bluuebunny/crossref_metadata_2025 huggingface dataset:
NEW WORLD JUGLANDACEAE. II. HICKORY NUT OILS, PHENETIC SIMILARITIES, AND EVOLUTIONARY IMPLICATIONS IN THE GENUS CARYA
Authors: Stone Donald E. , Adrouny George A. , Flake Robert H.
Published: January 2018

Gas chromatographic analyses of the nut oils of 155 samples, representing 15 taxa of Carya, confirm the basic uniformity of fatty‐acid composition within the walnut family. All taxa contain small amounts of the saturated fatty acids—palmitic and stearic—and variable amounts of the unsaturated oleic and linoleic acids, and at least trace amounts of linolenic. Quantitative differences in the relative amounts of the five fatty acids support the morphologic recognition of two sections within the genus. Members of the section Carya are characterized by higher linoleic and lower oleic acid percentages than are those of section Apocarya. It is also true, however, that tetraploids of section Carya tend to have higher linoleic and lower oleic acid percentages than diploids within the same section. Numerical analyses of the oil data reveal close similarities between certain members of the more “primitive” section Apocarya and the diploid members of section Carya. The highly heterogeneous assemblage within section Apocarya could be split into three groups on the basis of oil data. It is equally obvious, however, that the American taxa of the genus Carya have had a long and reticulate phylogeny and that recognition of additional categories above the species level would not result in natural assemblages.
HYBRIDIZATION STUDIES WITH SPECIES OF CYNODON FROM EAST AFRICA AND MALAGASY
Authors: Harlan Jack R. , de Wet J. M. J. , Richardson W. L.
Published: January 2018

A collection of 198 accessions of Cynodon from East Africa and Malagasy was grown in uniform nurseries at Stillwater, Okla., and classified morphologically, studied cytologically, and tested for crossability in hybridization studies. The following taxa were recognized: C. arcuatus, C. plectostachyus, C. aethiopicus, C. nlemfuensis var. nlemfuensis, C. nlemfuensis var. robustas, C. dactylon var. aridus, C. dactylon var. coursii, and C. dactylon var. dactylon. The magnitude of barriers to gene flow was estimated by ease of hybridization and by sterility of the hybrids obtained. C. arcuatus and C. plectostachyus are well isolated from all other species in the genus. The others are sufficiently related that they may be intercrossed. The barriers to gene flow vary demonstrably in strength between different combinations of taxa. The magnitude of a barrier required to establish species limits is, perhaps, more a matter of subjective opinion than a scientific conclusion. It was concluded that no completely satisfactory classification of the genus is possible. The system adopted was a compromise between classical morphological concepts of species, the biological concept of species, and pragmatic utility.
PINUS AVONENSIS, A NEW SPECIES OF PETRIFIED CONES FROM THE OLIGOCENE OF WESTERN MONTANA
Authors: Miller Charles N.
Published: January 2018

Fossils from the Oligocene of western Montana described in this treatment are the first structurally preserved ovulate cones of Pinus to be reported from the Tertiary of North America. They are about 5.5 cm long and have a maximum diam of 2.5 cm. Numerous scales are arranged spirally around the axis and each scale bears two winged seeds. The bract subtending the ovuli‐ferous scale is 3‐4 mm long and is free from the scale throughout its length. The pith and cortex of the axis are constructed of thick‐walled parenchyma cells and 18‐21 resin canals occur at the inner edge of the cortex. Resin canals entering the base of the ovuliferous scale are restricted to the abaxial side with vascular tissues occupying the adaxial side. Vascular strands near the tip of the scale are strongly rounded on the adaxial or phloem side. At the abaxial side of the tip of the ovuliferous scale is a broadly rhomboidal apophysis with a raised umbo that terminates in a short spine. The fossils differ from the several Recent cones examined in having fewer resin canals and biseriate rays in the secondary xylem of the cone axis. The shape of the cone, its anatomical features, and the morphology of the tip of the cone scale indicate affinity with the subgenus Diploxylon.
THE OCCURRENCE AND DISTRIBUTION OF ACRASIEAE IN FOREST SOILS. I. EUROPE
Authors: Cavender James C.
Published: January 2018

The deciduous forests of Europe contain fewer species of cellular slime molds than those of Eastern North America. Diclyostelium mucoroides is the most widely distributed and the most abundant species. In Europe this species is as a rule the sole dominant species in a forest‐soil acrasian population, a situation that rarely occurs in North America. An explanation of this difference may lie in the severity of the Pleistocene climate on European forests which resulted in the elimination of suitable habitats for the Acrasieae over a long period of time, and the replacement of the original forest by one much poorer in tree species. It is suggested that this modern forest does not offer the diverse of habitat which may be requited to support a mixed population of cellular slime molds.
GERMINATION AND SEEDLING DEVELOPMENT OF SOYBEANS IN A CARBON DIOXIDE‐DEFICIENT ATMOSPHERE
Authors: Green D. G. , Sudia T. W.
Published: January 2018

During the initial phase of germination and seedling development of soybeans, most of the increase in dry weight in the embryo axis occurred in the hypocotyl. The epicotyl did not undergo a rapid increase in size and dry weight until the 4th to 5th day of growth. From day 1 to 11 dry weights of the hypocotyls in the “CO2‐normal” and “CO2‐Iimiting” (less than 50 ppm [0.005%] atmospheric CO2) treatments were similar. By day 13 the CO2‐normal hypocotyls had continued their rapid increase in dry weight while the dry weight of the hypocotyls grown under CO2‐limiting conditions had decreased. The parallel decrease in dry weight of the cotyledons that occurred for both CO2 treatments (days 1 to 13) suggested that CO2 content of the atmosphere is not a controlling factor in the digestion or hydrolysis of food reserves in the cotyledon during germination and seedling development. This is supported by the failure of the CO2 treatments to produce significantly different patterns in utilization of lipids, total carbohydrates, or proteins in the cotyledons. The seedlings grown under either the limiting or normal CO2 atmospheres utilized their cotyledonary carbohydrates and lipids before the proteins. Sufficient food reserves are present in the soybean cotyledon storage cells for seedling development until about day 9. Net CO2 uptake by soybeans in a CO2‐normal environment first occurred between days 9 to 11.
THE ORIGIN AND RELATIONSHIPS OF LASTHENIA BURKEI (COMPOSITAE)
Authors: Ornduff Robert
Published: January 2018

Lasthenia burkei (Compositae) is a narrowly restricted California endemic closely related to L. conjugens and L. fremontii. These three species differ from each other by pappus and phyllary characters and in geographical distribution. All are freely intercrossable, but L. fremontii forms rather sterile artificial hybrids with its two relatives which, in turn, form fairly fertile artificial hybrids with each other. Lasthenia burkei and L. conjugens have homologous chromosomes, four of which are homologous with four of those of L. fremontii. The remaining two chromosomes probably have reciprocal translocations which lead to multivalent formation during meiosis in interspecific hybrids. Pollen viability is restored in most F2 generations, suggesting a close genetic relationship among the three species. The evolutionary relationship among these species may be a linear one with L. burkei occupying an intermediate position between L. fremontii and L. conjugens, although the direction of this linear phylogeny is not certain, or it may be one in which L. burkei has been derived from hybridization between its two relatives. Support for the latter hypothesis comes from the appearance of some individuals in F1 progenies of L. conjugens × L. fremontii that are morphologically indistinguishable from L. burkei (although fairly sterile). The apparently rather simple genetic basis for the morphological characteristics of each of the species in this trio suggests that the morphologically heterogeneous genus Lasthenia may be considerably more homogeneous genetically than might be suspected. Because of the diverse kinds of relationships among these three Lasthenias, possible alternative taxonomies for the group are dependent upon those relationships that a taxonomist wishes to communicate. Nevertheless, the patterns of diversification in this group have led to reaffirmation of an earlier decision that three species should be recognized.
ANATOMICAL AND CHROMOSOMAL OBSERVATIONS ON ORTHOCLADA LAXA (CENTOTHECEAE; GRAMINEAE)
Authors: Lersten Nels R. , Pohl Richard W.
Published: January 2018

Orthoclada laxa and O. africana have uncinate microhairs, which are compared to similar micro‐hairs of the unrelated genus Neoslapfia, previously thought to be a unique grass in this respect. The bicellular and marginal microhairs, as well as general leaf anatomy, are also described. The root hair pattern is of the “panicoid” type. The chromosome number from root tip preparations is 2ra = 24.
MEIOSIS IN THE OOMYCETES: I. A MICROSPECTROPHOTOMETRIC ANALYSIS OF NUCLEAR DEOXYRIBONUCLEIC ACID IN SAPROLEGNIA TERRESTRIS
Authors: Bryant Truman R. , Howard Kenneth L.
Published: January 2018

A cytological and cytochemical examination of Saprolegnia terrestris Cookson was undertaken to resolve the conflict of opinion regarding the life cycle of fungi in the Saprolegniaceae, i.e., whether meiosis is zygotic or gametic. Microspectrophotometric analysis reveals that pre‐divisional oogonial and antheridial nuclei are 4C; a subsequent reduction division in the sex organs produces 1C male and female gametes. These division products coexist in the developing oospore and presumably fuse to produce the diploid zygote. Analysis of the somatic hyphal nuclei shows a 2C DNA content, with the characteristic skew and bimodal character indicative of predominantly G1, and some S‐period and G2 types. The evidence is completely consistent with gametic meiosis, i.e., a predominant diploid vegetative phase and short haploid phase, and refutes the notion of zygotic meiosis. Further ramifications of the work are discussed along with preliminary results of related work in progress.
PATTERN FORMATION AND THE FINE STRUCTURE OF THE DEVELOPING CELL WALL IN COLONIES OF PEDIASTRUM BORYANUM
Authors: Gawlik S. R. , Millington W. F.
Published: January 2018

A single‐layered disc of peripheral pronged cells and central prongless cells impart the typical gear shape to colonies of Pediastrum, while the walls of each cell have a characteristic reticulate triangular pattern. The two‐layered wall forms in the cells during colony formation following zoospore aggregation and adhesion. The uniformly thin outer layer reflects contours resulting from differential thickening in the reticulate pattern of the inner, thicker, more fibrillar and granular wall layer. The reticulate pattern thus imparted to the outer wall layer persists in empty zoosporangia following the release of zoospores. Columns of electron‐dense material extend through the outer wall layer except at the ridges and centers of the reticulum. Following mitosis and cleavage, the resulting zoospores are extruded within a vesicle membrane consisting of the inner wall layer. Separation of this membrane from the parent cell occurs in material of the inner layer adjacent to the outer wall. Vesicles containing swarming zoospores also contain a granular material which appears to become associated with the aggregating and adhering cells of new colonies. Microtubules occur in zoospores prior to adherence but are absent during wall deposition.
STRUCTURE AND DEVELOPMENT OF THE DIMORPHIC BRANCH SYSTEM OF THEOBROMA CACAO
Authors: Greathouse D. C. , Laetsch W. M.
Published: January 2018

The vegetative morphology of Theobroma cacao, the cacao tree, was studied in order to provide a foundation for further investigations on the morphogenesis of the cacao dimorphic shoot system. The seedling of cacao has a determinate orthotropic shoot with a (2+3) phyllotaxis. Branch dimorphism is initiated after 1 to 2 years of growth at which time the apical meristem of the orthotropic shoot aborts and a pseudowhorl of plagiotropic branches is initiated from axillary positions in the shoot tip. The plagiotropic branches are characterized by a distichous phyllotaxis and indeterminate growth. Subsequently an axillary bud below the pseudowhorl develops into a new orthotropic shoot. The apical meristem of this shoot eventually aborts and another pseudowhorl is formed. The apical anatomy of the two types of shoots is similar. The developmental potentiality of the orthotropic shoot axillary buds to form one or the other type of shoot was investigated. The phyllotaxis of the axillary buds of the orthotropic shoot is spiral and that of the axillary buds of the plagiotropic branch is distichous. Pruning and apical puncture experiments showed that the axillary buds of a plagiotropic branch, and of an orthotropic seedling shoot which has not yet formed a pseudowhorl, always give rise to the parent type of shoot. However, the axillary buds of an orthotropic shoot which already bears a pseudowhorl give rise to either type of shoot for several nodes below the point of origin of the pseudowhorl. The type of shoot has no influence on the form of branch which develops from an axillary bud grafted to it. This evidence supports the hypothesis that the axillary buds are initiated as one or the other type of shoot, i.e., once initiated they are predestined.
THE RELATION BETWEEN GROWTH, CONIDIATION AND TREHALASE ACTIVITY IN NEUROSPORA CRASSA
Authors: Hanks David L. , Sussman Alfred S.
Published: January 2018

The extent to which trehalose is accumulated in the vegetative mycelium of strains of Neurospora crassa is significantly affected by conidiation. In heavily conidiating strains a rapid decrease in mycelial trehalose occurs following the initiation of conidiation. Meanwhile, trehalase activity in the vegetative mycelium of heavily conidiating strains increases rapidly following the initiation of conidiation, although apparently it is not directly caused by the sporulation process. High levels of both trehalase and trehalose appear concomitantly in the newly formed conidia.
POLLEN AND TAPETUM DEVELOPMENT IN DESMODIUM GLUTINOSUM AND D. ILLINOENSE (PAPILIONOIDEAE; LEGUMINOSAE)
Authors: Buss Paul A. , Galen Donald F. , Lersten Nels R.
Published: January 2018

Each of the four microsporangia has three or four wall layers, a uninucleate tapetum of various cell shapes with nuclei that remain in prophase, and 12‐24 pollen mother cells (PMCs). A sterile transverse septum sometimes bisects the microsporangium. PMCs secrete callose but not uniformly, and contact among them continues through meiosis. Simultaneous cytokinesis by furrowing isolates each microspore in callose, which later disperses. The separated microspores become vacuolate, undergo mitosis to become pollen, and later become filled with food reserves. Endothecial wall thickening and tapetal dissolution occur after pollen engorgement. Calcium oxalate crystals form in tapetal cells during the sporogenous stage, reach maximum size during early meiosis, and remain prominent until tapetal dissolution.
POLLEN EXINE DEPOSITION: A CLUE TO ITS CONTROL
Authors: Rogers C. M. , Harris Betty D.
Published: January 2018

The development of Linum microspores with very incomplete chromosome complements into miniature pollen grains with essentially normal exine and germ pores indicates that genetic control for exine deposition rests, not with the haploid genome, but with the spore cytoplasm. A close correlation between the amount of exine laid down with amount of cytoplasm in the spore also suggests that control of exine deposition is more closely related to the microspore cytoplasm rather than to the enclosed genome.
LEAF HISTOGENESIS IN LACTUCA SATIVA WITH EMPHASIS UPON LATICIFER ONTOGENY
Authors: Olson K. C. , Tibbitts T. W. , Struckmeyer B. Esther
Published: January 2018

The leaf primordia of Lactuca sativa ‘Meikoningen’ develop from a subapical initial in the second layer of the tunica on the side of a fiat shoot apex. Subsequent growth of the subsurface lamina is initiated by submarginal initials which divide anticlinally to produce an adaxial layer and ***a biseriate abaxiallayer, and periclinally to produce a middle layer from which procambium differentiates. The protoderm is derived from the first tunica layer by continuous anticlinal divisions. The activity of the subapical and submarginal initials is completed when the leaf is 0.3 mm in length and 4.0 mm in width, respectively. Continued growth of the leaf to 130‐150 mm results from intercalary cell division and enlargement. The mature venation is visibly delineated when the leaf is 25‐30 mm in length. Laticifer and phloem cells are initiated by the same mother cells in the ***procambium. The former become non‐septate laticifers by resorption of cross walls. They mature concurrently with the phloem and before the xylem.
THE POLLINATION ECOLOGY OF DICENTRA CUCULLARIA
Authors: Macior Lazarus Walter
Published: January 2018

In northeastern Iowa and southwestern Wisconsin the flowers of Dicentra cuculiarla were found to be pollinated almost exclusively by Bombus bimaculatus nectar‐foraging queens, which were phenologically synchronized in their emergence from hibernation with the flower's anthesis. Cinematographic and stereophotographic evidence indicated that pollen transfer was effected by the ventral side of the insect's head and anterior thorax contacting essential flower parts and to a lesser degree by the front and middle legs contacting pollen‐laden edges of the inner petals. Lepidoptera, Diptera, and small Hymenoptera occasionally encountered on the flowers were ineffective in pollination. Abundant Apis mellifera pollen‐foraging workers regularly effected pollination, but being an introduced species it exhibits no naturally developed pollination adaptation to the flower. Nectar spur perforation by B. affinis nectar‐foraging queens did not affect plant fertility, and this behavior was related only in part to forager tongue length. Nectar‐foraging behavior of B. bimaculalus queens on the flowers was correlated with the phenological development of the annual insect colonies.
FERTILIZATION IN BARLEY
Authors: Cass David D. , Jensen William A.
Published: January 2018

The mature embryo sac of barley consists of an egg, two synergids, a central cell, and up to 100 antipodal cells. At shedding the male gametophyte is 3‐celled, consisting of a vegetative cell with a large amount of starch and two sperms having PAS+ boundaries. Before pollination the nucleus and cytoplasm of each synergid appear normal. After pollination the nucleus and cytoplasm of one synergid undergo degeneration. The pollen tube grows along the surface of the integument of the ovule, passes through the micropyle, and enters the degenerate synergid through the filiform apparatus. The pollen tube discharges the vegetative nucleus, two cellular sperms, and a variable amount of starch into the degenerate synergid. Soon after deposition the sperms migrate by an unknown mechanism to the chalazal end of the degenerate synergid. Sperm nuclei then enter the cytoplasm of the egg and central cell, ultimately resulting in the formation of the zygote and primary endosperm nucleus, respectively. Sperm boundaries do not enter egg or central cell, but it was not possible to determine the fate of other sperm components. Degenerate vegetative and synergid nuclei remain in the synergid after fertilization, constituting what are considered to be X‐bodies in barley. The second synergid degenerates during early embryogeny.
STUDIES IN THE QUERCUS UNDULATA COMPLEX. IV. THE CONTRIBUTION OF QUERCUS HAVARDII
Authors: Tucker John M.
Published: January 2018

Scrub oak populations in the semidesert area of northeastern Arizona and southeastern Utah are ordinarily identified in regional manuals as Quercus undulata. They are very similar, both morphologically and ecologically, to Q. havardii of the Staked Plain of the Texas Panhandle and southeastern New Mexico. They differ, however, in a number of inconspicuous characters. Population sample analyses indicate that most of these differences are suggestive of Q. gambelii, and the deviant populations are thus interpreted as having been derived from ancestral Q. havardii through introgression by Q. gambelii. Two differences are not in accord with this interpretation; these are regarded as possible cases of transgressive segregation. Considering the evolution of these hybridized populations, it is speculated that the ancestral Q. havardii occurred to the south and west of the present range of this species during the Kansan period of the Pleistocene. During subsequent northward dispersal, it became split in two. The eastern portion ultimately came to occupy the present range of the species in the Staked Plain; the western portion—lying to the west of a north‐south mountain barrier in central New Mexico—became introgressed by Q. gambelii (and locally by Q. turbinella), resulting in the present populations of Arizona and Utah.
LIGNIFICATION DURING SECONDARY WALL FORMATION IN COLEUS: AN ELECTRON MICROSCOPIC STUDY
Authors: Hepler Peter K. , Fosket Donald E. , Newcomb Eldon H.
Published: January 2018

The fine structure of lignin deposition was examined in developing secondary walls of wound vessel members in Coleus. KMnO4, which was used as the fixative, selectively reacts with the lignin component of the cell wall and thus can be used as a highly sensitive electron stain to follow the course of lignification during secondary wall deposition. Lignin was first detected as conspicuuos electron‐opaque granules in the primary wall in the region where the secondary wall thickening arises and as fine granular striations extending into the very young secondary wall. As the secondary wall develops lignification becomes progressively more extensive. In cross sections the lignified secondary wall appears as concentric, fine granular striations; in tangent al or oblique sections it is seen as delicate, beaded fibrils paralleling the long axis of the thickening. High magnification of tangential or oblique sections shows that the fibrillar appearance is due to the presence of alternating light and dark layers each approximately 25‐35 A wide. It is assumed that the light layers are the cellulose microfibrils and the dark regions contain lignin which fills the space between the microfibrils. KMnO4, by selectively reacting with lignin, thus negatively stains the cellulose microfibrils revealing their orientation and dimensions.
CRYSTAL‐STRUCTURE OF RUTHENIUM RED AND STEREOCHEMISTRY OF ITS PECTIC STAIN
Authors: Steeling Clarence
Published: January 2018

A crystal‐structure analysis of ruthenium red has indicated a composition of [Ru3Cl8 (OH)3 (NH3)12 (H2O)3]. Each ruthenium ion is coordinated cubically with at least eight chloride ions, and it is coordinated octahedrally with (1) four ammonia molecules in a square planar configuration and (2) either two water molecules or two hydroxyl ions in the axis perpendicular to that plane. The staining group is composed of the ruthenium ion and the associated square planar complex of four ammonia molecules. The staining site in the host molecule must have two negative charges 4.2 A apart and space to accommodate the staining group, lying with its plane perpendicular to the axis between these charges. It is shown that in pectic acid such a staining site occurs between each monomer unit and its next adjacent neighbor.
KARYOTYPE RELATIONSHIPS IN THE SARCANTHINAE (ORCHIDACEAE)
Authors: Tara M. , Kamemoto H.
Published: January 2018

Karyotypes were analyzed for 25 species from 14 genera of the subtribe Sarcanthinae. The karyotypes of representatives of the following genera were recorded for the first time: Acampe, Chilochista, Gastrochilus, Pelatantheria, Robiquetia, Sarcanthus, and Thrixspermum. Most of the small‐flowered genera exhibited relatively symmetrical, primitive karyotypes which were difficult to distinguish. Intrageneric variations were encountered. The significance of karyotype analyses of the Sarcanthinae is briefly discussed.
TRICHOBLASTS IN HYDROCHARIS. II. NUCLEIC ACIDS, PROTEINS AND A CONSIDERATION OF CELL GROWTH IN RELATION TO ENDOPOLYPLOIDY
Authors: Cutter Elizabeth G. , Feldman Lewis J.
Published: January 2018

As shown previously, the trichoblasts of Hydrocharis morsus‐ranae L. are the smaller, more proximal (i.e., basal) products of unequal divisions of protodermal cells in the root tip. During development their nuclei and nucleoli attain greater volume than those of individual adjacent ordinary epidermal cells, the products of the sister cell of the original unequal division. Histochemical tests, microspectrophotometric measurements and historadioautographs show that the trichoblasts also contain more nucleohistone, total protein, nucleolar and cytoplasmic RNA, and more nuclear DNA than neighboring cells at the same distance from the root apex. The trichoblasts fail to divide, and their nuclei become increasingly polyploid with distance from the root tip until they have approximately 8 times as much DNA as the nuclei of adjacent epidermal cells, or about 18 times as much as the cells from which both types of cells originated. It is suggested that all plant cells pass through two phases of enlargement, an initial phase characterized by synthesis of DNA and cytoplasmic constituents and a later phase characterized by extensive vacuolation and intake of water. Because of the delayed maturation, the inhibition of cytokinesis, and the polyploid nature of the trichoblasts of Hydrocharis, these phases are more readily separable than in many other cells. Polyploidy is probably not a necessary prerequisite for formation of a root hair, though it affects the degree of cell growth, but a delay in maturation is probably one essential factor in the differentiation of such cells.
OBSERVATIONS ON SIEVE ELEMENTS IN THREE PERENNIAL MONOCOTYLEDONS
Authors: Ervin Edward L. , Evert Ray F.
Published: January 2018

Seasonal collections were made of rhizomes of Polygonatum canaliculatum and Typha latifolia and of aerial stems of Smilax hispida. Many metaphloem sieve elements in all three species remain functional for 2 or more years, or for the life of the plant parts in which they occur. Although the protoplasts of mature sieve elements remain similar in appearance from one time of year to the next, the amount of callose associated with the sieve plates and lateral sieve areas of such cells apparently varies with the seasons, being heavier in late fall and winter and lighter in late spring and summer. At maturity the metaphloem sieve elements contain strands derived from the slime bodies of immature cells. It is suggested that in mature sieve elements the slime strands normally occur as a network along the wall. Many mature sieve elements of S. hispida contained normal‐appearing nuclei.
A CHEMOSYSTEMATIC STUDY OF SELECTED TAXA OF CAPSICUM
Authors: Ballard Robert E. , McClure Jerry W. , Eshbaugh W. Hardy , Wilson Kenneth G.
Published: January 2018

Six taxa of Capsicum were chosen for a comparative chemosystematic study. A “key” individual from each taxon was selected for intensive chemical investigation. Thirteen flavonoids were isolated from leaf material and characterized by paper chromatography and absorption spectroscopy. The C‐glycosylflavones vitexin and isovitexin, and orientin and iso‐orientin, as well as O‐glycosides of the flavones apigenin, luteolin, and chrysoeriol, were isolated from the key individuals. Chromatographic analysis of collections from various regions of South America, Central America, and Mexico showed in general that flavonoid variability is more common in cultivated taxa than in wild. Three groups of Capsicum were recognized and the main systematic conclusions were: (1) The white‐flowered taxa in Group I, C. baccatum var. baccatum and C. baccatum var. pendulum, have identical flavonoids, corroborating previous conclusions that they are one species. The absence of chrysoeriol in this group separates it from Groups II and III. (2) The purple‐to‐white‐flowered C. eximium var. eximium and C. eximium var. lomenlosum, Group II, have a complex flavonoid chemistry which appears to link Groups I and III. (3) Two purple‐flowered species, C. cardenasii and C. pubescens, Group III, are chemically distinct from the other taxa examined.
FORMATION OF THE PROLAMELLAR BODY IN 8‐DAY, DARK‐GROWN SEEDLINGS
Authors: Weier T. E. , Brown D. L.
Published: January 2018

The development of the prolamellar body in etioplasts of dark‐grown seedlings of Phaseolus vulgaris is followed through the 8th day. From 2 to 6 days there is an increase in plastid size and starch content and synthesis of a system of porous lamellae which appear to arise, as such, from the inner component of the plastid envelope. From 6 to 8 days much of the starch disappears accompanied by rapid membrane synthesis resulting in an extensive prolamellar body. A model of the prolamellar body is discussed in which the basic structural unit is a six‐pointed star with four tubules joining at each node. Observation of face views of the porous peripheral lamellae at their juncture with the prolamellar body suggests the origin of the prolamellar body by the continued contraction of the porous lamellae and the formation of interconnecting tubules between adjacent lamellae. The pores of the peripheral lamellae appear to correspond to the areas of stroma within each star module. Short lengths of membranes of individual peripheral lamellae fuse, forming short overlaps which resemble small, two‐compartmented grana. It is postulated that this is the initial step in grana formation.
PHYTOCHROME CONTROLLED NYCTINASTY IN ALBIZZIA JULIBRISSIN. I. ANATOMY AND FINE STRUCTURE OF THE PULVINULE
Authors: Satter Ruth L. , Sabnis Dinkar D. , Galston Arthur W.
Published: January 2018

Under appropriate experimental conditions, phytochrome controls leaflet closure in Albizzia by regulating differential turgor changes in motor cells of the pulvinule. Closure occurs when subepidermal dorsal cells expand and ventral cells become compressed; reopening involves the reverse changes. The internal cells surrounding the vascular core remain relatively unchanged during leaflet movement. Fine structural studies revealed several unusual features of the motor cells including: (1) fibrils oriented parallel to one another in the cytoplasmic matrix; (2) numerous spherosomes that appear to coalesce and enlarge to form vacuoles; and (3) a multivacuolate condition.
CALLANDRIUM CALLISTOPHYTOIDES, GEN. ET SP. NOV., THE PROBABLE POLLEN‐BEARING ORGAN OF THE SEED FERN, CALLISTOPHYTON
Authors: Stidd Benton M. , Hall John W.
Published: January 2018

A new genus of pteridosperm pollen organ is described from Pennsylvanian age coal balls of Illinois. Individual sporangia are grouped into radial synangia which are borne in opposite pairs on the abaxial surface of slightly modified pinnules. Sporangia contain monosaccate pollen with a distinct sulcus, referable to the pollen genusVesicaspora. Pinnules are borne on a regularly pinnate frond which is circinately coiled when young. At least a large portion of the frond is fertile and possesses anatomical features similar to those ofCallistophyton. Phyletic relationships with other pteridosperm pollen organs are discussed.
NUMERICAL TAXONOMY APPLIED TO CUCURBITA RELATIONSHIPS
Authors: Bemis W. P. , Rhodes A. M. , Whitaker Thomas W. , Carmer S. G.
Published: January 2018

In a numerical study of taxonomic relationships in Cucurbita, the inclusion of F1 interspecific hybrids did not materially alter the species grouping in the phenogram. The F1 interspecific hybrids tend to cluster with one of the parent species or species groups unless the parents are widely divergent. Also, the F1 interspecific hybrids between wild and domesticated species cluster with the wild parent Both parent species or species groups of an F1 interspecific hybrid can usually be determined from Q‐correlation values. It is essential that compatibility relations be determined between species; i.e., species groups must be established before Q‐correlation values can be successfully used in determining the parentage of hybrids. Undescribed collections can usually be correctly placed in the proper species group.
WATER POTENTIAL, TEMPERATURE, AND KINETIN EFFECTS ON SEED GERMINATION IN SOIL AND SOLUTE SYSTEMS
Authors: Kaufmann Merrill R. , Ross Kathleen J.
Published: January 2018

Germination of lettuce and wheat in soil is reduced by a decrease in water potential, but a significant temperature‐water potential interaction exists for lettuce. At 35 C kinetin permits lettuce germination at 0 and —1.1 bars, and at 25 C and 15 C it enhances germination at lower water potentials, causing 30% germination at —8.0 bars. Wheat germinates well at —8.0 bars, but no germination occurs at —14.9 bars; temperature had little effect on wheat germination. Germination in soil and solute systems was compared to determine the usefulness of solute germination data for predicting germination in dry soil. Total germination of lettuce in polyethylene glycol‐6000 may approximate total germination in soil at the same water potential, but germination rates differ widely for the two systems. Kinetin‐treated lettuce seeds nearly completed germination in two days in polyethylene glycol solutions, but five days were required for similar germination percentages in the soil. Sucrose is not useful for simulating soil water stress; wheat seeds germinate at —14.9 bars in sucrose but fail to germinate in soil at the same potential, and germination is more rapid in sucrose than in the soil.
MORPHOGENETIC ASPECTS OF A LEAFLESS MUTANT IN TOMATO II. INDUCTION OF A VASCULAR CAMBIUM
Authors: Caruso John L. , Cutter Elizabeth G.
Published: January 2018

The vascular tissues of the leafless form of the “lanceolate” mutant in tomato resemble those of the normal hypocotyl in the lower portions. A divergence in development occurs in the middle region of the mutant hypocotyl: two xylary strands split acropetally into five to seven units, while in the normal hypocotyl four main vascular bundles are established. The three to four week old mutant hypocotyl shows a marked proliferation of cells in its central cylinder when it is grown on a simple nutrient medium; proliferation also occurs in older specimens grown in soil. This condition is averted if the mutant is grafted beneath an actively growing normal shoot tip. Instead of having numerous, random cell divisions in the central cylinder, the grafted mutant shows large pith parenchyma cells and an active vascular cambium. These features characterize the normal hypocotyl and they have not been observed in the intact leafless mutant. The observed behavior of intact and grafted mutant hypocotyls can be interpreted in terms of the normal shoot tip acting both as physiological sink, with respect to cell‐division stimuli produced mainly in the root system, and physiological source, with respect to cambial activating hormones.
ENVIRONMENTAL FACTORS AFFECTING RESISTANCE TO DESICCATION IN THE DIATOM STAURONEIS ANCEPS
Authors: Hostetter H. P. , Hoshaw R. W.
Published: January 2018

Several environmental parameters influence the ability of Stauroneis anceps Ehr. to survive periods of dehydration to equilibrium with atmospheric humidity. Cells grown in soil‐water are better able to survive desiccation than cells grown in defined medium and cells from older cultures survive better than those from young cultures. Since active culture growth and cell division do not hinder survival, the factor responsible for increased survival in older cultures may be the accumulation of secreted metabolites in the medium. There is no survival when drying occurs in artificial substrata with particles 50 microns or less in diameter. Survival occurs when the particulate matter is 100 microns or larger. Slow drying seems to enhance survival, perhaps by allowing cells to interact longer with environmental organic substances conferring some degree of protection. Desiccated cells are better able to withstand temperature extremes than are vegetative cells in an aqueous environment. Dry cells survived longer than 9 days at 60 C and longer than 8 hr at 80 C but normal cultures were unable to survive 1 hr at 60 C. Temperatures of —15 to —20 C were also sustained more consistently by desiccated cells. Cells stored at vapor pressure deficits of 11.9 mm Hg or higher survived longer than 16 months but storage at 5.9 mm Hg or lower reduced survival time.
THE POLLEN WALL OF CANNA AND ITS SIMILARITY TO THE GERMINAL APERTURES OF OTHER POLLEN
Authors: Skvarla John J. , Rowley John R.
Published: January 2018

The pollen wall of Canna generalis Bailey is exceptionally thick, but only a minor part of it contains detectable amounts of sporopollenin. The sporopollenin is in isolated spinules at the exine surface and in the intine near the plasma membrane. There is no sporopollenin in the > 10 μ thick channeled region between spinules and intine. We suggest that the entire pollen wall of C. generalis is similar to the thick intine and thin exine typical for germinal apertures in many pollen grain types. Considered functionally, the Canna pollen wall may offer an infinite number of sites for pollen tube initiation and would differ significantly from grains that are inaperturate in the sense of an exine lacking definite germinal apertures.
SPORES OF BOTRYOPTERIS GLOBOSA AND BOTRYOPTERIS AMERICANA FROM THE PENNSYLVANIAN
Authors: Phillips Tom L. , Rosso Samuel W.
Published: January 2018

A study of spores from fertile pinnae of Botryopteris from middle and upper Pennsylvanian coal balls from Iowa, Illinois, and Kansas indicates that there are two distinct species, Botryopteris globosa and B. americana. The organization and attachments of fertile pinnae and the sporangial morphology and dimorphism are identical in the two species. Data are given on fertile pinnae dimensions, attachments of six fertile pinnae, spore counts from individual sporangia, and spore morphology. The ornamentation of B. americana spores is verrucate to rugulate with verrucae fusing to a variable extent to form bars and convolute ridges; B. globosa spores are vermiculate or fossulate to densely rugulate with scattered verrucae. Comparisons are made with B. forensis and a re‐interpretation of the spore forms of B. forensis is suggested.
ULTRASTRUCTURE AND INITIATION OF WALL PATTERN IN PEDIASTRUM BORYANUM
Authors: Millington W. F. , Gawlik S. R.
Published: January 2018

The reticulate pattern in the wall of Pediastrum boryanum emerges rapidly during wall formation following aggregation of the swarming zoospores to form the coenobium. Electron micrographs during colony formation show that microtubules, present during the motile phase and aggregation, are gone prior to wall formation and probably do not participate in wall pattern regulation. A single dictyosome lies adjacent to the nucleus and from blebs of the nuclear membrane receives vesicles at its forming face. Vesicles formed at the maturing face have not been observed to contribute to the cell wall. Electron‐lucent patches occur in the plasma membrane prior to wall formation. The first indication of a reticulate pattern in wall development is the deposition on the plasma membrane of interconnected plaques of outer wall material at the corners of hexagons. The sites of the plaques may correspond to clusters of ribosomes on endoplasmic reticulum underlying the plasmalemma. Following completion of the outer wall the thicker inner wall layer is deposited and within it the reticulate pattern of ridges is soon evident in tangential sections as strips of greater electron density. It is suggested that the pattern of the wall is templated by the plasma membrane.
VENUS'S FLYTRAP OBSERVATIONS BY SCANNING ELECTRON MICROSCOPY
Authors: Mozingo Hugh N. , Klein Paula , Zeevi Yehoshua , Lewis Edwin R.
Published: January 2018

Observations of the digestive glands, trigger hairs, epidermal surface, nectar glands, touch receptors, and stomata of Dionaea muscipula, the Venus's flytrap, were carried out by means of scanning electron microscopy. Previously undescribed details of the surface topography were resolved which may correlate with certain functions of the plant.
THE PRODUCTION AND DIFFERENTIATION OF SECONDARY XYLEM IN XANTHIUM PENSYLVANICUM
Authors: Shininger Terry L.
Published: January 2018

The removal of leaves and buds from the shoot of Xanthium seedlings caused the cessation of xylem fiber differentiation in all internodes while allowing the production of cambial derivatives to continue toward both the xylem and the phloem. The potential xylem fibers developed into parenchymatous cells with thin cell walls. The vessels developed normally except for their small size. Cambial derivatives and vessels were produced linearly with time in intact plants (6.1 cells per file/day and 9.7 vessels per vascular bundle/day) and in decapitated plants (2.2 cells per file/day and 5.5 vessels per vascular bundle/day). Fiber production was linear with time in intact plants (163 fibers per vascular bundle/day) and did not occur in decapitated plants. When a single leaf was allowed to develop from a lateral bud of a decapitated plant, xylem fiber differentiation was restored for a period of time corresponding to the period of rapid expansion of the leaf blade. When the leaf passed the phase of rapid expansion, it no longer had an inductive effect on xylem fiber differentiation.
EFFECT OF DIMETHYL SULFOXIDE ON ZINC65UPTAKE, RESPIRATION, AND RNA AND PROTEIN METABOLISM IN BEAN (PHASEOLUS VULGARIS) TISSUES
Authors: Bajaj Y. P. S. , Rathore V. S. , Wittwer S. H. , Adams M. W.
Published: January 2018

The effect of dimethyl sulfoxide (DMSO) on zinc65uptake, respiration, RNA, and protein metabolism in various tissues of two bean (Phaseolus vulgarisL.) cultivars showing differential growth responses to zinc has been studied. At a concentration of 1%, DMSO stimulated zinc uptake in excised roots, stem‐callus tissue, leaf disks, and enzymically isolated leaf cells, but did not significantly alter the uptake and incorporation of C14‐uracil into RNA and C14‐methionine into protein, although a slight inhibition was discernible in some tissues. At a higher concentration (10%) DMSO increased Zn65uptake in excise roots incubated for 2 hr; however, at the same concentration, C14‐uracil and C14‐methionine uptake and incorporation were considerably inhibited in all the tissues. Oxygen uptake as measured with Warburg manometers was impaired, and the inhibition showed a time and concentration dependency. The fact that DMSO inhibited respiration and RNA and protein metabolism, while at the same concentration zinc uptake was increased, suggests that zinc uptake in beans is primarily a non‐metabolic process. The possible mechanisms of DMSO action are discussed in the light of its reported effects on membrane permeability and cell metabolism.
DETERMINATION OF NUMBER AND MITOTIC ACTIVITY OF SHOOT APICAL INITIAL CELLS BY ANALYSIS OF MERICLINAL CHIMERAS
Authors: Stewart R. N. , Dermen Haig
Published: January 2018

The dimensions of mericlinal sectors in periclinal chimeras resulting from replacement‐displacement phenomena have been used to determine the number of shoot apical initial cells and their mitotic activity. Narrow sectors were always short, extending an average of less than three nodes. All long sectors were wide, involving 1/3 or 1/2 of the circumference of the stem. These observations define the origin of all primary growth as from 1–3 apical initial cells in each of the apical layers. The sectors reveal a surprising stability of cellular position at the center of growth, with a specific initial cell maintaining its position during formation of over 100 nodes. During vigorous vegetative growth of Ligustrum ovalifolium the initials themselves divide only about once in 12 days during the formation of three nodes. The mitotic index of the initials in privet shoot apices is 1.4, and this rate of division is sufficient for them to be the ultimate source of all cells composing the shoot.
DNA SYNTHESIS, CELL DIVISION, AND CELL DIFFERENTIATION DURING LEAF DEVELOPMENT OF XANTHIUM PENNSYLVANICUM
Authors: Maksymowych R. , Kettrick M. A.
Published: January 2018

Leaf growth consists of two basic processes, cell division and cell enlargement. DNA synthesis is an integral part of cell division and can be studied with autoradiographic techniques and incorporation of some labeled precursor. Studies were made on the synthesis of nuclear DNA through incorporation of 3H‐thymidine in various parts of the lamina during the entire course of leaf development of Xanthium pennsylvanicum. The time course analysis of DNA synthesis was correlated with cell division and rates of cell enlargement. Significant differences in 3H‐thymidine incorporation were found in various parts of the lamina. Cell division and DNA synthesis were highest in the early stages of development. Since no 3H‐thymidine was incorporated after cessation of cell division (LPI 2.8) in the leaf lamina, it appears that DNA synthesis is not needed for enlargement and differentiation of Xanthium cells. Rates of cell enlargement were negligible in the early development and reached their maximum after cessation of mitoses, between plastochron ages (LPI) 3 and 4. Cells matured between LPI's 5 and 6. Enzymatic activity was correlated with cell division and cell differentiation at various stages of leaf development.
THE MISSING PETAL CHARACTER IN OENOTHERA AND ITS RELATION TO THE CRUCIATE CHARACTER
Authors: Cleland Ralph E.
Published: January 2018

Two characters are known in Oenothera which show inconstancy of behavior resulting in phenotypic mosaicism. These are absence of petals mp and cruciate petals cr. The latter character has been studied intensively by Oehlkers and Renner. The former is discussed here for the first time. The missing petal character exhibits mosaicism in essentially all cases. Flowers with four, three, two, one, or no petals may appear on the same plant on the same day. Where petals are present, they occupy normal positions and are usually normal in size and shape; where absent, no primordia are produced. It is suggested that the cr character is not based on a highly mutable locus (Oehlkers) or on one in which gene conversion occurs (Renner), but is the result of a mutant gene at a locus basic to the development of sepals which is. capable, under certain conditions, of functioning not only in the sepals, but also in cells of petal primordia, thereby suppressing genes for petal development. The sepaloid tissue which it produces in the petal is much more complex than, the petaloid tissue which it suppresses. The mp locus is basic to the initiation of petals; mp is a mutant gene with reduced potency. Whether it is able to function depends upon the cellular environment in which it finds itself. In both cases mosaicism is the result, not of frequently recurring alteration in genic structure, but of regulation of gene action based on variations in the cellular milieu.