bluuebunny/crossref_metadata_2025 huggingface dataset:
THE REQUIREMENT OF PHYSICAL CONTACT FOR MOSS GAMETOPHORE INDUCTION BY AGROBACTERIUM TUMEFACIENS
Authors: Spiess Luretta D. , Lippincott Barbara B. , Lippincott James A.
Published: January 2018

Gametophore induction in the moss Pylaisiella selwynii by Agrobacteriuin tumefaciens strain B6 does not occur in parabiotic chambers when the moss and bacterium are separated by filters of 0.22 μm pore diameter. The combination of moss plus bacteria which gives increased gametophore formation also had no effect on sterile moss plants separated from the mixture by these filters. Heat‐killed B6 cells inhibit gametophore induction by viable B6 cells when added prior to or with the viable bacteria but not when added 6 or more hr later. The concentration dependence of both gametophore induction by viable B6 cells and inhibition of this process by heat‐killed B6 cells appears linear, suggesting that each response may require only one particle. Gametophore induction by Agrobacterium, therefore, requires physical contact comparable to the bacteria‐site attachment step demonstrated essential for tumor induction in higher plants and shows similar concentration dependence. The size of the moss and the absence of a wound requirement for this response makes the Agrobacterium‐moss system particularly advantageous for further resolution of the site attachment step in Agrobacterium tumorigenesis.
ONTOGENY AND CORRELATIVE RELATIONSHIPS OF THE PRIMARY THICKENING MERISTEM IN FOUR‐O'CLOCK PLANTS (NYCTAGINACEAE) MAINTAINED UNDER LONG AND SHORT PHOTOPERIODS
Authors: Mikesell Jan E. , Popham Richard A.
Published: January 2018

The developmental anatomy of Mirabilis jalapa was investigated during the first 90 days of growth. The primary thickening meristem (PTM) initially differentiates in the pericycle at the top of the cotyledonary node 18 days after germination, then basipetally in the pericycle through the hypocotyl. The PTM differentiates acropetally into the stem and in the pericycle of the primaiy root, commencing 22 days after germination. Endodermis is easily identifiable in hypocotyls as well as in primary roots because of Casparian thickenings in its cells. It has not been definitely identified in stems. There are three rings of primary vascular bundles in the stem. The PTM differentiates as segments of cambium in a layer of cells (probably in the pericycle) on an arc between vascular bundles of the outer bundle ring. Later, arcs of PTM differentiate externally to the phloem of each bundle. Each arc forms a connection between original segments of PTM lying on either side of each vascular bundle. Thus, the PTM becomes a continuous cylinder. The PTM differentiates in the pericycle outside vascular tissue in the hypocotyl and root. Differentiation of the PTM and the mode of secondary thickening is similar in plants exposed to short (8‐hr) and to long (18‐hr) photoperiods, but some differences were observed. The PTM differentiates closer to the stem apex in all plants over 18 clays of age growing vegetatively under long photoperiods. That is, the diffuse lateral meristem, in whose cells the PTM differentiates in young intemodes, is shorter in nearly all investigated plants growing in long photoperiods. The hypocotyl and base of the primary root of 40‐day‐old plants in short photoperiods were more enlarged than those of the same age plants in long photoperiods; but, at the end of 64 days, the hypocotyl and primaiy root base were larger in plants growing under short photoperiods. Thirty‐four days after seed germination, flower initiation occurs in plants exposed to short photoperiods. One hundred fifty days after seed germination, flowers differentiate on plants exposed to long photoperiods.
CYTOPHOTOMETRIC MEASUREMENT OF NUCLEAR DNA IN SEVEN HETEROTHALLIC ISOLATES OF DIDYMIUM IRIDIS, A MYXOMYCETE
Authors: Collins O'Neil Ray , Therrien C. Dale
Published: January 2018

Absorption cytophotometry was used to measure nuclear Feulgen‐DNA content of myxamoebae and Plasmodia in seven heterothallic isolates of Didymium iridis. Measurements of myxamoebal nuclei from clones of four isolates (Hon 1, Pan 1, Pan 2, and CR 5) gave a mean DNA value of 0.34, whereas the nuclei of Plasmodia which develop from each of the four intraisolate crosses had a mean value of 0.63. These values correspond to the 2C haploid level in myxamoebae and the 4C diploid level in Plasmodia. DNA values in two additional isolates (Pan 3 and CR 2) are much higher than the mean for the other five. Accordingly, it is proposed that these may be polyploid. The question of polyploidy in D. iridis and in other myxomycetes is evaluated. The seventh isolate, Ky 1, is taxonomically very close to D. nigripes and was not included in calculations of mean values for D. iridis.
INVESTIGATIONS OF ANGIOSPERMS FROM THE EOCENE OF NORTH AMERICA: JUGLANDACEOUS WINGED FRUITS
Authors: Dilcher David L. , Potter Frank W. , Crepet William L.
Published: January 2018

The winged fruits of Engelhardia have been reported in many early Tertiary floras in the northern Hemisphere. Recent systematic revisions of the extant genera, Engelhardia, Oreomunnea, and Alfaroa provide a helpful guide to the study of the fossil fruits. Fruit form, venation, nut septations and flower parts are features that separate the extant Asian Engelhardia from the American Oreomunnea. Four types of fossil winged fruits can be recognized in Middle Eocene sediments of southeastern North America: Engelhardia, Paraoreomunnea gen. n., Paleooreomunnea gen. n., and Pararengelhardia. Both Paleooreomunnea and Paraengelhardia represent extinct lines; no living forms have similar winged fruits. The fossil fruits of Engelhardia and Paraoreomunnea are similar to the fruits of extant Engelhardia and Oreomunnea, respectively. The fossil taxa reported in this paper were sympatric. The present allopatric distribution of Engelhardia and Oreomunnea is the result of Neogene regional extinctions. Engelhardia and Oreomunnea have probably been distinct genera since early Paleogene time.
CHROMOSOME NUMBERS IN UMBELLIFERAE. V.
Authors: Constance Lincoln , Chuang Tsan‐Iang , Bell C. Ritchie
Published: January 2018

Chromosome numbers are reported for nearly 300 collections of Umbelliferae. Of these, 150 representing “new” or variant counts are figured. Karyotypes of fifteen of the genera included have apparently not been documented before.
THE GENOME CONSTITUTION AND PHYLOGENY OF ELYMUS AMBIGUUS
Authors: Dewey Douglas R.
Published: January 2018

Two Elymus ambiguus Vasey & Scribn. collections from Utah and Idaho were 2n = 28, and the species behaved meiotically as an allotetraploid. The E. ambiguus plants were highly self‐sterile, and they hybridized readily with Asian E. junceus Fisch. (2n = 14), E. karataviensis Roshev. (2n = 28), E. multicaulis Kar. & Kir. (2n = 28), and North American E. innovatus Beal (2n = 28). Chromosome pairing at metaphase‐I in the E. ambiguus X E. junceus triploid hybrids indicated that one E. ambiguus genome was closely homologous with the E. junceus genome. Chromosome pairing in the tetraploid hybrids indicated that both E. ambiguus genomes were more or less homologous with the genomes of E. karataviensis, E. multicaulis, and E. innovatus. The basic genome formula of E. ambiguus may be written as JJXX, where J is the E. junceus genome and X is a genome of unknown origin. Chromosome pairing in the hybrids indicated that E. ambiguus is more closely related to North American E. innovatus than to the Asian species. The E. ambiguus X E. innovatus hybrids were the only hybrids that set seed. Gene flow between E. ambiguus and E. innovatus is biologically possible, but geographic separation of the species precludes natural introgression.
PATTERNS OF MICROFIBRILLAR ORDER IN A DORMANT FERN APEX
Authors: Lintilhac Philip M. , Green Paul B.
Published: January 2018

An excised fern apex and young leaf primordium when seen in polarized light show distinct multicellular domains of parallel cellulose alignment which reflect the successive segmentations of the apical cell. The superficial walls of the most recent apical cell derivatives show the effects of highly ordered cellulose deposition in which the microfibrils lie parallel to the newly formed cell plate.
THE ROLE OF THE ENDOSPERM IN THE GERMINATION OF LEGUMES: GALACTOMANNAN, NITROGEN, AND PHOSPHORUS CHANGES IN THE GERMINATION OF GUAR (CYAMOPSIS TETRAGONOLOBA; LEGUMINOSAE)
Authors: McClendon John H. , Nolan William G. , Wenzler Herman F.
Published: January 2018

The endosperm of Cyamopsis tetragonoloba (“guar”) contains 41 % of the dry weight and 45 % of the acetone‐insoluble‐solids of the seed, but only 3–11 % of the nitrogen and phosphorus. At least 75 % of the acetone‐insoluble‐solids of the endosperm is galactomannan, only about 12% being accounted for as pentosan, pectin, protein, phytin, ash, and dilute‐acid‐insoluble residue. During a five‐day germination period at 30 C, all of the galactomannan and all but 5 % of the dry weight of the endosperm disappeared, being translocated to the cotyledons. About ⅓ of the nitrogen and phosphorus of the endosperm plus seed coat were also translocated. After a 36‐hr lag, the accumulation of the nitrogen and acetone‐insoluble‐solids in the seedling axis were linear, while the total dry weight and phosphorus showed a rapid increase followed by a slower accumulation during the five‐day period. In the cotyledons, the dry weight temporarily increased, but the acetone‐insoluble‐solids, nitrogen and phosphorus showed only a net decrease after 84, 36 and 36 hr, respectively. Scanning election micrographs of dry‐fractured and sectioned endosperm show that the bulk of the endosperm is a solid mass of galactomannan with essentially no cell lumina; a several‐cell layer (“aleurone”) of thick‐walled cells of similar structure is metabolically active.
CHROMOSOMES, HYBRIDS AND PLOIDY OF SEDUM CREMNOPHILA AND ECHEVERIA LINGUIFOLIA (CRASSULACEAE)
Authors: Uhl Charles H.
Published: January 2018

Sedum cremnophila and Echeveria linguifolia have generally been placed in different genera on the basis of their flowers—largely because the petals are spreading in one and erect in the other—and the genera have been placed in different subfamilies. However, they are very similar vegetatively and in their unusual inflorescence, their karyotypes are similar (n = 33), and they readily hybridize to produce fertile F1 hybrids. Study of hybrids of these two species with numerous others leads to the conclusion that each of the two is effectively diploid, with a genome consisting of 33 chromosomes that are all different and that do not pair with each other. Therefore, the good chromosome pairing and the fertility of the hybrid between them are the result of close structural and genetic homology between the corresponding chromosomes of the two species. Taxonomic revision to reflect their very close relationship is desirable. Some other species of Sedum and Echeveria also may need to be reclassified.
OBSERVATIONS ON THE PHI‐THICKENINGS AND CASPARIAN STRIPS IN PELARGONIUM ROOTS
Authors: Haas David L. , Carothers Zane B. , Robbins Robert R.
Published: January 2018

An ultrastructural examination of hypodermal cell walls failed to demonstrate the presence of casparian strips as has been reported in the literature. Rather, these cells have supportive phi‐thickenings which differ significantly from casparian strips. Adjacent phi‐thickenings are convex‐convex and stratified in transection, with an uneven surface like the rest of the phi‐cell's wall. They may be unbranched or branched and in the latter case, especially, they may appear on tangential as well as radial and transverse walls. They are lignified early in development and are associated with microtubules which lie parallel to the long axis of the thickening. Further, the plasmalemma exhibits no special adherence to the thickened wall region. In each of these and other characteristics phi‐thickenings contrast sharply with casparian strips.
FLORAL ANATOMY OF IDIOSPERMUM AUSTRALIENSE (IDIOSPERMACEAE)
Authors: Wilson Carl L.
Published: January 2018

The floral anatomy of Idiospermum australiense (Diels) S. T. Blake is described from studies on relatively mature but unopened flower buds. The vascular system and general morphology of the flower is compared with that of Calycanthus and Chimonanthus (Calycanthaceae), especially with Calycanthus, the genus in which Diels originally placed Idiospermum. Inverted cortical bundles are present in both taxa but occur in different patterns. The tepals of Calycanthus are all 3‐trace, whereas in Idiospermum only the upper tepals have three traces, the lower tepals having five to seven. All tepals of Calycanthus are spirally arranged; the lower tepals of Idiospermum are opposite or decussate in 1–3 pairs. The axial and recurrent bundle systems in Calycanthus are discrete except where the axial system turns downward, but in Idiospermum these systems, together with cortical bundles, are largely intermixed. The vascular supply to the carpel of Idiospermum, while possibly a modification of that of the carpels of Calycanthus, could also be interpreted as having an independent origin. Other differences and resemblances are described.
AN ULTRASTRUCTURAL STUDY OF SPERMATIUM FORMATION IN THE RUST FUNGUS GYMNOSPORANGIUM JUNIPERI‐VIRGINIANAE
Authors: Mims Charles W. , Seabury Frank , Thurston E. Laurence
Published: January 2018

Spermatium formation in G. juniperi‐virginianae is phialidic. The spermatia are blown out of the tips of spermatiophores which possess a thickened neck region and a distinct, flared collarette. Each spermatium initial is surrounded by a thin wall which is attached to the inner surface of the spermatiophore wall just below the thickened neck region. A spermatium is delimited by a centripetally developing septum and then pushed into the spermogonial cavity by the next spermatium initial. Mature spermatia are ellipsoid with tapered ends and are surrounded by a thin wall. Each contains a single nucleus, many ribosomes, a few small vacuoles, and a number of lipid bodies and mitochondria.
ULTRASTRUCTURE OF CEPHALEUROS VIRESCENS (CHROOLEPIDACEAE; CHLOROPHYTA). I. SCANNING ELECTRON MICROSCOPY OF ZOOSPORANGIA
Authors: Chapman Russell L.
Published: January 2018

Scanning election microscopic examination ofCephaleuros virescensgrowing on leaves ofMagnolia grandiflorahas provided detailed observations which parallel, extend, and, in general, confirm previous light microscopic studies. The present study has revealed that in the ontogeny of terminal zoosporangia, apical zones form in the surface of an enlarged pyriform cell and that these zones, in some cases, are surrounded by a circumferential ridge, an external indication of an internal septum. A similar circumferential ridge is seen at the base of developing terminal zoosporangia. Contrary to some published accounts, the abscission of terminal sporangia does not commence with tearing of the pedicel‐sporangium septal wall, but rather with an internal separation of the septum which is followed by a circumscissile tearing of the septal wall. The completion of abscission entails the emergence of a septal protuberance from the pedicel and/or the terminal sporangium in a process reminiscent of filament fragmentation in zygnematacean algae containing “replicate end walls.” Zoospore exit pores form in a lateral position on the terminal sporangia and are not coincident with the septal protuberances as has been reported in some recent accounts. Although both biflagellate and quadriflagellate zoospores have been seen in the light microscope, only the former have been observed with SEM. The SEM observations recorded in this study have provided a basis for comparison not only with light microscopic data, but also with transmission electron microscopic data which are now being recorded. Observations reported will be useful for interspecific and intergeneric comparisons.
DISPERSAL ECOLOGY OF CAREX PEDUNCULATA (CYPERACEAE), A NEW NORTH AMERICAN MYRMECOCHORE
Authors: Handel Steven N.
Published: January 2018

Carex pedunculata is the first North American species of the Cyperaceae that is identified as a myrmecochore. Many morphological and phenological features of this species and its breeding system are interpreted as adaptive for seed dispersal by ants. In laboratory tests, workers of the ant species Aphaenogaster rudis carry the diaspores to the nest, eat the elaiosomes, carry larvae to the elaiosomes to feed, and deposit diaspores whose elaiosomes have been eaten with other nest debris. The achenes then germinate. Achenes will also germinate without any handling by ants. Workers will also transport diaspores with uneaten elaiosomes when the nest is disturbed. Greenhouse tests show that seedling growth is greatly inhibited if a diaspore remains near the parent plant and cohort seedlings. Field studies of natural populations identify rotting logs (the location of ant nests) as forest floor microsites for colonization of C. pedunculata and other myrmecochores. Ant nesting behavior may pattern much of the herb stratum. This species is self‐compatible, and single seeds may start successful new populations. Three processes contribute to population growth: vegetative growth, germination of untransported diaspores, and germination of ant‐transported diaspores.
FERN GAMETOPHYTE DEVELOPMENT: CONTROLS OF DIMORPHISM IN CERATOPTERIS THALICTROIDES
Authors: Schedlbauer M. D.
Published: January 2018

Multispore cultures of Ceratopteris thalictroides (L.) Brongn. gametophytes contain plants of two distinct morphologies, hermaphrodite and male (Fig. 3). The male gametophyte has previously been shown to be induced by an antheridogen system. In the absence of the antheridogen all gametophytes become hermaphroditic. It is shown that the hermaphroditic gametophytes are first to develop in multispore cultures and are also the only source of antheridogen. Thus, since males are only produced in the presence of antheridogen, an explanation of the occurrence of two morphologies is evident. That is, the first gametophytes to develop do so in the absence of antheridogen, become hermaphrodites and produce antheridogen to which later developing gametophytes respond by becoming males. This does not explain why there is a range in development times for the gametophytes. Three possible controlling factors of development are investigated in multispore cultures: spore size, time of germination, and gametophyte growth. Data collected on these three factors are statistically analyzed. Analyses were done to determine the relative importance (singly or in combination) of these factors in predicting the developmental potential of a gametophyte. It was found that spore size most accurately indicated (ca 75% of the time) future gametophyte development.
BASIDIOSPORE INITIATION AND EARLY DEVELOPMENT IN COPRINUS CINEREUS
Authors: McLaughlin David J.
Published: January 2018

Early basidiospore development in Coprinus cinereus has been divided into four stages: 1) inception, 2) asymmetric growth, 3) equal enlargement, 4) elongation, all based on changes in spore size and shape, wall layering, and cytoplasm. The hilar appendix body formed on the adaxial side of the stage 1 basidiospore, persisted through all stages studied, and predicted the site of the hilar appendix. The hilar appendix formed in stage 2 by modification of certain wall layers. A band of peripheral endoplasmic reticulum covered an average of 38 % of the lower spore wall in stage 3 and was oriented around the axis of growth. Stage 4 was initiated by a break in wall layer 3 at the spore apex and the disappearance of the peripheral endoplasmic reticulum. A pore cap formed on the spore apex during spore elongation. The spore wall consisted at first of three layers and became six layered by deposition of layers between two of the initial layers. Cytoplasmic changes associated with spore growth included presence of small vesicles at stage 1 and larger Golgi vesicles later, absence of mitochondria and probable Golgi cisternae from the spore until stage 3, and presence of a zone nearly free of ribosomes and organelles under the spore apex in stage 4. Functions of the hilar appendix body, peripheral endoplasmic reticulum and the different wall layers in control of spore shape are discussed.
ABSCISIC ACID EFFECTS ON FRONDS AND ROOTS OF LEMNA MINOR L.
Authors: Newton R. J.
Published: January 2018

Plants of Lemna minor L. were grown in axenic culture in order to investigate the direct effect of abscisic acid (ABA) on individual fronds and roots. Both frond and root growth rates were inhibited by 60%, and total growth of both organs was reduced by 30% with ABA concentrations of 2 mg/l. Abscisic acid inhibited frond reproduction, and treated fronds tended to remain attached to parents. Reduction of root elongation and frond expansion occurred within 1–4 hr. Prolonged exposure to ABA inhibited both cell enlargement and cell division in the roots. The results are discussed in the light of current views on the control of growth with endogenous levels of promoter and inhibitor hormones.
INFLUENCE OF THE MULTILAYERED STRUCTURE ON THE MORPHOGENESIS OF MARCHANTIA SPERMATIDS
Authors: Kreitner Gerald L.
Published: January 2018

The multilayered structure (MLS) in a spermatid ofMarchantiais the morphogenetic blueprint of the headpiece in a mature sperm. As the nucleus begins elongation, a curved, tapered nuclear projection follows the path of microtubules extending from the MLS and becomes inserted into an indented zone at the rear of the asymmetric organelle. The indented zone defines the most forward penetration of the nucleus into the sperm headpiece. Partial disorganization of MLS lower strata nearest the nuclear projection facilitates overlapping of the nucleus with the rearward part of the anterior mitochondrion. At the front of the nascent headpiece, the mitochondrion is stabilized against microtubules following total disorganization of intervening MLS strata. Penetration of the nuclear projection along the MLS and directed disorganization of MLS lower strata control ultimate disposition of headpiece components. The headpiece is isolated and molded into final shape by undercutting and constriction of the cell membrane.
CHROMOSOME NUMBERS IN WESTERN GRASSES
Authors: Reeder John R.
Published: January 2018

Chromosome numbers are reported for 221 collections from eleven western states. These records represent 85 species included in 48 genera. Counts for the following species are here presented for the first time: Melica spectabilis, Blepharidachne kingii, Eragrostis obtusijlora, Hilaria rigida, Redfieldia flexuosa, and Sporobolus interruptus. The record for Redfieldia is also the first for that genus. In addition, numbers which differ from those in the literature are recorded for ten species, in three cases two different numbers for the same taxon. Cytological evidence is also presented indicating that Hilaria jamesii and H. rigida have hybridized and that the F1 has backcrossed to both parents.
PROMOTION OF CELL ARREST IN G2 DURING CELL MATURATION IN ROOTS OF PISUM SATIVUM BY EXOGENOUSLY APPLIED CYCLIC AMP
Authors: Evans Lance S. , Romeo David P.
Published: January 2018

Cyclic AMP and dibutyryl cyclic AMP promoted cell arrest in G2 in roots during tissue maturation in seedlings of Pisum sativum when applied in lanolin after cotyledon excision. 5' AMP did not promote arrest in G2 in a similar manner. Results demonstrate that cyclic AMP did not inhibit cell proliferation in root meristems when applied exogenously.
THE EXTRAFLORAL NECTARIES OF IPOMOEA CARNEA (CONVOLVULACEAE)
Authors: Keeler Kathleen H.
Published: January 2018

Ipomoea carnea (Convolvulaceae) possesses two types of extrafloral nectaries, located on the petiole and on the pedicel. These secrete a complex nectar containing sugars and amino acids. The insects attracted to the extrafloral nectaries are predominantly ants and they are relatively abundant throughout the year. A number of incidents of plant defense as a result of the presence of extrafloral nectary visitors at the extrafloral nectaries of I. carnea were observed and are consistent with the ant‐guard theory of the function of extrafloral nectaries.
SUCCESSIVE CAMBIA IN THE STEM OF PHYTOLACCA DIOICA
Authors: Wheat David
Published: January 2018

Phytolacca dioica L., an evergreen tree of the Phytolaccaceae, is one of the species of Phytolacca which shows anomalous secondary thickening in its stem. This mode of thickening has been regarded as successive cambial activity or alternatively, in some more recent interpretations, as thickening by unidirectional activity of a cambial zone. The stem thickening of P. dioica is of the former type. The cambium produces fascicular strands, showing centrifugal differentiation of xylem and centripetal differentiation of phloem on opposite sides of the cambial layer, and rays are produced between the fascicular areas. In both xylem and phloem the younger elements are closer to the cambium than the older elements. Succeeding cambia arise periodically by periclinal divisions in a layer of parenchyma cells two or three cells beyond the outermost intact phloem derived from the current cambium. Each cambium forms a few parenchyma cells on both sides before it forms derivatives which mature into lignified xylem elements or conductive elements of the phloem. The parenchyma thus formed toward the outside later becomes the site of the origin of the succeeding cambium. Only one or two layers of this phloem parenchyma go on to form the new cambium; the remaining cells accumulate between the outermost phloem and the cortex. P. weberbaueri shows stem structure similar to P. dioica. P. meziana, a shrub, shows normal stem structure.
NUTRIENT CONTENT OF FOREST SHRUBS FOLLOWING BURNING
Authors: Stark N. , Steele R.
Published: January 2018

Prescribed burning under mature Larch/Douglas‐fir forests produced changes in elemental uptake. Elemental analyses of individual species and existing biomass three years post‐burn from hot, medium, and lightly burned sites and unburned controls showed a significant shift in species composition with burn intensity. Few species from hotly burned sites had elevated levels of ions, except phosphorus and iron, but the aboveground shrub and herb biomass did have greater total cations, percent ash, and individual cations (except Ca and Mg) on hotly burned sites. Although the hotly burned sites had the greatest total biomass, only iron, manganese, total nitrogen, sodium, and phosphorus were significantly higher (5% level) in biomass from hot burns compared to control biomass (g/m2 basis). Hot burns alter the soil pH to the alkaline range making some elements like iron less soluble and available. Some species growing on hotly burned sites appeared able to alter nutrient uptake making more iron, phosphorus, and other elements available for growth, even with low available levels, compared to control sites. Three‐year‐old western larch (Larix occidentalis Nutt.) seedlings were able to accumulate high levels of Fe, K, and P relative to controls. Marchantia polymorpha L. concentrated some ions on hotly burned soils, but it was not possible to locate this plant on unburned areas for comparison.
RELLIMIA THOMSONII (PROGYMNOSPERMOPSIDA) FROM THE MIDDLE DEVONIAN OF NEW YORK STATE
Authors: Bonamo Patricia M.
Published: January 2018

Rellimia thomsonii, a progymnosperm known from the Givetian of Europe and the USSR, is described from New York. The spiral branching pattern and once dichotomized fertile organs prove to be consistent characters separating Rellimia from Tetraxylopteris. Both are abundant in New York: the simpler Rellimia restricted to Givetian (Middle Devonian) strata, the more complex Tetraxylopteris to Frasnian (Upper Devonian) beds. The primary xylem of Rellimia is described for the first time. It is a three‐lobed protostele with a continuous mesarch protoxylem strand in each lobe. The anatomical description of Rellimia supports its morphological distinction from Tetraxylopteris and emphasizes their generic validity within the Aneurophytales.
ONTOGENY AND CYTOCHEMISTRY OF ALKALOIDAL VESICLES IN LATICIFERS OF PAPAVER SOMNIFERUM L. (PAPAVERACEAE)
Authors: Nessler Craig L. , Mahlberg Paul G.
Published: January 2018

Development of alkaloidal vesicles in laticifers of opium poppy, Papaver somniferum L., was investigated at the ultrastructural level. Laticifer initials possessed abundant endoplasmic reticulum throughout their dense cytoplasm. During differentiation the endoplasmic reticulum organized into long, folded sheets that were parallel to the longitudinal walls along the periphery of the cell. Vesicles appeared to be derived from dilation of endoplasmic reticulum. This relationship was confirmed through cytochemical data obtained with zinc iodide‐osmium tetroxide and osmium tetroxide impregnation. Alkaloidal vesicles had electron‐dense regions or caps that occurred early in laticifer differentiation, but these caps became less conspicuous in mature cells. Caps appeared to be derived from small particles which condensed along the inner surface of the vesicle membrane and subsequently accumulated at one or two positions along the membrane of the vesicle.
THE TIME COURSE OF SIEVE TUBE AND VESSEL REGENERATION AND THEIR RELATION TO PHLOEM ANASTOMOSES IN MATURE INTERNODES OF COLEUS
Authors: Aloni Roni , Jacobs William P.
Published: January 2018

Quantitative counts of regenerative sieve tubes and vessels were made in a large number of samples of mature internode #5 of C. blumei, with concomitant study of the fine details of vascular regeneration and the occurrence of the normally developing phloem anastomoses. Such anastomoses were found in many of the plants, but their average number in the small regenerating area was low (viz., 0.9 ± 0.2). With the phloem anastomoses excluded from the counts, the time course of regeneration was clear cut—no strands completed their regeneration around the wound until three days after wounding. More regenerative sieve tubes completed their differentiation under all conditions than did regenerative vessels. The number of sieve tubes and vessels regenerated by four days was closely related to the number of preexisting bundles of that type of vascular cell that had been severed by the transverse wound. The ratio of bundles severed by the wound in the phloem to those in the xylem was 2.14, and the ratio of the regenerative sieve tubes to the regenerative vessels was 2.24. For both tracheary and sieve tube cells the initial regeneration was strongly polar (mostly above the wound), as expected from earlier IAA transport data. The path of tracheary regeneration was obviously related to that of the sieve tubes on the other side of the cambium.
THE SHOOT APICAL ONTOGENY OF THE PICEA ABIES SEEDLING. III. SOME AGE‐RELATED ASPECTS OF MORPHOGENESIS
Authors: Romberger J. A. , Gregory Robert A.
Published: January 2018

We have extended our previous analyses of growth in shoot apices of Picea abies seedlings. Quantification of apical dome volume changes, more detailed analysis of the subapical caulis profile, and of the vertical distance from the base of the dome to the nth primordium, all as functions of age, revealed the dynamics of various growth variables. As seedlings age from 10 to 136 days, apical dome volume increases about 30‐fold, plastochron duration declines from 31 h to about 5 h, height of primordial internodes declines from near 10 μm, to only 3.5 μm, and the caulis assumes a distinct neck‐and‐shoulder profile. Relative volume growth rates for the apical dome as a whole are about twice the base‐of‐dome values and decline from 36% to 21% per day as age increases to 136 days. Relative growth rates (radial, vertical, and volume) in the caulis change in a complex manner with both plant age and internode number. We also computed the total volume of tissue generated by an apical dome per day including that part invested in increased dome volume. The investment (ϕ) ratio is greater than 20% in the 10‐day dome, but declines rapidly to become negative after 136 days. The ϕ ratio controls apical dome volume and hence augurs future growth yield.
CHARACTERIZATION OF VACUOLAR BODIES IN SPARTINA ALTERNIFLORA: II. SOME PHYSICAL AND CHEMICAL PROPERTIES
Authors: Akers Stuart W. , Anderson Charles E. , Blum Udo
Published: January 2018

Spheres 0.5 to 2.5 μm in diameter with an outer golden matrix and usually one or more internal vesicles were found in certain leaf cells of Spartina alterniflora and were termed vacuolar bodies. Reactions of the vacuolar bodies to osmolality changes indicated that they were permeable to water and NaCl and accumulated NaCl and were relatively impermeable to sucrose. Cytochemical tests and tests on vacuolar body extracts suggested that vacuolar body matrices were composed of compounds tentatively identified as phenolic aldehydes. Microscopic bodies similar to vacuolar bodies in structure, chemical composition, and physical properties were formed from vacuolar body extracts. Vacuolar bodies and bodies formed in vitro have physical properties in common with two types of coacervate bodies. Possible function of these bodies is discussed.
WOOD ANATOMY OF TREMANDRACEAE: PHYLOGENETIC AND ECOLOGICAL IMPLICATIONS
Authors: Carlquist Sherwin
Published: January 2018

Stems of four species of the Australian family Tremandraceae furnished sufficient material for analysis of wood anatomy. Presence of simple perforation plates on vessel elements, occurrence of libriform fibers (some septate), tendency toward vasicentric parenchyma, presence of crystalliferous axial parenchyma strands, presence of crystals singly in ray cells, and occurrence of amorphous deposits in parenchyma are all features in which Tremandraceae resemble Pittosporaceae. Wood anatomy tends to support a “rosoid” rather than a sapindalean, rutalean, or polygalalean affinity for Tremandraceae, although wood is only a preliminary indicator. By the use of numerical indices as well as such indicators as helical thickening and presence of vascular tracheids, wood of Tremandraceae is shown to be highly xeromorphic. The genus Tremandra may represent a secondary entrant into wet forests of southwestern Australia; it clearly is not relict from mesic ancestry.
THE COMPARATIVE CELL CYCLE AND METABOLIC EFFECTS OF CHEMICAL TREATMENTS ON ROOT TIP MERISTEMS. I. IOXYNIL
Authors: Rost Thomas L. , Morrison Steven L. , Sachs Eric S.
Published: January 2018

In this study we investigated the cell cycle response of Vicia faba and Pisum sativum root tip meristems to ioxynil treatments at two concentrations, (10−‐4m and 10−‐6m). After 24 h of treatment at 10−‐4m concentration, O2 uptake and ATP concentrations were significantly reduced. The mitotic index was reduced and the cell cycle population position was shifted to indicate that previously inhibited cells reformed their nuclei and became tetraploid. Prolonged treatment at this concentration resulted in cell death. Treatment with ioxynil at 10−‐6m reduced the rate of entry into mitosis. Abnormal mitotic figures in all stages were observed, and the ploidy level of mitotically inhibited cells was doubled. These observations indicated that at 10−‐6m concentration ioxynil acts as a preprophase inhibitor, that is, it does not act directly on the mitotic apparatus but does affect processes on which mitosis depends.
CHROMOSOME NUMBERS AND THEIR SYSTEMATIC IMPLICATIONS IN LIPOCHAETA (COMPOSITAE:HELIANTHEAE)
Authors: Gardner Robert C.
Published: January 2018

Chromosome counts are reported for 71 collections in 14 taxa of Lipochaeta DC. (Compositae) of the Hawaiian Islands. Counts for 13 of the taxa are first reports. Lipochaeta contains diploids, n = 15, and tetraploids, n = 26. Ploidy level is taxonomically significant for recognizing sections, and on the basis of these data, together with morphological and chemical evidence, major realignments of species into the secions of Lipochaeta have been made.
PHENOTYPIC VARIATION IN STEPHANOMERIA EXIGUA SSP. CORONARIA (COMPOSITAE) AND ITS RECENT DERIVATIVE SPECIES “MALHEURENSIS”
Authors: Gottlieb L. D.
Published: January 2018

Phenotypic variation in 33 quantitative characters was analyzed in Stephanomeria exigua ssp. coronaria (Greene) Gottlieb and its recent derivative species, presently called “Malheurensis,” grown in a series of experimental environments. The study was made to determine whether their high genetic identity, previously revealed by electrophoresis of a sample of their enzymes, was correlated with a high similarity in quantitative traits of morphology, size, growth rates, and fecundity. The electrophoretic evidence provided correct information about the relative variability, similarity, and phylogenetic relationship of the two taxa. Thus, 90% of the between‐plant variance components from the analysis of variance were higher in ssp. coronaria and, therefore, concordant with its higher genetic variability. The between‐environment variance components in the two species were similar in magnitude and when ordered, from smallest to largest, were nearly identical in ranking. The quantitative study provided important additional evidence. Ssp. coronaria grew more rapidly and produced more florets than Malheurensis in all of the growth conditions and also was found to grow larger than Malheurensis in their native habitat in eastern Oregon where they grow sympatrically. These and other results indicate that the persistence of Malheurensis in nature cannot depend on advantages of size, growth rates, or number of flowers produced per individual. The large differences between the taxa in the size of their seeds was used as the basis for a model to account for the continued persistence of Malheurensis.
ECOLOGICAL FACTORS IN WOOD EVOLUTION: A FLORISTIC APPROACH
Authors: Carlquist Sherwin
Published: January 2018

Wood florulas from southwestern Australia were analyzed to determine whether wood anatomy is sufficiently correlated with ecology so that vessel element features can be said to have a predictive value. Indices for vulnerability (vessel diam: vessels per sq. mm) and mesomorphy (vulnerability × vessel element length) were calculated for each species in the following florulas: karri forest understory, coastal granitic slopes, bogs, sand heaths, and desert. Wood indices for the species studied and for each florula show that these florulas form a sequence in increasing xeromorphy in the order listed. Genera represented in more than one florula validate the trends. Data for Gyrostemonaceae, Loranthaceae, and Cupressaceae are calculated separately because these are succulents, epiparasites, and conifers, respectively. Comparison with categories from floras elsewhere in the world shows the flora of Western Australia as a whole to be relatively xeromorphic. The indices devised show promise of great reliability because correlations with rainfall, temperature, and other factors are very close. Functional nature of the vessel element is thereby believed to be clarified.
INTERSPECIFIC INCOMPATIBILITY IN GOSSYPIUM. IV. TEMPERATURE‐CONDITIONAL LETHALITY IN HYBRIDS OF G. KLOTZSCHIANUM
Authors: Phillips Lyle L.
Published: January 2018

A number of interspecific hybrids involving G. klotzschianum are embryo‐lethal or seedling‐lethal at temperatures considered optimal for cotton culture (26–32 C). At temperatures between 33–37 C, lethal symptoms (cell‐necrosis and vascular plugging) for both stages of lethality are greatly ameliorated and at 40 C lethal symptoms are absent and hybrid ontogeny is normal for embryo‐ and seedling‐lethals. Temperature‐repressed lethals revert to type within 12–24 h after being returned to a non‐repressive temperature regime.
SULLITHECA DACTYLIFERA GEN. ET SP. N.: A NEW MEDULLOSAN POLLEN ORGAN AND ITS EVOLUTIONARY SIGNIFICANCE
Authors: Stidd Benton M. , Leisman Gilbert A. , Phillips Tom L.
Published: January 2018

The pteridosperm (Medullosaceae) pollen organ Sullitheca dactylifera gen. et sp. n. is described from middle Pennsylvanian coal balls. The proximally fused units of the obpyriform compound synangium separate and extend distally as finger‐like projections. Each projection contains 4–6 vertically oriented cylindrical sporangia arranged in pairs along the radius of the unit; each unit extends from the outer cover wall toward the center. The distal portion of the compound synangium is hollow as a result of the lateral separation of the centripetally and distally directed synangial units. About 40 tubular sporangia are present in all and dehiscence occurs along a lateral slit in each sporangium. Vascular strands are disposed around the periphery of the organ in addition to a single strand paralleling each sporangium. Two‐ or three‐cell trichomes and stomata are present on the organ surface. Pollen of the Monoletes type is present. A paired row of sporangia in Sullitheca composing a synangial unit is considered the homologue of a paired row of sporangia in the more compact and highly evolved genus, Dolerotheca.
EVIDENCE FOR THE REPAIR OF OZONE‐INDUCED MEMBRANE INJURY
Authors: Sutton Rosemary , Ting Irwin P.
Published: January 2018

The increase in [14C]‐2‐deoxy‐D‐glucose uptake by leaf discs 24 hr after fumigation was used as a measure of ozone injury to pinto bean leaves (Phaseolus vulgaris). This method showed that the primary leaves were most affected by ozone when plants were 10 to 12 days old, which coincided with the time of maximum leaf necrosis. However, 8‐day‐old plants, which had no visible leaf injury, still showed a higher uptake rate than controls, indicating that injury occurred at the cellular level. In these younger plants, uptake was shown to return to normal over a 5 day period. Moreover, the rate of this “repair” was retarded by cold or continuous darkness, enhanced by continuous light, and very markedly increased by glucose applied to the leaves. The timing of the glucose application was not critical, nor did H2O or mannitol have an effect. The results suggest that ozone injury at the cellular level can be repaired by energy‐dependent processes so that necrosis of the leaf tissue does not occur. These experiments also show that conditions and treatments after ozone exposure can alter the degree of ozone injury.
AN ULTRASTRUCTURAL AND MICROSPECTROPHOTOMETRIC STUDY OF THE SHOOT APEX DURING THE INITIATION OF THE FIRST LEAF IN GERMINATING PINUS BANKSIANA
Authors: Cecich Robert A. , Horner Harry T.
Published: January 2018

The morphology and anatomy of the shoot apex in germinating Pinus banksiana seeds is described by using scanning and transmission electron microscopy and microspectrophotometry, with special attention given to events preceding the appearance of the first leaf primordia at about 72 hr post‐imbibition. The 2C nuclei begin DNA synthesis at about 43 hr. RNA increases until 52 hr and is followed by a reduction related to cytokinesis. Protein drops after 36 hr, apparently related to digestion of storage protein bodies, which by 48 hr are about 50% digested. The resulting protein body vacuoles do not enlarge. Starch is digested just prior to appearance of the leaves and may be mediated by α‐amylase production from stacks of endoplasmic reticulum. Heterochromatin increases in the nuclei during germination and coincides with an increase in repeated nucleotide sequences. Golgi bodies increase in number after the first mitoses.
POLLEN MORPHOLOGY AND DETAILED STRUCTURE OF FAMILY COMPOSITAE, TRIBE CICHORIEAE. II. SUBTRIBE MICROSERIDINAE
Authors: Feuer Sylvia , Tomb A. Spencer
Published: January 2018

A survey of pollen morphology of 40 species representing eight genera of the primarily North American subtribe Microseridinae reveals seven of the eight genera to have caveate, echinolophate, tricolporate grains, Picrosia being the only taxon with echinate pollen. Sectioned grains reveal the exine to consist of an ektexine and endexine. The ektexine, composed of spines, columellae, and foot layer appears to be of two basic types, one with six or seven levels of horizontally anastomosing columellae which are reduced to a single columellar layer under the paraporal lacunae and the second, a bistratified ektexine not reduced to a single layer below the paraporal lacunae. Sectioned exines of Pyrrhopappus are unusual, having very large columellae fused to the foot layer below ridges and highly reduced columellae under lacunae. Endexine organization is similar in most of the genera. Exceptions to this are Pyrrhopappus and some species of Agoseris, which have an “endexine 2” layer. Subtribe Microseridinae is essentially stenopalynous. The pollen data support most of the relationships suggested by Stebbins in his classification. The genera Agoseris, Microseris, Nothocalais, and Phalacroseris seem to form a natural group while Krigia and Pyrrhopappus form another cohesive series. The position of Picrosia, as an advanced offshoot of Pyrrhopappus, is not supported by the pollen data.
NUCLEAR DNA CONTENT OF MYXAMOEBAE AND PLASMODIA IN SIX NON‐HETEROTHALLIC ISOLATES OF A MYXOMYCETE, DIDYMIUM IRIDIS
Authors: Therrien C. D. , Bell W. R. , Collins O'Neil R.
Published: January 2018

The nuclear DNA content of six non‐heterothallic isolates of the myxomycete Didymium iridis was measured by combining the Feulgen reaction with absorption microspectrophotometry. This allowed us to distinguish between homothallic (sexual) and apogamic (non‐sexual) isolates. Four of the isolates studied, Panamanian 4 and 5, California 1, and Missouri 1 are homothallic. Moreover, the average DNA content of the myxamoebal and plasmodial nuclei (0.32 and 0.61 respectively) does not differ significantly from the calculated haploid and diploid values for heterothallic isolates of D. iridis (0.34 and 0.63). Hence, it is concluded that in each of these isolates the myxamoebae are haploid and the plasmodia diploid. In two of the isolates investigated, Georgia 1 and Hawaii 1, the DNA content of the myxamoebal and plasmodial nuclei did not differ significantly. Therefore, in both of these isolates the plasmodia appear to develop apogamically. In addition the mean DNA values recorded for the Ha‐1 isolate suggest that it is aneuploid.
SOME ULTRASTRUCTURAL ASPECTS OF METAPHLOEM SIEVE ELEMENTS IN THE AERIAL STEM OF THE HOLOPARASITIC ANGIOSPERM EPIFAGUS VIRGINIANA (OROBANCHACEAE)
Authors: Walsh Michael A. , Popovich Thomas M.
Published: January 2018

A light and electron microscope investigation was conducted on phloem in the aerial stem of Epifagus virginiana (L.) Bart. Tissue was processed at field collection sites in an effort to overcome problems resulting from manipulation. At variance with earlier accounts, Epifagus phloem consists of sieve elements, companion cells, phloem parenchyma cells, and primary phloem fibers. The sieve elements possess simple sieve plates and the phloem is arranged in a collateral type of vascular bundle. In addition, this constitutes the first study on phloem ultrastructure in the aerial stems of a holoparasitic dicotyledon, an entire plant which could be viewed as an “ideal sink.” Epifagus phloem possesses unoccluded sieve plate pores in mature sieve elements and a total lack of P‐protein in sieve elements at all stages of development. Mature sieve elements lack nuclei. Plastids were rarely observed in mature sieve elements. Vacuoles with intact tonoplasts were encountered in some mature sieve elements. Otherwise, the ultrastructural features of sieve elements appear to differ little from those described by investigators of non‐parasitic species.