bluuebunny/crossref_metadata_2025 huggingface dataset:
HISTOCHEMICAL LOCALIZATION OF ALCOHOL DEHYDROGENASE IN DEVELOPING BEAN SEEDS
Authors: Yeung Edward C. , Blackman Susan J.
Published: January 2018

Alcohol dehydrogenase activity can be readily localized within bean seeds using the tetrazolium method. In the seed coat, prior to the cotyledon stage of embryo development, staining was seen throughout, especially in the branched parenchyma cells and the integumentary tapetum. As the embryo entered the maturation stage, a gradual decrease in the staining intensity was observed throughout the seed coat. Embryos stained well at all stages of development. In the course of this investigation, a high activity of “nothing dehydrogenase” was observed. Since its activity could be inhibited by methylpyrazole, an ADH inhibitor, it is concluded that the nothing dehydrogenase activity is caused by alcohol dehydrogenase.
CHROMOSOME CYTOLOGY OF EUCHARIS, CALIPHRURIA, AND URCEOLINA (AMARYLLIDACEAE)
Authors: Meerow Alan W.
Published: January 2018

Karyotypes are presented for 19 taxa of Eucharis, Caliphruria, and Urceolina, a monophyletic group of Andean Amaryllidaceae within “infrafamily” Pancratioidinae Traub. All three genera are characterized by 2n = 46, the most common somatic number occurring in the “infrafamily.” Incidences of polyploidy are low. Only two tetraploid (2n = 92) species of Eucharis are so far known, E. bouchei and E. bonplandii, the northernmost species of E. subg. Eucharis. The 2n = 68 karyotype of E. amazonica is interpreted as triploid‐derived (3x – 1). Chromosomal heteromorphism is reported for C. subedentata. Karyotype data is analyzed with principal component analysis and unweighted pairgroup cluster analysis. In a number of cases, phenetic relationships among the karyotypes correlate with phenetic and cladistic relationships based on morphological data. Karyotype evolution among the three genera is discussed in the context of classical theories of karyotypic symmetry. Stability of chromosome number in Eucharis and related genera suggests that chromosomal evolution has proceeded via nonreciprocal interchanges between chromosomes and infrachromosomal structural change. In at least one case (E. bakeriana), rapid sympatric speciation may have been vectored by chromosomal change.
POLLINATION ECOLOGY OF A SEAGRASS, THALASSIA TESTUDINUM (HYDROCHARITACEAE), IN ST. CROIX
Authors: Cox Paul Alan , Tomlinson P. B.
Published: January 2018

The reproductive ecology of a dioecious Caribbean seagrass, Thalassia testudinum was studied in St. Croix, U.S. Virgin Islands. Flowering in Thalassia coincided with spring tides with anthesis and anther dehiscence in staminate plants occurring at night. As predicted by search theory, pollen is dispersed in negatively buoyant rafts of pollen grains (that superficially resemble strings of frog spawn) which are bound by a slime of apparent thecal origin. Dispersal of pollen is submarine and approximately two‐dimensional along the plane of the substratum. The stigmas on pistillate plants are linear, stiff, and densely papillate; they protrude from the mouth of the subtending leaf. Floral ratios of staminate to pistillate flowers were 60 to 1 with an average distance of 4.0 cm from pistillate flower to the closest staminate flowers. Populations included a high proportion of short shoots with numerous (> 100) leaf scars indicating ages for these axes of up to 3–4 years. Nonflowering shoots can be sexed and frequency of flowering can be assessed from scars of old inflorescences. Preliminary results suggest that there is no regular pattern of flowering, since the interval between flowering events is variable.
MORPHOLOGY AND DEVELOPMENT OF HYPERPLASIA ON CYSTOSEIRA OSMUNDACEA (PHAEOPHYTA) ASSOCIATED WITH HALOGUIGNARDIA IRRITANS (ASCOMYCOTINA)
Authors: Apt Kirk E.
Published: January 2018

The tissue of Cystoseira osmundacea (Turn.) C. Ag. (Fucales, Phaeophyta) undergoes pronounced developmental changes when in association with the fungus Haloguignardia irritans (Setchell et Estee) Cribb et Cribb (Sphaeriales, Ascomycotina). Nonmeristematic cortical cells are induced to divide and ultimately form a structure composed of tightly packed club‐shaped projections. Each projection contains a single fungal ascocarp or spermogonium. A protective multilayered algal tissue surrounds the fungal reproductive structures. This association significantly alters algal morphology to the apparent protective advantage of the fungus.
EFFECT OF MANIPULATION OF WATER AND NITROGEN SUPPLIES ON THE QUANTITATIVE PHENOLOGY OF LARREA TRIDENTATA (CREOSOTE BUSH) IN THE SONORAN DESERT OF CALIFORNIA
Authors: Sharifi M. R. , Meinzer F. C. , Nilsen E. T. , Rundel P. W. , Virginia R. A. , Jarrell W. M. , Herman D. J. , Clark P. C.
Published: January 2018

Two years of water and nitrogen augmentation experiments on Larrea tridentata (creosote bush) were carried out in a southern Californian warm desert wash plant community. Treatments consisted of control (C), water (W), water and soil nitrogen (W + SN), and soil nitrogen (SN). Quantitative phenological data and microclimatic measurements were collected prior to the onset of and during the growth period and treatments. Predawn and midday water potentials were lower in nonirrigated than irrigated individuals. Leaf conductance was higher in irrigated than in nonirrigated shrubs, with a maximum difference of 1 cm s‐1 observed in July 1984 under relatively low vapor pressure deficit conditions. Leaf production rates were significantly higher in the irrigated (W and W + SN) treatments than in the nonirrigated (C and SN) treatments in 1984. Addition of soil nitrogen caused no increased in vegetative growth rates in 1984. In 1985, a drier year, there was only minimal growth during the spring and summer growth periods in the nonirrigated treatments, while the W and W + SN treatments resulted in significantly higher leafand shoot growth rates. Growth rates in 1985 were significantly higher in the W + SN treatment than in the W treatment. Reproductive growth was higher in the nonirrigated than the irrigated treatments, with the lowest reproductive activity noted in the W treatment.
KINETICS OF SUPPRESSION OF CIRCUMNUTATION BY CLINOSTATTING FAVORS MODIFIED INTERNAL OSCILLATOR MODEL
Authors: Brown Allan H. , Chapman David K.
Published: January 2018

According to a well‐conceived gravity‐driven model, oscillatory growth movements called circumnutations are produced by a continuing set of gravitational responses with overshoot. In simplest form that model predicts that if the gravity stimulus could be removed completely and abruptly, growth oscillations would damp out within a time less than the period of oscillation. That condition was simulated by imposing on horizontally clinostatted sunflower shoots a unit g centripetal force in the direction that coincided with the plants' morphological axis. Circumnutations proceeded in quantitatively normal manner. By stopping the centrifuge, the plants were subjected abruptly only to clinostat simulated weightlessness. Circumnutations decreased but did not disappear. The half‐time for decline to a final low level of activity was about 4‐fold the period of oscillation at 1 g—about 8‐fold the period at simulated zero g. That slow damping was not consistent with the prediction based on the gravity driven model of circumnutation. The model needs to be revised.
ROLE OF ASYMMETRIC CELL DIVISION IN PTERIDOPHYTE DIFFERENTIATION. II. EFFECT OF CA2+ ON ASYMMETRIC CELL DIVISION, RHIZOID ELONGATION, AND ANTHERIDIUM DIFFERENTIATION IN VITTARIA GEMMAE
Authors: Ruth Jennifer B. , Kotenko Jane L. , Miller John H.
Published: January 2018

Gametophytes of Vittaria graminifolia reproduce vegetatively by means of gemmae. Each gemma consists of a linear array of six cells: four body cells and a knob‐shaped terminal cell at each end. When gemmae are shed from the gametophyte onto Knop's mineral medium, the two terminal cells do not divide, but elongate to form primary rhizoids. The body cells undergo asymmetric cell division, and the smaller daughter cells differentiate into either secondary rhizoids or prothalli. When gibberellic acid is included in the medium, antheridia are formed as a result of asymmetric cell division instead of vegetative structures. We studied the effect of Ca2+ on asymmetric cell division, rhizoid elongation, and antheridium formation in gemmae cultured on Knop's mineral medium and variations of Knop's medium. Ca2+ inhibited the onset of cell division and rhizoid elongation, but was required for differentiation of antheridia. Treatments which lowered the Ca2+ content of gemmae (EGTA and dilute HCl extraction, culture on verapamil‐containing and Ca2+‐deficient medium) caused an early onset of cell division and rhizoid elongation. The stimulation of growth was most pronounced when gemmae were deprived of Ca2+ during the first 24 hr of culture. The proportion of cell divisions which differentiated into antheridia in response to GA was greatly reduced when the Ca2+ status of gemmae was lowered with verapamil and Ca2+‐EGTA buffers.
REPRODUCTIVE BIOLOGY OF ERYTHRONIUM GRANDIFLORUM VARIETIES GRANDIFLORUM AND CANDIDUM (LILIACEAE)
Authors: Fritz‐Sheridan Jane K.
Published: January 2018

This four‐year (1982–1986) study compared the pollination biology and cytology of a relatively rare taxon, Erythronium grandiflorum Pursh var. candidum (Piper) Abrams, with that of a geographically widespread sister taxon, E. grandiflorum var. grandiflorum, in the Pacific Northwest. Breeding studies were used to study the reproductive systems of the taxa, to test for interfertility between them, and to seek abnormalities in the breeding system of the rare taxon that might account for its relative rarity. Chromosomes were counted in both taxa and in hybrids from artificial crosses. Ranges of the two taxa were determined from field studies and herbarium specimens. Although the ranges of the taxa overlap in part, populations are usually allopatric. Phenological factors are probably minor in preventing cross‐pollination between the taxa. Both taxa are protogynous obligate outcrossers pollinated by bees. Seed production apparently is not pollinator‐limited. The two taxa are interfertile only when individuals from allopatric populations are artificially crossed, and thus should be considered two biological species. When the taxa overlap in floral phenology in sympatric populations, they exhibit reciprocal incompatibility. Such incompatibility between closely related perennial species is unusual. It may have arisen via natural selection in mixed populations. Alternatively, if populations of each taxon vary with regard to their incompatibility alleles, they may have acquired their fertility barriers by chance before populations of the two taxa came into contact with each other.
RELATIONSHIP BETWEEN ISOZYMIC AND MORPHOLOGIC VARIATION IN THE DIPLOIDS CHENOPODIUM FREMONTII, C. NEOMEXICANUM, C. PALMERI, AND C. WATSONII
Authors: Walters Terrence W.
Published: January 2018

Levels of variation revealed by starch gel electrophoresis and morphologic character analysis were compared within and among four diploid species of Chenopodium: C. fremontii (sect. Chenopodium subsect. Leiosperma), C. neomexicanum, C. palmeri, and C. watsonii (sect. Chenopodium subsect. Cellulata). The data sets exhibited little concordance. Numerical analysis of morphologic characters demonstrated that C. neomexicanum and C. palmeri are relatively distinct, whereas allozyme analysis indicated a high degree of genetic similarity among populations of the two species. I concluded that C. palmeri should be reduced to a variety of C. neomexicanum. Chenopodium watsonii expressed the highest degree of allozyme heterozygosity and polymorphism and may represent the oldest extant member of subsection Cellulata. Although C. fremontii is classified in another subsection, it exhibited higher genetic identity values with C. neomexicanum and C. palmeri than did C. watsonii. In addition, morphologic and allozymic similarity between C. fremontii and C. neomexicanum suggests the need for further examination and possibly realignment of subsections Cellulata and Leiosperma.
UNDERGROUND MORPHOLOGY AND HABITAT RELATIONSHIPS OF THREE PAIRS OF FOREST HERBS
Authors: Antos Joseph A.
Published: January 2018

To evaluate the ecological importance of differences in underground morphology, ten individuals per species were excavated for three species pairs in a coniferous forest in the Cascade Mountains of Oregon. The two species of each pair had similar aboveground morphologies, divergent underground morphologies, and different geographical ranges and habitat relationships. Erythronium montanum and Clintonia uniflora have one or two elliptic leaves per ramet but E. montanum has a short, segmented rhizome and only one ramet per genet, whereas C. uniflora spreads vegetatively via long rhizomes. Streptopus roseus and Smilacina stellata have similar, determinant aerial shoots and spread by long rhizomes, but S. stellata has a dimorphic root and rhizome system that allows it to occupy a wider range of habitats. Rubus pedatus and Rubus lasiococcus both spread via stolons, but R. lasiococcus has deeper roots and can occupy drier habitats than R. pedatus. The differences in underground morphology within the species pairs are consistent with the species’ geographical ranges and habitats occupied, and may be causal in determining distribution patterns.
ECOLOGICAL DIVERSITY IN NORTH AMERICAN PINES
Authors: McCune Bruce
Published: January 2018

Ecological groups were identified from 34 North American species of pine using multivariate analysis of 18 ecological traits. Five adaptive modes are described: 1) fire‐resistant species that are large, thick‐barked, and have large cones and long needles; 2) tall, fast‐growing mesophytic species with moderately high shade tolerance; 3) stress‐tolerant species with animal‐dispersed seeds, occurring mainly on cold or dry sites where fire is infrequent; 4) fire‐resilient species that are precocious reproducers with small seeds, often in serotinous cones; and 5) species of southern mesic sites with fast growth, strong, heavy wood and short persistence of needles. Intermediates between these modes exist. Convergent evolution has occasionally occurred, as shown by high ecological similarity of species in different taxonomic sections within Pinus. However, the analogies between species are imperfect, suggesting the importance of constraint by shared ancestry and divergence produced by a diversity of environments.
AN INTERPRETATION OF PHENOTYPIC PLASTICITY IN AGROPYRON REPENS (GRAMINAE)
Authors: Taylor Douglas R. , Aarssen Lonnie W.
Published: January 2018

Phenotypic plasticity and genotypic variation were studied in Agropyron repens L. (Beauv.) collected from populations in two grassland communities which differed in the length of time since the last major disturbance. Twenty genotypes were collected from each population. Each genotype was vegetatively propagated, and subjected to six different treatments in a greenhouse. Phenotypic plasticity and genotypic variability were measured as across‐ and within‐treatment standardized variances respectively. Patterns of plasticity were measured by genotype correlations across treatments. The results were presented graphically by the regression method of Garbutt and Zangerl (1983). Analysis of variance revealed significant population, genotype and treatment effects. Significant positive correlations between magnitude and variability of performance were found for all characters. Phenotypic plasticity and magnitude of performance were generally greater in plants collected from the older established field. Evidence for greater specialization in the older population was suggested by negative correlations between performance in the most favorable and least favorable treatments and by greater dissimilarity of genotype response across treatments. A more variable phenotypic response across treatments (i.e., higher plasticity) for plants from the older population may therefore be a consequence of specialization and not an adaptive trait per se.
FLAVONOID SURVEY OF OENOTHERA (ONAGRACEAE): SECTS. GAUROPSIS, HARTMANNIA, KNEIFFIA, PARADOXUS, AND XYLOPLEURUM
Authors: Averett John E. , Huang Shong , Wagner Warren L.
Published: January 2018

An analysis of 60 populations of Oenothera sects. Gauropsis, Hartmannia, Kneiffia, Paradoxus, and Xylopleurum showed that 29 flavonols and 4 glycoflavones were present among 19 of the 20 species studied in these five sections. The four glycoflavones, representing the first report for this class of compounds for Oenothera, were present only in O. canescens, a highly specialized and isolated species within the genus. The most closely related species, O. dissecta, had a flavonoid profile more similar to species of sect. Hartmannia and sect. Kneiffia. The most striking feature of the analysis is that roughly 70% of the known flavonoids in the family were found in the group of sections studied. The large number of compounds in this one lineage of Oenothera contrasts sharply to the relatively low numbers found in most other genera of the family. Further, the occurrence of glucuronides and sulfates within Oenothera is restricted to these sections. Each species examined had a unique flavonoid profile, except O. deserticola and O. multicaulis (both sect. Hartmannia) which had identical profiles. This finding contrasts sharply with the uniform profiles of other sections of Oenothera and other genera in Onagraceae, such as Epilobium and Ludwigia. By contrast, O. havardii, a phyletically isolated species of the monotypic sect. Paradoxus, had only five flavonol glycosides, compared with 11–19 compounds in the other species. Based on morphological and seed anatomical data, O. havardii is only distantly related to sects. Gauropsis, Hartmannia, Kneiffia, and Xylopleurum, although along with sect. Lavauxia, it appears to represent the sister group to them. Overall, with the exception of O. havardii and O. canescens, the flavonoid profiles support the hypothesis recently suggested by seed anatomy that these four sections are more closely related to each other than any one of them is to another section of the genus.
CHROMOSOME STUDIES IN ASTERACEAE FROM THE UNITED STATES, MEXICO, THE WEST INDIES, AND SOUTH AMERICA
Authors: Keil David J. , Luckow Melissa A. , Pinkava Donald J.
Published: January 2018

Chromosome counts of Asteraceae are reported from Mexico, the United States, the West Indies, Peru, and Bolivia. First counts are reported for 27 species, eight infraspecific taxa, and three interspecific hybrids in Brickellia, Chrysanthellum, Cirsium, Egletes, Erigeron, Flaveria, Gnaphalium, Heterotheca, Hieracium, Hymenothrix, Koanophyllon, Layia, Lessingia, Pectis, Sclerocarpus, Stuessya, Tagetes and Wedelia. Counts are also reported for 196 taxa or hybrids for which chromosome numbers have been published previously. Of these, nine are new numbers. Taxonomic implications of certain counts are discussed.
EFFECTS OF DISTANCE BETWEEN POLLEN DONOR AND POLLEN RECIPIENT ON FITNESS COMPONENTS IN ESPELETIA SCHULTZII
Authors: Sobrevila Claudia
Published: January 2018

The effect of flowering time and of distance between pollen donor and pollen recipient on the proportion of filled achenes, aborted seeds, and seedling survivorship was studied in populations of Espeletia schultzii in the Venezuelan Andes. Hand‐pollinations were performed in two different years and at different times during the flowering season. Pollinations within‐population included crosses between plants within a few meters to a maximum of 500 m apart and between‐population pollinations included crosses between plants more than 10 km and up to 78 km away. Late in the flowering season, plants suffered a reduction in the proportion of filled achenes and an increase in aborted seeds. The proportion of filled achenes and aborted seeds did not vary significantly between the distances between pollen and ovules in crosses done early in the flowering season. However, the proportion of filled achenes in crosses between individuals within 30 m distance were very variable, either very successful or not successful. Beyond 30 m, for some of the populations, the frequency of unsuccessful crosses was almost 0. This pattern was observed at three elevation sites in two consecutive years. When crosses were done late in the flowering season, the proportion of filled achenes was lower in crosses between close individuals and between very distant ones. Seedling survivorship varied significantly between the crossing distances at the higher elevation only. The results show that a clear effect of the incompatibility alleles on the crossing success of the plants is present in the different populations examined, while they suggest that the effect of inbreeding or outcrossing depression is less clear but might still be present only under certain conditions. Late in the season, when plants might have fewer resources available for reproduction and at the high and intermediate site where cold and dry environmental conditions are less favorable for the plants, the discrimination among distances was stronger.
GROWTH IN MEDEOLA VIRGINIANA CLONES I. FIELD OBSERVATIONS
Authors: Cook Robert E.
Published: January 2018

The pattern of clonal growth in Medeola virginiana was mapped over twelve square meters in a successional white pine forest of eastern Massachusetts. From these maps and an additional sample of excavated plants, the distances and angles of divergence of daughter ramets from the base of the parent shoot were measured for 213 plants. All clonal growth parameters were found to be highly variable in the ñeld, with coefficients of variation ranging from 17–92%. The rules describing the pattern of growth of daughter ramets were found to be considerably more complicated than previously reported (Bell, 1974). The mortality of tubers, the natural variation of parameters of growth, and the complex patterns of daughter production all call into question the ability of idealized, deterministic models of growth to predict the form of clones and the position of ramets in the field.
YEAR‐TO‐YEAR CHANGES IN PHENOTYPIC GENDER IN A MONOECIOUS CUCURBIT, APODANTHERA UNDULATA
Authors: Delesalle Véronique A.
Published: January 2018

Year‐to‐year variation in phenotypic gender in the monoecious cucurbit, Apodanthera undulata Gray was investigated. Small plants produce no flowers. Larger plants produce only staminate flowers (“male” plants), while a somewhat greater threshold size is necessary for pistillate flower production (cosexual plants). Approximately 85% of the plants that bloomed did not change gender group between years. Two measures of phenotypic gender were used: prospective femaleness, a measure standardized to the population floral ratio, and morphological femaleness, an unstandardized measure. Femaleness of cosexes between years was positively correlated; r values were somewhat greater when using morphological femaleness values. Plants that opened only staminate flowers one year were likely to open only staminate flowers the next year. Similarly, cosexes were likely to be cosexes again the following year, with similar femaleness values. Beyond the threshold size for pistillate flower production, plant size was not correlated with femaleness. These patterns suggest that all plants are male until they reach a certain size and that plants in their cosexual phase may have an intrinsic femaleness tendency due to either genotype or microsite effects.
TRIGONOBALANUS (FAGACEAE): TAXONOMIC STATUS AND PHYLOGENETIC RELATIONSHIPS
Authors: Nixon Kevin C. , Crepet William L.
Published: January 2018

The fagaceous genus Trigonobalanus as recently treated includes 3 species, two in Malaysia and Southeast Asia and a single species in Colombia, South America. Character analysis suggests that the genus as currently circumscribed is paraphyletic, without synapomorphies to unite the three species. Each of the three species is a morphologically distinct relict of a group that probably was ancestral to the modern genera Quercus and Fagus. Each of the three species also has at least one autapomorphy which is unique within Fagaceae. Analysis of cupule morphology in Fagaceae provides an interpretation of evolution in cupules which differs substantially from Forman's interpretation. We interpret trigonobalanoid cupules as indicative of an ancestral type of inflorescence within Fagaceae. This inflorescence type is a dichasial structure in which the outermost axes are cupular valves, but the degree of branching and subsequent number of fruits are variable. Following this model, a strict relationship exists between valve number and fruit number as seen in cupules of Trigonobalanus (valves = fruits + 1). Fossil evidence is consistent with our interpretation of the phylogenetic position of the trigonobalanoids. We propose to segregate the three species of Trigonobalanus as three monotypic genera; two of these require names which we provide here: Formanodendron and Colombobalanus.
RESOURCE LIMITATION AND OFFSPRING SIZE AND NUMBER TRADE‐OFFS IN CIRSIUM ARVENSE (ASTERACEAE)
Authors: Lalonde R. G. , Roitberg B. D.
Published: January 2018

We employed high and low pollination treatments to examine the effect of varying offspring number on the allocation of resources to individual seeds in 5 female clones of the dioecious perennial, Canada thistle (Cirsium arvense (L.) Scop.). In comparison to high pollination plants, low pollination plants displayed a significantly reduced seed set, an unchanged rate of seed abortion, a significant increase in mean achene weight, and an altered pattern of achene weight allocation across primary, secondary, and tertiary flowerheads. These data do not support theoretical predictions for a uniform level of provisioning to individual seeds and are most consistent with the hypothesis that limitation of available resources constrains the level of provisioning to individual seeds. We discuss some of the assumptions underlying offspring provisioning theory in light of our results and discuss the usefulness of this theory as a descriptor of plant systems.
COORDINATED TIMETABLES FOR MEGAGAMETOPHYTE DEVELOPMENT AND POLLEN TUBE GROWTH IN RHODODENDRON NUTTALLII FROM ANTHESIS TO EARLY POSTFERTILIZATION
Authors: Palser Barbara F. , Rouse John L. , Williams Elizabeth G.
Published: January 2018

Rhododendron nuttallii T. W. Booth (Ericaceae) was used to derive concurrent timetables for megagametophyte, pollen tube and early postfertilization development from anthesis through 3 wk after pollination, based on timed collections of self‐pollinated pistils. Stages of development were determined for over 33,500 cleared ovules, including, for selected collection dates, stages on different portions of the placenta. Pollen tube information was obtained by fluorescence microscopy of pistil squashes stained with aniline blue. Because of the very large number of ovules observed, it was possible to recognize a much more closely graded series of stages in megagametophyte development than is usually the case. While a range of stages occurred on all days, development progressed steadily from a majority of functional spores and 2‐nucleate gametophytes on the day of anthesis to mostly a late zygote‐primary endosperm stage at 18 days, and some 2‐celled endosperm stages at 21 days, after pollination. At all times the most advanced stages, including first pollen tube entries, occurred on the outer surface of the lower half of the placenta, and the youngest on the inner surface of the uppermost portion. Fertilizable ovules were not found in any frequency until 8 days after pollination (then in only about 34% of the ovules); a few fertilized ones were seen after 10 days but constituted less than 5% until 12 days after pollination, thereafter increasing to about 60%. Fertilization occurred in any one of three morphologically recognizable stages distinguished by position and state of fusion of polar nuclei. Pollen germinated on the stigma 1–2 hr after pollination, and pollen tubes grew at a rate of about 1–1.25 cm/day, reaching the top of the ovary in 8–9 days with the first ovule entries seen after 10 days. There was a close correlation between megagametophyte development and pollen tube growth, with large numbers of functionally mature ovules not being found until pollen tubes had reached the ovary. While nuclei within ovules could not be distinguished in the squashes, three gametophyte stages that could be recognized—unelongated, elongated either without or with a pollen tube—were tallied for almost 29,000 ovules. The progression in these general stages corresponded well with that documented in more detail from cleared ovules. Unpollinated pistils showed a similar progression of gametophyte stages until the time fertilization would start to occur, after which there was continued accumulation of functionally mature ovules. A variety of abnormally developed and/or collapsing(ed) ovules or gametophytes were seen; collectively, they averaged over 8.6% of all ovules.
POLLINATION OF DALECHAMPIA MAGNOLIIFOLIA (EUPHORBIACEAE) BY MALE EUGLOSSINE BEES
Authors: Armbruster W. S. , Keller S. , Matsuki M. , Clausen T. P.
Published: January 2018

Flowers of Dalechampia magnoliifolia in eastern Peru were pollinated primarily by male Eulaema meriana and E. cingulata, which collected fragrance from the secretory gland borne in the staminate cymule. The fragrance contains carvone oxide, benzyl acetate, limonene, α‐pinene, myrcine, β‐pinene/camphene, and carvone. Trigona cf. pallens was the most abundant visitor, but was primarily a pollen thief. The rate of contact with the stigmas by Trigona, and hence the bee's efficacy as a pollinator, was highly variable and was determined by variation in the separation of anthers and stigmas. Dalechampia magnoliifolia co‐occurred with a congeneric species, D. cissifolia, but did not share pollinators with it.
EVOLSONIA, A NEW GENUS OF GIGANTOPTERIDACEAE FROM THE LOWER PERMIAN VALE FORMATION, NORTH‐CENTRAL TEXAS
Authors: Mamay Sergius H.
Published: January 2018

Evolsonia is a new gigantopterid genus (type‐species: E. texana), based on leaf impressions from 3 widely separated localities in north‐central Texas. The leaves are associated with terrestrial vertebrates in floodplain sediments of the Vale Formation in the Clear Fork Group, of late Leonardian (Early Permian) age. Evolsonia leaves are simple, with very large elliptic laminae reaching 27 cm in width and 80 cm, possibly more, in length. Leaf margins are sinuate to crenate, with mostly shallow concavities. Venation is pinnate, in 4 orders; all but the ultimate veins are very thick and protrude below the lamina, creating deep impressions in the matrix. The secondary and tertiary veins form a precise herringbone pattern, with the secondaries and exmedial tertiaries ending at the leaf margin between concavities. The other tertiary veins are either simple or divided into 2 nearly equal divisions; they produce simple or variously divided quaternary veins that end at a thin sutural vein, forming a dense reticulum; some of the terminally branched tertiaries delimit areolelike areas that enclose several quaternaries and meshes. One of 6 presently known American gigantopterids, Evolsonia most closely resembles the younger Delnortea in gross architecture; with its sutures and dichotomously divided veins, however, Evolsonia is architecturally intermediate between Delnortea and the older American gigantopterids with forked leaves. Sedimentary features indicate deposition under alternating periods of flooding and drought. Their huge size invites comparison of Evolsonia leaves with those of modern tropical plants, whereas their thick veins and preservational features suggest thick, coriaceous texture.
RELLIMIA THOMSONII FROM THE GIVETIAN OF NEW YORK: SECONDARY GROWTH IN THREE ORDERS OF BRANCHING
Authors: Dannenhoffer Joanne M. , Bonamo Patricia M.
Published: January 2018

Pyritized axes of the vegetative branching system of Rellimia thomsonii, from the Givetian of New York were described with emphasis on the presence and position of the secondary tissues in relation to the known axis orders. The morphology and anatomy of four axis orders (N, N + 1, N + 2, N + 3) was described using two well‐preserved specimens. One specimen showed the largest known (N) axis order, with spirally attached N + 1 axes. The other specimen, from a more distal portion of the plant, showed the N + 2 axis order with spirally arranged N + 3 axes. The shape of the primary xylem, discernible in three of the axis orders (N + 1, N + 2, N + 3), was a three‐lobed protostele with mesarch maturation of the primary xylem. The protostele of the N + 3 axis order, with only primary growth, was identical to that of fertile N + 3 axes. The other axis orders (N + 2, N + 1, N) had wood surrounding the primary xylem. The wood of the N+2 axis was limited, and occurred only in the basal portion of the axis, but that of the N+1 and N axes was extensively developed with two and three growth layers, respectively. This wood was pycnoxylic with narrow rays similar to other aneurophytalean progymnosperms. Surrounding the secondary xylem was secondary phloem indicating the vascular cambium in Rellimia was bifacial. The presence of growth layers was discussed in relation to the climatic interpretation placed on their presence and how it correlates with paleogeographic reconstructions of the Devonian.
GENE FLOW IN LIMBER PINE: EVIDENCE FROM POLLINATION PHENOLOGY AND GENETIC DIFFERENTIATION ALONG AN ELEVATIONAL TRANSECT
Authors: Schuster William S. , Alles David L. , Mitton Jeffry B.
Published: January 2018

Limber pine (Pinus flexilisJames) in Colorado occurs on sites from the upper treeline (3,350 m) to the lower treeline (1,650 m). In this study we examined pollination phenology at eight sites along this transect and allozyme frequencies in two populations at either end of the transect to evaluate the level of interpopulation gene flow. Pollen release and megastrobilus receptivity are synchronous within populations, lasting about 15 days. Pollination phenology is strongly affected by site elevation. Most sites that differ in elevation by more than 400 m do not have overlapping pollination periods, and thus interpopulation gene flow is restricted despite strong westerly winds. Gene frequencies are significantly different between upper and lower treeline populations at eight of the ten loci surveyed. Nevertheless, we estimate the level of gene flow to be 11.1 migrants per generation between these two populations. Stepping‐stone pollen transfer between intermediate populations and a high level of gene flow via seeds may be responsible. Thus, despite the elevational restriction on long‐distance gene flow via pollen, limber pine appears to maintain a high level of interpopulation gene flow.
STRUCTURALLY PRESERVED SPHENOPHYTES FROM THE TRIASSIC OF ANTARCTICA: VEGETATIVE REMAINS OF SPACIINODUM, GEN. NOV.
Authors: Osborn Jeffrey M. , Taylor Thomas N.
Published: January 2018

Sphenophyte remains of Early‐Middle Triassic age are described from silicified peat collected in the Transantarctic Mountains of Antarctica. The new sphenophyte, Spaciinodum collinsonii sp. nov., is represented by ribbed, jointed stems with characteristic pith and carinal canals. Stems are relatively small, ranging from 1.8–3.0 mm in diameter, lack secondary tissues, and are characterized by vallecular canals that are restricted to nodal regions. The internodal vascular system consists of 12–18 collateral bundles which alternate between successive internodes. A complete vascular ring is present in the nodal region and is surrounded by a continuous double endodermis. Xylem is endarch and composed of elements ranging from annular to reticulate. The Antarctic sphenophyte is compared with other Gondwana fossil articulates and extant Equisetum. Superficial stomata suggest affinities with modern Equisetum subgenus Equisetum; however, some anatomical differences preclude assignment with living species.
HARTIG NET STRUCTURE OF ECTOMYCORRHIZAE SYNTHESIZED BETWEEN LACCARIA BICOLOR (TRICHOLOMATACEAE) AND TWO HOSTS: BETULA ALLEGHANIENSIS (BETULACEAE) AND PINUS RESINOSA (PINACEAE)
Authors: Massicotte H. B. , Peterson R. L. , Melville L. H.
Published: January 2018

Hartig net structure and ontogeny were compared in ectomycorrhizae synthesized between the broad host range fungus, Laccaria bicolor and two hosts, Betula alleghaniensis and Pinus resinosa. In B. alleghaniensis, the Hartig net was present in the epidermis of the three ectomycorrhizal types formed, fast‐growing first‐order laterals with proximal colonization, clavate second‐order laterals, and nonclavate second‐order laterals. Root hair‐fungus interactions occurred in this association. In P. resinosa, the Hartig net developed in epidermal and cortical cell layers of monopodial and dichotomously branched first‐order laterals. Short monopodial laterals exhibited a mantle only. Fungal hyphae in the Hartig net exhibited a complex labyrinthine mode of growth in ectomycorrhizae of both tree species.
SPATIAL DISTRIBUTION, SURVIVAL, AND FECUNDITY OF DIOON EDULE (ZAMIACEAE) IN A TROPICAL DECIDUOUS FOREST IN VERACRUZ, MEXICO, WITH NOTES ON ITS HABITAT
Authors: Vovides Andrew P.
Published: January 2018

A natural habitat of the cycad Dioon edule Lindl. in central Veracruz, Mexico is described. Prolonged drought periods and fire are factors contributing to seedling death resulting in a population structure with a reverse ‘J’ or Deevey type III survivorship curve. The cycads exhibited a ‘clumped’ or contagious distribution on shallow soils of the habitat and on rocky outcrops. This distribution was attributed to exclusion by competition from other species for water, soil nutrients, and/or seed dispersal by rodents. Estimated coning frequency varied from 2.8 to 8.8 years in male plants and from 10.0 to 52.0 years in female plants, though shorter intervals are known to occur, especially following exceptionally wet years. Chamberlain's age estimate for D. edule has been confirmed and a life table is presented.
TRANSLOCATION IN POLYTRICHUM COMMUNE (BRYOPHYTA). III. LOADING OF SUGARS IN SOURCE LEAVES
Authors: Thomas Robert J. , Grethlein Andrew J. , Perou Charles M. , Scheirer Daniel C.
Published: January 2018

Polytrichum commune, the common hair‐cap moss, possesses a system of long‐distance food‐conducting cells that can be traced from leaves into stems and down through underground rhizomes. Cytochemical analysis indicates that high adenosine triphosphatase activity is associated with the membranes of sugar‐conducting deuter cells in Polytrichum leaves. Incipient plasmolysis determinations reveal high solute concentrations of leaf deuters. These two lines of evidence suggest that long‐distance transport of photosynthate is initiated in this species by a process analogous to phloem loading of minor veins in leaves of flowering plants. Two sets of experimental observations suggest that sugar loading in Polytrichum is coupled with the transport of protons: the moderating effects of N‐ethylmaleimide, p‐chloromercuribenzenesulfonic acid, sodium orthovanadate, and fusicoccin on labeled sucrose uptake (as determined by liquid scintillation techniques), and correlated effects on acid flux from isolated leaves (as determined by computer‐aided titrimetry).
CARBOHYDRATE PHYSIOLOGY OF ORCHID SEEDLINGS. III. HYDROLYSIS OF MALTOOLIGOSACCHARIDES BY PHALAENOPSIS (ORCHIDACEAE) SEEDLINGS
Authors: Ernst Robert , Arditti Joseph
Published: January 2018

Germinating seeds and developing seedlings of Phalaenopsis Habsburg and Phalaenopsis Ruth Burton × (Phalaenopsis Abendrot × Phalaenopsis Abendrot) can utilize glucose, maltose, maltotriose, maltotetraose, maltopentaose, maltohexaose, and maltoheptaose as carbon sources. Fresh weight decreased significantly with increased polymerization from glucose through maltoheptaose. Seedling survival declined on higher molecular weight sugars reaching levels which were significantly different from those on glucose. Sugar uptake increased moderately with increasing molecular weight of oligomers. The maltooligosaccharides used in these experiments are hydrolyzed by the orchid seedlings and of the sugars which can support good growth glucose, but not maltose accumulate in culture media. As a result, media which supported seedlings contained substantial levels of glucose, the starting sugars, and decreasing amounts of the next shorter oligomers. This suggests enzymatic endwise hydrolysis of these maltooligosaccharides. Similar results were obtained with Phalaenopsis seedlings produced from seeds which were germinated on sugar‐free medium and transferred to a solution containing the same oligomers. Sugars in media which did not support seedlings were not hydrolyzed.
ROLE OF MYCORRHIZAL FUNGUS ORIGIN IN GROWTH AND NUTRIENT UPTAKE BY GERANIUM ROBERTIANUM
Authors: Boerner Ralph E. J.
Published: January 2018

Prior field studies have shown that populations of forest herbs on relatively nutrient poor soils have higher vesicular‐arbuscular mycorrhizal (VAM) infection intensity than plants on rich soils. However, the growth responses and ability to take up P against the soil nutrient gradient are often not linearly related to infection intensity. To determine if intraspecific differences among populations of the common VAM fungus Glomus occultum could differentially affect growth and nutrient uptake, Geranium robertianum seedlings were inoculated with Glomus occultum isolated from four forest types along a gradient of soil fertility, and grown in a greenhouse at P levels typical of the extremes of that gradient. Plants given inoculum from relatively infertile forest sites generally produced greater root, shoot, and total mass than plants given inoculum from fertile sites or uninoculated plants, especially at the low P supply rate. Total P uptake and both P and N uptake efficiency were also highest in plants given inocula from low fertility sites. These results indicate that local adaptation and intraspecific variations in the ability of VAM fungi to induce growth and nutrient uptake effects on host plants may be as important as interspecific differences among VAM fungus species.
EARLY LEAF ONTOGENY AND SHOOT DEVELOPMENT IN BROWNEA ARIZA (LEGUMINOSAE)
Authors: Stein Otto L. , Johnson Claire M.
Published: January 2018

Brownea ariza Benth. (Leguminosae: Caesalpinioideae) shows early shoot tip abortion and subsequent renewal growth from the pseudoterminal bud. This species is unusual in that the entire shoot system is formed before flushing from the bud occurs, shoot tip abortion occurs during flushing, and the aborting portion contains three to six leaves as well as primordial structures varying from hood to peg shape. This study focused on the morphological changes from initiation of scale and foliage leaf primordia in the “resting” renewal bud through bud elongation to flushing and bud abortion. Scanning electron microscopy revealed that embryonic scale leaves are hood‐shaped while foliage leaf primordia show early segmentation into leaflets and stipules. No transitional stages were observed. Bud scales and foliage leaves show opposite developmental trends. In bud scales, length at maturity increases from first to last formed, while length decreases in sequentially formed foliage leaves. Early in leaf development the stipules keep pace with the elongation of the rachis. When the bud reaches about one half of its final length the leaf rachis begins to exceed the lengths of its stipules. This young rachis terminates in a distinct mucro that persists until maturity at which time it abscises. Growth patterns indicate that mucro and rachis are a single developmental unit. The early abortion of a shoot tip containing several leaves cannot be easily rationalized. Previous suggestions have involved maintenance of form and ecological adaptation. We add the possibility of elimination of cell progeny encumbered by mutations. From this and other studies of this group, it is clear that at maturity leaves of different species may look alike, e.g., Hymenaea and Colophospermum are bifoliolate; Brownea, Saraca, and others are multifoliolate. However, early stages of leaf ontogeny are quite diverse and may be of systematic value, since these early differences are lost or masked by later development.
FOUR‐YEAR GROWTH AND REPRODUCTION OF CYCLOPOGON CRANICHOIDES (ORCHIDACEAE) IN SOUTH FLORIDA
Authors: Calvo Ricardo N.
Published: January 2018

Thirty‐five flowering individuals of the orchid Cyclopogon cranichoides were marked in 1986, and their leaf area, number of flowers, and number of fruits were recorded from 1986 to 1989. In 1986 and 1987 all the flowers on 20 individuals were hand‐pollinated. The number of plants with above‐ground growth steadily decreased by about 20% each year. In some cases there was evidence that disappearance of plants was not due to mortality but to a transition into a subterranean state. Small plants were most likely to make this transition. Flower number was significantly associated with plant size. Fruiting success was pollinator‐limited throughout this study; fruit set of hand‐pollinated individuals was higher than 96%, whereas natural fruit set ranged from 26% in 1987 to 62% in 1988. Fruit set did not have any effect on growth or reproduction the following year.
DISTANCE‐DEPENDENT REGULATION OF STAMEN NUMBER IN CROSSES OF SCLERANTHUS ANNUUS (CARYOPHYLLACEAE) FROM A DISCONTINUOUS POPULATION
Authors: Svensson Linus
Published: January 2018

Scleranthus annuus is a highly inbreeding annual that has varying numbers of fertile stamens per flower. Two stamen‐positions always have fully fertile stamens, whereas the other eight carry staminoids or stamens to varying degrees. I measured male expression in progeny produced by crossing individuals growing in a discontinuous population. Four types of progeny were analyzed: from self‐pollinations, from cross‐pollinations within a patch, from cross‐pollinations between patches, and from cross‐pollinations between populations. Selfed progeny showed the lowest total male fertility (25.8), followed by between‐population crosses (26.7), between‐patch crosses (27.4), and within‐patch crosses (27.8). The effect of crossing, as measured by the relative increase in frequency of fully fertile stamens compared to selfed progeny, is highest for within‐patch crosses and declines with increasing spatial separation between parents. The increase was strongest for one of the antipetalous stamen positions in progeny produced by between‐patch crosses (490%). The response to crossing measured as an increase in stamen fertility was not the same for all ten stamen positions. A strong increase of fertile stamens is noted in all types of crossed progeny for the five stamen positions in the outer whorl (antipetalous stamens), positions that in selfed progeny carry staminoids. The three positions in the inner whorl that are not occupied by fully fertile stamens show varying responses to crossing.
LATE TERTIARY MICROFOSSIL FLORA FROM THE REPUBLIC OF HAITI
Authors: Graham Alan
Published: January 2018

Twenty‐five fossil pollen and spore types have been recovered from the late Miocene to possibly middle Pliocene Artibonite flora of Haiti. These include monolete fern spore (36%), Alsophila (6%), Pteris types 1–3 (type 1 = 11%), cf. Antrophyum, trilete fern spore (types 1, 2), Pinus (16%), Palmae (types 1, 2), Hygrophila, Chenopodiaceae/Amaranthaceae, Compositae (types 1–4; 9%), Alchornea, Alfaroa/Oreomunnea, Oryctanthus, Malpighiaceae, Allophylus, and unknown types 1–3. The principal vegetation types suggested by the fossil flora are pine forest and cloud forest, with a fern marsh bordering the depositional basin. Communities of drier to arid aspect, savannas, and high altitude vegetation are not represented. Annual temperatures ranged between about 23 and 26 C at 400 m elevation, and 17 and 19 C at elevations of about 1,400 m. Annual rainfall is estimated at about 1,300 mm and was seasonal. The affinity of the flora is distinctly North American, consistent with plate tectonic models showing the proto‐Greater Antilles located off southwestern Mexico during the early Tertiary. The development of South American affinities, other than by long‐distance dispersal throughout the Cenozoic, was facilitated in later Tertiary times by eastward movement away from Mexico/proto‐Central America and by emergence of the Lesser Antilles in the Eo‐Oligocene.