bluuebunny/crossref_metadata_2025 huggingface dataset:
PHYLOGENETIC TRANSITIONS IN THE CHLOROPLASTS OF THE ANTHOCEROTALES I. THE NUMBER AND ULTRASTRUCTURE OF THE MATURE PLASTIDS
Authors: Burr F. A.
Published: January 2018

Representatives of three genera of anthooerotes were examined: Phaeoceros, Notothylas, and Megaceros. Species of the first two genera were found to exemplify the typical anthocerote plastid condition. This condition is characterized by the presence in each cell of the gametophyte of only a single large chloroplast containing a “multiple” pyrenoid. The genus Megaceros, however, proved to be quite different. In two species of Megaceros the pyrenoid was observed to be composed of a highly subdivided thylakoid system of even greater complexity than the “multiple” pyrenoids of Phaeoceros. In another species only an indistinct “pyrenoid‐like” area was noted while in a fourth species no evidence was found for any internal differentiation. Associated with these changes in plastid structure there are corresponding alterations in the number and the size of the chloroplasts. Together they indicate an evolutionary trend away from a primitive, algal‐like condition to a more advanced land plant form.
GIBBERELLIN AND AUXIN RELATIONSHIPS IN ABSCISSION
Authors: Muir Robert M. , Valdovinos Jack G.
Published: January 2018

Gibberellic acid (GA) has no effect on abscission when applied proximally or distally to the abscission zones of debladed petioles of Coleus. Application of GA to the stem apex increases the rate of abscission of debladed petioles. The effect on abscission is accompanied by an increase in the level of endogenous auxin in the stem. Correspondingly proximal applications of indoleacetic acid (IAA) accelerate abscission, whereas the longevity of the debladed petiole approaches that of the intact leaf only in the presence of a continuous distal supply of IAA. No correlation is found between petiole elongation and its longevity. The experimental data support the view that auxin acts at the abscission zone in regulating separation processes and that the effect of GA is through its effect on the level of endogenous auxin.
LINKAGE STUDIES IN THE TRUE SLIME MOLD DIDYMIUM IRIDIS
Authors: Ling Hubert , Collins O'Neil Ray
Published: January 2018

Through the use of eight markers, which included six plasmodial fusion markers, the plasmodial color locus (b1) and the mating locus (A), three linkage groups with two markers each were recognized. The other two markers segregated independently. An estimation of the haploid chromosome number in Didymium iridis has been made. Based on a Poisson distribution, a reasonable estimate would be about six to sixteen chromosomes.
MORPHO‐HISTOGENIC STUDIES ON TENDRILS OF VITACEAE
Authors: Shah J. J. , Dave Y. S.
Published: January 2018

The origin and development of the tendrils were studied in 16 species of the Vitaceae: Ampelopsis (7 sp.), Parthenocissus (4 sp.), Vitis (3 sp.), and Tetrastigma (1 sp.). Two types of arrangement of leaf and tendril occur: (a) two successive nodes have leaf‐opposed tendrils alternating with each other, followed by a third node, with a leaf unopposed by the tendril; (b) all the nodes have leaf‐opposed tendrils. The tendril, like a leaf, is a lateral product of the apical meristem of the shoot. A leaf opposite a tendril is initiated earlier than the tendril. Anticlinal and periclinal divisions in the second and/or third layer of the peripheral meristem of the shoot apex initiate the tendril. The procambium of the tendril first appears towards its abaxial side. Vascularization of the tendril is independent of the axillary bud of the next node below. The positional relationship of the nodal plate vis‐à‐vis the leaf‐opposed tendril shows that the tendril and the leaf belong to the same node. Histological evidence does not show the uplifting of the tendril to the next node above during internodal differentiation. Ontogenetic and morphologic correlation and homology between the inflorescence and the tendril do not substantiate that the tendril in the Vitaceae is an organ sui generis. All available evidence indicates that the tendril is an extra‐axillary lateral branch.
THE TRANSPORT OF AUXIN AND REGENERATION OF XYLEM IN OKRA AND PEA STEMS
Authors: Thompson Neal P.
Published: January 2018

Internodes were isolated from okra and pea plants grown from seed under controlled conditions. Isolated internodes were treated apically or basally with IAA‐C14 or 2,4‐D‐C14 and several vascular bundles were severed in the middle of the internodes. Transport of auxins was basipetally polar, IAA moving with greater facility than 2,4‐D. Apically applied auxin stimulated vascular regeneration in the wound area; basally applied auxin did not, but radioactivity from basally applied IAA reached the wound. This suggests that the path of transport or mode of presentation to cells is important unless basally and apically applied auxin are metabolized differently.
THE MORPHOLOGY AND RELATIONSHIPS OF BARBEYA OLEOIDES
Authors: Dickison William C. , Sweitzer Edward M.
Published: January 2018

Barbeya, a monotypic genus of dioecious, arborescent dicotyledonous plants from northeast Africa and adjacent Arabia, is usually regarded as having affinities within the Urticales. It is placed either in the Ulmaceae or segregated as a closely related, monotypic family. Leaves are opposite, exstipulate, and vascularized by a single, crescent‐shaped trace from a unilacunar node. Wood anatomy indicates specialization at about the same level as other Urticales. Sieve tube elements of the secondary phloem exhibit highly oblique, compound sieve plates which indicate a low level of evolutionary advancement. The vascularity of the flower is described and compared with other Urticales. Pollen is tricolporate. The relationships of the genus to Moraceae, Ulmaceae, Urticaceae, and Eucommiaceae are discussed. The totality of anatomical and morphological evidence supports the retention of the family Barbeyaceae.
THE RELATIONSHIP OF XYLEM MATURATION TO THE ABSORPTION AND TRANSLOCATION OF P32
Authors: Burley J. William A. , Nwoke Festus I. O. , Leister Geoffrey L. , Popham Richard A.
Published: January 2018

Techniques were developed to supply radioactive phosphorus to specific regions of the roots of corn and to ascertain the extent of functional xylem. The data support the view that all regions of the root are effective in absorbing phosphorus but translocation of the absorbed phosphorus to the shoot was correlated with the presence of functional xylem in the region where phosphorus was supplied.
STRUCTURE, DEVELOPMENT, AND TAXONOMY IN THE GENUS LOPHOPHORA
Authors: Boke Norman H. , Anderson Edward F.
Published: January 2018

Structural and developmental data indicate that Lophophora (Cactaceae) should be retained as a genus, which appears to be most closely related to Thelocactus (sensu lato). Within Lophophora morphological differences suggest that two species should be recognized. In the extensive northern population (Texas along the Río Grande to San Luis Potosí in Mexico) the tubercles are usually arranged as distinct ribs or elevated podaria, whereas in the restricted southern population (limited to the Mexican State of Querétaro) podaria and ribs are poorly developed or lacking and there are also differences in pollen structure. We believe that these two populations should be recognized as distinct species, L. williamsii and L. diffusa, respectively. We further believe that the latter represents the ancestral type.
THE DEVELOPMENTAL ANATOMY OF OPUNTIA BASILARIS II. APICAL MERISTEM, LEAVES, AREOLES, GLOCHIDS
Authors: Freeman Thomas P.
Published: January 2018

The shoot apex of Opuntia basilaris Engelm. & Bigel. shows zonation during the second day of growth. Rapid development of the shoot is characterized by the appearance of leaf primordia during the third day of growth and the initiation of areole meristems in seedlings 4 days old. Leaves are not typically dicotyledonous and consist of cells relatively uniform in size and compactly arranged. Areole meristems are similar to the shoot apical meristem and should be interpreted as lateral buds. Leaves and glochids exhibit many similarities during ontogeny.
INTERCHANGE HETEROZYGOSITY IN DIPLOID INTERSPECIFIC HYBRIDS IN GRINDELIA (COMPOSITAE)
Authors: Dunford Max P.
Published: January 2018

Some interspecific hybrids between geographically separated diploid taxa of Grindelia have meiotic configurations which indicate interchange heterozygosity, while others do not. Hybrids between G. procera Greene, G. hallii Steyermark, and G. camporum var. davyi (Jepson) Steyer‐mark (all from California) have 6II***, as do those between G. oxylepis var. eligulata Steyermark (Mexico) and G. squarrosa (Pursh) Dunal (Utah and New Mexico). When G. procera, G. camporum var. davyi, and G. hallii are crossed to G. oxylepis var. eligulata the hybrids have 4II and 1IV as do hybrids between G. oxylepis var. eligulata and G. havardii Steyermark (New Mexico). The G. procera × G. havardii and G. camporum var. davyi × G. havardii hybrids had a maximum configuration of 2II and 2IV, which indicates the interchanges in the genomes of the California diploids and G. havardii do not involve the same chromosomes. Hypothetical chromosome end arrangements and names for the respective genomes, based on G. oxylepis as a standard, are presented. These data corroborate a previously published phylogenetic scheme of the genus based on morphological, ecological, and distributional studies.
ALLOCHYTRIDIUM EXPANDENS, GEN. ET SP. N.: GROWTH AND MORPHOLOGY IN CONTINUOUS CULTURE
Authors: Salkin Ira F.
Published: January 2018

A new technique for describing members of the Chytridiales is presented in this discussion of a new fungus, Allochytridium expandens. Through the adaptation of a Coleman mammalian tissue culture perfusion system, continuous observations of individual developing thalli were made under controlled experimental conditions. Furthermore, the organism's growth in this controlled environment was compared to its morphology and development on agar and natural substrata. These studies revealed that Allochytridium was clearly distinguished from other members of the subfamily Chytridioideae by the formation of its sporangium from an expansion of the germ tube and the fusion of the sporangium with the zoospore cyst. In addition, variations in the size of the zoospore, cyst, and lipoid bodies; pigmentation of the zoospore cyst; and developmental pattern were found to be correlated with the substratum upon which the organism was grown.
THE NATURAL AFFINITY OF THE CARBONIFEROUS SEED, CALLOSPERMARION
Authors: Stidd Benton M. , Hall John W.
Published: January 2018

A seed of Callospermarion pusillum has been found attached to a long slender stalk. Significant features of the seed based upon additional specimens are described. Secretory cavities in the integument are similar to those in the stem of Callistophyton poroxyloides and the fertile foliage bearing the pollen organ Callandrium callistophytoides. Vesicaspora sp. pollen similar to that found in Callandrium, occurs in the pollen chamber. Callistophyton, Callandrium, and Callospermarion are considered to represent the detached organs of a new seed fern family, Callistophytaceae.
TRIPLOID AND TETRAPLOID HYBRIDS FROM DIPLOID X TETRAPLOID CROSSES IN GRINDELIA (COMPOSITAE)
Authors: Dunford Max P.
Published: January 2018

Crosses between the diploids G. oxylepis var. eligulata Steyermark (Mexico) and G. havardii Steyermark (New Mexico) and the tetraploid G. aphanactis Rydb. (New Mexico) were made. With G. aphanactis as the pistillate parent and G. havardii as the pollen parent a triploid hybrid was obtained in which the maximum meiotic configuration observed was 6m. The plant was 10 % fertile. Two triploid hybrid plants were also obtained when G. aphanactis was used as the pistillate parent and G. oxylepis var. eligulata was the pollen parent. One plant was about 20 % fertile and the other had a maximum configuration of 3II + 4III. The reciprocal cross produced a tetraploid which had a maximum configuration of 6II + 3IV and was 8 % fertile. The tetraploid plant undoubtedly resulted from the union of an unreduced gamete from the 2n parent and a normally reduced gamete from the tetraploid. Morphology of the hybrids was usually intermediate when compared with the parental species, although some characters in the triploids were those of the diploid parent. Chromosome end arrangements of the respective genomes and putative pairing relationships are presented and phylogenetic implications are discussed. It is concluded that G. aphanactis is more closely related to G. havardii than to G. oxylepis var. eligulata.
COMPARATIVE MORPHOLOGY OF THE COCHLOSPERMACEAE. II. ANATOMY OF THE YOUNG VEGETATIVE SHOOT
Authors: Keating Richard C.
Published: January 2018

The generic scope and systematic position of the Cochlospermaceae were evaluated using observations from the anatomy of the stem, node, and leaf. There are few basic differences in vegetative anatomy between Amoreuxia and Cochlospermum. Secretory cells and canals, dilated phloem rays, and banded phloem are unifying features. Mature nodal anatomy is 3‐trace, trilacunar, and the leaves of both genera have elongate, unicellular, branched idioblasts in the spongy mesophyll. Bixa has some features in common with Amoreuxia and Cochlospermum but is distinctive in vascularization of the petiole, leaf anatomy, and vestiture. Rhopalocarpus is quite different from the above genera, and its placement in a separate family is justified on anatomical grounds. The Cochlospermaceae, consisting of Amoreuxia and Cochlospermum, seem more closely related to the Sterculiaceae and Tiliaceae than to the Flacourtiaceae, Cistaceae, or Violaceae.
CYTOLOGICAL STUDIES OF THE TELIAL STAGE OF CEROTELIUM DICENTRAE
Authors: Berkson Burton M.
Published: January 2018

The cytology of telial germination and basidial meiosis is followed. A filament extends from the chromosomes to the nuclear membrane during zygotene, and various types of metaphase figures, nucleolus‐organizing chromosomes, and distinct centrioles occur. Clamp connections are not associated with the dikaryotic mycelium of this fungus, and it is suggested that the centriole is involved in nuclear motility.
DEVELOPMENT OF PERIPHERAL VACUOLES IN PLANT CELLS
Authors: Mahlberg Paul G. , Olson Kenton , Walkinshaw Charles
Published: January 2018

The vacuolar apparatus of various plant cells consists of two distinct features: the large central vacuole and peripheral vacuoles which are derived from invaginations of the plasma membrane. Peripheral vacuoles are conspicuous structures in both living and fixed hair or filament cells of Tradescantia virginiana. They occur as spherical structures along the inner boundary of the peripheral cytoplasm and can be recognized as projections into the central vacuole. These structures are variable in size and number within a cell and can represent a significant proportion of the volume of the vacuole. Peripheral vacuoles most frequently are observed in motion with the streaming cytoplasm although their velocity is usually somewhat slower that that of the cytoplasmic organelles. Ultrastructural studies show two closely approximated membranes, one for each vacuole, in areas where a peripheral vacuole projects into the central vacuole. These are separated by an intermembrane zone continuous with the peripheral cytoplasm. The movement of organelles over the perimeter of the peripheral vacuole is presumed to occur along this intermembrane zone. The internal area of the peripheral vacuoles may appear empty although some contain a vesicular content of unknown origin and function.
INCOMPATIBILITY AND THE POLLEN ECONOMY OF JEPSONIA PARRYI
Authors: Ornduff Robert
Published: January 2018

Jepsonia parryi (Saxifragaceae) has heterostylous flowers and is strongly self‐incompatible. Pin flowers have long styles, large stigmas, short stamens, and numerous, small pollen grains with finely sculptured walls. Thrum flowers have short styles, small stigmas, long stamens, and fewer, larger pollen grains with coarsely sculptured walls. Pin plants and thrum plants occur in a 1:1 ratio in field populations. Although the insect pollinators of J. parryi transfer ample compatible pollen to pin and thrum stigmas to account for full seed production, much of the pollen deposited on stigmas is incompatible. Analysis of the pollen deposits on stigmas collected from field populations indicates that compatible “legitimate” pollination of pin and thrum flowers is essentially random and is not obviously aided by floral dimorphism. It is suggested that although heterostyly had a positive adaptive value in the past evolutionary history of Jepsonia it is no longer adaptive under the present pollination regime, although it is maintained because of its strong genetic fixity.
EFFECTS OF ESTER CHAIN LENGTHS ON THE GROWTH REGULATING ACTIVITY OF 2,3‐DICHLOROBENZOATES
Authors: Steffens G. L. , Buta J. G.
Published: January 2018

The activities of the n‐C1 through n‐C10 esters of 2,3‐dichlorobenzoic acid (DCBA) were tested as inhibitors of terminal growth of Xanthi‐nc tobacco plants. The C2 and C3 esters were the most active as emulsions at 2.5 × 10–2m. They retarded growth of the entire bud for 10 days and longer upon repeated applications. Treatment of plants with 2,3‐DCBA or its potassium salt at dosages up to 5 × 10–2m caused only slight growth regulating effects. In a dosage‐response study, it was clearly shown that the C3 ester inhibited stem elongation but the C8 ester did not. The striking differences in plant growth due to treatment with 2,3‐DCBA esters of different alkyl chain lengths are discussed in terms of penetration, ester hydrolysis, and growth factor interactions.
SECRETORY CELLS OF LILY PISTILS. I. FINE STRUCTURE AND FUNCTION
Authors: Rosen Walter G. , Thomas Herbert R.
Published: January 2018

The fine structure of the cells which line the canal of Lilium longiflorum pistils confirms the secretory function which has been ascribed to them. The cells differ in structure from the secretory cells which cover the stigma surface and are therefore referred to as canal cells rather than stigmatoid cells. Their most striking feature is an elaborate wall, 8–14 μ in maximum depth, on the side facing the canal, which with associated structures, we term the secretion zone. Pollination, which triggers chemotropic activity in the style and secretory activity in the canal cells, is not correlated with marked changes in the fine structure of the canal cells. The canal cells appear to fit well into that category which Gunning and Pate have termed “transfer cells.”
ANGIOSPERM WOOD FROM THE UPPER CRETACEOUS OF CENTRAL CALIFORNIA. III
Authors: Page Virginia M.
Published: January 2018

Five species representing five genera are described. The specimens are part of a collection of woods from the Upper Cretaceous Panoche Formation of central California. Lardizabaloxylon cocculoides sp. n. resembles wood of those species of Cocculus of the Menispermaceae lacking included phloem. Carpinoxylon ostryopsoides sp. n. is similar to the wood of the Coryleae of the Betulaceae, particularly Ostryopsis. Riboidoxylon cretacea gen. et sp. n. is similar to the wood of Ilex of the Aquifoliaceae and also falls within the range of variation of the woods of the two closely related families, the Grossulariaceae and the Escalloniaceae. Mulleroxylon eupomalioides sp. n. falls well within the range of variation of the woods of the Magnoliaceae.
THE EFFECT OF LIGHT INTENSITY AND TEMPERATURE ON PLANT GROWTH AND CHLOROPLAST ULTRASTRUCTURE IN SOYBEAN
Authors: Ballantine J. Elizabeth M. , Forde B. J.
Published: January 2018

Soybean plants grown in controlled environment cabinets under light intensities of 220 w/m2 or 90 w/m2 (400–700 nm) and day to night temperatures of 27.5–22.5 C or 20.0–12.5 C in all combinations, exhibited differences in growth rate, leaf anatomy, chloroplast ultrastructure, and leaf starch, chlorophyll, and chloroplast lipid contents. Leaves grown under the lower light intensity at both temperatures had palisade mesophyll chloroplasts containing well‐formed grana. The corresponding leaves developed under the higher light intensity had very rudimentary grana. Chloroplasts from high temperature and high light had grana consisting of two or three appressed thylakoids, while grana from the low temperature were confined to occasional thylakoid overlap. Spongy mesophyll chloroplasts were less sensitive to growth conditions. Transfer experiments showed that the ultrastructure of chloroplasts from mature leaves could be modified by changing the conditions, though the effect was less marked than when the leaf was growing.
GENETIC EVIDENCE FOR ZYGOTIC MEIOSIS IN PHYTOPHTHORA CAPSICI
Authors: Timmer L. W. , Castro J. , Erwin D. C. , Belser W. L. , Zentmyer G. A.
Published: January 2018

Variation of several traits among single‐oospore isolates of the heterothallic oomycete, Phytophthora capsici, was studied to determine genetically the place of meiosis in the life cycle. Low percentages of met– offspring were recovered from two crosses of met– X prototrophic isolates. Arg– cultures were also recovered from the crosses indicating the possible presence of a suppressed arg– gene in one of the parental cultures. Three arg– X met– crosses yielded all four of the possible classes of offspring. Thus meiosis was either zygotic or, if gametangial, the original parental cultures must have been heterozygous at both the arg and met loci. However, when these parental cultures were crossed, only prototrophic offspring were recovered. A ratio of 3 prototrophs: 1 met– was obtained from cross R in which two prototrophic offspring from a previous arg– X met– cross were mated. This indicated the presence of a suppressor of met– and may explain the low recovery of met– offspring from earlier crosses. From backcrosses of met– offspring from this cross to the A2 prototrophic parent, ratios close to the expected 1:1 were obtained. When the A1 prototrophic parent of cross R (K‐10) was crossed to an A2 prototrophic isolate, met– offspring were again recovered, which indicated that K‐10 carried a suppressed met deficiency. In two crosses of streptomycin‐resistant (Sr) X sensitive (Ss) isolates, ratio of 108 Ss: 14 Sr and 84 Ss:14 Sr were obtained. Although 1:1 ratios would have been expected if meiosis were zygotic, segregation of Ss and Sr in the F1 generation indicated that gametangial meiosis was unlikely. Segregation of the A1 and A2 mating types in all crosses also indicated that meiosis was zygotic in P. capsici. Possible control of mating type by a single pair of alleles, by plasmids, and by more complex mechanisms is discussed in relation to the mating type ratios obtained.
THE COMPARATIVE MORPHOLOGY OF THREE CYLINDROPUNTIAS
Authors: Hamilton Margaret W.
Published: January 2018

The three species discussed in this article have at one time been considered congeneric in Grusonia. Present evidence indicates the three are specifically distinct and should be congeneric, but as cylindropuntias in Opuntia. There seems to be no valid reason for retaining the genus Grusonia. Except for branching and decomposition, Opuntia bradtiana and O. santamaria are more similar anatomically and morphologically than O. kunzei is to either of the two.
PLEIOTROPIC EFFECTS ON SEED DEVELOPMENT OF THE INDETERMINATE GAMETOPHYTE GENE IN MAIZE
Authors: Kermicle J. L.
Published: January 2018

Not more than half the seeds borne by maize plants of the W23 inbred strain, homozygous for a mutant gene termed “indeterminate gametophyte” (ig), develop normally. The remainder exhibit polyembryony (6 %), heterofertilization (7 %), elevated ploidy level of the endosperm (45 %), or other less frequent anomalies. The ig effects were identified and characterized by chromosome counts and genetic tests. Twins were regularly found to be diploid and concordant for heterozygous marker genes introduced maternally. When the marker genes were introduced paternally, twins frequently were non‐concordant, or the embryo and endosperm phenotypes did not correspond. The proportion of the various types and the absence of conjoined embryos indicated that, although identical in their maternal inheritance, the twins were regularly dizygotic. Those twins identical in paternal inheritance probably originate from the fertilization of two genetically identical eggs by the two sperm of one male gametophyte. When ig ig compared to normal diploid plants were pollinated by tetraploids, the proportion of plump seed formed was markedly increased. Evidently this result is the consequence of elevation of the endosperm ploidy level by the ig gene. The ig gene thus appears to interfere with differentiation of the components of the female gametophyte so that the number of eggs and polar nuclei, instead of being one and two, is indeterminate.
CHROMOSOME RACES IN CLAYTONIA LANCEOLATA (PORTULACACEAE)
Authors: Stewart Dennis , Wiens Delbert
Published: January 2018

Chromosome numbers of n = 8, 12, and 16 were determined for 11 populations of Claytonia lanceolata occurring in the southwestern Rocky Mountains of Utah. No evidence of the wide infra‐populational variation of chromosome numbers known in the related eastern species, C. virginica, was observed. The chromosome numbers in C. lanceolata probably evolved from a base number of x = 8. Diploids(n = 8) apparently produced tetraploids (n = 16) of putative autoploid origin. Pairing relationships, including the presence of univalents, bivalents, and trivalents, suggest the chromosome numbers of n = 12 are triploids derived from natural hybridization between diploids and tetraploids. Higher chromosome numbers previously reported in C. lanceolata from Colorado, and presumably based on x = 12, can be explained by subsequent polyploid increases in the triploids. The diploid and tetraploid populations analyzed in this study occupy different ecological habitats. The diploids occur at lower elevations along the foothills, whereas the tetraploids are restricted to higher montane and sub‐alpine elevations. The triploids were discovered at intermediate elevations.
GERMINATION ECOLOGY OF PHACELIA DUBIA VAR. DUBIA IN TENNESSEE GLADES
Authors: Baskin Jerry M. , Baskin Carol C.
Published: January 2018

The germination characteristics of a population of the winter annual Phacelia dubia (L.) Trel. var. dubia from the middle Tennessee cedar glades were investigated in an attempt to define the factor(s) regulating germination in nature. Factors considered were changes in physiological response of the seeds (after‐ripening), temperature, age, light and darkness, and soil moisture. At seed dispersal (late May to early June), approximately 50 % of the seeds were non‐dormant but, would germinate only at low temperatures (10–15 C). As the seeds aged from June to September, there was an increase in rate and total percent of germination at 10, 15, and 20 C, and the maximum temperature for germination increased to 25 C. Little or no germination occurred at the June, July, and August temperatures in 0‐ to 2‐month‐old seeds, even in seeds on soil that was kept continuously moist during this 3‐month period. At the September, October, and November temperatures 3‐ to 5‐month‐old seeds germinated to high percentages. In all experiments seeds germinated better at a 14‐hr photoperiod than in constant darkness. Inability of 0‐ to 2‐month‐old seeds to germinate at high summer temperatures allows P. dubia dubia to pass the dry summer in the seed stage, while increase in optimum and maximum temperatures for germination during the summer permits seeds to germinate in late summer and early fall when conditions are favorable for seedling survival and eventual maturation.
MORPHOLOGY OF NECTRIA HAEMATOCOCCA
Authors: Hanlin Richard T.
Published: January 2018

Ascocarp development in Nectria haematoccocca begins with the formation of deeply staining coils as lateral branches of the vegetative hyphae. As these coils develop into multicellular, multi‐nucleate ascogonia, they are surrounded by a pseudoparenchymatous envelope. During ascocarp development an apical meristem produces cells that elongate downward into the centrum, forming long, filamentous, apical paraphyses. When fully developed the cells of the apical paraphyses swell, producing a tissue that is pseudoparenchymatous in appearance. The ascogonium proliferates to form a layer of multinucleate ascogenous cells across the base of the ascocarp. Asci form from the ascogenous cells by means of croziers. The asci grow up among the apical paraphyses, which disintegrate as the ascocarp matures. This pattern is typical of the Nectria‐type of development, indicating that this species belongs in the Hypocreales.
THE PROTEIN COMPOSITION OF NUCLEAR CRYSTALS IN LEAF CELLS
Authors: Weintraub M. , Ragetli H. W. J. , Schroeder Bea
Published: January 2018

The chemical composition of perinuclear crystals of Lychnis chalcedonica and intranuclear crystals of Dianthus barbatus in leaf tissue embedded in glycol methacrylate was tested by differential enzyme digestion of ultra‐thin sections. The Lychnis crystals were digested readily by pepsin but with great difficulty and never to completion by trypsin. The Dianthus crystals were rapidly and completely digested by pronase; inconsistently and with difficulty by pepsin; and were unaffected by trypsin. Pre‐incubation with water increased the effectiveness of pepsin digestion. Neither RNase nor DNase had any effect, either alone, or when preceded or followed by the proteinases. It was concluded that the Lychnis crystals are composed of protein that is probably high in aromatic amino acid content, and possibly low in the basic amino acids arginine and lysine. The Dianthus crystals also seem to be protein, but because of their amino acid composition or conformation, and possibly because of complex reactions with the fixative, these crystals are not readily hydrolyzed by pepsin and trypsin.
ANALYSIS OF N‐ALKANES FROM THREE SPECIES OF CLARKIA
Authors: Tin Wa , Vasek F. C. , Scora R. W.
Published: January 2018

Sixteen n‐alkanes were isolated and identified from the herb Clarkia unguiculata, fourteen from C. exilis and seven from C. tembloriensis. These alkanes ranged from C20H42 to C35H72. In all three taxa, the odd numbered alkanes were generally present in greater quantities than even numbered ones, which is similar to the alkane patterns of Monarda that were observed in our laboratories. Clarkia tembloriensis has a characteristically high percentage (95%) of the C20 alkane.
ADDITIONAL STUDIES ON THE MORPHOLOGY OF BLIND VEIN‐ENDINGS IN THE LEAF OF CIRCAEASTER AGRESTIS
Authors: Foster Adeiance S.
Published: January 2018

An intensive study has been made of the general structure and varied topography of blind vein‐endings in the dichotomous venation of Circaeaster agrestis Maxim. The venation patterns of leaves of plants collected in various parts of the geographical range of this species as well as the vasculature of leaves of specimens raised in a growth‐chamber have been studied and compared. Blind endings may be associated in various ways with the branches of simple terminal vein‐dichotomies and are either intrusive or extrusive in position. Descriptions are also given of the various relations between intrusive and extrusive blind endings and the more complex asymmetrical or symmetrical dichotomized vein‐systems found in various parts of the lamina. “Unlike the main veins of the leaf, which consistently vascularize corresponding marginal teeth, a blind vein‐ending usually extends toward or terminates directly below the sinus between two adjacent marginal teeth. There appears to be no correlation between the occasional formation of rudimentary marginal teeth and the development of blind vein‐endings. It is concluded that a well‐developed unbranched blind ending morphologically represents one of the vascular strands derived from a normal vein‐dichotomy. The smaller blind endings, associated with terminal vein‐dichotomies, are more difficult to interpret and possibly may represent “supernumerary” veinlets. The parallelism in topography between the blind endings in the leaves of Kingdonia and Circaeaster is briefly discussed, and attention is also drawn to the occurrence of similar blind endings in the dichotomous venation patterns of perianth‐segments and petals of certain angiosperms.
CYTOLOGICAL AND CHEMICAL VARIATION IN PITYROGRAMMA TRIANGULARIS
Authors: Smith Dale M. , Craig Sally P. , Santarosa Janet
Published: January 2018

The cytology and chemistry of three populations of the species complex Pityrogramma triangularis from Santa Barbara County, California, were studied. The basic chromosome number of these ferns is x = 30, and there are diploids, triploids, and tetraploids. Although gross morphology in the plants is similar, four chemical types are observed when extracts of the external frond pigments are analyzed. Ten of the twelve possible combinations of ploidy level and pigment types have been found. Correlations of spore condition, cytology, and chemistry which indicate either an autotetraploid or allotetraploid derivation of the complex are discussed.
THE STIGMATIC SECRETION OF THE SWEETPOTATO
Authors: Martin Franklin W. , Telek Lehel
Published: January 2018

The stigmatic exudate of sweetpotato, when removed with organic solvents, consisted chiefly of lipid and phenolic compounds. Only traces of sugar were obtained. The esterified lipids were similar in chain length to capric and lauric acids. The two prinicpal phenolic compounds have UV absorption peaks, and bathochromic shifts on ionization with NaOH similar to those of esters of caffeic acid. On acid hydrolysis, caffeic acid was obtained from these and from three minor phenolic compounds. From two of the minor phenolic compounds, glucose was released by hydrolysis. The phenolic content of stigmas increased up to 20–24 hr before anthesis, and then gradually decreased. Neither compatible nor incompatible pollination affects the amount or composition of the stigmatic exudate.
STUDIES IN THE QUERCUS UNDULATA COMPLEX. V. THE TYPE OF QUERCUS UNDULATA
Authors: Tucker John M.
Published: January 2018

The original material of Quercus undulata Torr. was collected by Edwin James on Major Long's expedition to the Rockies in 1820. The type locality was stated by Torrey as “sources of the Canadian and the Rocky Mountains.” Evidence is here adduced that the type locality is on Ute Creek, a tributary of the Canadian River, in northeastern New Mexico. The site was found to harbor Q, gambelii, Q. grisea, and numerous intermediate hybrid forms. Certain of the latter match the type of Q. undulata quite closely. The type sheet includes three elements—a branchlet regarded as the type, a twig of Q. grisea, and an isolated acorn of Q. havardii. Torrey's new species was illustrated by a figure which does not closely resemble the type, but which is more similar to Q. havardii. The acorn of Q. havardii on the type sheet must have been collected in the Texas Panhandle or western Oklahoma, where Long's party would have encountered this species. In my opinion, Torrey's figure could have been drawn from a specimen collected there, which, except for the isolated acorn, has since been lost.
ORIGIN AND DEVELOPMENT OF PLASMA MEMBRANE DERIVED INVAGINATIONS IN VINCA ROSEA L.
Authors: Mahlberg Paul , Olson Kenton , Walkinshaw Charles
Published: January 2018

The plasma membrane in immature cells is often irregular in contour. Some irregularities become conspicuous folds that continue to enlarge into the cytoplasm. These invaginations may continue to increase in size and typically expand into the central vacuole. Sections show two closely parallel membranes in areas where the invagination projects into the vacuole. A narrow layer of cytoplasm may traverse the intermembrane zone between the membranes. The interior of an invagination may lack obvious content, or may be occupied by a fibrous material, or vesicular and tubular structures. The small vesicles bound by a single membrane appear to be derived from a projection formed most frequently near the orifice of the invagination. The origin of large vesicles and tubules possessing one membrane is not certain although they may arise by the fusion of several small vesicles. Alternatively, tubules, once formed, often possess constrictions along their length which suggest that these structures may become divided into a series of smaller vesicles. There is some evidence that cytoplasmic vesicles may fold into the membrane of the invagination and subsequently be pinched off into the interior of the sac. These vesicles are bounded by two membranes. Vesicles frequently contain an electron‐dense content more or less homogeneous in composition and unlike the typical ribosomal character of the cytoplasm. The function of the invaginations or their content remains to be elucidated.
CHROMOSOME NUMBERS IN UMBELLIFERAE. IV.
Authors: Constance Lincoln , Chuang Tsan‐Iang , Bell C. Ritchie
Published: January 2018

Chromosome numbers are reported for 167 collections representing 100 taxa of Umbelliferae. More than four‐fifths of the counts apply to members of subfamilies Hydrocotyloideae (29) and. Saniculoideae (50); the remaining 21 belong to Apioideae. Chromosome numbers of plants belonging to 68 taxa are published here for the first time; chromosome numbers are verified for 23 taxa; and chromosome numbers differing from those published previously are reported in nine instances. No chromosome counts have previously been reported for 19 of the genera included. Polyploidy has been established for Azorella, Mulinum, Coaxana, Enantiophylla, and Tiozimia.
STRUCTURE AND HISTOGENESIS OF THE EMBRYO OF ACER SACCHARINUM. I. EMBRYO SAC AND PROEMBRYO
Authors: Haskell D. A. , Postlethwait S. N.
Published: January 2018

Structure of the embryo sac and development of the proembryo of Acer saccharinum L. are described from paraffin sections. The embryo sac is monosporic and identical to the 8‐nucleate Polygonum type in all respects. Cell, nuclear, and nucleolar sizes are constant within a narrow range and sharply distinctive for all components of the mature sac. Polar nuclei fuse before double fertilization. The longitudinal axis of symmetry of the egg, zygote, and proembryo is variously oriented with respect to the longitudinal axis of the embryo sac and is determined by the point of attachment of the presumptive egg cell to the sac wall. Subsequent development of the young embryo is responsive to aligning factors within the embryo sac and is collateral with the longitudinal axis of the sac. The first segmentation is transverse to the longitudinal axis of the zygote; the second and third are transverse in the basal cell and longitudinal in the apical cell. Descendants of ci form a short irregular suspensor; ca and m give rise to the apical and basal halves respectively of the embryo proper. The contribution of the proembryonic tiers to the older embryo differs in embryos of different initial orientation. Distribution and orientation of mitosis in the proembryo are shown in two accumulation maps.
EFFECT OF SALINITY ON POLLEN I. POLLEN VIABILITY AS ALTERED BY INCREASING OSMOTIC PRESSURE WITH NaCl, MgCl2, and CaCl2
Authors: Reddy P. R. , Goss James A.
Published: January 2018

Petunia (Petunia hybrida Vilm. cv. ‘Snowstorm') plants were grown in saline solution (NaCl, MgCl2, and/or CaCl2) of 0, 1, 2, and 3 bars osmotic pressures. Pollen viability was tested by tetrazolium chloride staining and by germination (by the hanging drop method, using 15 % sucrose and 0.01 % boric acid as the nutrient medium, at 27 ± 1 C). Pollen viability decreased with increased salinity. Pollen from plants grown in single salt solutions of NaCl, MgCl2, and CaCl2 (each at 0, 1, 2, or 3 bars osmotic pressure) was germinated in base culture medium. Pollen viability decreased more with NaCl than with MgCl2 or CaCl2. In vitro studies of the effects of three salts, viz., NaCl, MgCl2, and CaCl2, on pollen germination and tube growth showed that NaCl inhibited germination and pollen tube growth more than did MgCl2 or CaCl2. MgCl2 was least injurious, and even promoted tube growth at 0.5 and 0.75 bars osmotic pressure. Adding low concentrations of MgCl2 reduced the toxic effect of NaCl and increased the percentage of germination. CaCl2 reduced the effect of NaCl less than did MgCl2. We conclude that specific ion effects were more important than osmotic pressure.
SOME FACTORS INFLUENCING THE FREQUENCY OF BARK LICHENS IN NORTH CENTRAL OKLAHOMA
Authors: Adams David B. , Risser Paul G.
Published: January 2018

Frequency data for 21 species of corticolous macrolichens in 14 upland forest stands were analyzed in relation to a number of environmental variables, using correlation and ordination techniques. Results indicate the predominance of macroclimate—especially precipitation—in determining the frequency behavior of bark lichens within the limited area of this study. Less important, though significant, factors include the frequency of preferred host‐tree species, the age structure, and tree‐species composition of stands.
PALYNOLOGY AND SYSTEMATICS OF CUPHEA (LYTHRACEAE). II. POLLEN MORPHOLOGY AND INFRAGENERIC CLASSIFICATION
Authors: Graham Shirley A. , Graham Alan
Published: January 2018

Present taxonomic studies in Cuphea (Lythraceae) reveal that a broad spectrum of biosystematic data is required for an understanding of evolutionary relationships among this large and complex group of species. As part of these studies pollen data have proven to be of greater pragmatic value than is frequently true for more stenopalynous taxa. A survey is made of pollen types in 160 species of Cuphea with special reference to specific taxonomic problems, and a summary presented of points at which pollen data can profitably contribute to taxonomic revision of the genus.
A SYNOPSIS OF THE GENUS CHARA, SERIES GYMNOBASALIA (SUBSECTION WILLDENOWIA RDW)
Authors: Proctor Vernon W. , Griffin Dana G. , Hotchkiss Arland T.
Published: January 2018

The seriesGymnobasalia, a sharply differentiated subgeneric complex within the genusChara, consists of at least seven morphologically distinct species. All seven species are reproductively isolated from one another. No evidence of even limited hybridization between the seven was encountered. The two dioecious members of the complex occupy restricted and, possibly partially overlapping ranges in South America. Monoecious members are in general more widely distributed but still appear to have originated in Central or South America. The holotype ofC. zeylanicaKleinexWilldenow was examined and found to be tetrascutate. For the abundant and widely distributed monoecious‐conjoined, octoscutate member of the complex, previously shown to be distinct fromC. zeylanica, the earlier nameC. haitensisTurpin is here validated.Chara foliolosaMuhl.exWilldenow is considered conspecific with, but to hold priority over,C. sejunctaBraun.
A SURVEY FOR BENZOIC AND CINNAMIC ACIDS OF THE CYCADACEAE
Authors: Wallace James W.
Published: January 2018

A survey for cinnamic and benzoic acids in 22 species representing the 10 extant genera of the Cycadaceae revealed the presence of p‐coumaric, caffeic, ferulic, p‐hydroxybenzoic, protocatechuic, and vanillic acids in all of the species. Two genera had detectable quantities of 2,4‐dihydroxy‐benzoic acid. In addition sinapic acid was detected in two genera, indicating that it has a wider distribution in vascular plants than was previously indicated.
A COMPARISON OF VARIABILITY IN UTRICULARIA CORNUTA AND UTRICULARIA JUNCEA
Authors: Kondo Katsuhiko
Published: January 2018

Although Utricularia cornuta Michx. and U. juncea Vahl, sympatric in the southeastern United States, have been considered conspecific by various authors, the present biosystematic approach shows them to be separate species. The taxa are seasonally isolated. While both have the same chromosome number (n = 9), strong internal isolation is apparent since artificial hybrids cannot be produced by standard methods. In Utricularia cornuta the mean values of characters studied quantitatively are much higher than those of U. juncea though the extremes of the ranges may overlap. Utricularia juncea has both cleistogamous flowers and chasmogamous flowers while U. cornuta has only chasmogamous flowers. The flowers are self‐fertile and apparently are usually, if not always, self‐pollinated, even though they are highly adapted to specialized insect pollinators.
ELECTRON PROBE ANALYSIS OF SILICON AND OTHER ELEMENTS IN LEAF EPIDERMAL CELLS OF THE RICE PLANT (ORYZA SATIVA L.)
Authors: Soni Sarvjit L. , Kaufman Peter B. , Bigelow Wilbur C.
Published: January 2018

By means of electron probe analysis, the effects of significant amounts of accumulation of silicon on the accumulation of calcium, potassium, magnesium, manganese, phosphorous, iron, and sodium in the silica cells of rice leaves are described. The silica cells of both the surfaces of the leaf blade and leaf sheath were studied. Silicon accumulation in the silica cells appears to decrease the amount of accumulation of potassium on both the surfaces of the leaf blade and sheath. The effect of significant amounts of silicon accumulation on the accumulation of other elements in a particular cell varies in different organs or on different surfaces of the organ of the same plant. Magnesium, manganese, iron, and phosphorus could not be detected in the adaxial epidermis of the leaf sheath and magnesium and iron in the adaxial epidermis of the leaf blade. Manganese, magnesium, and phosphorus were not detected in the abaxial epidermis of the leaf blade nor iron in the abaxial epidermis of the leaf sheath. Sodium was not revealed in either surface of the leaf blade and leaf sheath. Possible mechanisms for the effects of silicon accumulation on the accumulation of these elements in rice leaf epidermal cells are discussed.
FLORAL PIGMENTATION STUDIES IN THE GENUS GOSSYPIUM. IV. EFFECTS OF DIFFERENT GROWING ENVIRONMENTS ON FLAVONOID PIGMENTATION
Authors: Parks C. R. , Sandhu S. S. , Montgomery K. R.
Published: January 2018

Petal extracts of Gossypium were analyzed chromatographically to determine if flavonoid constituents are modified by different environments. In the initial phase, fourteen inbred stocks from four species were grown in a plot that was replicated in five different localities ranging from the Mojave Desert to Raleigh, North Carolina. Petal samples were collected from each stock at each site, and chromatograms developed from these samples looked highly similar regardless of the locality of the growing site. In the second phase, two stocks were phytotron grown under a series of regimes in which daylength, temperature, and mineral nutrition were varied. Each stock showed very little floral flavonoid variation despite the growing conditions. A chromatographic survey of leaf extracts from these same phytotrongrown plants showed them to be much more variable. In cotton, flower petal constituents appear to be less variable than leaf constituents. The chemotaxonomic significance of these results are discussed.
INVESTIGATIONS OF NORTH AMERICAN CYCADEOIDS: EARLY OVULE ONTOGENY
Authors: Crepet W. L. , Delevoryas T.
Published: January 2018

Ovules on cones of the genus Cycadeoidea from the Cretaceous were found preserved at the pregametophytic stage of nucellar development. At this stage, the ovules are distinct from those of extant gymnosperms in that there is a greater degree of differentiation in both the integuments and the nucellus in Cycadeoidea. Linear clusters of three or four cells, which consistently occur in the middle of the nucellus, are interpreted to be the remains of linear tetrads of megaspores. This example of exceptional preservation allows, for the first time, a comparison of early ontogenetic events in a fossil seed with those of extant seeds.