bluuebunny/crossref_metadata_2025 huggingface dataset:
THE POLLINATION DYNAMICS OF SYMPATRIC SPECIES OF PEDICULARIS (SCROPHULARIACEAE)
Authors: Macior Lazarus Walter
Published: January 2018

Sympatric populations ofPedicularis oederi, P. cystopteridifolia, andP. groenlandicaon the Beartooth Plateau (Montana) were obligately dependent onBombuspollinators. Their corolla colors were mutually distinct to insect vision, but their nectars had identical sugar components. Analysis of corbicular pollen loads of pollinating insects indicated a high degree of polylecty. Queen/worker ratios of pollinators on plant species corresponded to the parallel phenological sequences of plant blooming and insect caste development. The total number of individual pollinators of eachBombusspecies on all plants was directly related to the number of plant species it pollinated, but a comparable relationship between the number of pollinators on a plant species to the number ofBombusspecies pollinating it was not found. Morphological and behavioral correspondence of floral mechanisms and pollinators form an integral part of the general pattern of coadaptive evolution of the floral ecology ofPedicularisin North America known from previous studies. Reproductive isolation betweenPedicularisspecies in this study is attributed to internal barriers. Wide overlaps of blooming seasons, proboscis lengths of bumblebee species and castes, and pollinator species onPedicularisspecies suggest resource sharing, rather than resource partitioning or competition for resources among plant and insect species and individuals.
HORMONAL REGULATION OF EPIPHYLLOUS BUD RELEASE AND DEVELOPMENT IN BRYOPHYLLUM CALYCINUM
Authors: Houck Duane F. , Rieseberg Loren H.
Published: January 2018

The effects of various concentrations of several auxins and cytokinins separately and in combination on epiphyllous budding of Bryophyllum calycinum were investigated, using a marginal leaf strip method. The number of buds released per leaf in 10−6 m benzyladenine (BA) was 2.8 times greater than those in water, and 1.6 times greater in 10−5 m isopentyladenine (IPA). BA, IPA and kinetin were antagonistic to indoleacetic acid (IAA) or naphthaleneacetic acid (NAA) when used in combination treatments. The IAA oxidase co‐factor p‐coumaric acid (PCA) increased the number of epiphyllous buds to twice that of the water controls. This stimulatory effect of PCA on bud release suggests that an increase in IAA oxidase activity may be one of the significant changes that precedes the release of epiphyllous buds.
PROLIFERATION AND PLANT REGENERATION FROM THE NODAL REGION OF ZEA MAYS L. (MAIZE, GRAMINEAE) EMBRYOS
Authors: Vasil Vimla , Lu Chin‐yi , Vasil Indra K.
Published: January 2018

Immature embryos of Zea mays L. (maize), cultured on Murashige and Skoog's medium containing 2,4‐dichlorophenoxyacetic acid (2,4‐D, 0.25–1.0 mg/l) and sucrose (3, 6 and 12%), produced a narrow ridge of tissue in the nodal region of the embryo axis, opposite the scutellum. Only those embryos which were placed with the scutellum in contact with medium showed such a response. The ridge of tissue further proliferated and formed a compact and opaque callus that appeared similar to the scutellar callus. Morphogenesis took place on media containing low concentrations of both 2,4‐D and sucrose. Plant regeneration was achieved and is interpreted to take place by the precocious germination of somatic embryos. It is suggested that the ridge of tissue formed at the node may represent an evolutionarily extinct epiblast of the maize embryo and may be cotyledonary in nature.
EFFECTS OF BORON DEFICIENCY ON MITOSIS AND INCORPORATION OF TRITIATED THYMIDINE INTO NUCLEI OF SUNFLOWER ROOT TIPS
Authors: Moore Helen M. , Hirsch Ann M.
Published: January 2018

Boron deprivation has multiple effects upon root growth within 6 hr after this essential micronutrient is withheld. Root elongation is inhibited and this response has been attributed to a cessation of mitosis and DNA synthesis. Our preliminary results using an autoradiographic analysis of sunflower roots labeled with [3H]‐thymidine demonstrated no difference in label distribution between +/‐B root tips. We found that mitosis in inhibited in ‐B roots but does not completely cease. Scintillation counting of whole root tips shows that boron‐deficient roots up to 72 hr of treatment incorporate radioactive label at a level comparable to that of the controls. Because mitosis and presumably DNA synthesis are affected by prolonged boron deficiency, these results may be brought about by a change in membrane integrity or permeability. We propose that effects of boron deprivation on DNA synthesis and mitosis in sunflower are secondary and that primary events involve alterations in cellular membranes.
FOLIAR TRICHOMES OF PLEUROTHALLIDINAE (ORCHIDACEAE): FUNCTIONAL SIGNIFICANCE
Authors: Benzing D. H. , Pridgeon A. M.
Published: January 2018

Foliar surfaces of nine pleurothallid orchids (Cryptophoranthus lepidotus L. O. Wms., Octomeria sp., Pleurothallis pidax Luer, P. poeppigii Lindl., P. revoluta (Ruiz & Pav.) Garay, Restrepiella ophiocephala (Lindl.) Garay & Dunsterv., Restrepia muscifera Rchb. f. ex Lindl., Scaphosepalum rapax Luer, Stelis endresii Rchb. f.), four nonpleurothallid orchids (Cyrtopodium punctatum (L.) Lindl., Encyclia cochleata (L.) Lemee, E. tampensis (Lindl.) Small, Paphiope‐dilum hybrid) and five tillandsioid bromeliads (Catopsis nutans (Sw.) Griseb., Tillandsia fas‐ciculata Sw., T. streptophylla Scheidw., T. stricta Soland., T. tectorum E. Morr.) were assayed for permeability to Ca, S and P ions. Compared to leaves of the atmospheric bromeliads, those of the orchids proved less permeable to Ca and S. Moisture exchange profiles were determined for two of the bromeliads and three orchids; bromeliad leaves were able to rehydrate completely, orchid leaves only partially. Absorptive capacities of trichomes borne by five taxa were tested by autoradiographic analysis. Unlike bromeliad trichomes, those of the orchids exhibited no capacity to accumulate 3H‐leucine. These results and other considerations described here suggest that, unlike tillandsioid bromeliads, neither the pleurothallid nor the nonpleurothallid orchids examined in this survey rely heavily on shoots for mineral and moisture procurement.
STRUCTURAL CHANGES OCCURRING IN NUCLEI OF BARLEY ROOT CELLS IN RESPONSE TO A COMBINED EFFECT OF SALINITY AND AGEING
Authors: Werker E. , Weimberg Lerner R. , Poljakoff‐Mayber A.
Published: January 2018

Electron microscopic observations of epidermal and cortical cells of the root tips of barley (Hordeum vulgare L.) grown in 192 mm NaCl and aged in 192 mm NaCl + 0.2 mm CaSO4 revealed marked condensation of chromatin in the nuclei which was not observed in freshly cut tissue grown in the presence of 192 mM NaCl. Other changes due to salinity were observed, such as the increase of the number of ribosomes and of mitochondria and the appearance of translucent areas in slightly swollen mitochondria. The mechanism by which the nuclear changes occurred or their meaning for cell function are not understood.
STUDIES OF VEGETATIVE COMPATIBILITY‐INCOMPATIBILITY IN HIGHER PLANTS. IV. THE DEVELOPMENT OF TENSILE STRENGTH IN A COMPATIBLE AND AN INCOMPATIBLE GRAFT
Authors: Moore Randy
Published: January 2018

Three phases of adhesion between the stock and scion are observable during the formation of a compatible autograft in Sedum telephoides and an incompatible heterograft between Sedum telephoides and Solanum pennellii. The first phase of adhesion is similar in both systems in that it 1) lasts 2 to 3 days, and 2) is characterized by an average increase in tensile strength of 1 g breaking weight (BW)/mm2 graft area (GA)/day. In the compatible Sedum autograft, the second phase of adhesion lasts from Days 3 to 11 after grafting and is correlated with a 28‐fold increase in the tensile strength of the graft union to approximately 56 g BW/mm2 GA by 11 days after grafting. The third phase of adhesion in the compatible autograft is characterized by a leveling off of the tensile strength of the graft union at approximately 56 g BW/mm2 GA, roughly equal to that of an ungrafted internode. Graft formation is now complete. These results suggest that the ratio of the tensile strength of the graft union : tensile strength of a comparable ungrafted internode provides an estimate of the percent development of compatible autografts. In the incompatible heterograft between Sedum and Solanum, Phase II adhesion 1) lasts from Days 2 to 5 after grafting, and 2) peaks at 12 g BW/mm2 GA at 5 days after grafting. Phase III adhesion in the incompatible heterograft occurs subsequent to Day 5 after grafting and is characterized by an average decrease in the tensile strength of the graft union of 0.3 g BW/mm2 GA/day. The results of this study are discussed relative to the quantitative contributions of various structural events to the tensile strength of a graft union.
FLORAL ORGANOGENESIS IN NICOTIANA TABACUM: A COMPARISON OF TWO CYTOPLASMIC MALE‐STERILE CULTIVARS WITH A MALE‐FERTILE CULTIVAR
Authors: Rosenberg Susan M. , Bonnett Howard T.
Published: January 2018

Flower buds of two cytoplasmically male‐sterile cultivars and one male‐fertile cultivar of Nicotiana tabacum (L.) were studied by light and scanning electron microscopy to compare their floral ontogenies. In [gla]tbc, a cultivar with N. tabacum nuclear genes and N. glauca cytoplasm, the five small stamen primordia cease growth soon after they are initiated. They remain unchanged at the flanks of the ovary throughout flower maturation, so the mature flower appears stamenless. In `[pbg]tbc,‘ a N. tabacum cultivar with cytoplasm that was thought to have been derived from N. plumbaginifolia, the divergence from normal stamen development occurs before carpel emergence at which point the primordia are already notably smaller and less cylindrical than primordia of the male‐fertile cultivar. After carpel emergence the primordia continue to develop, forming pink structures called petalodes, which are more similar to petals than stamens. Histological sections show that formation of procambial vascular traces is similar in the abortive stamen primordia of [gla]tbc, the petalode primordia of `[pbg]tbc‘ and stamen primordia of male‐fertile N. tabacum.

The two cytoplasmic male‐sterile cultivars studied here and one reported elsewhere show a common developmental stage at which the normal ontogenic pattern is altered. We suggest that this stage is the first visible point in N. tabacum androgenesis which requires genetic input from the mitochondrial genome.
MORPHOGENESIS OF POLLEN CALLUS CULTURES OF HYOSCYAMUS NIGER
Authors: Raghavan V. , Nagmani R.
Published: January 2018

Morphogenesis of calluses of single pollen grain origin shed from anthers of Hyoscyamus niger cultured in a liquid medium containing 2,4‐dichlorophenoxyacetic acid (2,4‐D) was followed upon their transfer to a solid medium with or without 2,4‐D. In a solid medium lacking 2,4‐D, small calluses consisting of one to five nodular groups of cells at the time of inoculation differentiated root and shoot systems and formed miniature seedlings. In the same medium large calluses with several nodules initially formed a crop of bipolar somatic embryoids with well‐defined root and shoot axes which subsequently differentiated into seedlings. Irrespective of their size at the time of transfer, calluses grown in a solid medium containing 2,4‐D continued to proliferate without showing signs of organogenesis or embryogenesis.
THE OCCURRENCE OF ADVENTITIOUS AND PREVENTITIOUS BUDS WITHIN THE BARK OF SOME TEMPERATE AND TROPICAL TREES
Authors: Fink Siegfried
Published: January 2018

Endogenous adventitious buds develop in situ from dedifferentiated parenchyma cells of the trunk‐bark in the temperate trees Tilia platyphyllos, Acer pseudoplatanus, and Fraxinus excelsior, as well as in the tropical cauliflorous trees Artocarpus integrifolia, Swartzia schomburgkii, and Couroupita guianensis. On aerial roots of Clusia rosea endogenous adventitious buds originate within the proliferated phelloderm beneath lenticels. In Salix alba, Fraxinus excelsior, and Terminalia arjuna, exogenous dormant buds are overgrown during secondary growth and engulfed within the bark tissue, so that they give the impression of apparent endogeny. In the leaf axils of young shoots of Araucaria angustifolia, superficial tissue layers divide and form axillary protrusions, which soon become parenchymatic and partly suberized. A few cells at their bases stay meristematic, however, and develop as rudimentary endogenous bud primordia, which persist in the bark for many years.
A MORPHOMETRIC ANALYSIS OF CELLULAR DIFFERENTIATION IN THE ROOT CAP OF ZEA MAYS
Authors: Moore Randy , McClelen C. Edward
Published: January 2018

In order to quantify the ultrastructural changes associated with cellular differentiation, we have performed a morphometric analysis of the ultrastructure of the calyptrogen, columella, and peripheral cells of the root cap of Zea mays. The relative volumes of the nucleus, nucleolus, and mitochondria in the protoplasm gradually decrease as a cell moves through the root cap. The relative volume of plastids increases 240% during the differentiation of calyptrogen cells into columella cells. This increase is transient, however, since the relative volume of plastids as well as starch in plastids decreases markedly as columella cells differentiate into peripheral cells. Dictyosomes and spherosomes increase more gradually than plastids, peaking in relative volume in the innermost peripheral cells (PCI). The relative volume of the vacuome decreases as calyptrogen cells differentiate into columella cells, after which it increases during the differentiation of peripheral cells. By the time the outermost peripheral cells (PCIII) are sloughed from the cap, the relative volume of the vacuome has almost tripled. These results indicate that each cell type comprising the root cap of Zea mays is characterized by a distinctive ultrastructure. Furthermore, the ultrastructural changes associated with the differentiation of these cells are organelle specific. The results of this study are discussed relative to the function of the various cell types of the root cap.
INTERSPECIFIC HYBRIDIZATION AND TAXON UNIFORMITY IN ARABIS (CRUCIFERAE)
Authors: Rollins Reed C.
Published: January 2018

Intermixed populations ofArabis holboelliiHornem. var.pendulocarpa(A. Nels.) Roll.,A. williamsiiRoll., and their putative hybrids; and ofA. holboelliivar.retrofracta(Grah.) Rydb.,A. drummondiiGray andA. divaricarpaA. Nels., the latter also considered to be a probable hybrid taxon, were studied in the field in Montana and Wyoming. In spite of the “intermediacy” of the putative hybrids in both cases, hybrid swarms were not found. In each instance, the “intermediate” as well as the taxa regarded as parental were remarkably uniform. The existence of three relatively uniform morphotypes in each of the several populations is contrary to the usual situation involving hybridizing taxa. A possible explanation is that seed production, at least in the “intermediate” morphotype individuals, involves apomixis, thus circumventing the usual sexual process that would result in a hybrid swarm. Amphiploidy as a possible mechanism for producingA. divaricarpaas a stable hybrid was ruled out in one population where the chromosome number 2n =14 was found in all three taxa present in the population.

Arabis divaricarpa, widely distributed in northern North America, often occurs as a uniform morphotype where no other species ofArabisgrows. If it is of hybrid origin, as the evidence suggests, a mechanism other than sexual reproduction must be present to keep up uniformity and at the same time perpetuate the taxon. It is suggested that facultative apomixis is involved in the reproductive process and that it controls the genetic variability that would otherwise be present by insuring maternal inheritance in each successive seed crop.
REGENERATION IN THE COENOCYTIC MARINE ALGA, CAULERPA, WITH RESPECT TO GRAVITY
Authors: Matilsky Michael B. , Jacobs William P.
Published: January 2018

Small pieces of the green algal coenocyte Caulerpa are capable of regenerating complete new plants. This study investigated the effect of gravity on the site of differentiation of newly forming organs during regeneration. Pairs of 3.0‐cm blade segments from C. prolifera and C. mexicana, as well as 3.0‐cm rhizome segments of C. prolifera, were randomly assigned to either upright or inverted positions. This orientation was maintained throughout each experiment. Results revealed that the blade segments maintained a strict polarity of regeneration regardless of inversion and/or centrifugation. Rhizoids and rhizomes formed at the original basal end of the segment, while blades formed at the apical end. This polarity was seen throughout the length of long blades. Rhizome segments, on the other hand, failed to exhibit a strict polarity of regeneration with respect to gravity.
SEQUENTIAL YIELD COMPONENT ANALYSIS AND MODELS OF GROWTH IN BUSH BEAN (PHASEOLUS VULGARIS L.)
Authors: Doust Jon Lovett , Doust Lesley Lovett , Eaton G. W.
Published: January 2018

We describe the effect of repeated fruit harvest on yield and components of yield in bush bean, and we construct several growth models. Multiple‐regression analysis was used to estimate the relative contributions of individual components to overall yield, and a technique comparing ‘backward’ and ‘forward’ multiple regressions was used to identify points of direct and indirect influence on the ontogenetic series contributing to yield. By testing alternative models we were able to identify components which did not contribute significantly to yield.

Plant height was an important direct and indirect determinant of yield in both treated and untreated plants. There were more compensation effects between components in plants which were continuously harvested, perhaps because pods no longer contributed photosynthate, or because harvested plants were ‘rejuvenated’ through bud release, thus more resource sinks were competing actively for limited resources. Competition between resource sinks apparently occurs earlier in the model sequence where pods are harvested continuously, and becomes important later, as pods mature, in plants left intact to the end of the experiment.

The reciprocal of leaf area ratio was another major component of yield. In both treated plants and controls, this ratio of leaf area to total plant dry weight behaved indirectly, apparently influencing yield through other components.
DETECTION OF SILICA IN PLANTS
Authors: Dayanandan P. , Kaufman P. B. , Franklin C. I.
Published: January 2018

Silica in plants can be stained by silver Chromate, methyl red, and a colorless crystal violet lactone which are adsorbed by the silanol groups resulting in red‐brown, red, and blue colors, respectively. Specialized silica cells in grasses can also be detected through polarization colors due to form birefringence. Silica in the bulliform and silica cells of rice leaves is amorphous and is made up of 1–2‐nm particles aggregating into 2.5 X 0.4‐μm rods with oblique ends.
PROLIFERATION OF AND PLANT REGENERATION FROM THE EPIBLAST OF TRITICUM AESTIVUM (WHEAT; GRAMINEAE) EMBRYOS
Authors: Ozias‐Akins Peggy , Vasil Indra K.
Published: January 2018

Cultured immature embryos of wheat, approximately 1 mm in length, often showed proliferation of the epiblast. Murashige and Skoog's medium with 0.2 or 0.4 mg/l 2,4‐dichlorophenoxyacetic acid and 0.2 mg/l benzylaminopurine supported epiblast proliferation in 20–90% of the embryos depending upon their orientation. Epiblast growth occurred more frequently when the scutellum of the embryo was placed in contact with the medium. The compact tissue derived from the epiblast resembled scutellar callus morphologically and in its developmental potential. Differentiation took place by the formation of a leafy structure along one side of the epiblast proliferation, followed by the initiation of shoot primordia. The pathway through which rooted plants were formed has been interpreted as precocious germination of somatic embryos. The relevance of these observations to the interpretation of the homology of the epiblast is discussed.
EQUIVALENCE OF COMPETITORS IN PLANT COMMUNITIES: A NULL HYPOTHESIS AND A FIELD EXPERIMENTAL APPROACH
Authors: Goldberg Deborah E. , Werner Patricia A.
Published: January 2018

One of the underlying assumptions of both theoretical and empirical community ecology is that the processes determining community composition and abundance of species are interactions specific to particular pairs of species. However, we argue that, in sessile plants at least, competitive interactions are not usually species‐specific and that there exists a large degree of equivalence of the effect of species of similar growth form on the ability of any particular species to establish within a community. This null hypothesis of equivalence of competitive effects is based on three characteristics of plants: homogeneity of resource requirements among autotrophs; low encounter probabilities between individuals of any particular species pair; and the predominance of size asymmetries between competing individuals (e.g., seedling‐adult interactions.) We present an experimental design to quantify competitive interactions among plant species under field conditions and therefore enable statistical comparisons of competitive abilities among species. The competitive effect of one “neighbor” species on one “target” species is measured as the slope of a regression of performance of target individuals on biomass (or other measure of amount) of its immediate neighbors. Use of the design to test for equivalence of competitive effects and other advantages are described.
SELF‐INCOMPATIBILITY SYSTEMS IN THE RUBIACEAE OF A TROPICAL LOWLAND WET FOREST
Authors: Bawa K. S. , Beach J. H.
Published: January 2018

A program of experimental field pollinations was carried out on 14 species of woody Rubiaceae in a Costa Rican wet forest in order to test for the presence of self‐incompatibility systems. Species of Cephaelis, Coussarea, Faramea, Hamelia, Posoqueria, Psychotria, Rudgea, and Warszewiczia were investigated in the study. Ten of the species are distylous, and of these, nine were found to be self‐incompatible. The site of the incompatibility barrier varied between and within species. Short style plants always had stigmatic inhibition of pollen tubes following self and intraform pollinations, but the site of the rejection response in long style plants was quite variable. In several species, pollen tubes, resulting from incompatible pollinations of the long style flowers, penetrated to the base of the style. Fruit set was followed in two of these species, and despite deep penetration of self and intraform pollen tubes in the long style morph, only interform pollinations resulted in fruit set. Four of the species tested are florally monomorphic and each was found to be self‐incompatible on the basis of fruit set patterns. Pollen tubes in the styles of self‐pollinated flowers of two of the monomorphic species, penetrated to the ovary, but no fruits resulted from selfpollinations.
THE STIGMATIC PAPILLAE OF AMYEMA (LORANTHACEAE): DEVELOPMENTAL RESPONSES TO PROTANDRY AND SURFACE ADAPTATIONS FOR BIRD POLLINATION
Authors: Bernhardt P. , Knox R. B.
Published: January 2018

The flowers of Amyema miquelii and A. miraculosum are protandrous and pollinated by birds. Their dry‐type stigmatic surface is composed of unicellular papillae. At the male phase, these papillae are constricted with rugulose surfaces. During the transition to the female (pollen receptive) phase these cells expand, almost doubling in width while their surface becomes much smoother. Beneath the thin proteinaceous pellicle, the papillar wall consists of an extraordinarily thick bi‐layered cuticle overlying the primary wall. The two layers of the cuticle are stained by lipid dyes, but are distinguished by their different responses to other cytochemical tests. The reaction product for the enzyme esterase is present within crenulations on the papillar surface in small amounts, and in dense deposits in the cuticular clefts at the base between papillae. Not surprisingly, pollen tubes are unable to penetrate the thick papillar cap and enter the style through these clefts. The unusual thickness of the cuticle is interpreted as an adaptive response to pollination by perching birds (passerines) probing for nectar.
INFLUENCE OF FLORAL OPTICAL PROPERTIES ON THE ULTRAVIOLET RADIATION ENVIRONMENT OF POLLEN
Authors: Flint Stephan D. , Caldwell Martyn M.
Published: January 2018

Pollen in unopened flowers of most species is totally screened from solar ultraviolet‐B radiation by imbricated petals that are largely opaque to UV‐B. Following flower opening but before anther dehiscence, the anther walls of the species investigated filter out over 98% of the UV‐B radiation. Reflectance of UV from corollas of open flowers does not generally appear to add significantly to the solar UV‐B radiation environment of pollen.
OBSERVATIONS OF CHROMOSOMES IN CIRCAEA (ONAGRACEAE)
Authors: Seavey Steven R. , Boufford David E.
Published: January 2018

Observations of meiotic and/or mitotic chromosomes for 16 specific, infraspecific, and hybrid taxa from 56 populations are presented; chromosome numbers for 11 taxa are reported for the first time. All samples reported have 2n = 22, with the exception that 3 of 12 collections of C. × intermedia have at least some individuals that are triploid. North American diploid collections of this hybrid are heterozygous for one reciprocal translocation; only 1 of 5 European diploid collections also exhibited a translocation. Meiosis in four naturally occurring Asian hybrids is also analyzed: C. × ovata (C. cordata × C. mollis), C. × decipiens (C. erubescens × C. lutetiana) and C. x× dubia (C. cordata × C. eurbescens) possess a single translocation; C. × mentiens (C. alpina × C. eurbescens) is structurally homozygous. With the exception of the translocation, chromosome pairing in these hybrids is normal. Early diakinesis chromosomes possess densely staining centric regions and diffusely staining arms that are subequal in length.
THE EFFECTS OF KINETIN AND NAPHTHALENEACETIC ACID ON IN VITRO SHOOT MULTIPLICATION AND ROOTING IN THE FISHTAIL FERN
Authors: Beck Michael J. , Caponetti James D.
Published: January 2018

This study is concerned with the determination of the shoot and root inducing effects of kinetin (K) and naphthaleneacetic acid (NAA) on shoots ofthe fishtail fern (Nephrolepisfalcata formafurcans) in sterile tissue culture. The data shows that K is the major factor involved in maximal shoot production. The NAA is not essential. Specific concentrations ofNAA must be present with specific concentrations of K for maximal root production. At the same time, the data also demonstrate that shoots on media containing no NAA but with K concentrations of 5 × 10−7 and 10−6 M produced as many roots as with any other NAA concentration. The data can be used as a guide to rapid commercial propagation of fishtail fern, and demonstrate that media available commercially for Boston fern multiplication will induce maximal shoot production in fishtail fern.
VASCULAR SYSTEM OF LODICULES OF DACTYLIS GLOMERATA L.
Authors: Pizzolato Thompson Demetrio
Published: January 2018

The vascular system for the two lodicules in a floret of Dactylis glomerata L. was studied in serial sections. The floret stele contained a few modified tracheary elements and xylem transfer cells enveloped by a phloem of squat sieve‐tube members and intermediary cells. A single sieve tube and associated phloem parenchyma exited the right and left sides of the stele and upon nearing the base of each lodicule branched and formed the minor veins of the lodicule. The minor veins underwent limited branching and anastomosing to form a small three‐dimensional system which described an arc during its ascent in the adaxial portion of each lodicule. The sieve tubes in the minor veins extended halfway up the lodicule and contained short sieve‐tube members with transverse, slightly oblique, or lateral simple sieve plates. The associated phloem parenchyma cells were intermediary cells, companion cells, and less intimate parenchyma cells. Intermediary cells terminated the minor veins and touched the distal ends of the terminal sieve‐tube members, which lacked distal sieve plates. Although the transverse area of the sieve‐tube members remained constant up the lodicule, the transverse area of the associated phloem parenchyma fluctuated.
TRANSMISSION AND SIGNIFICANCE OF B CHROMOSOMES IN ANTHURIUM WAROCQUEANUM
Authors: Marutani Mari , Kamemoto Haruyuki
Published: January 2018

Somatic and meiotic chromosomes of one plant of Anthurium warocqueanum J. Moore and its selfed offspring were analyzed. The parent showed 2n = 30 + 3B in both somatic cells and pollen mother cells. The B chromosomes divided normally in somatic cells, but meiotic associations of Bs varied. Three configurations of three B chromosomes were observed at metaphase I of parent meiosis: one trivalent, one bivalent and one univalent, or three univalents. The number of B chromosomes in offspring ranged from 0 to 6, indicating their transmission from both male and female gametes. Offspring with two B chromosomes appeared in greatest frequency. It was hypothesized that both male and female gametes of the 3 B parent frequently contained one B chromosome through the normal distribution of the bivalent Bs at meiosis and the elimination of the univalent B chromosome due to lagging. Examination of pollen mother cells of offspring also revealed irregular behavior of B chromosomes. With a high number of B chromosomes, normal A chromosome bivalent formation seemed to be reduced. No phenotypic effects of B chromosomes were observed.
OXYGEN CONCENTRATION WITHIN THE NITROGEN‐FIXING ROOT NODULES OF MYRICA GALE L.
Authors: Tjepkema John D.
Published: January 2018

Microelectrodes were used to study the oxygen concentration within Myrica gale L. nodules. Low oxygen concentrations were found only in the region of the mature, nitrogen‐fixing endophyte, and appeared to correspond to clusters of infected host cells. The oxygen concentration in the remainder of the nodule was much higher. Interconnected intercellular air spaces were demonstrated by infiltration with India ink. Infiltration of the spaces with water greatly reduced oxygen concentration throughout the nodule, indicating that they function in supplying oxygen to the infected cells and remainder of the nodule. These results differ from those found previously for soybean nodules and provide evidence that legume and actinorhizal nodules have different mechanisms for protecting nitrogenase from oxygen.
THE EFFECTS OF THE MOUNT ST. HELENS ERUPTION CLOUD ON FIR (ABIES SP.) NEEDLE CUTICLES: ANALYSIS WITH SCANNING ELECTRON MICROSCOPY
Authors: Winner William E. , Casadevall Thomas J.
Published: January 2018

Dead fir needles were collected from standing trees of Abies amabilis in five sites at the margin of the blast zone and located progressively farther from the eruption crater of Mount St. Helens. Scanning electron microscope techniques were used to determine patterns of cuticular melting for these needles and for Abies grandis needles which were heated at specific temperatures for 2 min. Comparisons between cuticular appearances of oven‐heated needles and needles from Mount St. Helens were made to determine air temperatures at the collection sites at the time of the eruption. Air temperatures at these sites are estimated to have ranged from about 50 C to about 250 C. Analysis of cuticular sulfur content showed these needles adsorbed little or no volcanic S02. Conifer needles provided a record of maximum air temperatures during the eruption, and helped reveal the pattern of heat distribution from the eruption cloud. This technique may prove useful for ecological studies in other heat‐stressed habitats.
ULTRASTRUCTURAL STUDIES OF IN SITU DEVONIAN SPORES: BARINOPHYTON CITRULLIFORME
Authors: Taylor Thomas N. , Brauer David F.
Published: January 2018

Each sporangium in the Upper Devonian taxon Barinophyton citrulliforme contains both microspores and megaspores. Microspores range up to 50 μm in diam and possess a homogeneous sporoderm characterized by an outer separable layer. The sporoderm of the megaspores (up to 900 μm) is constructed of sporopollenin units that are loosely arranged in the outer portion of the wall, and that give the megaspore wall a spongy organization. Ultrastructural evidence suggests that the small spores were not abortive megaspores, but that both spore types were functional. The spores of this plant, as well as other Devonian spores that show less dramatic size differences, are suggested as demonstrating a phase in the evolution of heterospory where sex determination was established in spores within the same sporangium prior to the evolution of micro‐ and megasporangia.
BUMBLEBEE POLLINATION RELATIONSHIPS ON THE BEARTOOTH PLATEAU TUNDRA OF SOUTHERN MONTANA
Authors: Bauer Paul J.
Published: January 2018

The coadaptive, dynamic relationship between the members of a floral community and their respective bumblebee pollinators was studied on the alpine‐tundra of the Beartooth Plateau in southern Montana. A total of ten species of Bombus was observed foraging for pollen and/or nectar on Castilleja pulchella, Delphinium bicolor, Lupinus monticola, Mertensia ciliata, Oxytropis campestris, Penstemon procerus, and Trifolium dasyphyllum. The number of Bombus species per plant species ranged from 1 to 9. Based on relative percentage of pollen types in corbicular loads, monolectic foragers comprised 53.5% and polylectic foragers 46.5% of the bumblebees. Examinations of relative length of nectariferous corolla‐tubes, tongue‐length of pollinators, foraging frequency of pollinators, phenology of floral anthesis, and stature of plants did not indicate specific resource partitioning. Non‐tundra‐nesting bumblebees from lower elevations preferred adventive or typically non‐tundra plants. Examination of perianth colors in visible light by reflectance spectrophotometry and in long‐wave (360 nm) ultraviolet light by photography disclosed well‐defined visible light reflectance spectra in all species but ultraviolet reflectance patterns only in D. bicolor. Insect collections and exclosure studies indicated all plant species except D. bicolor and P. procerus are highly reliant on bumblebee pollinators.
MORPHOLOGICAL VARIATION AND DEVELOPMENT IN RAMALINA MENZIESII TAYL.
Authors: Larson Douglas W.
Published: January 2018

The common west coast lichen Ramalina menziesii Tayl. has been studied in an attempt to determine the extent of morphological variation and to understand the factors that determine its form. An analysis of a typical population near Santa Barbara, CA, suggested that intrapopulation variation in form was controlled primarily by size increase during growth. Test populations obtained from latitudes as far north as 54°N and as far south as 28°N had values for various morphological characters that were very similar to the Santa Barbara population. It is concluded that variation in form may be the result of differential rates of growth and possibly varying frequency of environmental stresses which disintegrate the thallus.
THE DEVELOPMENT OF MUCILAGINOUS RAPHIDE CRYSTAL IDIOBLASTS IN YOUNG LEAVES OF TYPHA ANGUSTIFOLIA L. (TYPHACEAE)
Authors: Kausch Albert Paul , Horner Harry T.
Published: January 2018

Raphide crystal idioblast initiation occurs in the uppermost region of intercalary meristems in young leaves of Typha angustifolia L., and development proceeds acropetally. Idioblast differentiation commences with a loss of stored lipids, depletion of starch from amyloplasts, enlargement of the nucleus and nucleolus, cell elongation, and the formation of a central vacuole. Crystalloplastids are formed via dedifferentiation of amyloplasts, followed by an increase in plastid number as cell volume increases with cell elongation. Crystalloplastid membranes stain intensely with periodic acid‐thiocarbohydrazide‐silver proteinate (PA‐TCH‐SP). Following crystal production within the central vacuole, crystalloplastids differentiate lobed regions, dense with plastid ribosomes, thylakoids, lamellae, and plastoglobuli. Mucilage, which stains with PA‐TCH‐SP, appears to be formed at the tonoplast in the central vacuole and follows differentiation of crystalloplastid lobes. Crystal chambers are surrounded by lamellae during mucilage accumulation and the crystals undergo a change in shape. Lobed crystalloplastids may be involved in vacuolar mucilage formation in these types of raphide crystal idioblasts.
SYSTEMATICS OF TRIPSACUM SECTION FASCICULATA (GRAMINEAE)
Authors: Wet J. M. J. De , Brink D. E. , Cohen C. E.
Published: January 2018

Tripsacum section Fasciculata is characterized by staminate spikelet pairs in which one spikelet is sessile and the other is supported by a long and slender pedicel. In section Tripsacum both spikelets of a staminate pair are sessile, or one is supported by a short and stout pedicel. Section Fasciculata includes five closely allied species. Tripsacum lanceolatum Ruprecht ex Fournier (2n = 72) extends from Durango in Mexico to the Huachuca mountains of southern Arizona. It resembles T. jalapense de Wet & Brink spec. nov. (2n = 72) from Guatemala in having terminal inflorescences with 3–10 racemes, but they differ in growth habit and are genetically isolated. Terminal inflorescences of the remaining three species have 15–50 racemes. Tripsacum laxum Nash (2n = 36) from the eastern escarpment of the Central Mexican Plateau is the only species of the group with essentially glabrous basal leaf‐sheaths. It resembles the more widely distributed T. maizar Hernandez & Randolph (2n = 36, 72) in respect to inflorescence morphology, but is genetically isolated from this species. The widely distributed T. pilosum Scribner & Merrill (2n = 72) was divided into var. pilosum and var. guatemalense de Wet & Brink var. nov.
ATTACHED LEAVES, INFLORESCENCES, AND FRUITS OF FAGOPSIS, AN EXTINCT GENUS OF FAGACEOUS AFFINITY FROM THE OLIGOCENE FLORISSANT FLORA OF COLORADO, U.S.A.
Authors: Manchester Steven R. , Crane Peter R.
Published: January 2018

Specimens showing staminate and pistillate inflorescences attached to branches bearing Fagopsis longifolia (Lesq.) Hollick foliage, from the Oligocene Florissant flora of Colorado, permit a relatively complete characterization of the extinct Fagopsis plant. The alternately arranged simple leaves have pinnate craspedodromous venation and prominent simple teeth. Staminate inflorescences are globose on a stout peduncle and contain anthers with tricolporate pollen. Pistillate inflorescences are ovoid heads with compact, helically arranged three‐flower units and are interpreted to have three styles per flower. The infructescence consists of small wedge‐shaped cupules, each containing three tiny fruits, and subtended by a persistent bract. The cupules unravel from the swollen peduncle at maturity and are often dispersed as strings of adhering fruit‐wedges which frequently take on a regular, more or less circular appearance. Fagopsis is unlike any living genus but has characters which support a relationship to the Fagaceae. Unlike extant members of the family, which typically have fruits adapted for animal dispersal, Fagopsis is less obviously specialized and perhaps adapted for wind dispersal. The striking differences in fruiting structures between Fagopsis and extant Fagaceae parallel the differences between the extant genera Platycarya and Juglans in the Juglandaceae, and Alnus and Corylus in the Betulaceae.
THE RELATIONSHIP BETWEEN THE PRIMARY THICKENING MERISTEM AND THE SECONDARY THICKENING MERISTEM IN YUCCA WHIPPLEI TORR. II. ONTOGENETIC RELATIONSHIP WITHIN THE VEGETATIVE STEM
Authors: Diggle Pamela K. , DeMason Darleen A.
Published: January 2018

Histological and anatomical observations were made on plants ranging from embryos to 1‐yr‐old plants of Yucca whipplei Torr. ssp. percursa Haines. Our objective was to determine the time and position of origin, ontogenetic relationship, and function of the primary thickening meristem (PTM) and the secondary thickening meristem (STM) during development of the vegetative axis. The PTM arises in the stem periphery during germination. It is longitudinally continuous from beneath the youngest leaf primordia to the primary root, and functions in the production of primary vascular bundles and ground tissue. The STM arises ontogenetically from the PTM in the base of 2‐ to 3‐month seedlings and produces secondary vascular bundles and ground tissue. The PTM and STM, primary and secondary vascular bundles, and files of primary and secondary ground tissue are continuous at all developmental stages studied. Development of the primary body is histologically and quantitatively similar to development in monocotyledons which possess only a PTM; and secondary growth is interpreted as a developmental continuation of the process of primary thickening.
MORE CHROMOSOME STUDIES IN COMPOSITAE
Authors: Strother John L.
Published: January 2018

Chromosome observations, including number, from meiotic cells from 155 collections (most from Chiapas, Mexico) representing 138 species from 76 genera of Compositae provide taxonomically useful information, especially first counts (for Espejoa [n = 9], Gymnolaena [n = 13], and Rojasianthe [n = 19] and for 39 species in other genera) and counts that differ from other reports. Pollen stainabilities do not always correlate with meiotic irregularities.
FURTHER OBSERVATIONS ON NATHORSTIANA (ISOETACEAE)
Authors: Karrfalt Eric
Published: January 2018

The patterns of root arrangement and stelar morphology in the Lower Cretaceous fossil Nathorstiana are essentially identical with those of extant Isoetes. These structural similarities imply a similar mode of development in both plants and are used to infer an Isoetes‐like, linear, root‐producing meristem along the lower end of the stele in Nathorstiana. The root‐bearing base of Nathorstiana differs from that of Isoetes principally in two respects. In earlier developmental stages, the rooting base of Nathorstiana was unlobed and radially symmetrical, whereas Isoetes is originally bilobed. Unlike Isoetes, which lacks stelar elongation and sheds its root‐bearing cortex at the periphery of the cortical lobes, the downward growth of the root‐bearing base of Nathorstiana resulted in the accumulation of a substantial extent of axial root‐bearing surface.
SUPPRESSED BUDS EMBEDDED IN THE BARK ACROSS THE BOLE AND THE OCCURRENCE OF THEIR CIRCULAR VESSELS IN FICUS RELIGIOSA
Authors: Aloni Roni , Wolf Asnat
Published: January 2018

A latitudinal suppressed bud which is embedded in the outer bark across the bole of Ficus religiosa is described. It might be very long and extend over half of the bole's circumference. The suppressed bud contains cambium which forms secondary xylem and phloem. Circular vessels and circular sieve tubes were frequently observed in the base of the bud as well as above its constriction areas.
DEVELOPMENTAL AND GENETIC SOURCES OF SEED WEIGHT VARIATION IN RAPHANUS RAPHANISTRUM L. (BRASSICACEAE)
Authors: Stanton Maureen L.
Published: January 2018

Seed weight is known to have a marked impact on emergence and post‐emergence productivity in wild radish (Raphanus raphanistrum). In this paper, I describe several levels of seed weight variation in plants taken from a natural population in Hamden, Connecticut. Six maternal plants from the 1981 season were analyzed in detail: the weights and positions of all seeds within a fruit were recorded, and some of these seeds were used the following summer for competition studies and progeny analysis. Within a plant, average seed weight decreased as the number of seeds within a fruit increased, suggesting that developing embryos compete for maternal resources. Seed weight also varied significantly among the six maternal plants used in the study. Comparison of the average weights of seeds produced by offspring of those six plants with the average weights of seeds borne by the maternal plant revealed a significant genetic component to seed weight variation. Seed weight varied up to six‐fold within single fruits of R. raphanistrum; large seeds tend to occur near the pedicel or in the middle positions. Seed size variation seen within single fruits is of sufficient magnitude to result in differential reproductive output among closely related seeds under competitive field conditions.
ALMIRA HART LINCOLN PHELPS (1793–1884) AND THE SPREAD OF BOTANY IN NINETEENTH CENTURY AMERICA
Authors: Rudolph Emanuel D.
Published: January 2018

Mrs. Phelps was influenced by her older sister Emma Willard, a well known educational reformer, and by Amos Eaton, who helped form her botanical and scientific understanding. Feeling the lack of a suitable botanical textbook particularly for female students who were becoming more prevalant, she wrote, Familiar Lectures on Botany, published in 1829, using her first husband's surname (Lincoln). It quickly became popular and continued to be revised and reprinted through 1869. In 1833, a second botany text for lower level students, Botany for Beginners, appeared. It too, went through many reprintings up to 1891. Mrs. Phelps’ other books and writings on science and education were popular also. The botanical texts were educationally innovative in starting with flower structure using common living examples and integrating morphological and physiological aspects of plants. The Linnaean System was used to classify the “most common native and foreign” plants that were described mainly from Eaton's manuals. Clear figures, often copied from well‐known authorities helped to instruct teachers and students. Because of its wide usage, even in later years in competition with the widely used textbooks of Asa Gray and Alphonso Wood, Mrs. Phelps’ books were an important factor in educating many students, especially females, in botany and inducing some of them to have a life‐long interest in the science and in teaching it to others. She was, through her writings, a person who helped provide a favorable climate for the developing profession of botany in America.
ACID EFFLUX PATTERNS OF PRIMARY AND LATERAL ROOTS OF PHASEOLUS VULGARIS (FABACEAE)
Authors: Moore Randy
Published: January 2018

Graviresponding primary roots of Phaseolus vulgaris were characterized by more acid efflux on the upper (i.e., rapidly growing) side of the root than on the lower side of the root. Acid efflux patterns of the upper and lower sides of horizontally‐oriented lateral roots were symmetrical. Addition of sodium orthovanadate (an inhibitor of auxin‐induced H+ efflux) to the growth medium abolished gravicurvature and development of acid efflux asymmetry in horizontally‐oriented roots. These results 1) support the suggestion that auxin redistribution may cause the asymmetry of acid efflux that mediates gravitropism, and 2) indicate that the lack of an auxin‐induced asymmetry of acid efflux may be involved in explaining the minimal graviresponsiveness of lateral roots.