐grown as well as dark‐grown, could prove useful in bioassays and probably should be investigated. Although elongation of segments from high‐intensity‐light‐grown cabbage and cucumber hypocotyls and oat coleoptiles had essentially stopped by the time of cutting, their growth and response to IAA as sections were considerable. Neither oat coleoptile nor pea internode sections can be considered representative because of differences in responses to sucrose, of dark‐grown sections to light, and to an inhibitor prepared from cabbage. Sucrose generally did not stimulate and even inhibited response of most hypocotyls to IAA. Sucrose was absorbed by sections, increasing final dry weight while not affecting elongation. Sucrose reduced the rate of respiratory decay in cabbage and sunflower, but IAA did not affect respiration. Changes in length and fresh weight of cucumber hypocotyl sections were comparable.
FLORAL ANTHOCYANINS IN SPECIES AND HYBRIDS OF BROUGHTONIA, BRASSAVOLA, AND CATTLEYOPSIS (ORCHIDACEAE)
Authors: Arditti Joseph
Published: January 2018

Chromatographic and spectrophotometric methods were used to identify the floral anthocyanins of Broughtonia domingensis, B. negrilensis, B. sanguinea, Brassotonia ‘John Miller,’ Diabroughtonia, Brassavola nodosa, Cattleyopsis lindenii, and Cattleytonia ‘Rosy Jewell’ for the purpose of establishing chemotaxonomic relationships and inheritance patterns. Flowers of Brassavola nodosa were found to contain raphanusin C, an anthocyanin not present in Cattleyopsis lindenii or in any of the Broughtonia species and hybrids. Pelanin is present in flowers of Broughtonia domingensis and B. negrilensis, but not in those of B. sanguinea. Raphanusin B, raphanusin D, and pelargonidin‐3‐glucoside, 5‐sophoroside which are present in B. sanguinea were also found in its intergeneric hybrids with Diacrium and Brassavola. These findings suggest that Cattleyopsis lindenii should not be transferred to Broughtonia and that B. domingensis, B. negrilensis, and B. sanguinea are separate species.
SURVIVAL PATTERNS IN FOUR PRAIRIE GRASSES TRANSPLANTED TO CENTRAL TEXAS
Authors: McMillan Calvin
Published: January 2018

Transplanted clones of four widespread prairie grasses, Andropogon scoparius, A. gerardii, Panicum virgatum, and Sorghastrum nutans, that had survived in cultivation 1958‐1962 in central Texas were studied without cultivation 1963‐67 to determine survival patterns. In all four species, clones from northern and eastern sites in the United States were eliminated. Survival of A. scoparius was restricted to plants originating in central and southern Texas and in northern Mexico. Surviving clones of A. gerardii, P. virgatum, and S. nutans were chiefly of Texas origin but included other clones mostly from the south central United States. Population samples of the four species from a central Texas grassland community showed greatest survival in a multi‐ramet comparison of clones originating from North Dakota to Mexico City and in a multi‐clone comparison from six sites in Texas and one in New Mexico. While the superior adaptation to the local habitat by the local populations might have been expected, this study documented the survival potential of organisms in the local ecosystem.
FURTHER OBSERVATIONS ON ZOSTEROPHYLLUM LLANOVERANUM FROM THE LOWER DEVONIAN OF SOUTH WALES
Authors: Edwards Dianne
Published: January 2018

Zosterophyllum llanoveranum was first described by Croft and Lang in 1942. This account presents the anatomy of the axes. Details of the sporangium wall in the vicinity of the dehiscence line are reported and the spores are described. The plant is compared with other members of the genus Zosterophyllum and also with those Devonian plants possessing exarch protosteles and lateral sporangia, which Banks has placed in the subdivision Zosterophyllophytina.
MOSQUITO POLLINATION OF HABENARIA OBTUSATA (ORCHIDACEAE)
Authors: Thien Leonard B.
Published: January 2018

The floral morphology and pollination of Habenaria obtusata (Orchidaceae) are described. Habenaria obtusata occurs in Alaska, Canada, Norway, Siberia, etc., in great numbers and is pollinated by mosquitoes of the genus Aedes. The pollination process is described as observed in glass cages.
THE ANATOMY OF TUMORS INDUCED ON CITRUS BY CITRUS VEIN‐ENATION VIRUS
Authors: Hooper G. R. , Schneider Henry
Published: January 2018

Citrus vein‐enation virus‐induced tumors on leaves, thorns, stems, and roots of Citrus auranti‐folia (Christm.) Swingle and C. jambhiri Lush. were investigated. Leaf vein tumors are initiated as cytological abnormalities of phloem fiber primordial cells adjacent to protophloem sieve tubes. The tumors then enlarge through hyperplasia of the affected fiber primordia. The mesophyll and epidermal tissues on the abaxial side of affected veins divide less prolifically and contribute to the tumor mass. Leaf vein tumors are determinate, like the protophloem where they originate, and cease enlarging as the leaf matures. Most thorn tumors are initiated in fiber primordia and develop similarly to vein tumors. Stem tumors and some thorn tumors develop from affected cells of the procambial tissue that lies between the metaxylem and metaphloem of vascular bundles. The cambium which differentiates in these areas is composed of affected cells and produces large amounts of abnormal xylem tissue. The resulting woody tumors are indeterminate like the cambium and secondary xylem.
SEASONAL DEVELOPMENT OF THE SECONDARY PHLOEM IN ACER NEGUNDO
Authors: Tucker C. Milton , Evert Ray F.
Published: January 2018

Functional sieve elements are present year‐round in the secondary phloem of the trunk of Acer negundo L., the box elder tree. Judging from numerous collections made between May, 1962, and May, 1964, the seasonal cycle of phloem development is as follows: cambial activity and new phloem differentiation begin in late March or early April; xylem differentiation begins about a month later and is completed in most trees in late August. At the time of cessation of cambial activity most of the relatively wide sieve elements of the current season's increment are mature. However, numerous groups of narrow, immature sieve elements and companion cells located on the outer margin of the cambial zone do not reach maturity until fall and winter. By the time of cambial reactivation in spring, most, if not all, of these narrow elements are mature. Some of the sieve elements which reach maturity either shortly after cessation of cambial activity or during dormancy become non‐functional within 6 weeks after resumption of cambial activity in spring, while others remain functional until mid‐August. For the phloem increment of a given year, cessation of function begins in September with the accumulation of definitive callose on the sieve plates of the first‐formed sieve elements and spreads to all but the last‐formed ones by the end of December.
CHROMOSOME NUMBERS IN COMPOSITAE VII: ASTEREAE III
Authors: Solbrig Otto T. , Anderson Loran C. , Kyhos Donald W. , Raven Peter H.
Published: January 2018

Reports of 129 new chromosome counts are made for the tribe Astereae of Compositae. They are mostly based on determinations of meiotic material, including first counts for one genus and 43 species or subspecies. Counts are now available for more than 63 of the 100‐120 genera and 564 of the approximately 2,000 species in the tribe. Three of every four genera with more than one species counted show more than one chromosome number; 15 genera have species with populations with different numbers. Such variation is very high and indicates the need for more detailed cytotaxonomical study in the group.
ULTRASTRUCTURE OF BETA POLLEN. I. CYTOPLASMIC CONSTITUENTS
Authors: Hoefert Lynn L.
Published: January 2018

Cytoplasmic structure of developing pollen grains of Beta vulgaris L. was studied with the electron microscope. The following stages were investigated: tetrads, ely microspores, vacuolate microspores, and binucleate pollen grains. Two unique cytoplasmic features were encountered— the reticulum complex and cytoplasmic microtubules—both of which were present from the last meiotic stage to the binucleate pollen‐grain stage. The reticulum complex is connected to the nuclear membrane and juxtaposed to the plasma membrane and may function in synthesis or movement of materials through the pollen cytoplasm.
CHROMOPLASTS OF TOMATO FRUITS. I. ULTRASTRUCTURE OF LOW‐PIGMENT AND HIGH‐BETA MUTANTS. CAROTENE ANALYSES
Authors: Harris William M. , Spurr Arthur R.
Published: January 2018

Three pigment lines of the tomato cultivar ‘Pearson’ with isogenic backgrounds were studied to determine the relationship between certain carotenoids and the development of chromoplasts during fruit ripening. The lines were normal red (r+/r+), in which about 90% of the carotenoids in the ripe fruit is lycopene; high‐beta (B/B) mutant, in which beta‐carotene is the major pigment and the mature fruit color is deep orange ; and low‐pigment (r/r) mutant, in which carotenoids are drastically reduced and the mature fruit is pale yellow‐orange. This paper reports pigment analyses for the three lines and the ultrastructural changes in plastids of the two mutant lines. Very young, pale green fruits contain proplastids with limited lamellar structure. As the fruits reach the mature green stage, the plastids in all three lines develop into typical chloroplasts. Differences in pigment content and in ultrastructure among the lines are not apparent until ripening commences. In the low‐pigment mutant carotenoids are reduced as ripening progresses and no carotenoid crystalloids are formed. As chlorophyll decreases the fruits become pale yellow. The grana become disorganized and the thylakoids appear to separate at the partitions and tend to be arrayed in lines, some still with their ends overlapping. Globules increase slightly in number. In the high‐beta mutant the grana break down during ripening and globules increase greatly in size and number. Beta‐carotene, presumed to be largely in the globules, crystallizes into elongated or druse type forms which may distort the globules. The crystals may affect the shape of the chromoplasts; long crystals may extend the length of the plastid to over 15 μ. Thylakoid plexes with a regular lattice structure sometimes occur in the chromoplasts of the high‐beta mutant. Granules resembling aggregations of phytoferritin particles occur in the chromoplasts of both of these mutants.
ECTODESMATA IN RELATION TO BINDING SITES FOR INORGANIC IONS AND UREA ON ISOLATED CUTICULAR MEMBRANE SURFACES
Authors: Franke Wolfgang
Published: January 2018

Binding of radioactive ions and molecules penetrating isolated cuticles of green onion leaves does not occur in the whole cuticular membrane but is restricted to pointlike areas of a characteristic distribution as was recently demonstrated by microradioautography. Comparison of the localization of these binding sites in isolated cuticles and of ectodesmata in outer epidermal walls reveals that the pattern of binding sites coincides with that of ectodesmata. It is concluded that in intact epidermal cells the binding sites in the cuticle lie on top of ectodesmatal spaces in the wall and that together they form combined pathways of favored penetrability for aqueous solutions which are to be absorbed or excreted.
CHROMOSOME NUMBERS OF SOME SACCHARUM SPECIES HYBRIDS AND THEIR CELL SUSPENSION CULTURES
Authors: Heinz Don J , Mee Grace W. P. , Nickell L. G.
Published: January 2018

Chromosome numbers of five Saccharum species hybrids and their cell suspension cultures were determined. The chromosome number was stable in four parental clones (2n = 122, 114, 114, and 112), but was variable in another (2n = 108‐128). The cell suspension cultures have been maintained in a yeast extract‐enriched nutrient medium for more than 6 years. These cultures were variable in chromosome number for all clones, with a partial aneuploid series at the haploid and/or polyploid level. Each clone had different chromosomal population modes after 6 years of culture. The loss of chromosomes over a period of time would have an effect on the genetic makeup of a cell population. This has implications in the use and interpretation of data from pathological, cytogenetical, biochemical, and physiological studies using cell cultures and is probably a partial explanation for the loss of totipotency in 6‐year‐old sugarcane tissue and suspension cultures.
THE FERTILE SPIKE OF OPHIOGLOSSUM PETIOLATUM. II. CONTROL OF SPIKE ELONGATION AND A STUDY OF ABORTED SPIKES
Authors: Peterson R. L. , Cutter Elizabeth G.
Published: January 2018

The peduncle subtending the sporangial area of the fertile spike of Ophioglossum petiolatum elongates considerably bringing the sporangial area above the sterile segment of the frond. Surgical removal of the sterile segment of the frond has no effect on subsequent peduncle elongation, nor does removal of the sterile tip or any fraction of the sporangial area, providing a few basal sporangia are left intact. However, excision of the entire sporangial area results in an immediate cessation in peduncle elongation. Replacing the excised sporangial area with various growth substances indicates that, of those investigated, only auxins are able to induce peduncle elongation, but to a lesser degree than if the sporangia are left intact. Auxins stimulate peduncle cells to elongate without maintaining the mitotic activity of the intercalary meristem. An investigation of 19 rhizomes shows that three types of fronds are normally produced by this species: sterile fronds, fronds bearing a normal fertile spike, and fronds with an aborted spike. Aborted spikes lack sporangia and an intercalary meristem and fail to elongate.
THE MOVEMENT OF IAA‐C14 IN THE HYPOCOTYL OF PHASEOLUS VULGARIS
Authors: Smith C. W. , Jacobs W. P.
Published: January 2018

The amount of IAA‐C14 transported basipetally through excised hypocotyl sections was strongly affected by the pH of the donor blocks, less so by the pH of the receivers. The effect of donor pH was mostly on uptake. The small amount of acropetal movement was not noticeably affected by pH. Sucrose added to the donor resulted in increased basipetal transport. The time‐course of C14 movement into basal receivers followed a linear course from 1.5 to 3 hr as expected, but there was no net loss from the donors until after 30‐45 min. The usual type of velocity calculation, which assumes uptake starting from zero time, would therefore be lower than the true value. Basipetal transport through segments cut from various positions in the hypocotyl and from seedlings of various ages was maximal in 6‐8‐day‐old hypocotyl segments cut 25‐30 mm below the cotyledons. Acropetal movement was minimal at all positions of all ages tested.
DEVELOPMENT OF FLORAL ORGANS IN THE SITES OF LEAF PRIMORDIA IN PINGUICULA VULGARIS
Authors: Raju M. V. S.
Published: January 2018

Plants of Pinguicula vulgaris L. have either clockwise or counterclockwise spiral phyllotaxy. The inception of floral primordia occurs in leaf sites as a normal sequence of development. Only two leaf primordia initiated late in the season develop into floral primordia in the following year. They do not represent a direct modification of the apical meristem nor of the detached meristem. The apical meristem continues to produce leaves in the vegetative phase and flowers in the reproductive phase, and thus the plants show a monopodial growth. Axillary buds are not developed in this perennial species and instead additional buds of adventitious ontogeny appear. Such buds are produced on the older leaves of larger plants, and they are extremely useful in the vegetative propagation of the species.
GENOME AND KARYOTYPE RELATIONSHIPS IN THE GENUS DENDROBIUM (ORCHIDACEAE). I. CROSSABILITY
Authors: Wilfret G. J. , Kamemoto H.
Published: January 2018

A hybridization study was made utilizing 37 species of 10 sections in 41 intra‐ and intersectional combinations. A total of 721 pollinations was made with 138 fruits harvested; 89 produced viable crosses. Five intrasectional and 20 intersectional combinations resulted in successful hybrids. Among the intrasectional crosses, Phalaenanthe × Phalaenanthe exhibited the highest percentage of fruits and successful crosses while Callista × Callista produced no successful crosses. Eugenanthe × Eugenanthe exhibited low crossability. Among the intersectional crosses, Ceratobium × Phalaenanthe gave the highest percentage of successful crosses, indicating a close relationship between the two groups. Also, there appears to be a fairly close relationship between Latourea and Ceratobium based on crossability. Although the sectional classification of the genus by Schlechter on the basis of vegetative and floral morphology appears to be valid, crossability studies suggest that the Ceratobium and Phalaenanthe sections might be integrated and the Eugenanthe section separated into sections or subsections.
ULTRASTRUCTURE OF CHLORELLA PYRENOIDOSA AS AFFECTED BY ENVIRONMENTAL CHANGES
Authors: Budd Thomas W. , Tjostem John L. , Duysen Murray E.
Published: January 2018

Chlorella pyrenoidosa (van Niel's strain) was cultured in four environmental conditions: light‐glucose, light‐galactose, dark‐glucose, and dark‐galactose. The gradual change in structure was observed when the cultures were transferred from light to darkness (dark adaptation). Cells grown in light contained well‐developed chloroplasts and the normal cytoplasmic sub‐units. During the transition to the complete heterotrophic mode of nutrition, the chloroplast regressed to the proplastid stage with a gradual reduction in thylakoid number. A prolamellar body was noted in the most regressed proplastid condition and plastid storage material was observed in all stages. The cell wall thickened during the transition. Cells adapted to darkness on galactose exhibited abundant cytoplasmic storage material with osmiophilic properties.
SEEDLING MORPHOLOGY IN MARAH (CUCURBITACEAE) RELATED TO THE CALIFORNIAN MEDITERRANEAN CLIMATE
Authors: Schlising Robert A.
Published: January 2018

Studies in reproductive ecology were made in indigenous, western American plants in the genus Marah (Cucurbitaceae), with particular attention given plants of M. oreganus occurring in the Berkeley Hills near San Francisco Bay in California. These tuberous perennials produce capsular fruits on their annual aboveground shoots; the fruits dehisce in early summer, each one exposing about three large seeds with an average seed weight of 1.05 g. The embryo of a M. oreganus seed has two thick and fleshy cotyledons packed with protein granules. The embryonic axis, with shoot and root apices, is ca. 0.5‐1.0 mm long, roughly ½0 or less the length of the seed. In the Berkeley Hills dispersal of the seeds is accomplished by nocturnal rodents, after which germination begins with the fall rains and cooler temperatures of November and December. Instead of a radicle emerging first from the seed at germination, the minute radicle and epicotyl are pushed or carried far out of the seed, down into the soil, by the elongating bases of the cotyledons. These cotyledon bases, or petioles, are fused, and as they elongate they form a hollow tube that bears the embryonic axis at its extreme tip. The cotyledonary petiole tube ceases elongation by January, when it may be 5‐25 or more cm long in a seedling of M. oreganus. Then, from its tip, the radicle grows downward and the epicotyl upward—up the hollow petiole tube. The green shoot (epicotyl) reaches the soil surface by early March in this area, completes the first season's growth, and dries up by late May, when the arid summer season is beginning. But even before the epicotyl grows out of the petiole tube and above ground, the seedling's hypocotyl begins to enlarge, forming a tuber. The fleshy cotyledon blades remain in the seed coat below ground, and some food from the blades is transferred to the tuber that produces shoots in the following growing seasons. This pattern of germination and seedling establishment is now known for species of Marah and for a very few other dicotyledonous plants, all of them growing mainly in areas of hot and dry habitat that are generally referred to as having Mediterranean climate. This elongation of the fused hypogeal cotyledons is considered a complex adaptation in dicotyledons that helps ensure fast and successful seedling establishment in seasonally arid areas such as “Mediterranean” California.
INFLUENCE OF THE TONIC EFFECT OF GRAVITATION AND AUXIN ON CELL ELONGATION AND POLARITY IN ROOTS
Authors: Burström H. G.
Published: January 2018

The influence of a longitudinal (tonic) gravitational force and of auxin on the pattern of growth and cell polarity has been studied on intact roots of wheat seedlings. A klinostat technique was used for controlling gravitation. Growth in length was evaluated as cell division activity, rate of cell elongation (μ/h) and duration of elongation (h). Exogenous auxin (1‐NAA) increases the rate of cell elongation in all concentrations tested (10−8 — 3 × 10−7m) and shortens the time of elongation with increasing concentration. It promotes rate of cell elongation in roots as it does in shoots. It also accentuates the polar insertion of root hairs and their growth. The tonic effect of gravitation resembles that of an increase in auxin both in light and darkness. The results are discussed in relation to plagiotropic growth of roots, root growth promotions by auxin, and the difference between root and shoot growth.
THE VALUE OF PLANT MATERIALS FOR RADIOCARBON DATING
Authors: Godwin H.
Published: January 2018

A survey is made of the advantages and disadvantages of the various types of plant material that may be used in radiocarbon dating. Annual crops and individual tree rings allow yearly fluctuations in atmospheric radiocarbon concentration to be followed, and co‐ordination with dendrochronology affords an extremely powerful means of refining carbon dating, testing the hypotheses on which it rests, and extending its applications into palaeoclimatology. Peat mires are shown to have great advantages for co‐ordinated research involving carbon dating alongside pollen‐analysis and other fields of Quaternary research. They require use with circumspection, however, a qualification applying at least as strongly to the organic muds of lakes, where allochthonous origin, mixing, and above all the incorporation of ancient carbon by the “hard‐water error” have to be reckoned with. Marine plant material suffers these drawbacks to an even greater extent. Finally it is emphasized that misassociation of an event and the plant material to be dated involves an error outside rectification by the dating laboratory; such misassociation is exceedingly wasteful and can only be avoided by painstaking and informed field work.
LEAF DEVELOPMENT IN SCHIZAEA AND ACTINOSTACHYS
Authors: Bierhoest David W.
Published: January 2018

Observations on the initiation and growth of the fertile digits and of their assemblages in Schizaea and Actinostachys as well as of the entire frond in S. dichotoma are presented. The leaf of S. dichotoma, although dichotomous in appearance at maturity, goes through a series of dichotomous and lateral ramifications during ontogeny. It is compared with the entire frond (“aerial shoot”) of Psilotum nudum. The sporangiate fructifications of Schizaea develop as their mature form suggests, i.e., by acropetal initiation and development of pinnately arranged digits. The counterpart in Actinostachys, irrespective of fertile digit number, develops as only three pinnae, two lateral and one terminal. It cannot be said, therefore, that the condition in Actinostachys, i.e., the digitate arrangement of fertile parts, is fundamentally the condition which exists in Schizaea but with a very short rachis. The fundamental difference is in pinna number and frequency of dichotomies which establish the final digit number.
RESPIRATORY METABOLISM IN ACHLYA AMBISEXUALIS
Authors: Warren Charles O. , Mullins J. T.
Published: January 2018

Manometric and spectrophotometric techniques were utilized in studying respiratory metabolism in intact mycelia and cell‐free extracts of the heterothallic water mold, Achlya ambisexualis Raper. Enzymes representing the hexose monophosphate pathway, the Embden‐Meyerhof‐Parnas scheme, the tricarboxylic acid (TCA) cycle and a terminal cytochrome system were demonstrated. In addition, glycerol phosphate dehydrogenase and lactic dehydrogenase activities were observed. Activities of selected enzymes were observed to decline with culture‐age, with the exceptions of glucose‐6‐phosphate dehydrogenase and glycerol‐phosphate dehydrogenase. Oxygen uptake in the male strain more than doubled in the presence of sexual hormone A.
THE INFLUENCE OF KINETIN AND ANTIMETABOLITES ON THE SYNTHESIS OF FATTY ACIDS IN LEAVES
Authors: Donaldson R. , Loescher W. , Newman D. W.
Published: January 2018

Green leaf tissues contain relatively higher proportions of unsaturated fatty acids, especially α‐linolenic acid, than do etiolated or senescent tissues. There appear to be developmental changes in the fatty acid composition of leaves during maturation and senescence. The normal rate of development of spinach (Spinacia oleracea L.) and bean (Phaseolus vulgaris L.) leaf tissues was altered by the application of kinetin and antimetabolites. Spinach was used for the kinetin studies and bean for the antimetabolite studies. Supposedly the kinetin retarded senescence and the antimetabolites retarded normal development. Special emphasis was placed on the incorporation of acetate into palmitate, the most abundant saturated fatty acid, and into linolenate, the most abundant unsaturated fatty acid. Kinetin does not enhance linolenate synthesis, but kinetin‐treated tissues contain proportionately more linolenate. In contrast, tissues treated with antimetabolites contain proportionately less linolenate. Actinomycin‐D and puromycin seem to have a greater effect on the synthesis of linolenate than on the synthesis of palmitate. Chloramphenicol does not have this same differential effect. The possible influence of antimetabolites on the synthesis of unsaturated fatty acids is discussed.
ULTRASTRUCTURAL STUDIES ON STOMATA DEVELOPMENT IN INTERNODES OF AVENA SATIVA
Authors: Kaufman P. B. , Petering L. E. , Yocum O. S. , Baic D.
Published: January 2018

A study of stornata development in internodes fixed with glutaraldehyde and osmium tetroxide revealed the following features: (1) young subsidiary and guard cells have proplastids, but in the mature stomatal apparatus only guard cells have starch‐containing plastids; (2) cytoplasmic continuities found in the developing stomatal apparatus included (a) plasmodesmata between young guard and subsidiary cells and (b) pores at each end of the guard cells in the wall common to these two cells (the pores are found in immature as well as mature stornata); (3) a locus of microtubules was found just inside the plasmalemma of the wall common to the two guard cells. These microtubules are generally parallel to the radial axis of this wall. They are concentrated at the site where localized wall thickening and aperture formation occur. After wall thickening begins around the developing aperture, microtubules are found running primarily in a plane perpendicular to the wall thickening. The possible functional significance of these microtubules and the cytoplasmic continuities in the stomatal apparatus is discussed.