bluuebunny/crossref_metadata_2025 huggingface dataset:
TENDRILS OF PASSIFLORA FOETIDA: HISTOGENESIS AND MORPHOLOGY
Authors: Shah J. J. , Dave Y. S.
Published: January 2018

Passiflora foetida bears an unbranched tendril, one or two laterally situated flowers, and one accessory vegetative bud in the axil of each leaf. The vegetative shoot apex has a single‐layered tunica and an inner corpus. The degree of stratification in the peripheral meristem, the discreteness of the central meristem, and its centric and acentric position in the shoot apex are important plastochronic features. The procambium of the lateral leaf trace is close to the site of stipule initiation. The main axillary bud differentiates at the second node below the shoot apex. Adaxial to the bud 1–3 layers of cells form a shell‐zone delimiting the bud meristem from the surrounding cells. A group of cells of the bud meristem adjacent to the axis later differentiates as an accessory bud. A second accessory bud also develops from the main bud opposite the previous one. A bud complex then consists of two laterally placed accessory bud primordia and a centrally‐situated tendril bud primordium. The two accessory bud primordia differentiate into floral branches. During this development the initiation of a third vegetative accessory bud occurs on the axis just above the insertion of the tendril. This accessory bud develops into a vegetative branch and does not arise from the tissue of the tendril and adjacent two floral buds. The trace of the tendril bud consists of two procambial strands. There is a single strand for the floral branch trace. The tendril primordium grows by marked meristematic activity of its apical region and general intercalary growth.
A NEW PTERIDOSPERM MALE FRUCTIFICATION FROM THE MIDDLE PENNSYLVANIAN OF ILLINOIS
Authors: Leisman Gilbert A. , Peters John S.
Published: January 2018

Rhetinotheca tetrasolenata gen. et sp. n. is described from a Herrin #6 coal ball from Illinois. It consists of an ellipsoidal cluster of small synangia bearing spores of the Monoletes type. Although the synangia are partially connected to each other by sparse sterile tissue, evidence indicates that the synangia are immature, and it is presumed that they separated and spread apart at maturity. A small portion of a protostelic axis is present near the center of the cluster. Individual synangia consistently contain four sporangial tubes and measure 2.0–3.6 mm long by 0.7–1.2 mm in diam. A conspicuous central columella is present. When compared with compression forms, Rhetinotheca tetrasolenata compares most favorably with Aulacotheca iowensis. On this basis, arguments are advanced disputing the classical concept of whittleseyan fructifications. It is contended that none of them possessed a hollow central cavity as depicted in most reconstructions.
POLLEN COMPETITION AND RELATEDNESS IN HAPLOPAPPUS SECTION ISOPAPPUS (COMPOSITAE). II.
Authors: Smith Edwin B.
Published: January 2018

Pollen competition in mixed pollinations involving a time handicap was studied among the five aneuploid members of section Isopappus of Haplopappus. Foreign pollen was applied to the stigmas of a plant followed after a delay of 0–180 min by domestic pollen. Domestic pollen was prepotent over foreign pollen in all cases, but with increasing delay an increasing percentage of hybrids appeared in the progeny. The time interval required to produce 50% of hybrids in the progeny (at which time the two pollen types were competitively matched in potency) was determined for each cross. The interval is correlated with relatedness, with chromosome number, and with length of the style of the pollen parent. It can be used as an estimate of the potential frequency of hybridization in nature, with all other factors being equal.
SYNAPTONEMAL COMPLEXES AND MEIOSIS IN MYXOMYCETES
Authors: Aldrich Henry C. , Mims Charles W.
Published: January 2018

Synaptonemal complexes (SC) have been observed in spores 18–24 hr past cleavage in natural fruitings of Physarum cinereum, P. bogoriense, Hemitrichia stipitata, Tubifera ferruginosa, and Arcyria incarnata. Laboratory fruitings of Arcyria cinerea, Stemonitis herbatica, and a homothallic isolate of Physarum pusillum also have SC's present in spores during the same postcleavage period. The presence of these paired chromosomes of meiotic prophase in spores of species collected in nature and in a diversity of taxa suggests that the usual position of meiosis in Myxomycetes is inside the postcleavage spore. Criteria are proposed for evaluating the validity of the SC as an indicator of meiosis.
ORIGIN OF FRAGARIA POLYPLOIDS. II. UNREDUCED AND DOUBLED‐UNREDUCED GAMETES
Authors: Bringhurst R. S. , Gill Tarlock
Published: January 2018

Offspring from natural hybrids between octoploid Fragaria chiloensis (2n = 56) and diploid F. vesca (2n = 14) backcrossed under natural conditions to F. chiloensis were studied. The natural F1 hybrids themselves were of three kinds: (1) The expected pentaploids which resulted from the union of normally reduced gametes of diploid F. vesca and octoploid F. chiloensis; (2) A hexaploid F1 hybrid which resulted from the union of an unreduced gamete from diploid F. vesca with a normally reduced gamete from octoploid F. chiloensis; and (3) A 9‐ploid F1 hybrid which probably arose from the union of an unreduced gamete of the octoploid F. chiloensis with a normally reduced gamete of diploid F. vesca. The progenies that resulted from the natural backcrossing of each of the three sorts of F1 hybrids to F. chiloensis were as follows: The pentaploid F1 hybrids (2n = 35) yielded mostly 9‐ploid offspring from unreduced 5X gametes; a relatively high percentage of 14‐ploid plants arising from doubled‐unreduced 10 X gametes and a few 2N = ±46 aneuploids from reduced gametes. The hexaploid F1 hybrid (2n = 42) on backcrossing yielded over 50% 10‐ploid offspring with the rest 2n = ±50 aneuploids from reduced gametes. The 9‐ploid F1 hybrid (2n = 63) on backcrossing yielded mostly aneuploids normally distributed about a modal 2n = 59 chromosome class resulting from a 31 chromosome gamete, with a few 2n = 56 and 2n = 63 euploids. The 9‐ploids may facilitate diploid Å octoploid introgression. Screening of the open‐pollinated offspring from F. chiloensis revealed almost 2% 12‐ploid (2n = 84) offspring from the union of the reduced and unreduced F. chiloensis gametes. The probable genomic constitution of the observed novel ploidy levels and those that theoretically may be generated from the known hybrids are presented. The origin of the existing polyploids from diploids through simple unreduction is postulated.
RETICULATE EVOLUTION IN PHLOX AS SEEN THROUGH PROTEIN ELECTROPHORESIS
Authors: Levin Donald A. , Schaal Barbara A.
Published: January 2018

Seed protein profiles were used to document the genome constitutions of seven Phlox taxa believed to be stabilized derivatives of hybridization between P. pilosa and P. carolina, P. drummondii or P. amoena. These species have very distinctive seed protein profiles. Analyses of profiles from these and other phloxes not involved in the reticulum (P. maculata, P. glaberrima and their hybrid derivative P. maculata subsp. pyramidalis) demonstrated that profile components are inherited as co‐dominant units, alteration of ploidal level does not alter the profile, profile components may undergo segregation and recombination, and profile components in hybrids do not re‐combine in vivo or in vitro to produce new proteins. The putative derivatives of hybridization between P. pilosa and P. carolin, i.e., P. pilosa subsp. detonsa, P. pilosa subsp. sangamonensis, P. floridana and P. pulcherrima, display protein profiles which are nearly summations of the parental patterns as do the putative derivatives of P. pilosa and P. drummondii. i.e., P. villosissima and P. aspera. The putative derivative of P. pilosa and P. amoena, i.e., P. pilosa subsp. deamii, displays a completely additive profile. Genome constitutions judged from morphological, cytological, and chromatographical data are fully corroborated by the protein profiles.
TRANSPIRATION RESISTANCE IN VACCINIUM MYRTILLUS
Authors: Janke Robert Arthur
Published: January 2018

Measurements of transpiration resistance of Vaccinium myrtillus at various wind speeds indicate that this quantity is relatively insensitive to variations in wind speed in the range normally experienced under field conditions. The resistance is relatively low when compared with values reported in the literature for other plants. Placed in an identical environment, V. myrtillus plants from sunny sites were found to have measurably lower resistance and lower leaf temperatures than those from shady sites. Transpiration resistance appears to be inversely related to stomatal density.
SOMATIC GENETIC ANALYSIS OF THE APICAL LAYERS OF CHIMERAL SPORTS IN CHRYSANTHEMUM BY EXPERIMENTAL PRODUCTION OF ADVENTITIOUS SHOOTS
Authors: Stewart R. N. , Dermen Haig
Published: January 2018

Many commercial chrysanthemum cultivars display unusual somatic variability. The ‘Indianapolis’ family of chrysanthemum sports was analyzed for the genetic potential for color of each of the three layers in the apical meristem of their shoots. Populations of each cultivar were grown and sectors and off‐color plants recorded. The location of the pigment within cells and between tissues was determined by microscopic examination of free‐hand sections of fresh petals. Adventitious buds were forced from the stems of each cultivar by excising all normal lateral buds. These observations, showed 12 of the 16 ‘Indianapolis’ cultivars to be periclinal chimeras. Adventitious shoots often originated from two or more cells, derived from at least two different apical layers, and thus were themselves periclinal chimeras. While somatic mutation is the ultimate source of the variability in ‘Indianapolis’ chrysanthemums, the most frequent type of sporting resulted from the loss in mitosis of a chromosome carrying a supressor for the formation of yellow chromoplasts, giving a yellow sector or shoot. Sectors resulting from rearrangement of layers in the periclinal chimeras were less frequent than the sectors from chromosome loss.
ASSESSMENT OF EVOLUTIONARY AFFINITIES IN GOSSYPIUM BY PROTEIN ELECTROPHORESIS
Authors: Johnson B. Lennart , Thein Mating Myint
Published: January 2018

Protein band patterns from 25 species of Gossypium were obtained by electrophoresis of crude seed extracts on polyacrylamide gel. Band homologies between species were verified by electrophoresis of a mixture of their extracts. The patterns were found to be largely consistent with the conventional classification of the diploids into 6 genomic groups, A–F. However, G. triphyllum and G. bickii showed unique patterns differing respectively from those of the B and C groups, and G. australe showed closer affinity with the Arabian E‐ than with the Australian C‐genome species. Affinities among the D‐genome species were different from those implied by their former grouping into taxonomic sections but remarkably similar to those indicated in the most recent taxonomic revision of the genus. They were classifiable into two subgroups, β and ɛ. The clustering pattern of the diploids based on correlation coefficients calculated from densitometer curves of the electrophoretic spectra suggested that the genomic groups were derived from an African progenitor type, and that the American β and ɛ subgroups, most closely related to the African B‐ and the Arabian E‐genome groups respectively, evolved under comparative mutual isolation, possibly separated by the Tertiary Amazonas basin.
MUCILAGE‐PRODUCING CELLS IN THE SEED COAT OF PLANTAGO OVATA: DEVELOPMENTAL FINE STRUCTURE
Authors: Hyde Beal B.
Published: January 2018

As the ovule of Plantago ovata matures into a seed its epidermal cells are transformed from undifferentiated parenchyma to thin‐walled containers of almost pure mucilage. During this process the volume of the cells increases 60–80 fold, and the protoplast degenerates to a remnant. Rapid cell expansion begins with pollination and is accompanied by an increase in the size of the nucleus and nucleolus, a change in the random arrangement of ribosomes, a decrease in the thickness of cell walls, and synthesis of starch. Deposition of mucilage inside vacuoles and between the plasma membrane and cell wall accompanies a marked increase in the number and size of Golgi vesicles. Histochemical evidence using the thiocarbohydrazide‐osmium vapor method shows polysaccharide to be present within Golgi vesicles while they are still attached to the Golgi apparatus. Mucilage deposition is associated with further cell expansion, separation of the protoplast from the cell wall, fusion of vacuoles and extra protoplasmic space, and the disappearance of starch.
PHENOLOGY OF SIX UNITED STATES PROVENANCES OF LIQUIDAMBAR STYRACIFLUA UNDER CONTROLLED CONDITIONS
Authors: Williams George J. , McMillan Calvin
Published: January 2018

Laboratory‐germinated seedlings from Connecticut, New Jersey, Illinois, Tennessee, Texas, and Florida were compared under four photoperiod temperature programs. Under each controlled condition, seedlings of northernmost provenances demonstrated least stem elongation and earliest dormancy. Greatest sensitivity to cool temperatures and short photoperiods was demonstrated by northernmost provenances. At warm temperatures, dormant bud formation was controlled by photoperiod in all populations tested except those from Texas and Florida. The reported differences among populations reflect the effects of natural selection upon different Liquidambar populations, insuring survival of the species in various habitats.
A STUDY OF TRIPLOID AND 3 X – 1 ANEUPLOID PLANTS IN THE GENUS GOSSYPIUM
Authors: Douglas C. R. , Brown M. S.
Published: January 2018

Cytological comparisons were made of triploid and 3x – 1 plants of Gossypium hirsutum (haplo 17 and 18) X G. aridum, G. armourianum, G. harknessii, and G. raimondii. Tests and observations led to these conclusions: (1) Chromosome conjugation varied significantly from plant to plant and date to date within plants. (2) The D genome chromosomes of G. hirsutum are closer in homology to G. raimondii than to the other species tested. (3) The chromosomes of G. aridum, have closer homology to the A genome of G. hirsutum than do the chromosomes of the other D species tested. (4) The D genome of G. hirsutum has a small translocation as compared to the genomes of the four D species studied.
MICROSPOROGENESIS IN CITRUS LIMON (RUTACEAE)
Authors: Horner Harry T. , Lersten Nels R.
Published: January 2018

Prior to meiosis tapetal cells become binucleate, and callose deposition separates spore mother cells from each other. No cytomictic channels are present during meiosis. Cytokinesis is simultaneous, by furrowing. The primexine and a rudimentary exine are laid down while the microspores are still in tetrads. After callose dissolution the released microspores gradually become vacuolate and the exine becomes more complex and massive. During the tetrad stage tapetal walls are gradually lost and orbicules are deposited outside the plasmalemma. This continues after microspore release. Later, at the vacuolate microspore stage, the tapetal cells become amoeboid and intrude among the microspores. Tapetal dissolution occurs just prior to the appearance of large amounts of starch and lipids in the microspores.
FINE STRUCTURE OF ANNELLOPHORES. I. SCOPULARIOPSIS BREVICAULIS AND S. KONINGII
Authors: Hammill Terrence M.
Published: January 2018

Fine‐structure observations of annelloconidium production in filamentous Hyphomycetes are reported for the first time. The difference in conidium morphology between Scopulariopsis brevicaulis and S. koningii was quite distinct. In S. brevicaulis, verrucosities appeared early in conidium ontogeny and formed an integral part of the primary wall layer of mature conidia. In S. koningii, verrucosities were absent. In S. brevicaulis, annellations did not invariably result on conidiophore necks with the production of each conidium in the basipetal sequence, but alternatively could be left on subapical regions of subsequently formed conidia. In S. koningii, annellations were more distinct, and the position of a conidium‐delimiting septum was variable. If a septum were formed at a position proximal to previous septa, a portion of the annellophore neck remained attached to the base f the seceding conidium. In both species, a spherical electron‐dense body, perhaps analogous to septal pore plugs in vegetative hyphae, plugged the pore between conidia and conidiophores and remained embedded in the base of seceded conidia.
MORPHOGENESIS IN TRICHODERMA: AUTONOMOUS AND NONAUTONOMOUS PIGMENTATION IN HETEROKARYONS OF COLOR MUTANTS IN TRICHODERMA VIRIDE
Authors: Greenshpan Dvora , Galun Esra
Published: January 2018

The final step in the process of conidiation—conidial pigmentation—was studied in the fungus Trichoderma viride. Twenty‐nine auxotrophic, color mutants, isolated from the same green wildtype strain, were paired to produce stable heterokaryons in all possible combinations and grouped according to their complementation behavior. No complementation (green pigmentation) was found in any of the heterokaryons formed by pairs of white (W) mutants. However, these mutants could be separated into two groups with respect to their behavior when paired with yellow (Y) and brown (Br) mutants. When Wc mutants were paired with any of the Y or Br mutants complementation took place. However, Wd mutants displayed this reaction with only one group of yellow mutants (Ya) and not with the other (Yb) nor with Br mutants. In noncomplementing heterokaryons such as Yb/Wd, only yellow and white conidia were produced, pigmentation being autonomous. On the other hand, in heterokaryons in which complementation did take place, as for instance Ya/Wd, green as well as white and yellow conidia were produced. Differential sensitivity to UV irradiation was used to show that the green conidia were of either Wd or Fa genotype, indicating a nonautonomous type of gene action. It is suggested that the genes Wc, Ya, Yb and Br have a sequential structural role in the biosynthesis of the green pigment, while Wd controls the activity of three (Wc, Yb, Br) of these genes.
THE GAMETOPHYTE OF ANEMIA COLIMENSIS
Authors: Pray Thomas R.
Published: January 2018

Anemia colimensis, the most primitive known species of the genus, has been investigated with respect to gametophyte development and morphology. In the early stages the thalli are in general similar to those of species of Anemia which are charcterized by the development of an initially lateral marginal meristem. One significant difference was noted in the frequent appearance of meristematic zones on both sides of the young plate. One of these becomes the marginal meristem; the other eventually ceases activity. The mature gametophyte is a spherical cushion of complex organization, the result of extreme ruffling of the wings of the thallus and the remarkable abundance of filamentous outgrowths and deep lobing of the wings. This form of gametophyte is unique among the investigated anemias. It is proposed that the formation of a lateral meristem, the “Ceratopteris type” of prothallial development, is primitive in Anemia and that the “Adiantum type,” at least in the Schizaeaceae, is derived. This suggestion is discussed in relation to other possible interpretations.
SYSTEMATICS OF THE COREOPSIS PETROPHILOIDES—LUCIDA—TEOTEPECENSIS COMPLEX
Authors: Crawford Daniel J.
Published: January 2018

In a systematic study of Coreopsis petrophiloides and two closely related species (C. lucida and C. leolepecensis), field and herbarium studies revealed extreme interpopulational variation in both the leaves and capitula. The variation was found to be continuous, and it was thus impossible to delimit morphologic units within the complex. Both C. lucida and C. teotepecensis fit into the pattern of morphological variation found within the complex as a whole. Chromosome counts from plants representing nearly every morphological type showed that all had a number of 2n = 52. Greenhouse hybridization studies revealed that the various morphologic and geographic races are highly inter‐compatible, and preliminary data indicate them to be interfertile. The flavonoid chemistry of the leaves and floral tissues was very uniform in all plants sampled (including C. lucida and C. teotepecensis from their type localities). On the basis of these data, Coreopsis lucida and C. teotepecensis are considered to be synonyms of C. petrophiloides, and the latter species is recognized as a wide ranging, variable taxon with no discernible subspecific units.
INHIBITION OF NODULATION OF INOCULATED LEGUMES BY LEAF LEACHATES FROM PIONEER PLANT SPECIES FROM ABANDONED FIELDS
Authors: Rice Elroy L.
Published: January 2018

Leaf leachates of three forbs, Ambrosia psilostachya, Euphorbia supina, and Helianthus annuus, and three grasses, Arislida oligantha, Bromus japonicus, and Digitaria sanguinalis, all of which are important in the pioneer stages of old‐field succession, were tested to see if they would affect nodulation of heavily inoculated red kidney bean (Phaseolus vulgaris), white clover (Trifolium repens), and Korean lespedeza (Lespedeza stipulacea) growing in soil. Leachates of all inhibitor species except Ambrosia psilostachya and Digitaria sanguinalis significantly reduced the nodule number of Korean lespedeza in at least one experiment. Nodule numbers of red kidney bean and white clover were not significantly reduced by any leachate. It is significant that Korean lespedeza is the most important legume in our revegetating old fields. In almost all experiments in which the nodule number was significantly reduced, the nodules were small and grey or at least not a bright pink as were the control nodules. Leachate of Helianthus annuus reduced the hemoglobin content of Korean lespedeza nodules per plant by 36 %, and Euphorbia supina reduced the hemoglobin content per clover plant by 24 % even though the nodule number was not changed significantly in the latter case. Based on previous research, this indicated a definite reduction in the nitrogen‐fixing capacity of the test nodules. Root exudates of all six inhibitor species were previously found to reduce nodule numbers significantly in the three legume species as were very small amounts of decaying material (1 g per 454 g of soil) of each forb. It appears likely, therefore, that the inhibition of nodulation of legumes in old fields by the six species under test would slow the rate of addition of nitrogen and thus the rate of plant succession, because it was previously demonstrated that the order in which species enter our old fields is the same as the order based on increasing nitrogen requirements.
QUANTITATIVE THERMAL‐INDUCED CHANGES IN GROWTH AND CELL POPULATION KINETICS OF HELIANTHUS ROOTS
Authors: Burholt Dennis R. , Hof Jack Van't
Published: January 2018

A complete kinetic analysis of temperature‐induced changes in primary root growth of Helianthus annuus was undertaken. Growth rate was expressed in terms of the rate of cell production per file and the average cell length at maturity. Growth rate increased from 0.014 cm · hr−1 at 10 C to a maximum of 0.162 cm · hr−1 at 25 C and decreased at higher temperatures. The rate of cell production per file, which is dependent on the mitotic cycle duration and the number of proliferating cells in the meristem, reached a maximum of 8.55 cells hr−1 at 25 C. The mitotic cycle duration decreased from 46.4 hr at 10 C to a minimum of about 6.3 hr at 30 and 35 C. The mitotic index remained constant between 10 and 35 C. At 30 and 35 C the duration of the S period was about 65% of the total cycle time, while at 10 C it was about 50 %. The number of proliferating cells in a meristem remained constant between 15 and 25 C and decreased with further increase in temperature. Therefore, the temperature at which the rate of cell production was maximum was not the temperature at which cycle time was minimum. The maximum length of mature cells occurred between 15 and 30 C. The contribution of each of the above parameters to temperature‐induced changes in growth rate is discussed.
PRE‐TERTIARY RECORDS OF SALVINIACEAE
Authors: Jain R. K.
Published: January 2018

New reproductive material of fossil Salviniaceae from the Edmonton Formation is described. It establishes the existence of Salvinia in the Upper Cretaceous of North America. Taxonomic and morphologic evaluations of the Cretaceous species of Salviniaceae are presented and their evolutionary significance discussed.
FLORAL POLYMORPHY AND AMPHIMICTIC BREEDING SYSTEMS IN RUELLIA CAROLINIENSIS (ACANTHACEAE)
Authors: Long Robert W.
Published: January 2018

The taxonomically complex eastern U. S. species R. caroliniensis produces six functional or partially functional floral morphs. They are chasmogenes, reduced chasmogenes, morphologic protogynous chasmogenes, multistylous chasmogenes, cleistogenes, and semi‐cleistogenes. The plants are uniformly self‐compatible and generally produce normal fruits and seeds. The species has the morphological basis of a nearly balanced breeding system between allogamous and autogamous reproduction. Observations and comparisons on garden and greenhouse cultures suggest that R. caroliniensis is a seasonal cleistogamic species, and it is proposed that the different breeding systems are the chief causes of the difficult taxonomic problem in the species.
VOLVARIELLA VOLVACEA AND ITS LIFE HISTORY
Authors: Chang Shu‐Ting , Yau Chung‐Kei
Published: January 2018

Volvariella volvacea (Bull. ex Fr.) Sing. is a large pileate edible fungus of the tropics and sub‐tropics. It has two kinds of spores, one being the sexual basidiospores in tetrads and the other the asexual chlamydospores. Both monosporous and vegetative hyphae are multinucleate, and there are no clamp connections. Fifty monospores were isolated from two fruiting bodies, and were cultivated individually with four replicates under controlled laboratory conditions. On the average, 76% of the monosporous progenies were fertile. The fungus is homothallic. The development and life cycle of the fungus are described. The possible mechanisms of homothallism are also discussed.
ACRYLAMIDE GEL ELECTROPHORESIS OF PROTEINS FROM ASPERGILLUS SPECIES
Authors: Sorenson William G. , Larsh Howard W. , Hamp Susan
Published: January 2018

Polyaorylamide gel electrophoretic studies were conducted with soluble protein extracts from the mycelium of five species of the genus Aspergillus. The results obtained do not support the concept that such protein patterns can be used in the identification of species, but suggest that the technique might be of value in assessing the degree of similarity between species of the same genus or of closely related genera.
DEVELOPMENTAL ANATOMY IN ROOTS OF IPOMOEA PURPUREA. I. RADICLE AND PRIMARY ROOT
Authors: Seago James L.
Published: January 2018

The developmental anatomy of the primary root of Ipomoea purpurea was studied at several growth stages, beginning with the radicle. The radicle is generally composed of three superimposed tiers of initials, which produce the vascular cylinder, cortex, and columella; and a peripheral band of lateral rootcap‐epidermal initials. The radicular cortex contains 16–19 immature laticifers; none of the tissue regions in the radicle contains mature cells. Following germination and during the first 2–3 cm growth of the primary root the apical meristem and its derivative tissues undergo a series of modifications. Root apical diameter decreases as cells in lateral portions of the rootcap elongate; meanwhile, the columella enlarges vertically. The relationship between cortical and columellar initials changes as fewer mitoses occur in the former while the latter remain active. In longer roots the columellar initials are directly in contact with the vascular initials. Cortical size diminishes during early root growth as cortical laticifers and their associated cells cease to be produced by the outer cortical initials and ground meristem. Early procambium, at the level of vascular pattern initiation, decreases in diameter by cellular reorientation, and the vascular cylinder decreases in overall diameter although the tetrarch pattern remains unchanged.
SURFACE WAX DEPOSITS ON FOLIAGE OF PICEA PUNGENS AND OTHER CONIFERS
Authors: Hanover James W. , Reicosky David A.
Published: January 2018

Epicuticular waxes of five cultivated varieties of Picea pungens and six other species of conifers were examined directly with a scanning electron microprobe. The quality, quantity, and distribution patterns of surface wax deposits varied between species, within species, within plants, and within individual leaves. Two basic types of wax were observed, structural and amorphous. Structural wax is associated with glaucousness and the blue foliage color in Picea pungens and other species. The degree of occlusion of the stomatal pore by surface waxes also varied from heavily occluded to completely free of wax. Wax in the epistomatal chamber may be another resistance barrier to gas exchange by conifer needles.
ANATOMY AND RELATIONSHIPS OF SOME DEVONIAN PROGYMNOSPERMS FROM NEW YORK
Authors: Scheckler S. E. , Banks H. P.
Published: January 2018

New specimens of Triloboxylon ashlandicum Matten and Banks (1966) show additional features of the anatomy and morphology of the plant. The primary xylem has strands of parenchyma associated with trace formation. Secondary xylem and phloem are described for the first time. The outer cortex, previously unknown, contains hypodermal fiber strands. The ultimate appendages are much divided and planated. Specimens of Aneurophyton hallii (Arnold, 1940) were reexamined and newly prepared. They are transferred to the genus Triloboxylon as T. hallii. Triloboxylon is transferred from Pteropsida‐Incertae Sedis to the Aneurophytales. New information on the morphology and anatomy of Telraxylopteris is presented and its identity to Sphenoxylon is supported.
ON THE ANATOMY AND MORPHOLOGY OF LATERAL BRANCH SYSTEMS OF ARCHAEOPTERIS
Authors: Beck Charles B.
Published: January 2018

A large collection of specimens, consisting primarily of Archaeopteris macilenta, forms the basis for an anatomical and morphological study of the lateral branch systems. Emphasis is placed on the main axes of the branch systems, which are found to be characterized by a variable number of orthostichies of lateral appendages, ranging from 7 to probably 11. The number of orthostichies seems to correspond to the number of ribs of the stele. There may be an equal number of rows of leaves on either side of the plane in which the two rows of lateral branches lie, or one side may have one or two more leaf orthostichies than the other. In all specimens for which both part and counterpart were available, however, there is a greater density of leaves on one side (hypothesized to be the adaxial) than on the other, caused primarily by an apparent abortion of leaf primordia early in development on the side of least density. Leaves and branches occur in the same ontogenetic spiral and in one specimen comprise a ‘phyllotaxis’ of 2/9 and contact parastichies of 5 + 9. On both the main and lateral axes, leaves are characterized by long, decurren bases which essentially ensheath the axrs on which thay are borne. Phyllotaxis and the correlated stelar form apparently vary considerably within Archaeopteris. It is suggested that Archaeopteris was more closely related to the coniferophytes than to any other gymnosperms.
AUXIN‐INDUCED HYPONASTY OF THE LEAF BLADE OF PHASEOLUS VULGARIS
Authors: Lippincott Barbara B. , Lippincott James A.
Published: January 2018

The lateral margins of immature primary leaf blades of Phaseolus vulgaris L. cv. ‘Pinto’ curve up and in toward the midrib when auxin is applied to the leaf. The leaves are most sensitive to auxin shortly after they first unfold and leaves which have grown to about 60 % or more of their ultimate area no longer give this hyponastic response. The response is specific for auxins and is inhibited by the anti‐auxins, trans‐cinnamic acid and para‐chlorophenoxyisobutyric acid. Ethylene and ethylene‐generating compounds failed to induce hyponasty, suggesting the response is due to a positive growth promotion by auxin. Measurements of the distance between the lateral margins of the leaf at its maximum width were used to provide quantitative estimates of the degree of hyponasty. Between 2 and 4 hr after auxin application a direct proportionality was found between the amount of curvature and the logarithm of the indoleacetic acid concentration over the range of 10−6 to 10−3 m. The relative sensitivity of the leaves to different auxins was qualitatively similar to that observed in many straight‐growth bioassays. Similar responses were obtained when auxin was applied by a carborundum wounding procedure. Potential applications of this auxin bioassay for investigations of the role of auxin in the normal plagiotropic growth behavior of leaf lamina and of the role of auxin in the initiation of various plant diseases are suggested.
CARBOHYDRATE PHYSIOLOGY OF ORCHID SEEDLINGS. II. HYDROLYSIS AND EFFECTS OF OLIGOSACCHARIDES
Authors: Ernst Robert , Arditti Joseph , Healey Patrick L.
Published: January 2018

Orchid seedlings were grown on nutrients containing cold‐sterilized sugars as sources of carbon. Action by an extra‐cellular invertase was implied from the hydrolysis by seedlings of sugars containing α‐D‐glucopyranosyl‐(1 → 2)‐β‐D‐fructofuranoside bonds. D‐galactosides (α and β) were also hydrolyzed, indicating the presence of extracellular galactosidases. Hydrolysis of α‐D‐fructofuranosides and α‐D‐galactosides decreased with increasing molecular weight. Seedling damage and growth retardation were paralleled by galactose accumulation in the substrate. Rupture of tonoplast and evagination of the nuclear envelope suggests that this sugar may alter some factor(s) responsible for the maintenance of membrane permeability.
STIMULATION OF ISOPEROXIDASES BY ACTINOMYCIN D
Authors: Novacky Anton , Wheeler Harry
Published: January 2018

Treatment of oat leaves for 24 hr with solutions containing 1–25 μg/ml of actinomycin D resulted in marked increases in activity of certain isoperoxidase bands. When higher concentrations of actinomycin D were used, all isoperoxidase bands showed reduced activity. Similar though less striking results were obtained with puromycin whereas p‐fluorophenylalanine caused only inhibition. The isoperoxidase bands stimulated by actinomycin D are the same ones that increase in activity in mechanically wounded leaves and in those treated with the pathotoxin victorin. We suggest that all three cases represent nonspecific responses of the plant to injury.
THE ROLE OF POPULATIONAL DIFFERENTIATION IN EXPERIMENTAL INFECTION OF PROSOPIS BY PHORADENDRON
Authors: May David S.
Published: January 2018

Experimental infection of Prosopis species with the mistletoe Phoradendron tomeniosum subsp. tomentosum in a uniform garden demonstrated that differences in infection success between species, populations, and individuals can be caused by genetically‐based differences in both hosts and parasites. Prosopis glandulosa var. glandulosa was least resistant to infection; P. laevigata was more resistant; and P. torreyana was most resistant. A population of P. glandulosa var. glandulosa grown from seeds collected in the lower Rio Grande valley was significantly more resistant to infection than three populations of the same variety from central and northern Texas. The higher resistance of the Rio Grande valley population appears to be due to introgression with P. laevigata. The experimental population of Phoradendron tomentosum subsp. tomentosum from northeastern Mexico and the population of the same subspecies from southern Texas had greater infectivity than did those from central and northern Texas, corresponding to the greater resistance of the southern Prosopis populations.
THE PALM GYNOECIUM
Authors: Uhl Natalie W. , Moore Harold E.
Published: January 2018

The morphology, anatomy, and histology of the gynoecia at or close to anthesis are described for 20 genera of palms selected to represent different taxonomic alliances and to include major gynoecial types within the family. Palms may have 1–10 carpels, but most have three. Fifteen genera, including 14 coryphoid palms and the monotypic Nypa fruticans, are apocarpous and the remainder, approximately 190, are syncarpous. Fusion of carpels in some gynoecia begins in the base, in others in the styles. Pseudomonomerous pistils occur in several different alliances: the ovarian parts of two carpels are reduced but three usually equal and functional styles and stigmas are present. The carpel is often follicular in shape with the ventral suture open or, more frequently, partially or completely closed. The carpel may be stipitate or sessile and usually has a conduplicate laminar part. Most carpels are spirally and laterally inserted on the receptacle, but the carpel in some unicarpellate genera (e.g., Thrinax) appears terminal. Stipes, ovarian parts, styles, and stigmas vary in structure and development. Septal nectaries which differ in size, in the presence or absence of specialized canals, and in position, characterize all genera of some groups but only some genera of others. Diverse vascular configurations in the bases of gynoecia vary according to the extent of the floral axis, the development of carpellary stipes, and the connation of the carpels and their adnation to the tip of the floral axis. Four types of carpellary vascular systems are present in the genera described: (1) most palm carpels have three major traces consisting of a dorsal bundle and two ventral bundles, and they may also have up to four pairs of lateral bundles or occasionally more; (2) in certain cocosoid palms no ventral bundles can be distinguished, but a dorsal bundle, many parallel lateral bundles, and a row of immature ventral strands vascularize each carpel; (3) carpels of Phytelephas have a dorsal bundle, two pairs of major lateral bundles and about four pairs of shorter lateral bundles, with no identifiable ventral bundles; (4) carpels of Nypa have many dichotomously branched bundles but none that are recognizable as dorsal, ventral, or lateral strands. Additional peripheral bundles or systems may be present in each of the above types. Ovules are supplied by 1–15 bundles. These are derived either from the carpellary stele; from ventral bundles only; from ventral, lateral, and dorsal bundles; or from a combination of these origins. Certain areas of the gynoecia or certain parts of dorsal carpellary walls in some genera are much less mature at anthesis than surrounding tissues. Implications for floral biology and relationships within the palms and of palms to other groups are discussed.
POLLEN WALL AND TAPETAL ORBICULAR WALL DEVELOPMENT IN SORGHUM BICOLOR (GRAMINEAE)
Authors: Christensen Jon E. , Horner Harry T. , Lersten Nels R.
Published: January 2018

Pollen wall development in Sorghum bicolor is morphologically and temporally paralleled by the formation of a prominent orbicular wall on the inner tangential surface of the tapetum. In the late tetrad stage, a thin, nearly uniform primexine forms around each microspore (except at the pore site) beneath the intact callose; concurrently, small spherical bodies (pro‐orbicules) appear between the undulate tapetal plasmalemma and the disappearing tapetal primary wall. Within the primexine, differentially staining loci appear, which only develop into young bacula as the callose disappears. Thus, microspore walls are devoid of a visible exine pattern when released from tetrads. Afterwards, sporopollenin accumulates simultaneously on the primexine and bacula, forming the exine, and on the pro‐orbicules, forming orbicules. Channels develop in the tectum and nexine, and both layers thicken to complete the microspore exine. Channeled sporopollenin also accumulates on the orbicules. A prominent sporopollenin reticulum interconnects the individual orbicules to produce an orbicular wall; this wall persists even after the tapetal protoplasts degenerate and after anthesis. While the pollen grains become engorged with reserves, a thick intine, containing conspicuous cytoplasmic channels, forms beneath the exine. Fibrous material collects beneath the orbicular wall. The parallel development and morphological similarities between the tapetal and pollen walls are discussed.
PLANT DENSITY, CLEISTOGAMY, AND SELF‐FERTILIZATION IN NATURAL POPULATIONS OF LITHOSPERMUM CAROLINIENSE
Authors: Levin Donald A.
Published: January 2018

Lithospermum caroliniense has a heteromorphic incompatibility system complemented by self‐compatibility via cleistogamy. Plants typically are either solely chasmogamic or solely cleistogamic. The percentage of cleistogamic plants in northern Illinois and Indiana populations varied from zero to 4.7. However, the percentage seed from self‐fertilization varied from zero to 51.5, because cleistogamic plants produced 1.5 times as many ovules as chasmogamic plants, and the former type averaged 3.4 seeds per flower in contrast to 0.23 in chasmogamic flowers. Interpopulation differences in cleistogamy and self‐fertilization were strongly correlated with plant density, an increase in density being accompanied by increases in the aforementioned features. Most populations had an excess of thrums, but there was no relationship between cleistogamic seed production and thrum:pin ratio.
TRANSLOCATION OF PHOTOSYNTHATE IN THE BROWN ALGA NEREOCYSTIS
Authors: Nicholson Nancy L. , Briggs Winslow R.
Published: January 2018

Translocation of photosynthates was found to occur when blades ofNereocystiswere illuminated in the presence of C14bicarbonates. Rates of translocation averaging 37 cm/hr in the laboratory were observed. Samples from the epidermis, cortex, and medulla of the stipes of plants with blades exposed to tracer showed that the radioactivity in organic compounds was confined to medulla where sieve filaments occurred. Girdle preparations of blades, interrupting the mucilage ducts and leaving the blade medulla intact, allowed translocation to take place. These data indicate that conduction of photosynthate takes place in the medulla. Similarities between the anatomy of algal sieve filaments and angiosperm sieve tubes, coupled with the continuity of the sieve filaments from blade medulla to stipe medulla suggested indirectly that the sieve filaments were conducting elements. Further support of this hypothesis was provided from collections of radioactive exudate from cells in the medulla of the lower stipe that were continuous with the sieve filaments. Tracer applied to the blades was partially recovered as organic material in a clear fluid that collected inside the pneumatocyst. Continued accumulation of radioactivity in this fluid was dependent on living blades; fluid with low specific activity that did not increase during the experiment accumulated slowly if blades were killed with ethanol after an exposure to tracer. It is possible that the system that produced the stipe fluid was part of (or a side effect of) the system responsible for maintaining volume in the conducting system. It may also provide an alternate route (other than the sieve filaments) for delivery of photosynthates to the base of the plant. Carbon‐14 applied to blade tips as bicarbonate was recovered in part as radioactive mannitol in the translocation stream.
DISPERSAL ECOLOGY OF VANCOUVERIA (BERBERIDACEAE)
Authors: Berg Rolf Y.
Published: January 2018

All Vancouveria species are habitual myrmecochores of the Viola odorata type. The anatropous, bitegmic seed develops an unusual elaiosome in the form of a large, empty, folded and lobed sac of epidermal tissue. The thin‐walled assimilating capsule dehisces along an oblique weak zone that probably represents the suture between two fused and unequal carpels. In V. hexandra the capsule opens early to expose immature assimilating seeds. Decurved pedicels, down‐turned fruits, and weak funiculi produce tachyspory. The related Epimedium, Jeffersonia, and Plagiorhegma have appendaged seeds and other possible myrmecochorous features resembling those of Vancouveria. Myrmecochory was probably established in the early or middle Tertiary period. The Vancouveria‐Epimedium complex indicates that enormous plant migrations may be accomplished by means of ants.
STOMATAL BEHAVIOR OF AVENA SATIVA TREATED WITH TWO PHYTOTOXINS, VICTORIN AND FUSICOCCIN
Authors: Turner Neil C.
Published: January 2018

The transpiration and stomatal behavior of blight‐susceptible and blight‐resistant oats (Avena sativa L.) were followed after treatment with victorin, the host‐specific toxin of Helminthosporium victoriae, and fusicoccin, the toxin produced by Fusicoccum amygdali. Victorin, at 0.012 units/ml and greater, significantly decreased the transpiration of the blight‐susceptible variety in 3 hr, but had no effect on the transpiration of the blight‐resistant variety. The stomatal resistance, measured with a ventilated diffusion porometer, showed that the decrease in transpiration was caused by stomatal closure; the greater the concentration of victorin the earlier the stomata closed. At high concentrations of victorin the stomata reopened in the blight‐susceptible variety, and partial stomatal closure was observed in the resistant variety. Inactivated toxin had no effect on the stomata of either oat variety. When fusicoccin and victorin were compared under the same environmental conditions, victorin closed the stomata of the blight‐susceptible leaves, whereas fusicoccin opened the stomata in both the blight‐susceptible and resistant leaves. It is concluded that the two toxins differ in their effects on the guard cells; their possible modes of action are discussed.
THE DEVELOPMENTAL ANATOMY OF LONG‐BRANCH TERMINAL BUDS OF PINUS BANKSIANA
Authors: Curtis John D. , Popham Richard A.
Published: January 2018

A study of the composition of long‐branch terminal buds (LBTB) of Pinus banksiana Lamb. and the yearly periodicity associated with their formation, development, and elongation was undertaken. Each LBTB has lateral bud zones and zones of cataphylls lacking axillary buds. When present, staminate cone primordia differentiate from the lowest lateral buds in the lowest lateral bud zone of the LBTB. Ovulate cone primordia and lateral long‐branch buds can differentiate from the upper lateral buds in any lateral bud zone. When both types of buds are present, lateral long‐branch buds are uppermost. Dwarf‐branch buds occur in all lateral bud zones. During spring LBTB internodes elongate, new cataphylls are initiated, dwarf branches elongate, needles form and elongate, pollen forms and is released, and ovulate cones are pollinated. During summer buds form in the axils of the newly formed cataphylls. By early fall the new LBTB are in overwintering condition and the four types of lateral buds are discernable. The cytohistological zonation of the LBTB shoot apex is similar to that of more than 20 other conifer species. Cells in shoot apices of pine are usually arranged in distinct zones: apical initials, subapical initials, central meristem, and peripheral meristem. Periclinal divisions occur in the surface cells of the apex; therefore no tunica is present. At any given time, shoot apex volume and shape vary among LBTB in various positions on a tree. In any one LBTB on a tree, shoot apex shape changes from a low dome during spring to a high dome during summer to an intermediate shape through fall and winter.
DIMENSIONAL CORRELATIONS IN DEVELOPING SELAGINELLA SPORANGIA
Authors: French James C.
Published: January 2018

With length of sporangia as a developmental index, the growth relationships of sporangia during differentiation were studied in strobili of Selaginella bigelovii. The strobili usually contain two rows of megasporangia and two rows of microsporangia with a mega‐ opposite a microsporangium at each node. Prior to the sporocyte stage a sporangium in a megasporangiate row is larger and elongates more rapidly than a sporangium opposite it at the same node in a microsporangiate row. The number of sporogenous cells is similar in sporangia of the same length from both rows until cell multiplication ceases in sporangia of the megasporangiate row, while it continues in sporangia of the same size in the microsporangiate row. The observed growth differences between sporangia of the micro‐ and megasporangiate rows are interpreted as events in the differentiation of two sporangial types.