bluuebunny/crossref_metadata_2025 huggingface dataset:
CYTOGEOGRAPHIC STUDIES IN DICENTRA. I. DICENTRA FORMOSA AND D. NEVADENSIS
Authors: Stern Kinfsley R.
Published: January 2018

Dicentra formosa (Haw.) Walp. is morphologically the most variable of the nine North American species in the genus. It constitutes a complex of rhizomatous perennials distributed throughout mountainous regions of the Pacific States. Dicentra nevadensis Eastw. is confined to high elevations in Tulare County, California. Two chromosomal races of Dicentra formosa exist. A tetraploid race, with n = 16, appears to be confined to coastal mountains and valleys, while a diploid race, with n = 8, is distributed along inland mountain ranges, except in Josephine County, Oregon, where the two races could be sympatric. Morphological associations with ploidy level occur, but they appear to be inconstant.
INDUCTION OF ANTHERIDIA IN ASCOBOLUS STERCORARIUS
Authors: Bistis G. N. , Olive L. S.
Published: January 2018

Sexual organs develop in the hermaphroditic, heterothallic ascomycete Ascobolus stercorarius only when strains of opposite mating‐type are paired under appropriate conditions. A previous study of the two reciprocal compatible interactions, A‐antheridial/a‐ascogonial and a‐antheridial/A‐ascogonial, revealed several differences between them. The present study of the induction of antheridia has uncovered several other differences. Such induction occurred on severed hyphae, non‐germinated oidia and germinated oidia of mating‐type A but not of a under two different sets of conditions: (1) when such elements were placed on an agar medium containing only the secretions of a compatible mycelium, and (2) when they were in close proximity to a second group of compatible non‐germinated or germinating oidia on an agar surface. This tendency for vegetative elements of A to differentiate as male structures more readily than those of a is consistent with the previous observation that the interaction of A‐antheridial/a‐ascogonial is generally the more vigorous one. It may also be responsible for a condition approaching functional sexual dimorphism in many mixed (A + a) mycelial cultures.
CELL FINE STRUCTURE OF DEVELOPING LIMA BEAN SEEDS RELATED TO SEED DESICCATION
Authors: Klein Shimon , Pollock Bruce M.
Published: January 2018

Cell fine structure of developing cotyledons and embryonic axes of Phaseolus lunatus L. seeds was studied relative to stage of seed development and the ability of excised embryonic axes to grow and withstand desiccation. Two stages in the development of the seed were recognized: (a) a ripening stage, characterized by more rapid increase in dry weight than in fresh weight, resulting in a decrease in seed moisture to 60%, and (b) a maturation stage during which seeds lost water without increase in dry weight. Above 70% water, excised embryonic axes failed to grow. Complete potential for growth developed by the time the seed reached 55–50% water. The axes were able to grow before they developed the ability to withstand desiccation. In cells of the youngest axes the ribosomes tend to be grouped into polysome units which surround the endoplasmic reticulum. As the cells mature the polysomes disappear and free ribosomes appear in the cytoplasm. Mitochondria in young axes contain electron‐dense matrices and swollen cristae; with maturation the mitochondrial matrix becomes optically empty and the cristae less swollen. Chloroplasts in young cells contain grana which disappear as the seeds mature. Similar changes occur in the cells of cotyledons. The data suggest that changes in cell fine structure during maturation are not destructive changes caused by excessive loss of water, but they indicate physiological changes which may be necessary to prepare the cells to withstand desiccation.
A LIVING ORGANISM MORPHOLOGICALLY COMPARABLE TO THE PRECAMBRIAN GENUS KAKABEKIA
Authors: Siegel S. M. , Siegel B. Z.
Published: January 2018

A living species of the fossil genus Kakabekia, isolated from a soil sample secured at Harlech Castle, Wales, is described. It resembles the type species K. umbellata Barghoorn in all major respects: tripartite structure consisting of mantle, stiple and basal enlargement, and size range of 5–15 μ. Variations in the cultured form include mantle margin (entire to scalloped), mantle radial structure (6‐ to 8‐parted, but sometimes 5‐ to 9‐parted) and concentric rings. The name K. barghoorniana is proposed in recognition of the discoverer and author of the fossil genus.
STEM ABSCISSION IN THE TUMBLEWEED, PSORALEA
Authors: Becker Donald A.
Published: January 2018

Abscission was studied in Psoralea argophylla Pursh, a prairie tumbleweed. This process is responsible for the detachment of the stem from its perennial base. In a single plant abscission may proceed through one or more intercalary meristems located at or near ground level. During senescence a separation layer differentiates within each of these meristems. Chemical changes occur within the compound middle lamellae which result in the conversion of insoluble pectic compounds into soluble forms. Cell separation takes place only after removal of the pectic compounds, meristematic activity, and attenuation of cell walls. Unlike reports of other angiosperms the protective layer is not formed adjacent to the separation layer, but forms some distance underground at the stem‐root junction.
BIOSYSTEMATIC STUDIES IN SINNINGIA AND RECHSTEINERIA (GESNERIACEAE)
Authors: Clayberg Carl D.
Published: January 2018

Tests of crossability and F1 hybrid fertility for 16 species of Sinningia and Rechsteineria show that these two genera constitute a single comparium made up of well‐defined cenospecies. Floral structure suggests that divergence has resulted from adaptation to different principal pollinators. Recommendations are made for redefining sectional limits and combining Sinningia and Rechsteineria in one genus.
OBSERVATIONS ON PENETRATION OF LINDEN BRANCHES BY STYLETS OF THE APHID LONGISTIGMA CARYAE
Authors: Evert R. F. , Eschrich W. , Medler J. T. , Alfieri F. J.
Published: January 2018

Penetration of the bark of Tilia americana L., the linden tree, by Longistigma caryae (Harr.) is mainly intracellular. Like other aphids, L. caryae secretes a saliva sheath which encloses the path of the stylets, beginning with an external collar of sheath material on the surface of the periderm. Stylet sheaths within the bark gave positive reactions for callose, suggesting that, in reaction to wounding, punctured parenchyma cells secrete callose which diffuses throughout the stylet sheaths. Other, more conspicuous effects of wounding included: proliferation and enlargement of cells of the cortex and dilated rays bordering some stylet sheaths, formation of tylosoids in punctured sieve elements, deposition of massive amounts of callose in penetrated sieve elements and in sieve elements bordering penetrated cells, and stimulation of cambial activity and xylem differentiation. Stylet tips located in living sieve elements projected beyond their sheaths which terminated outside the sieve‐element walls. It is suggested that such sieve elements can be considered to be functional. None of the living sieve elements containing stylet tips showed any signs of injury which could be attributed to the presence of the stylets. Stylet tips of feeding aphids were found in living sieve elements of both 1965 and 1966 phloem increments clearly indicating that L. caryae can feed on linden sieve elements more than 1 year of age.
HORMONAL CONTROL OF PEROXIDASE ACTIVITY IN CULTURED PELARGONIUM PITH
Authors: Lavee S. , Galston A. W.
Published: January 2018

Freshly excised Pelargonium pith tissue lacks peroxidase activity toward guaiacol or benzidine, but it develops such activity within 24–36 hr in aseptic culture. All the activity is manifested as a single enzyme moving toward the cathode during electrophoresis on starch gel at pH 9.0. This development of peroxidase activity is at first (up to ca. 50 hr in culture) inhibited and later (ca. 100–150 hr in culture) promoted by IAA. This dual effect of IAA resembles that previously reported for specific isoperoxidases in tobacco pith cells. Kinetin alone also inhibits peroxidase formation, but in the presence of IAA those concentrations which enhance growth enhance peroxidase formation as well.
STRUCTURE OF THE PEAR LEAF CUTICLE WITH SPECIAL REFERENCE TO CUTICULAR PENETRATION
Authors: Norms R. F. , Bukovac M. J.
Published: January 2018

Study of the pear leaf cuticle (Pyrus communisL. ‘Bartlett‘), in both intact and enzymatically isolated forms, has revealed that the cuticular membrane is separated from the underlying epidermal cell wall by a layer of pectic substances which extend into but not through the membrane. A layer of embedded birefringent waxes occurs towards the outer surface of the cuticular membrane. Platelet‐like epicuticular waxes are deposited on the outer surface. The upper cuticular membrane is astomatous. The lower epidermis is stomatous, and the outer cuticular membrane is continuous with that lining the substomatal cavity. The lower cuticular membrane is also generally thicker than the upper, and both the upper and lower cuticular membranes are thicker over veinal than over mesophyll tissue. The birefringence frequently is discontinuous over anticlinal walls and over veinal tissue. The lower cuticle appears to contain fewer embedded waxes (as indexed by birefringence) than the upper. Enzymatic isolation of the cuticular membrane from the underlying tissues does not appear to cause any discernible change in structure as viewed with a light microscope. These findings are discussed in light of current knowledge concerning penetration of foliar applied substances into the leaf.
VASCULAR CONSTRUCTION AND DEVELOPMENT IN THE AERIAL STEM OF PRIONIUM (JUNCACEAE)
Authors: Zimmermann Martin H. , Tomlinson P. B.
Published: January 2018

The aerial stem of Prionium has been studied by motion‐picture analysis which permits the reliable tracing of one among hundreds of vascular strands throughout long series of transverse sections. By plotting the path of many bundles in the mature stem, a quantitative, 3‐dimensional analysis of their distribution has been made, and by repeating this in the apical region an understanding of vascular development has been achieved. In the mature stem axial continuity is maintained by a vertical bundle which branches from each leaf trace just before this enters the leaf base. Lateral continuity results from bridges which link leaf traces with nearby vertical bundles. Development of the provascular system involves a meristematic cap into which the blind ends of vertical bundles can be followed. Leaf traces are produced continuously in association with developing leaf primordia for a period of over 30 plastochrones; they connect with the vertical bundles in the meristematic cap and so establish the essential vascular configuration which is later reorientated through about 90° by overall growth of the crown. The last bundles to differentiate from the leaf do so outside the meristematic cap and thus fail to make contact with the axial system; they appear in the mature axis as blind‐ending cortical bundles. Prionium is only distantly related to palms and its vascular histology is quite different. Nevertheless, the course of vascular bundles and the origin of this pattern in the stem resembles that of a palm. It is suggested that we are examining the fundamental pattern of vascular development in large monocotyledons.
PHAEODISCUS, A NEW GENUS OF SCLEROTINIACEAE (INOPERCULATAE: DISCOMYCETES)
Authors: Batra Lekh R.
Published: January 2018

Phaeodiscus, a new genus of Sclerotiniaceae, is described with P. rhamnicola Batra as the single species. It is characterized by an ectal excipulum of subhyaline textura prismatica and textura porrecta; dichotomously branched, golden brown, aculeate paraphyses; and golden brown, narrowly ellipsoid, usually biguttulate ascospores. The two guttules fuse at maturity to form a single central guttule. The apothecia arise from pseudosclerotia consisting of numerous interconnected sclerotules. A number of other Sclerotiniaceae related to the new fungus are compared with it.
RATES OF PHOTOSYNTHESIS AND RESPIRATION OF THE MOSS BRYUM SANDBERGII AS INFLUENCED BY LIGHT INTENSITY AND TEMPERATURE
Authors: Rastorfer James R. , Higinbotham N.
Published: January 2018

Using differential respirometry and air enriched to 3% CO2 (v/v), the rates of photosynthesis and dark respiration of the moss Bryum sandbergii were measured as influenced by temperature and light intensity. The optimal temperature for net (apparent) photosynthesis was between 24 to 30 C; however, the photosynthesis/respiration ratio was about 11 to 27 between 4 to 24 C and dropped to lower values at 34 C., which indicates a wide temperature tolerance for this moss in short‐term experiments. The maximum temperature for photosynthesis was about 41 C and the minimum was below –5 C. At 20 C light saturation was approached at 6.2 mw cm–2 (ca. 700 ft‐c) but not completely reached at 12 mw cm‐2; the light compensation point was estimated to be 0.4 mw cm‐2 (ca. 40 ft‐c). At 4 C light saturation and the compensation point were at lower levels and apparently solarization occurred at 12 mw cm‐2. Light intensity had little or no apparent effect on dark respiration. However, respiration increased with temperature over various ranges extending from –5 to 39 C with temperature quotients of about 2.5 to 1.2. The significance of these characteristics is discussed with respect to the ecological relationships of the species.
THE DISTRIBUTION AND TAXONOMIC SIGNIFICANCE OF LIGNIN IN THE LEMNACEAE
Authors: Blazey Edward B. , McClure Jerry W.
Published: January 2018

Lignification characteristics of 14 species of Lemnaceae were studied by the alkaline oxidation technique in an attempt to resolve conflicting reports of the presence of lignin and to provide chemotaxonomic data for supplementing previous systematic treatments. Four species of Spirodela, eight of Lemna, Wolffiella oblonga, and Wolffia microscopica were clonally subcultured, homogenized, exhaustively extracted and the insoluble residue oxidized in alkaline cupric hydroxide. Barley (Hordeum vulgare), Elodea densa and Spirogyra sp. were examined to validate the technique. The benzaldehydes were extracted, separated by thin‐layer chromatography, and quantitated spectrophotometrically. Recovery of syringaldehyde, vanillin, and to a lesser extent p‐hydroxybenzaldehyde, was accepted as evidence that these plants are lignified. The highest yields of syringaldehyde and vanillin were recovered from S. intermedia, the largest member of the Lemnaceae. Lesser amounts were obtained from S. polyrhiza and S. oligorhiza. Spirodela biperforata yielded no syringaldehyde which substantiates its distinctiveness from the morphologically similar S. polyrhiza. All Lemna species are nerved, yet vanillin (but not syringaldehyde) was recovered only from L. trinervis, L. perpusilla, L. minor, and L. minima. The species L. trisulca, L. gibba, L. obscura, and L. valdiviano yielded only p‐hydroxybenzaldehyde. Thus the presence of nerves is not evidence for lignification within the genus Lemna, and the relationships suggested by their gross morphology are not supported by their lignin chemistry. Wolffiella is non‐lignified by these criteria. Wolffia microscopica is the smallest flowernig plant and it has no nerves; vanillin was unexpectedly recovered and microscopic examination showed highly lignified anther walls.
APICAL ORGANIZATION IN ROOTS OF THE CONVOLVULACEAE
Authors: Seago James L. , Heimsch Charles
Published: January 2018

A sampling of radicles and germinated primary roots was obtained for several species of the Convolvulaceae in order to study ontogenetically the organization of the protomeristem. The findings differ from earlier studies in that only a few radicles and primary roots exhibited proto‐meristems with layered initials. Most radicles exhibited a pattern of layered initials in which the outer cell layers of cortex were not aligned with a layer of cortical initials but with cells at the base of the columella. In long primary roots the protomeristem, consisting of central cylinder initials, lateral rootcap‐epidermal initials, and common initials for the cortex and columella, was the general pattern for the members of the family. The reorganization of the protomeristem from a layered condition to common initials generally occurred upon germination. Different expressions of intermediate patterns indicated that periclinal divisions in the outer layers of cortex near the initials or in the immediate derivatives of the cortical initials were responsible for cellular displacements and new cell alignments. After reorganization, periclinal divisions in the peripheral portions of the common initials maintained the cellular continuity from the cortex into the columella. In addition, a few primary roots with a degenerated columella and a transversal meristem were observed.
DEVELOPMENTAL CHANGES IN THE VASCULAR CAMBIUM OF POLYGONUM LAPATHIFOLIUM
Authors: Cumbie B. G.
Published: January 2018

Developmental changes in the vascular cambium of Polygonum lapathifolium were determined primarily by an analysis of the secondary xylem. The cambium and xylem consist of fascicular and interfascicular regions in this herbaceous dicotyledon. Near the pith vessels are restricted to the fascicular regions of the xylem. During secondary growth vessels are formed in some radial files in the interfascicular regions. Anticlinal divisions are of two types, oblique and lateral. In interfascicular files consisting of fibers only, about two‐thirds of the anticlinal divisions are oblique. The oblique partition averages 31% of the length of the dividing initials. In interfascicular files consisting of vessel elements and fibers, there are almost equal numbers of oblique and lateral divisions. The oblique partition averages 37% of the length of the dividing initials in these files. Lateral divisions account for approximately three‐fifths of the anticlinal divisions in the fascicular regions, consisting of vessel elements and fibers. The partitions formed in oblique anticlinal divisions average 64% of the length of the dividing cells in the fascicular regions. The frequency of anticlinal division is much higher in files consisting of vessel elements and fibers than in those consisting of fibers only. There is no loss of fusiform initials, except by ray formation. Ray initiation occurs by simple subdivision of fusiform initials. The findings are discussed in relation to the developmental changes in the vascular cambium in plants of different habits.
ON STROMATOPTERIS AND ITS ILL‐DEFINED ORGANS
Authors: Bierhorst David W.
Published: January 2018

New information presented on the morphology of Stromatopteris includes a description of the mature embryo, of the structure and ontogeny of various leaf‐ and stem‐like axes and roots, and of young gametophytes of spore origin. This new information compounds the difficulty of specifying the organs in classical terminology. It further supports the presumed relationships of this genus to the Psilotaceae and Schizaeaceae. The mature embryo is composed of a lower hemisphere (foot) and an upper hemisphere. An indefinite number of very thin, avascular, primary sporophy‐tic axes originate superficially over the surface of the upper hemisphere and break through the calyptra. All other parts of the sporophyte eventually are derived from these axes. The roots of Stromatopteris, although quite usual in many ways show peculiarities in tissue derivation from cells cut off distally from the apical cell. They are also non‐absorbing organs devoid of root hairs. Long‐cell and short‐cell regions along the various axes are described. In the roots vascular interruption is correlated with short‐cell zones.
TRANSLOCATION OF C14‐LABELED PHOTOSYNTHATE IN NODULATED LEGUMES AS INFLUENCED BY NITRATE NITROGEN
Authors: Small J. G. C. , Leonard O. A.
Published: January 2018

Translocation of C14‐labeled photosynthate was studied in nodulated pea and subterranean‐clover plants which were grown either continuously without combined nitrogen or exposed to NaNO3 in the nutrient solution for five days prior to C14O2 assimilation. Supplying combined nitrogen decreased the proportion of photosynthate translocated to nodules with a corresponding increase in the proportion going to roots. Nodules on plants grown without combined nitrogen had a higher radioactivity than nodules on plants treated with sodium nitrate.
DORMANCY FACTORS IN IRIS (IRIDACEAE) SEEDS
Authors: Arditti Joseph , Pray Thomas R.
Published: January 2018

Utilizing a newly developed radish seed bioassay, it has been demonstrated that Iris seed dormancy is caused by water‐soluble inhibitor(s). Leached Iris seeds germinate freely when planted in soil without previous chilling. The inhibitor(s) can prevent germination of representative species of both monocotyledonous and dicotyledonous seeds.
GRAFT UNION FORMATION IN DOUGLAS‐FIR
Authors: Copes Donald
Published: January 2018

Greenhouse‐grown Douglas‐fir (Pseudotsuga menziesii [Mirb.] Franco) graft unions were examined between 2 and 84 days after grafting. Room temperature was maintained at 60‐70 F throughout the growing season. In most respects grafts of Douglas‐fir followed development patterns previously reported for spruce and pine grafts, but specific differences were noted in contributing cell types, time of formation, and mode of healing. The time interval from first occurrence to occurrence in 80% of the grafts is as follows: contact layers, 2 days; callus bridges, 10‐14 days; periderm, 10‐17 days; cambia, 17‐23 days. Callus bridges were generally of secondary phloem or cortex origin. Callus lignification began along cut edges of the union at 14 days and was completed across the entire length of the union by 17 days. Lignified tracheids were continuous across union zones at 35 days. When proper grafting techniques were used, all tissue systems necessary for a successful union were present 35 days after grafting. Poor grafting techniques at times retarded cambium formation for 3 months or more.
THE STRUCTURE OF GRANA IN FLOWERING PLANTS
Authors: Paolillo Dominick J. , MacKay Norma Chao , Graffius Judith Reighard
Published: January 2018

A model of granum structure, consisting of multiple helical frets wound around each cylindrical granum, is proposed as a representation of granum structure for flowering plants in general. This model was originally formulated for grana in the mesophyll plastids of Zea mays and was subsequently extended to grana of Phaseolus vulgaris by additional studies. The model is now shown to be applicable also to grana in the plastids of Cannabis sativa, Elodea canadensis, Nicotiana rustica, Pisum sativum, and Spinacia oleracea. This sample of seven angiosperms includes genera commonly studied by other workers in their ultrastructural investigations of plastid structure.
BIFURCATION OF THE STEM APEX IN ASCLEPIAS SYRIACA
Authors: Nolan James R.
Published: January 2018

In Asclepias syriaca the overall inflorescence is an anthoclad in which the peduncles are non‐axillary, each occurring about 60° away from the axil of a leaf. Ontogenetically, a peduncle is initiated when the stem apex expands laterally and bifurcates into separate apices, neither of which is subtended by any type of organ. One of the two apices continues as the functional apex of the stem (bifurcating again at each subsequent node), and the other functions as the apex of the peduncle. The peduncle first produces a bract and, then, a pedicel in the axil of the bract. Subsequent pedicels are each axillary to separate bracts. The pedicels, therefore, can be interpreted as ordinary lateral branches. However, because the bifurcations of the stem apex are not associated with subtending organs, the branching of the stem does not conform to expected monopodial or sympodial systems in the angiosperms. This suggests the possibility that each bifurcation of the stem apex is a true dichotomy. The anthoclad axis, thus, is a series of dichotomies. Although such a series may have been phylogenetically derived from a monopodial or sympodial ancestor, it is also possible that it may have been retained from a primitive, dichotomizing inflorescence.
ANATOMY AS AN AID TO CLASSIFYING THE CYPERACEAE
Authors: Metcalfe C. R.
Published: January 2018

During a period of about 10 years the systematic anatomy of the vegetative organs of more than 280 species belonging to 90 genera of the taxonomically complex family Cyperaceae have been examined, some of them for the first time. Abstracts of about 250 published articles relating to the anatomy of the Cyperaceae have also been prepared. The combined results of this investigation and literature survey are to appear as Vol. 5 of a reference book entitled Anatomy of the Monocotyledons. In the present article particulars are given of the anatomical characters which have proved to be among the most important as an aid in classifying the tribes and genera within the family. Special attention has been devoted to silica‐bodies in surface‐view preparations of the leaf epidermis. In transverse sections of the lamina, the relationship between genera and species in which there are dorsiventral, isobilateral, pseudodorsiventral, and cylindrical leaves, respectively, appears to be of special interest. Selected conclusions concerning the affinities between tribes and between certain genera and the tribes to which they belong within the Cyperaceae are presented. The relationship of the Cyperaceae to other families is briefly discussed.
ABOUT MESOZOIC PTERIDOPHYLLS
Authors: Zimmermann Walter
Published: January 2018

Two types of pteridophylls are very common in the Mesozoic era: the Polypodium and the Dipteridaceae. The Polypodium‐type formed by pendulous overtopping is represented in the Mesozoic era by the form‐genus Cladophlebis, in the Paleozoic era by the form‐genus Pecopteris, and today by Dryopteris. Overtopping differs in these three pteridophylls. Nearly all Paleozoic pteridophylls show a catadromic structure. Today pteridophylls with anadromic and combined catadromic/anadromic structures are the dominant ones. The Mesozoic genera demonstrate a transitional structure: catadromic structures are still frequent, but equally frequent are combined catadromic/anadromic structures. Pteridophylls solely with anadromic structures are unknown in the Mesozoic era. The Dipteridaceae‐type is almost exclusively Mesozoic. It is primitive in the dichotomy of the rachis, but advanced in that it is net‐veined. Thus the Mesozoic pteridophylls represent connecting links between Paleozoic and recent leaf‐types. This nature of Mesozoic pteridophylls can be understood only on the basis of the telome theory.
ESSENTIAL LEAF OILS IN REPRESENTATIVES OF THE AURANTIOIDEAE (RUTACEAE)
Authors: Scora Rainer W. , Duesch G. , England A. B.
Published: January 2018

The distribution of essential leaf oils in representatives of 12 genera in the Aurantioideae has been studied by gas chromatography. Of the individual oil components, 40 were identified by retention times on two columns, augmentation, and some by IR spectrophotometry. Twelve groupings of components were established and these compared between the tribes Clauseneae and Citreae, among the subtribes clauseninae, balsamocitbinae, and citrinae, and between the “primitive” and the “near citrus group.” The essential oils conform to the botanical groupings, except for Pleiospermium in the citrinae and Murraya in the clauseneae. Fortunello crassifolia (Citbeae), a possible garden hybrid, seems to be more closely related to the Clauseneae, the remote citroids, than to the near Citrus group. Atalantia also might be an intertribal hybrid with remote or other citroids. A specimen of Aeglopsis chevalieri (balsamocitbinae) from Florida appears to be of hybrid origin with the parental source close to Citrus.
SPORANGIAL FRAGMENTS REFERRED TO DICTYOPHYLLUM IN TRIASSIC CHERT FROJVI SARAWAR
Authors: Gastony Gerald J.
Published: January 2018

Sporangial fragments of several Mesozoic fern taxa are organically preserved in a Triassic (Norian) chert from Sarawak. The more nearly entire annuli in the deposit are divided into two size classes. Structural features of the smaller annuli (capsule diam 0.26‐0.3R mm) suggest affinities with the Gleicheniaceae, Matoniaceae, and Dipteridaceae. The three‐dimensional preservation of the larger annuli (capsule diam 0.50‐0.63 mm) reveals features of annular structure and stomial detail which are usually obscured in compressed specimens. Sporangia featuring these larger annuli were probably more‐or‐less pyriform and sessile, and they exhibited an oblique, uninterrupted annulus with greatly reduced induration in the stomial and hypostomial regions. The large size of these sporangia and their probable large spore number indicate that they are not conspecific with the TriassicClathropteris meniscoidesBrongn., also reported from Sarawak. On the basis of general morphology and their unusually large size, these sporangia are tentatively referred toDictyophyllum exile(Brauns) Nathorst.
THE ORIGIN OF AGROPYRON ALBICANS
Authors: Dewey Douglas R.
Published: January 2018

Previous suggestions of introgression between Agropyron spicatum (Pursh) Scribn. & Smith, 2n = 14 & 28, and Agropyron dasystachyum (Hook.) Scribn., 2n = 28, were confirmed. Fertile, meiotically regular, 28‐chromosome plants morphologically identical to Agropyron albicans Scribn. & Smith, 2n = 28, occurred in first‐ and second‐generation open‐pollination progenies of diploid A. spicatum × A. dasystachyum hybrids, presumably by backcrossing to A. dasystachyum. These A. albicans‐like derivatives were fully cross‐compatible with naturally occurring A. albicans. First and second generation open‐pollination progeny of tetraploid A. spicatum × A. dasystachyum F1's contained approximately 5% A. albicans‐like plants; but none was tetraploid, cytologically stable, and fertile. Although introgression occurs freely between tetraploid A. spicatum and A. dasystachyum, derivation of fertile true‐breeding A. albicans from their early‐generation progeny seems unlikely. Agropyron griffithsii Scribn. & Smith ex. Piper, the glabrous counterpart of A. albicans, probably originated from hybrids between diploid A. spicatum and Agropyron riparium Scribn. & Smith, the glabrous form of A. dasystachyum. Genome formulas of diploid A. spicatum, A. dasystachyum (riparium), and A. albicans (griffithsii) may be written as S1S1, S2S2XX, and S1‐2 S1‐2XX, respectively. The relationship between A. albicans and A. dasystachyum is so close that A. albicans should be regarded as no more than a subspecies of A. dasystachyum.
STUDIES ON THE ULTRASTRUCTURE OF THE GUARD CELLS OF OPUNTIA
Authors: Thomson W. W. , De Journett R.
Published: January 2018

The guard cells of Opuntia contain numerous mitochondria, elements of endoplasmic reticulum, dictyosomes, and microbodies. A complex array of small to large vacuoles which contain small, membrane‐bounded vesicles occur in each guard cell. The variety of cytoplasmic constituents and vacuoles suggest that the guard cells are complex in function. A highly reduced grana‐fretwork system within the plastids indicates that the photosynthetic capacity of the guard cells is probably rather low. No plasmodesmata occur in the walls between the guard cells and the subsidiary cells while there are numerous invaginations of the guard cell plasmalemmas. Many of the variations in the plasmalemma probably indicate that the plasmalemma is a highly active interface.
GROWTH AND DEVELOPMENT IN MICROCULTURE OF GAMETOPHYTES FROM STORED SPORES OF EQUISETUM
Authors: Jones Leo E. , Hook Patricia W.
Published: January 2018

Spores of Equisetum telmateia Ehrh. retained 74% viability after two years of storage under glycerine at minus 10 C. Stored spores germinated, grew, and formed mature gametangia on mineral nutrient media in petri plates and in micro‐cultures where detailed cytological observations could be made. Growing gametophytes were favorable materials for studies of mitosis, chloroplast replication, gametogenesis, and senescence.
INCOMPATIBILITY OF MERISTEMATIC AND FILAMENTOUS GROWTH IN THE FERN GAMETOPHYTE
Authors: Sobota Anthony E.
Published: January 2018

Gametophytes of Pteridium aquilinum can be maintained in red light as either 1‐ or 2‐dimensional structures. The mode of growth realized in red light is dependent upon the activity of the meristem. An active meristem in a 2‐dimensional structure will permit a continued development of that structure. A breakdown in meristematic activity results in filament formation. It is suggested that a group of actively dividing cells in some manner inhibits cell elongation and thus prevents filament formation in red light.
IN VITRO DEVELOPMENT OF THE ISOLATED SHOOT APICAL MERISTEM OF ANGIOSPERMS
Authors: Smith Roberta Hawkins , Murashige Toshio
Published: January 2018

Development of complete plants was achieved from isolated shoot apical meristems of Nicotiana tabacum L., Daucus carota L., Nicotiana glauca Grah., Tropaeolum majus L., and Coleus blumei Benth. The explants consisted of only meristematic dome tissue with no visible leaf primordia. A simple nutrient medium composed of the Murashige and Skoog salt mixture, 100 mg/liter myo‐inositol, 0.4 mg/liter thiamin‐HCl, 1‐2 mg/liter IAA, 30 g/liter sucrose, and 1% agar was adequate. Histologically there occurred principally tissue enlargement during the first 3‐6 days, followed by appearance of bipolar organization in 6‐9 days and formation of a well‐defined root apex and initiation of first leaf primordium by 12 days.
METHYLPURINE INHIBITION AND BENZYLADENINE STIMULATION OF AXILLARY BUD GROWTH
Authors: Sharpe F. T. , Schaeffer G. W.
Published: January 2018

Methylpurine effectively inhibits tobacco axillary buds at concentrations higher than 10−4 m and inhibits tissue cultures of tobacco at concentrations higher than 10−6 m. The cytokinin, 6‐benzylaminopurine, not only overcomes apical dominance, but also reverses the inhibition of axillary buds by 6‐methylpurine. 6‐dimethylaminopurine does not alter the growth rate of axillary buds and neither 6‐dimethylaminopurine nor 6‐methylaminopuriue alter the growth rates of tissue cultures except at high concentrations.
DEVELOPMENTAL AND CYTOLOGICAL STUDIES OF BANGIA FUSCOPURPUREA IN CULTURE
Authors: Sommerfeld Milton R. , Nichols H. Wayne
Published: January 2018

Two isolates of the red alga Bangia fuscopurpurea have been cultured for over 3 years. The diplobiontic life history consists of morphologically dissimilar generations, the Bangia‐ and Conchocelis‐phases. The life history includes reproduction of the thallus by monospores and conchospores and of Conchocelis by carpospores. Spore germination and development into the two plant types are described. The chromosome number of both Bangia‐ and Conchocelis‐phases is 3.
EOCENE ALGAE AND PLANT HAIRS FROM THE GREEN RIVER FORMATION OF WYOMING
Authors: Bradley W. H.
Published: January 2018

Four new species of algae and two kinds of fossil plant hairs are described from a rich oil shale bed of the mid‐Eocene Green River Formation of Wyoming. Two of the algae belong to the Cyanophyceae and two to the Chlorophyceae. On the basis of their morphology alone, they are assigned to four new species among four genera, as follows: Symploca hedraia, sp. n.; Stigonema anchistina, sp. n.; Schizochlamys haywellensis, sp. n.; and Spirogyra wyomingia, sp. n. One kind of fossil plant hair is similar to those observed in organic sediments of an existing lake and identified with trichomes on the under surface of live oak leaves (Quercus virginiana). Assignment of the fossil trichomes to a taxon is not warranted at present.
A SEROLOGICAL COMPARISON OF UMBELLIFERAE SUBFAMILIES
Authors: Pickering Jerry L. , Fairbrothers David E.
Published: January 2018

Serological techniques were employed to compare the three subfamilies Hydrocotyloideae, Saniculoideae, and Apioideae of the Umbelliferae. Data obtained from turbidimetric and double diffusion analyses of seed proteins from thirteen genera demonstrated three distinct serological groupings. These groupings correspond to the three subfamilies. The serological data indicated that one grouping (Apioideae) was more similar to Saniculoideae than to Hydrocotyloideae.
MULTIPOLAR MEIOSIS IN DIPLOID CRESTED WHEATGRASS, AGROPYRON CRISTATUM
Authors: Tai William
Published: January 2018

A new model of spindle organizers is proposed: The spindle organizer in a higher plant is similar to the centriole of animal cells. It is a unit cell organelle which follows regular cell division cycles and is genome specific. Each genome carries its own spindle organizer. During fertilization, a male spindle organizer enters the egg cell. It may fuse with the female spindle organizer, or either one may degenerate. In a hybrid, both male and female spindle organizers may exist, and multipolar divisions separate different genomes into different groups. The same mechanism can be used to explain the formation of a polyhaploid from a polyploid. The chromosome behavior of an individual is believed to be an interaction of chromosome homology and the homology between chromosomes and their spindle organizers. This model is based on observations of multipolar meiosis which occurred in two cultures of diploid crested wheatgrass, Agropyron cristatum (L.) Gaertn. In these two cultures multipolar meiosis occurred at every stage after late diakinesis. The seven bivalents were separated into groups at late diakinesis. More than one equatorial plate was formed at metaphase I. Each micrometaphase plate behaved as an independent unit and had its own anaphase movement. Usually the chromosome complement separated into two groups with (4–3), (5–2), and (6–1) separations observed in about an equal number of cells. Cells with chromosomes divided into three or four groups were found less frequently. Multipolar meiosis may take place at either first or second division. Cell plates were formed across each spindle apparatus, cleaving each group of chromosomes into smaller micro‐cells. At the “quartet” stage, 4‐ to 12‐celled “quartets” were observed. Pollen stainability was measured at above 75% in both cultures. Stained pollen grains could be classified into two distinct size classes. Darkly stained, small pollen grains represented the result of multipolar meiosis and may have been viable. Multipolar cell divisions provided a mechanism which polyploids might reduce their ploidy level.
EVOLUTION OF COTYLEDONARY AND NODAL VASCULATURE IN THE JUGLANDACEAE
Authors: Stone Donald E.
Published: January 2018

Cotyledonary nodal patterns of the Juglandaceae range from 1‐gap, 2‐trace to multi‐gap, multi‐trace. The development of increased nodal complexity is associated with at least two independent evolutionary shifts from epigeal to hypogeal germination. The taxa with epigeal germination such as Engelhardia sect. Engelhardia, Engelhardia sect. Psilocarpeae, Platycarya, and Pterocarya all have 1‐gap, 2‐trace nodes. The change to hypogeal germination in Engelhardia sect. Oreomunnea and Alfaroa is correlated with the development of 1‐gap, 3‐trace cotyledonary nodes. The second line has led to large, heavy‐fruited members with hypogeal germination and complex cotyledonary nodes ranging from 2–6 gaps. The diversity of nodal patterns is the result of variation on a common theme; five basic vascular strands in the cotyledon, undergoing variations in dichotomy, fusion, and separation, are associated with one to many gaps. Presumably the complex development of the cotyledonary node is a response to increased functional demands of hypogeous cotyledons.
CHARACTERISTICS OF SALTS SECRETED BY TAMARIX APHYLLA
Authors: Berry Wade L.
Published: January 2018

The composition and concentration of salts secreted by the salt glands of Tamarix aphylla L. grown under controlled nutrient conditions were determined. Eight ions, Na, K, Mg, Ca, Cl, NO3, HCO3, and SO4, constituted 99 % + of the dry weight of salts secreted by plants grown on half‐strength Hoagland's solution. The divalent cations Mg and Ca accounted for most of the cations; HCO3 comprised about 60 % of the anions. The micronutrients B, Mn, Cu, Zn, and Mo were present in enriched concentrations in the secretion. The composition of the secretions was highly dependent on the composition of the root environment. The predominating cation in the saline culture solutions was also the predominant cation secreted. The accompanying anion in the culture solution influences the cation composition of the secreted salt. The concentration of the salt gland secretion averaged 0.5n, a 50‐fold increase in concentration over the nutrient solution in which the plants were grown.
UNUSUAL DARK‐GROWTH AND ANTHERIDIAL DIFFERENTIATION IN SOME GAMETOPHYTES OF THE FERN ONOCLEA SENSIBILIS
Authors: Miller John H. , Miller Pauline M.
Published: January 2018

A fertile frond of O. sensibitis was found which yielded spores with unusual growth characteristics. About 25% of the gametophytes derived from the spores were able to undergo 2‐dimensional development in darkness, in contrast to normal plants which are filamentous in darkness. When the aberrant spores were cultured in darkness under conditions of reduced ethylene concentration, the proportion of 2‐dimensional plants rose to 75%, and, moreover, up to 50% of the gametophytes produced antheridia within 2 weeks. Under comparable conditions normal gametophytes produced no antheridia. The medium from antheridial cultures of the aberrant spores failed to induce the formation of antheridia in other plants.
THE ROLE OF ROOTS IN THE NUTRITION OF AQUATIC VASCULAR PLANTS
Authors: Bristow J. Michael , Whitcombe Mark
Published: January 2018

Rooted stems of three aquatic species were cultured in a two‐compartment apparatus which allowed the upper and lower portions of the stem to be kept in different nutrient solutions. P32 was supplied to either the upper or lower compartment. At the end of a 10‐day growth period, the specific activity of phosphate was determined in axillary shoots which developed during the course of the experiment from buds in the upper compartment. The results indicated that most of the phosphate in these shoots was not absorbed from the ambient medium but was derived from the rooted stem base in the lower compartment (over 90 % in Myriophyllum brasiliense, 59 % in M. spicatum, and 74 % in Elodea densa). These results give a very different but probably more accurate picture of phosphate absorption in rooted aquatic vascular plants than short‐term experiments, in which phosphate is readily taken up from the ambient medium by leaves of M. spicatum and E. densa. In M. brasiliense the amount of phosphate translocated is related to the mass of roots present. Evidence is presented that normal growth of axillary shoots occurs even when all mineral ions have to be obtained by translocation from the lower compartment.
SEED GERMINATION RESPONSE AND EVIDENCE FOR HEIGHT ECOPHENES IN SPARTINA ALTERNIFLORA FROM NORTH CAROLINA
Authors: Mooring Molly T. , Cooper Arthur W. , Seneca Ernest D.
Published: January 2018

A study was conducted to determine germination response to temperature and salinity and seedling response to salinity by three height forms of the salt marsh grass Spartina alterniflora Loisel. Germination tests showed that seeds cannot withstand drying at moderate temperature, as viability was lost within 40 days in seeds stored dry at 72 F. Cold storage at 43 F is adequate to prevent desiccation up to 40 days, but after 8 months viability is lost. Viability is retained at least 8 months when seeds are stored in sea water at 43 F. Germination response was good in a 65–95 F alternating diurnal thermoperiod but was poor in a 72 F constant thermoperiod. Germination response to salinity was an inverse curvilinear relationship with germination inhibition at high salinities apparently due to osmotic effects. The maximum tolerance limit for germination lies between 6 and 8 % NaCl. Seeds from short, medium, and tall plants responded similarly in storage and temperature studies. However, in salinity studies, seeds of the Ocracoke Island short form and the Oak Island tall form performed best. A logarithmic curve best described seedling growth response to various NaCl levels. Growth response as measured by seedling dry weight was best in 0.5 % NaCl solution. Seedlings grew taller in both 0.5 and 1.0 % NaCl than in 0 % NaCl. No significant difference in seedling growth response due to height form of the parent plant was detected. Thus, on the basis of germination and seedling responses, the height forms of S. alterniflora in North Carolina salt marshes are best described as ecophenes.
CAMBIAL ACTIVITY IN ALASKAN WHITE SPRUCE
Authors: Gregory Robert A.
Published: January 2018

Cambial activity in white spruce stems in Alaska was observed during a 2‐year period in 50–60‐year‐old natural stands. Mitotic index was used as a measure of the rate of periclinal division of fusiform cells in the cambial zone. Anticlinal divisions were relatively rare, averaging only one per 27S periclinal divisions in most stems. Mitotic index, at any given time, appeared uniform throughout the cambial zone of an internode, among internodes of the same tree, and even among trees growing at markedly different rates. Diurnal variation in mitotic index was observed. There were three distinct growing season periods: early, grand, and late. Early period activity was characterized by reactivation of periclinal division, erratic mitotic indices, and an approximate doubling of the number of cambial zone cells per radial file (NCZ). Production of the first new xylem and phloem elements marked the beginning of the grand period. Rate of cell production in the cambial zone remained about equal to derivative production for the next 45–50 days, when about 80 % of annual xylem and phloem increment occurred. There was a drop in NCZ at the beginning of the late period coincident with a decline in mitotic index, and NCZ soon dropped to the dormant level. Complete termination of cambial activity was gradual, extending through late August and perhaps into September.
RACES OF PERONOSPORA MANSHURICA IN THE UNITED STATES
Authors: Dunleavy J. M.
Published: January 2018

I propose a set of 11 soybean varieties for the differentiation of races of Peronospora manshurica: Pridesoy, Norchief, Mukden, Richland, Roanoke, Illini, S 100, Palmetto, Dorman, Kabott, and Ogden. When I employed these, I found fifteen new races of Peronospora manshurica, the casual agent of downy mildew of soybeans, described them, and assigned numbers 9 through 23. Race 8 was encountered most frequently and occurred at 40% of the locations from which seed samples were obtained. Races 1, 2, 10, 12, 18, and 23 occurred at 5–8% of the locations sampled. Race 10 was common in the southern U. S. Of 247 soybean seed lots sampled, 73% contained some oospore‐encrusted seeds. These ranged from 12–26% lighter than healthy seeds. The percentage of oospore‐encrusted seeds occurring in seed lots ranged from 0–25%.
FLORAL ANATOMY OF KRAMERIA LANCEOLATA
Authors: Milby T. H.
Published: January 2018

The anatomy of each of the series of floral organs of Krameria lanceolata was examined. The sepals are characterized by three main veins each, an undifferentiated mesophyll, and stomata on the upper epidermis. The fleshy petals are distinguished by their numerous veins as well as by palisade‐like epidermal cells on the outer surface. The three partially united petals have each a single vein and long, narrow epidermal cells similar to those on other floral organs. The stamens are united at their bases and bear tetra‐sporangiate, conical anthers. The gynoecium includes a sterile and a fertile carpel. In the receptacle the veins to the sepals and petals are separated by a wide gap; those to the petals and stamens, by a narrow gap. Anatomical characteristics of the flower dissociate Krameriaceae from the legumes with which they have frequently been thought to be allied.