bluuebunny/crossref_metadata_2025 huggingface dataset:
PETRIFIED CONES AND NEEDLE‐BEARING TWIGS OF A NEW TAXODIACEOUS CONIFER FROM THE EARLY CRETACEOUS OF CALIFORNIA
Authors: Miller Charles N.
Published: January 2018

Ovulate cones identified as Abietites ellipticus Fontaine, from the Early Cretaceous of northern California, have been reinvestigated. Rather than being preserved as imprints as originally described, the fossils are petrified. Two cones are attached to needle‐bearing twigs. The organs are similar to those of the living Cunninghamia lanceolata. However, the scale portion of the bract‐scale complex of the fossil cones is situated close to the bract apex, while that in modern Cunninghamia cones is midway between the bract base and apex. This plus other structural differences warrant treatment of the material as a new species of Cunninghamiostrobus Stopes and Fujii.
ORCHID PHYTOALEXINS. II. ISOLATION AND CHARACTERIZATION OF POSSIBLE STEROL COMPANIONS
Authors: Arditti Joseph , Flick Brigitta H. , Ehmann Axel , Fisch Michael H.
Published: January 2018

Four sterols have been isolated from extracts of Cymbidium pseudobulbs infected with Rhizoctonia repens M 32. One of them, ergosterol peroxide, is most probably an artifact of extraction. The other three, sitosterol, stigmasterol, and campesterol, occur in a 70:25:5 ratio. Appearance of phytoalexin(s) in pseudobulb extracts coincides with increase of sterol production. This raises the question whether Cymbidium phytoalexins are related, biosynthetically or structurally, to sterols. Since the same three sterols occur (free or conjugated) in Cattleya and Arundina, but in different ratios to each other than in Cymbidium, they may be of value in chemotaxonomy.
SOME EPIDERMAL CHARACTERISTICS OF PALEAS OF DICHANTHELIUM, PANICUM, AND ECHINOCHLOA
Authors: Clark Carolyn A. , Gould Frank W.
Published: January 2018

The apical portion of paleas of the perfect (upper) floret of 11 species of Dichanthelium, 10 species of Panicum, and one species of Echinochloa were examined with a scanning electron microscope. The surfaces of the Dichanthelium palea tips uniformly had simple, rounded papillae, widely spaced in regular rows, whereas the palea tips of most Panicum species had irregularly arranged, compound or aggregated papillae. Unusual epidermal features were observed in P. obtusum, P. hians, and P. hemitomon. The Echinochloa crusgalli palea surface exhibited a pattern of papillae or spicule development similar to that of P. hians. Transverse sections of Dichanthelium palea showed the papillae to be little if at all thickened. An electron beam x‐ray microanalysis indicated a high concentration of silicon in the papillae.
TUBULES IN DILATED CISTERNAE OF ENDOPLASMIC RETICULUM OF THLASPI ARVENSE (CRUCIFERAE)
Authors: Hoefert Lynn L.
Published: January 2018

Tubular inclusions in dilated cisternae of endoplasmic reticulum (ER) were found in healthy and virus diseased pennycress (Thlaspi arvense L., Cruciferae). The dilated cisternae were encountered more often in virus‐infected cells than in comparable cells from healthy control plants. Dilated ER cisternae were found in vascular parenchyma cells and were shown to be interconnected. The tubules measured 30 nm in diam and cisternae that contain them may be more than 10 μm in length.
NUMMULARIA BROOMEIANA: CONIDIAL STATE AND TAXONOMIC ASPECTS
Authors: Rogers Jack D.
Published: January 2018

The hyphomycetous state of Nummularia broomeiana (Berk. and Curt.) J. H. Miller produces conidia blastically from conidiogenous cells borne on swollen vesicular apices of long unbranched or sparingly branched conidiophores. This conidial state is referable to Basidiobotrys Höhnel and is similar to conidial states previously described for Hypoxylon punctulatum and H. tinctor. Nummularia broomeiana also has stromatal developmental features reminiscent of the above Hypoxylon species, further indicating a close taxonomic alliance among them.
NUTRITION AND SEXUAL REPRODUCTION IN THE WATER MOLD ACHLYA
Authors: Mullins J. Thomas , Warren Charles O.
Published: January 2018

The entire sexual reproductive progression in the heterothallic water mold Achlya ambisexualis Raper occurs in the absence of exogenous nutrients. Mated male and female mycelia, previously grown on a chemically defined medium, can utilize endogenous materials for the formation and maturation of sexual reproductive structures. Under these conditions the initiating sexual hormone antheridiol, produced by the female, exerts its morphogenetic effect on male mycelium in the absence of exogenous nutrients.
THE CENTRUM OF THE SOOTY MOLD ASCOMYCETE LIMACINULA SAMOENSIS
Authors: Reynolds Don R.
Published: January 2018

Centrum development in the sooty mold Ascomycete Limacinula samoensis von Hoehnel emend. Reynolds proceeds in an ascostroma which begins as a small cushion of somatic tissue and enlarges by multiplication of cells in an apical region and by cell enlargement. A two‐layered ascocarp wall initially surrounds a pseudoparenchymatous core into which the bitunicate asci protrude. Interascal strands of pseudoparenchymatous tissue disintegrate at maturity of the ascocarp. An apical meristem eventually culminates activity with formation of a short ostiolate neck. Centrum development is homologous to the Dothidea type. The centrum development of other capnodiaceous fungi is reviewed.
INTERSPECIFIC INCOMPATIBILITY IN GOSSYPIUM. II. LIGHT AND ELECTRON MICROSCOPE STUDIES OF CELL NECROSIS AND TUMORIGENESIS IN HYBRIDS OF G. KLOTZSCHIANUM
Authors: Phillips Lyle L. , Reid Robert K.
Published: January 2018

Many Gossypium interspecific hybrids that involve G. klotzschianum result in either embryo or seedling lethals. Histologically, lethal symptoms are characterized by necrotic cells and tumors that appear 10–15 days after fertilization in the embryo lethals and at the first true‐leaf stage in the seedling lethals. Ultrastructural studies of cell necrosis in seedling lethals show that the first subcellular abnormality is the degeneration of the inner membrane and cristae of the mitochondria. Mitochondrial degeneration is essentially complete before other organelles show evidence of structural aberrations.
SEEDS AND EMBRYOS OF ARAUCARIA MIRABILIS
Authors: Stockey Ruth A.
Published: January 2018

Seeds and embryos contained within the silicified ovuliferous cone Araucaria mirabilis from the Cerro Cuadrado petrified forest are described. One wingless seed, 0.8–1.3 cm in length and 0.2–0.6 cm in width, is embedded in each ovuliferous scale. Seeds show a three‐layered integument and a prominent wavy nucellus which is attached basally to the endotesta. The megagametophyte contains cellular inclusions that may represent starch grains. Ovule vascularization is complex and appears most similar to that of Araucaria bidwillii. Embryos 2 mm long and 0.25 mm wide appear to be in a telo‐stage period of development. Shoot apex, cotyledons, root meristem, and calyptroperiblem are present in the embryos in which vascular tissues and secretory elements were beginning to differentiate at the time of fossilization. Embryo ontogeny is considered in light of stages encountered in extant gynmosperm taxa. The absence of the microgametophyte phase in the Cerro Cuadrado collection is discussed.
PLASTID ORGANIZATION IN PHENOTYPICALLY GREEN LEAF TISSUE OF A GENETIC ALBINO STRAIN OF NICOTIANA (SOLANACEAE)
Authors: Susalla Anne A. , Mahlberg Paul G.
Published: January 2018

Plastid organization within phenotypically green leaf tissue that forms in albino plants of a genetic albino strain of Nicotiana has been examined with the transmission electron microscope. Studies revealed the presence of plastids with and without thylakoids. When present, thylakoids were loosely and irregularly scattered in the stroma or organized either into several large spindle‐shaped grana or into a single compound granum with deeply indented margins. Plastids without thylakoids were vesiculated and resembled the typical genetic albino type. Plastid types were not segregrated into individual cells and no plastid type appeared to be typical for the mutant tissue. Orientation of grana and thylakoid membrane associations were noted as well as the presence of osmiophilic globules, starch grains and DNA‐like fibrillar areas.
VARIABILITY AMONG DANTHONIA SERICEA (GRAMINEAE) POPULATIONS IN RESPONSES TO SUBSTRATE MOISTURE LEVELS
Authors: Quinn James A.
Published: January 2018

Populations of Danthonia sericea from the New Jersey Pine Barrens were investigated as to possible ecological differentiation in moisture tolerances at germination, seedling, and mature plant stages. Field studies had indicated that populations with pubescent lemmas and leaf sheaths are restricted to well‐drained sandy upland sites and that relatively glabrous populations are found in open bogs or low wet areas bordering rivers or ponds. Greenhouse studies of responses of clonal and seed materials to saturated, moist, and dry moisture levels showed significant differences among populations in germination, growth, and survival. Reciprocal transplants at upland and bog sites provided a field evaluation (1969–1974) of the survival and performance of the morphological variants in each other's habitat under competitive conditions. Restriction to respective habitats was found to be primarily intolerance of wet site factors for the pubescent plants coupled with an inability of glabrous plants to successfully compete in upland sites.
EXPERIMENTAL STUDIES OF CYTOPLASMIC ORGANIZATION IN ZONARIA APICAL CELLS
Authors: Walker D. C. , Chi E. Y. , Neushul M.
Published: January 2018

Rapidly growing thalli of Zonaria have been treated with colchicine (10,000, 5,000, and 1,250 μg/ml) and phenobarbital (10,000 and 5,000 μg/ml). Responses of the meristems to drug treatment have been described at the ultrastructural, cellular, and organismic levels. With colchicine treatment microtubule disruption, nuclear envelope abnormalities, nuclear lobing, and increased nuclear sizes were observed. Apical cells ceased dividing but continued to elongate until cessation of treatment when abnormal cytokineses, irregular cell shapes, and cell deaths were observed. The coordinated growth of the meristem margin was disrupted, regions recovering left a zone line on the thalli, and cell deaths resulted in thallus branching. With phenobarbital treatment ER elaboration, inactive‐appearing dictyosomes, pyrenoid‐like structures, and deeply cup‐shaped mitochondria aggregated with ER were observed. Apical cell elongation ceased and the mitotic cycle appeared to be arrested just after cytokinesis. Recovery from 10,000 μg/ml phenobarbital was low, with subapical cells and occasional apical cells starting new thalli. Recovery from 5,000 μg/ml was good, with occasional cell death dividing the meristem and zone lines resulting from the temporary synchrony. Correlations of responses at the ultrastructural, cellular, and organismic levels are discussed.
FLEXIBILITY IN ONTOGENY AS SHOWN BY THE CONTRIBUTION OF THE SHOOT APICAL LAYERS TO LEAVES OF PERICLINAL CHIMERAS
Authors: Stewart R. N. , Dermen Haig
Published: January 2018

The development of leaves on apically stable, periclinal chimeras was studied in a number of dicot genera. The mutant cell layers of the shoot apex and the tissues derived from them were as active developmentally as the normal layers. Ontogeny was the same in these chimeras as in nonchimeras, and growth of their leaves can be outlined as follows. Formation of the buttress, the axis, and the lamina of simple dicot leaves were independent events. In each the first growth included derivatives of the apical layers, usually three in number, found in the apex of the shoot and the lateral buds. Most cell divisions in the outer layers (L‐I and L‐II) were anticlinal relative to the new structures. Therefore, in the proximal regions of the buttress, axis (petiole and midrib), and lamina, the derivative cells of L‐I and L‐II were usually present in single layers. The rest of the internal tissue was from L‐III. As formation of the axis and the lamina proceeded, derivatives of L‐II replaced L‐III internally in the distal and marginal regions leaving cells of L‐III behind. Both the determinate growth of leaves and the pattern of cell divisions at and near the leading edges of growth meant that no cells in the leaf were comparable to the initial cells of the shoot apex. As the lamina extended, there were extensive intercalary cell divisions, both anticlinal and periclinal, so that in any given region of a leaf the layers of internal cells were from either L‐II or L‐III. At any point along the axis, L‐III participated or did not participate in laminar extension. At any given stage in laminar growth either of two sister cells in any internal layer divided either a few times or extensively. The extreme variability in direction and frequency of cell division during leaf development was under an overriding genetic control, which resulted in the normal or typical size, shape and thickness of leaves.
LIGHT MICROSCOPE AND ULTRASTRUCTURAL STUDIES OF THE MALE GAMETOPHYTE IN GINKGO BILOBA: THE SPERMATOGENOUS CELL
Authors: Gifford Ernest M. , Lin Joseph
Published: January 2018

A light microscope and ultrastructural study was made of the pollen tube of Ginkgo biloba, with special emphasis given to the spermatogenous cell that gives rise to two motile sperms. Just prior to the mitotic division that results in the formation of two sperms, the spermatogenous cell consists of a large nucleus, two blepharoplasts, two large osmiophilic globules, and a conspicuous lipo‐protein body. Other organelles in the cytoplasm include numerous electron‐dense proplastids (with some lamellar development), mitochondria, small vacuoles, and lipid bodies. Ribosomes are present in abundance, but endoplasmic reticulum and dictyosomes are sparse. The nucleus, prior to mitosis, is relatively Feulgen‐negative, due undoubtedly to the diffuse distribution of DNA. Each blepharoplast, the main organelle of interest, is nearly spherical, measures 3.5–4.5 μm in diam, and supports about 1,000 probasal bodies. The interior of a blepharoplast consists of an electron‐dense matrix and of less dense regions which appear to be infiltrated by a network of microtubules. Each probasal body is composed of a cylinder of nine separate tubules (singlets) at the basal or proximal end. The cylinder becomes elaborated distally into nine pairs of subtubules (doublets) and then into nine sets of subtubules (triplets). A central tubule is present the entire length of the probasal body. Some of the subtubules, as well as microtubules from the interior of the blepharoplast, extend into the cytoplasm and probably constitute the “astral rays” as seen with the light microscope. Comparisons are made with other published accounts of the organization of blepharoplasts in plants and of centrosomes and centrioles in animals.
MORPHOLOGY OF PROTOSALVINIA FROM THE UPPER DEVONIAN OF OHIO AND KENTUCKY
Authors: Niklas Karl J. , Phillips Tom L.
Published: January 2018

Protosalvinia has a large thallus on which P. arnoldii and P. ravenna forms develop. Light and scanning electron microscopy of Upper Devonian compression forms of Protosalvinia arnoldii, P. ravenna and P. furcata from the Ohio Shale of Kentucky and Ohio, statistical analyses of their cellular dimensions and patterns, and mathematical constructs of thallus shapes and sizes indicate that P. ravenna and P. furcata forms could be ontogenetically derived from a P. arnoldii stage. Tetrads, interpreted as the meiotic sporangial products, are morphologically identical for the three forms; tetrads contain a sporopollenin fraction and occur singly in closed, hypodermal conceptacles. Solitary, multicellular, stalked clavate structures occur in similar closed chambers. Fossil thalli are composed of hydrocarbons with some lignin‐like compounds interpretable as cuticular in nature. P. ravenna and P. furcata are morphological forms of a single species showing phenotypic plasticity within an onshore‐offshore paleoecological gradient. The form of thallus and the resistant spores are interpreted as adaptations to a littoral environment. The morphology and mode of reproduction of Protosalvinia suggest a heteromorphic diplobiontic life‐cycle, similar to the Heterogeneratae (Phaeophyta).
SIEVE‐ELEMENT ULTRASTRUCTURE IN PLATYCERIUM BIFURCATUM AND SOME OTHER POLYPODIACEOUS FERNS: THE NACREOUS WALL THICKENING AND MATURATION OF THE PROTOPLAST
Authors: Evert Ray F. , Eichhorn Susan E.
Published: January 2018

Sieve elements of various ages were examined in petioles and midribs of Platycerium bifurcatum (Cav.) C. Chr. and Phlebodium aureum (L.) J. Sm., only older ones in similar parts of leaves of Polypodium schraderi Mett. and Microgramma lycopodioides (L.) Copel. Nacreous walls apparently are formed by most, if not all, protophloem and metaphloem sieve elements in all four species. In Platycerium and Phlebodium nacreous wall formation is closely correlated with the appearance of numerous membranes or vesicles in the region of the wall. These extracytoplasmic membranes apparently are derived from protrusions of the plasmalemma. After the nacreous layer is fully thickened, many endoplasmic reticulum (ER) membranes apparently end up outside the plasmalemma of Platycerium, where they degenerate and gradually intergrade in appearance with the fibrillar material comprising the nacreous thickening. In Phlebodium, Polypodium, and Microgramma the ER forms multivesicular bodies. As the cells approach maturity, the membranes delimiting the multivesicular bodies fuse with the plasmalemma and their vesicular contents, which are not discharged into the region of the wall, disappear. Gradually, the nacreous layer decreases in thickness and disappears. At maturity the enucleate sieve‐element protoplasts of all four species are essentially similar. They are lined by a plasmalemma and a parietal, anastomosing network of ER and contain both plastids and mitochondria. The plastids in Polypodium and Microgramma are chloroplasts, but those in Platycerium and Phlebodium lack grana and intergrana lamellae.
CELLULAR SLIME MOLDS OF SOUTHEAST ASIA. II. OCCURRENCE AND DISTRIBUTION
Authors: Cavender James C.
Published: January 2018

Soils were collected from thirteen tropical forest sites in the Southeast Asian countries of Singapore, Malaysia, Thailand, Indonesia, and the Philippines. Soil dilutions of 1:25 were prepared and cellular slime molds identified from clones which subsequently developed when 0.5 ml of the dilutions were spread on dilute hay infusion agar plates seeded with pregrown bacteria (Escherichia coli #281). A total of 2998 clones representing sixteen species was produced by this procedure. Species were tabulated in order of ecological importance which was based on their frequency, relative density and presence throughout the area of study. Five species were very common and widespread. Four species were less common but occurred in about half the forest sites; the remaining seven species, including all but one of the new forms, were much more localized in distribution and were considered rare. These results were comparable to those obtained from studies in the American tropics. Diversity was similar and the important (common and widespread) species were the same in both areas. In general, those species that appeared to be endemic to either area belong among the rare species.
HETEROTHALLISM AND HOMOTHALLISM: A STUDY OF 27 ISOLATES OF DIDYMIUM IRIDIS, A TRUE SLIME MOLD
Authors: Collins O'Neil Ray
Published: January 2018

Single pore studies of 27 isolates of Didymium iridis from several geographical locations revealed that 11 are heterothallic, displaying a one‐locus, multiple allelic mating system. Collectively, 9 of the 11 possess a total of 12 mating types in one multiple allelic series. Each of the remaining two isolates has a pair of mating types which are either incompatible with the 12 or they have not yet been tested against them. Sixteen isolates proved to be homothallic.
PHIALIDE AND CONIDIUM DEVELOPMENT IN ASPERGILLUS CLAVATUS
Authors: Hanlin Richard T.
Published: January 2018

Phialide formation in Aspergillus clavatus begins with the formation of thin areas in the vesicle wall. These thin‐walled regions and adjacent cytoplasm then push out synchronously to produce the phialides. Mature phialides are broadly oval with an attenuated base and tapered apex. A secondary wall forms inside the phialide apex. The entire phialide apex pushes out to form the first conidium which is delimited by formation of a septum inside the mouth of the phialide. No collarette is present as the first conidium forms, but as the second conidium begins to develop, the outer wall breaks at the mouth of the phialide, leaving a collarette. The walls of the second and subsequent conidia are continuous with the inner wall of the phialide apex, from which they form. Conidia are held in chains by a connective which is a greatly thickened septum.
PHOSPHATE METABOLISM IN BLUE‐GREEN ALGAE. II. CHANGES IN PHOSPHATE DISTRIBUTION DURING STARVATION AND THE “POLYPHOSPHATE OVERPLUS” PHENOMENON IN PLECTONEMA BORYANUM
Authors: Sicko‐Goad Linda , Jensen Thomas E.
Published: January 2018

Physiological aspects of phosphate utilization by the blue‐green alga Plectonema boryanum were studied. It was found that the external phosphate concentration influenced the distribution of phosphorus‐containing compounds in the cell. Culturing the alga in concentrations of 10, 100, and 1000 mg PO4/l resulted in increases in the level of acid‐soluble and acid‐insoluble polyphosphates. The values reported for 100 and 1000 mg PO4/l were the same, indicating that the cells were able to assimilate and utilize only fixed amounts of phosphates. The total phosphorus value for these cells was calculated to be 6.5 μg P per 106 cells. Culturing the alga in 1 mg PO4/l led to a decrease in phosphate concentration of all cell fractions. Cells grown in the absence of phosphate for 5 days had total cell phosphorus levels of 0.76 μg P per 106 cells. Cells in culture for two months or longer were found to have total cell phosphorus levels of 0.73 μg P per 106 cells. This was determined to be the minimum cell phosphorus level limiting growth. Transfer of cells from either culture condition to a medium containing phosphate led to an “overplus” phenomenon. This overplus phenomenon was characterized by increases in all cellular phosphorus fractions. The most dramatic increase was found in both the acid‐soluble and acid‐insoluble polyphosphates. These fractions often increased by more than an order of magnitude. The greatest phosphate uptake occurred within 1 hr of transfer of phosphate‐starved cells into a medium containing a known amount of phosphate and is essentially complete at 4 hr. The total cell phosphorus levels for uptake never increased beyond 18.9 μg per 106 cells.
CORTICAL ONTOGENY IN ROOTS. I. ZEA MAYS
Authors: Seago James L. , Wolniak Stephen M.
Published: January 2018

Serial growth stages of young Zea mays primary roots were analyzed for patterns of ground meristem ontogeny. The number of cell layers in the cortex decreases from approximately 15 to 11 during early root growth. The cortex arises mostly by periclinal divisions in the outer portions of the ground meristem at levels 50–150 μm from the meristem tip, although some layers of outer cortex arise beyond 150 μm. The proendodermis contributes 3–5 cell layers to the cortex, but this contribution diminishes during early seedling growth as anticlinal divisions occur in the proendodermis. The relationship between the ground meristem and protoderm changes at the tip of the meristem during root elongation.
CHROMOSOME STUDIES IN COMPOSITAE
Authors: Strother John L.
Published: January 2018

Original chromosome observations, including number, from meiotic preparations from 65 collections representing 57 species in 43 genera of Compositae are reported. Of these, eight are first reports. Meiotic irregularities were noted in several species; pollen stainabilities are given for these. Observations that differ from earlier reports are discussed.
THE DEVELOPMENT OF APOSPOROUS GAMETOPHYTES AND REGENERATED SPOROPHYTES FROM EPIDERMAL CELLS OF EXCISED FERN LEAVES: AN ANATOMICAL STUDY
Authors: Hirsch Ann M.
Published: January 2018

Three different types of outgrowths develop from epidermal cells of excised juvenile leaves of Microgramma vacciniifolia: aposporous gametophytes, intermediates, and regenerated sporophytic plantlets. The gametophytes and intermediates arise from derivatives of epidermal cell divisions which are developed to the exterior of the leaf surface, whereas the sporophytic regenerants originate from derivatives produced by cell divisions to the interior of the leaf. Anatomical observations of excised leaves grown in vitro demonstrate that only the epidermal cells are stimulated to divide and give rise to the various types of outgrowths. Incorporation of tritiated thymidine by the nuclei of leaf epidermal cells gives further evidence for the metabolic activity of these cells.
CONTRIBUTION TOWARD A MONOGRAPH OF RAMARIA III. R. SANGUINEA, R. FORMOSA. AND TWO NEW SPECIES FROM EUROPE
Authors: Petersen Ronald H.
Published: January 2018

A neotype specimen is designated for R. formosa and a representative specimen for R. sanguined, thus securing taxonomic concepts for these names. Two very similar taxa are proposed as new: R. eosanguinea, which differs from R. sanguinea chiefly in exhibiting clamp connections, and R. neoformosa which differs from R. formosa chiefly in the absence of clamps. The subject of mimic taxa is briefly discussed.
DISTRIBUTION OF COAGULATION OF YOUNG SHOOT HOMOGENATES IN THE AURANTIOIDEAE
Authors: Esen Asim , Geraci Giuseppe
Published: January 2018

Distribution of coagulation of young shoot homogenates was surveyed in 430 accessions from the orange subfamily Aurantioideae. Representatives of four genera available for study (Clausena, Glycosmis, Aegle, Feronia) were coagulating taxa. The genus Citrus included both coagulating and noncoagulating taxa. Nineteen genera (Murraya, Merillia, Pamburus, Paramignya, Triphasia, Aeglopsis, Afraegle, Balsamocitrus, Feroniella, Swinglea, Atalantia, Citropsis, Hesperethusa, Pleiospermium, Severinia, Clymenia, Eremocitrus, Poncirus, Fortunella) were noncoagulating. The status of eight genera (Micromelum, Wenzelia, Monanthocitrus, Oxanthera, Merope, Luvunga, Burkillanthus, Limnocitrus) is not known. Homogenized tissue from coagulating taxa turned into a paste while tissue from noncoagulating taxa was thin and juicy. Coagulation did not take place when the pH of the grinding medium was 11 or higher but it would occur if the pH was lowered. Homogenates of noncoagulating taxa become coagulated below pH 5.2–5.3, but remained noncoagulating above this. Noncoagulating taxa contained an unidentified substance which inhibited coagulation of tissue from coagulating taxa. The mechanism of coagulation and noncoagulaton is not presently known. The significance of coagulation and its absence as a taxonomic and genetic marker is discussed.
THE ISOLATION AND CULTURE IN VITRO OF THE QUIESCENT CENTER OF ZEA MAYS
Authors: Feldman Lewis J. , Torrey John G.
Published: January 2018

Using 3‐day‐old seedling roots of Zea mays L., cv. Kelvedon 33, it was possible to remove the root cap by a simple surgical manipulation without damage to the root proper. By a further small cut, the quiescent center (QC) itself was isolated. This double‐convex lens‐shaped tissue piece 100 X 250 μm is composed of 1000–1500 cells representing only 0.25 mm3 in volume. The explant was demonstrated unequivocally by 3H‐thymidine incorporation before excision and then by autoradiography to be composed of the specific cells usually designated the quiescent center. Using sterile techniques, the QC's were placed on nutrient agar slants and allowed to grow in culture. Of a number of nutrient media tested, only a medium supplemented with organic nitrogen components, indoleacetic acid, kinetin and inorganic nutrients plus sucrose (S2M + K ‐2,4‐D) was effective in eliciting development. Thirty to 40 percent of the 150 isolated QC's grown on this medium formed elongated roots, up to 2 cm in length in 3–4 weeks. Roots developing on agar medium showed in their proximal portion a vascular pattern with 5–6 metaxylem elements or variations of this pattern, but as the root elongated, the vascular pattern was progressively reduced in complexity at the more distal end to a small central group of metaxylem elements. When agar‐grown roots were transferred after one week in culture to a liquid nutrient medium of the same composition, the initially reduced vascular pattern evident in the proximal tissues became progressively more complex in the distal portion of the root and after 2 cm of elongation, showed an essentially normal primary vascular tissue pattern characteristic of the seedling root.
ANTHER MORPHOLOGY AND THE ORIGIN OF THE TETRAPLOID WHEATS
Authors: Dhaliwal Harcharan S. , Johnson B. Lennart
Published: January 2018

Anther morphology of various species of the genus Triticum is consistent with previous evidence that different biotypes of T. boeoticum (AA) and T. urartu (BB) contributed the respective A and B genomes to the emmer (AeAeBeBe) and timopheevi (AtAtBtBt) tetraploid complexes. Anther length of T. dicoccoides (2.8 mm) and T. araraticum (3.0 mm) is mid‐way between that of T. boeoticum (3.6) and T. urartu (2.2) and the same as that of the sterile hybrid T. boeoticum X T. urartu. With respect to mode of dehiscence, post anthesis reflexion of anther lobes and twisting of the anthers, T. dicoccoides resembles T. boeoticum, whereas T. araraticum resembles T. urartu. With respect to anther apex, T. dicoccoides resembles neither T. boeoticum nor T. urartu but is identical with their F1 hybrid. Among amphiploids involving four different Aegilops species and T. boeoticum lines, none could similarly account for the length or other diagnostic attributes of the tetraploid anthers. Anther morphology is consistent with the presumed genomic composition of the cultivated tetraploid and hexaploid wheats and seems to distinguish effectively the different genomic groups of the genus Triticum.
REPRODUCTIVE BIOLOGY OF THREE SPECIES OF EUPHORBIA SUBGENUS CHAMAESYCE (EUPHORBIACEAE)
Authors: Ehrenfeld Joan
Published: January 2018

The breeding system, pollen tube development, and floral biology of three species ofEuphorbiasubgenusChamaesycefrom southeastern Arizona have been examined in field and greenhouse studies.E. albomarginatais entirely dependent on insect vectors for pollination and seed production,E. capitellatarequires insect visitors for maximum seed set but is capable of limited self‐pollination, andE. hyssopifoliais self‐pollinating and entirely independent of insect vectors. All three species are self‐compatible. The differences in reliance on insect vectors, diversity of insects and probable amount of outcrossing are related to differences in cyathial size and arrangement. The reproductive biology of the three species is similar to that described for other weedy plant taxa.
VASCULAR ORGANIZATION IN SHOOTS OF CACTACEAE. I. DEVELOPMENT AND MORPHOLOGY OF PRIMARY VASCULATURE IN PERESKIOIDEAE AND OPUNTIOIDEAE
Authors: Gibson Arthur C.
Published: January 2018

Primary shoot vasculature has been studied for 31 species of Pereskioideae and Opuntioideae from serial transections and stained, decorticated shoot tips. The eustele of all species is interpreted as consisting of sympodia, one for each orthostichy. A sympodium is composed of a vertically continuous axial bundle from which arise leaf‐ and areole‐trace bundles and, in many species, accessory bundles and bridges between axial bundles. Provascular strands for leaf traces and axial bundles are initiated acropetally and continuously within the residual meristem, but differentiation of procambium for areole traces and bridges is delayed until primordia form on axillary buds. The differentiation patterns of primary phloem and xylem are those typically found in other dicotyledons. In all species vascular supply for a leaf is principally derived from only one procambial bundle that arises from axial bundles, whereas traces from two axial bundles supply the axillary bud. Two structural patterns of primary vasculature are found in the species examined. In four species of Pereskia that possess the least specialized wood in the stem, primary vascular systems are open, and leaf traces are mostly multipartite, arising from one axial bundle. In other Pereskioideae and Opuntioideae the vascular systems are closed through a bridge at each node that arises near the base of each leaf, and leaf traces are generally bipartite or single. Vascular systems in Pereskiopsis are relatively simple as compared to the complex vasculature of Opuntia, in which a vascular network is formed at each node by fusion of two sympodia and a leaf trace with areole traces and numerous accessory bundles. Variations in nodal structure correlate well with differences in external shoot morphology. Previous reports that cacti have typical 2‐trace, unilacunar nodal structure are probably incorrect. Pereskioideae and Opuntioideae have no additional medullary or cortical systems.
COMPARATIVE ONTOGENETIC STUDIES IN YOUNG SPOROPHYTES OF TREE FERNS. I. A PRIMITIVE AND AN ADVANCED TAXON
Authors: Lucansky Terry W. , White Richard A.
Published: January 2018

Ontogenetic studies of young sporophytes were undertaken to determine anatomical and morphological differences between a primitive (Lophosoria quadripinnata) and an advanced (Sphaeropteris elongata) tree fern. In both species the first leaf is simple, fanshaped, and possesses dichotomous venation. Later‐formed leaves exhibit either a pinnate or bipinnate pattern of laminar dissection. As the sporophyte matures, the stelar pattern changes from a protostele to an amphiphloic siphonostele, and finally to a dictyostele in Sphaeropteris. Medullation of the protostele occurs either prior to or after the formation of the first leaf trace in both species. Differentiation of xylem in the shoot is acropetal and the appearance of mature protoxylem occurs closer to the apical meristem in Sphaeropteris. The nodal pattern varies within each species with a no gap 1‐trace pattern characteristic for the first two or three leaves, depending upon the taxon. In Lophosoria subsequent leaves possess a unilacunar 1‐trace nodal pattern, whereas a complete nodal series (1 gap 1‐trace to 1 gap 6‐trace) occurs in Sphaeropteris. Fusiform leaf gaps are noted in both species. The shoot apical meristem is dominated by a single apical cell, with an organized apical cell first found in P2. Stem, root, and petiole anatomy are discussed.
DEVELOPMENT AND DISTRIBUTION OF MUCILAGE CANALS IN LYCOPODIUM
Authors: Bruce James G.
Published: January 2018

Two distinct types of mucilage canals are found in Lycopodium. One type, the veinal canal, is found in both sporophylls and in vegetative leaves, and is always in close proximity to the leaf trace. The other, the basal canal, is restricted to the strobilus where it forms a complex and extensive mucilaginous cylinder in the outer cortex and extends into the base of the sporophylls. Protruding secretory cells are formed in both types during a lysigenous developmental process. The occurrence of these two types of canals correlates with the three subgenera. Urostachys which lacks canals, Lepidotis which possesses both veinal and basal canals, and Lycopodium which possesses only basal canals.
THE ORGANIZATION OF THE VASCULAR SYSTEM IN THE STEMS OF THE NYMPHAEACEAE. I. NYMPHAEA SUBGENERA CASTALIA AND HYDROCALLIS
Authors: Weidlich W. H.
Published: January 2018

The vascular system in the stems of Nymphaea odorata and N. mexicana subgenus Castalia, and N. blanda subgenus Hydrocallis consists of continuing axial stem bundles with eight being the usual number. The stem bundles are concentric and xylem maturation is mesarch. Xylem elements consist of tracheids with spirally or weakly reticulated secondary wall thickenings. The phloem is made up of companion cells and short sieve tube members with simple sieve plates that are nearly transverse. At the node each leaf is supplied with two lateral leaf traces and a median leaf trace. A root trace is also present and supplies a series of adventitious roots borne on the leaf base. Flowers and vegetative buds develop directly from the apical meristem and occupy leaf sites in a single genetic spiral. Each flower or vegetative bud is related to a leaf through specific spatial and vascular association. The related leaf is separated from the related flower by three members of the genetic spiral and occupies an adjacent orthostichy. Vascular tissue for the related flower arises from the inner surfaces of the four stem bundles supplying leaf traces to the related leaf and extends through the pith to the flower or vegetative bud via a peduncle fusion bundle. The vascular system organization in the investigated species of Castalia and Hydrocallis is not typically monocotyledonous or dicotyledonous, nor can it be considered transitional between them. The ontogeny of the vascular system is similar to typical dicotyledons and the investigated species of Nymphaea can, therefore, be considered to represent highly specialized and modified dicotyledons.
POLARITY AND LOCALIZATION OF AUXIN MOVEMENT IN THE HEPATIC, MARCHANTIA POLYMORPHA
Authors: Maravolo Nicholas C.
Published: January 2018

Transport of 11C‐indoleacetic acid in thallus explants of Marchantia polymorpha was basipetal and localized in midrib tissue. Transport was inhibited by aging, 2,3,5‐triiodobenzoic acid, cinnamic acid, and ethylene. Similarities between these responses and auxin transport in higher plants are considered and morphogenetic potential of the phenomenon in Marchantia identified.
APOLAR MOVEMENT OF ZEATIN THROUGH COLEUS PETIOLES AND PISUM ROOTS AS ESTIMATED BY BIOASSAY AND RADIOACTIVE LABELLING
Authors: Jacobs William P.
Published: January 2018

The movement and polarity of zeatin, a highly active, endogenous cytokinin, through petioles and roots were tested in the classical experimental arrangement using excised 5‐mm sections. Zeatin in the receiver cylinders of agar was measured by soybean callus bioassay and by liquid scintillation counting of 14C that had been added in the donor cylinders as [8‐14C] zeatin. Both methods agreed in showing movement, but there was no polarity in Coleus #5 petioles. The amounts moved were about one‐tenth of the GA‐3 movement through petioles of the third pair of leaves of the same clone. Movement of 14C‐zeatin through Pisum roots was similarly statistically significant but non‐polar; the amounts moved were similar to those previously observed for polar GA‐3 movement through Zea roots.
ECOLOGICAL ADAPTATIONS OF SALT MARSH GRASS, DISTICHLIS SPICATA (GRAMINEAE), AND ENVIRONMENTAL FACTORS AFFECTING ITS GROWTH AND DISTRIBUTION
Authors: Hansen D. J. , Dayanandan P. , Kaufman Peter B. , Brotherson J. D.
Published: January 2018

Salt grass is an important pioneer plant in early stages of succession. The sharp‐pointed rhizomes with numerous epidermal silica cells, and the aerenchymatous network of the rhizome, leaf sheath, and roots facilitate development of the plant in heavy clays, shales, and inundated soils. In salt marshes of southern Utah, salt grass contributes to a hummock‐building process that favors localized removal of salts by capillary action and evaporation. This process provides a narrow strip of soil that is favorable for the rooting of extended rhizomes. In laboratory experiments, maximum growth for Distichlis spicata, a perennial salt marsh grass, was obtained at 15,000 ppm soluble salts in nutrient solution cultures. Comparable concentrations of salts occurred in soils of the habitat from which plants were taken. Nearly equal concentrations of sodium and potassium were found in the plant tissue where the growth of the plants was optimal; such a ratio was maintained in the plants during most of the growing season. In the field the greatest amount of growth of salt grass takes place when temperatures are cool and soil moisture is quite high during the early spring. During mid‐summer as air temperatures rise, crude protein in the plant decreases. During periods of high salt and water stress, morphological and anatomical adaptations of the stomata, salt glands, and trichomes of salt grass are important for survival. Stomata on exposed ridges of vascular bundles, where desiccation is greatest, usually are covered by four epidermal cells. In contrast, stomata found in the grooves between vascular bundles tend to be uncovered. The salt gland is composed of a large basal cell and a cap cell and actively excretes (in a diurnal rhythm) excess sodium, potassium, and chloride ions. A mechanism for salt excretion from this gland is postulated. The silica‐containing trichomes on the leaves may play a role in cooling the leaf under conditions of high solar radiation and also serve to protect the plant against attack by herbivores.
ENVIRONMENTAL EFFECTS ON THE PERCENTAGE OF STAINABLE AND PRESUMED NORMAL POLLEN IN ASTER (COMPOSITAE)
Authors: Jones Almut G.
Published: January 2018

Pollen stainability is often equated with pollen viability or fertility and is used by botanists to evaluate degree of hybridity among individuals of a plant population. Under certain conditions, however, the effects of meiotic irregularities resulting from hybridization may be masked by those of the environment. In the genus Aster high percentages of pollen stainability were obtained in most samples from plants flowering in the greenhouse, including hybrids of distantly related species. When grown outdoors, plants of the same clones frequently suffered significant reduction in the amounts of normal pollen produced. During the period of flower development, two climatic parameters were assessed, relative humidity and maximum/minimum temperatures. Fluctuations in relative humidity were considerable but of nearly equal amplitude both in the greenhouse and in the open field. Diurnal temperature fluctuations, however, were much less drastic in the greenhouse than outdoors. The differential percentages of stainable pollen observed are probably attributable to the sum of environmental factors, including hard rains and strong winds, rather than any single parameter. In the genus Aster high amounts of aborted pollen grains appear to be largely a reflection of sensitivity to unfavorable microclimatic conditions during the post‐meiotic period of flower development, and data on pollen stainability cannot be employed as a measure of fertility or degree of hybridity.
A NEW CONCEPT FOR THE TAXONOMY OF THE FAMILY DICTYOSTELIACEAE (CELLULAR SLIME MOLDS)
Authors: Traub Franz , Hohl Hans R.
Published: January 2018

In addition to the typical whorls of branches, fruiting bodies of the genus Polysphondylium bear spores that are characterized by the presence of polar spore granules (PG). This spore character is highly correlated with less easily assessible features of the life cycle such as the nature of the chemotactic response towards cAMP, mode of center initiation, absence of preaggregative cell adhesiveness and overall morphogenetic pattern. Many new strains were isolated which possess the PG character and the cluster of associated features but produce sorocarps which are not regularly branched. This newly recognized group represents a clearly separate unit with common, defined properties. Its taxonomic position in relation to the presently accepted genera of the Dictyosteliaceae, namely Dictyostelium and Polysphondylium, is discussed.
ULTRASTRUCTURE OF THE PSEUDOCAPILLITIUM AND SPORES OF THE MYXOMYCETE LYCOGALA EPIDENDRUM. LICEALES
Authors: Gaither Thomas W.
Published: January 2018

The pseudocapillitium and spores of L. epidendrum were studied by transmission (TEM) and scanning electron microscopy (SEM). The SEM reveals that the pseudocapillitial surface is covered by bands of “wartlike” processes that alternate with non‐ornamented regions. Otherwise, the pseudocapillitium is a hollow structure composed of three regions. The outer region is thin, electron dense and continuous with many irregular processes. Internal to this area is an amorphous region containing scattered electron dense material. The innermost region of the pseudocapillitium is thin, inconspicuous and usually electron dense. L. epidendrum possesses spores that are covered by a surface reticulum consisting of polygonal areas which are continuous with the outermost spore layer. The outer spore layer is thin and electron dense. The inner spore layer is an electron transparent region that contains granular or fibrillar components. Sections of spores showed a dense cytoplasm possessing most of the usual organelles along with microtubules and microbodies.
PLANTLETS FROM PETAL SEGMENTS, PETAL EPIDERMIS, AND SHOOT TIPS OF THE PERICLINAL CHIMERA, CHRYSANTHEMUM MORIFOLIUM ‘INDIANAPOLIS'
Authors: Bush Susan R. , Earle Elizabeth D. , Langhans R. W.
Published: January 2018

Cultivated chrysanthemums, especially the greenhouse series of ‘Indianapolis’ cultivars, are probably periclinal chimeras for flower color. Therefore, in vitro propagation of chrysanthemum, which has recently been described, might produce plants not true to type. To test this, plantlets were generated from cultures of petal segments, petal epidermis, and shoot tips; these plantlets were grown to flowering to determine whether chrysanthemums with two genetically different chimeral layers in the petals are stable in tissue culture. Layer I displaced layer II in the formation of new meristematic areas in shoot tip and petal culture, showing that such chimeras are unstable in culture. Many more abnormal morphological types were exhibited by the plants which were regenerated from petal cultures rather than those from shoot tip cultures. Abnormalities included quilled and incised petal forms, as well as lack of anthocyanin pigmentation, characteristics which may not be attributable to the rearrangement of chimeral layers. Paramutation, true mutation, and environmenal effects are offered as possible explanations for this phenomenon.
OBSERVATIONS ON ORGANIC VOLATILES FROM GERMINATING SEEDS AND SEEDLINGS
Authors: Stotzky G. , Schenck S.
Published: January 2018

Germinating seeds of several plant species evolved oxidizable volatile compounds, including aliphatic aldehydes. Formaldehyde comprised only a small percentage of the total aldehydes detected. Most seeds evolved these compounds only during the first three or four days after imbibition, with peak production occurring during the second day. In general, larger seeds evolved greater quantities than smaller seeds, but, on a unit weight basis, smaller seeds evolved more. Dry, non‐germinating, or killed seeds evolved little or no volatiles, indicating that active seed metabolism was required for the production of volatiles. The light‐dark regime appeared to have little effect on volatile evolution.
MORPHOLOGY AND THERMAL DEATH POINT OF OLPIDIUM BRASSICAE
Authors: Campbell R. N. , Lin M. T.
Published: January 2018

The morphology of single‐sporangial isolates of lettuce, tomato, mustard, and oat Olpidium brassicae (Wor.) Dang. growing in their respective hosts as well as in cowpea were compared in situ and after extraction from the roots. The sporangia, zoospores, and resting spores of all isolates were within the established limits of the species. Single exit tubes or pores predominated which means that these isolates should not be transferred to the genus Pleotrachelus. A satisfactory assay for the presence of resting spores was developed by air‐drying of the roots for a week or longer. This treatment killed zoospores and vegetative sporangia, but not resting spores. Factors affecting resting spore formation were investigated unsuccessfully. The thermal death point of zoospores of mustard isolates that did not form resting spores was between 40 and 45 C for 10 min.