bluuebunny/crossref_metadata_2025 huggingface dataset:
MATERNAL INVESTMENT AND FRUIT ABORTION IN PHASEOLUS VULGARIS
Authors: Nakamura Robert R.
Published: January 2018

Plants lose some of their parental investment through fruit abortion. Resource conservation theory predicts that the maternal plant should abort those fruits furthest from maturity in order to conserve scarce resources. Embryo‐quality theory predicts that the maternal plant should favor offspring of particular genotypes. I recorded the patterns of maternal investment in floral cohorts of domesticated and wild beans, Phaseolus vulgaris L. In accord with the resource conservation theory, late pod cohorts have the highest fruit abortion rates. When domesticated beans are grown in smaller pots, late cohort survivorship declines. When domesticated beans are crossed with pollen donors of different degrees of relatedness, the fruit abortion rate is the same even though seeds from the outbred crosses weigh more. The challenge for ecologists is to model and test the combined and possibly conflicting effects of selection for resource conservation and high offspring quality.
EXPERIMENTAL HYBRIDIZATION, CHROMOSOMAL DIVERSITY, AND PHYLOGENY WITHIN GAURA SECTION STIPOGAURA (ONAGRACEAE)
Authors: Carr Bruce L. , Gregory David P. , Raven Peter H. , Tai William
Published: January 2018

Experimental hybridization data generally agree with patterns of morphological, ecogeographic, and chromosomal variation in support of current taxonomic hypotheses for Gaura section Stipogaura. Average rates of capsule‐set for intersectional crosses are significantly lower than for interspecific crosses within Stipogaura (14% vs. 63% respectively, P < 0.001). Post‐mating reproductive isolation within the section is not well‐developed, as indicated by comparable averages of cross‐success for interspecific (19%) and intraspecific (17%) crosses. Within Stipogaura, lowered rates of capsule‐set (for G. filipes crosses) and germination (seed from G. calcicola, G. filipes, and G. sinuata crosses) segregate the five species into four fertility groups. Gaura calcicola (n = 7) and G. sinuata (n = 14) differ by lower pollen staining in the hybrids of G. sinuata, a result of odd‐ploid hybridity. The order of average, interspecific cross‐success is G. mckelveyae (35%), G. villosa (25%), G. calcicola (14%), G. sinuata (10%), and G. filipes (2%). Patterns of interspecific fertility do not precisely parallel phylogenetic hypotheses based upon morphology. Three diploid taxa that closely resemble one another in growth habit (G. mckelveyae, G. calcicola, G. filipes) differ widely in rates of crossing success. Gaura villosa is relatively specialized morphologically but retains a high degree of interspecific fertility. Gaura sinuata is also specialized, but readily produces hybrids in crosses with three of the diploids.
SEXUAL ALLOCATION AND ANDROMONOECY: RESOURCE INVESTMENT IN MALE AND HERMAPHRODITE FLOWERS OF SOLANUM CAROLINENSE (SOLANACEAE)
Authors: Solomon Bruce Peary
Published: January 2018

Male and hermaphrodite flowers from the andromonoecious perennial Solanum carolinense were compared. Hermaphrodite flowers were 11–16% heavier than males, and this difference was consistent for two clones studied. Hermaphrodite flowers contained a greater amount of nitrogen than did male flowers, but males had higher percent nitrogen. Male and hermaphrodite flowers had equal investment in male structures: stamen mass, number of pollen grains, mass of pollen grains ejected by vibration, and pollen size were all similar for the two flower types. In contrast, male flowers had reduced masses of disfunctional female structures: ovaries of males were ⅓ as massive, and styles 1/7; as massive, as those of hermaphrodites. These results are consistent with the hypothesis that male flowers (which occur where fruit set is unlikely) increase male fitness through pollen donation, while saving resources that would otherwise be invested in hermaphrodite flowers that abscise.
A REEVALUATION OF THE DISCONTINUITY PLATE IN PSORALEEAE AND AMORPHEAE (LEGUMINOSAE)
Authors: Grimes James W.
Published: January 2018

The discontinuity plate, once thought to be a unique feature of the Leguminous tribes Psoraleeae and Amorpheae, has been used as evidence for a close relationship of the two tribes. It is here further studied for taxonomic utility. It is shown that the discontinuity plate comprises four phenomena, distributed in four tribes. Tribe Amorpheae has a discontinuity between the pedicellar and gynoecial traces with a profusion of tracheids at the junction of the gynoecial vascular traces, forming a plate‐like structure. This is present and developed at very early stages of the flower and corresponds to the discontinuity plate as originally described. Segregate genera of Psoralea as proposed by Stirton (1981) and Rydberg (1919) also have distinctive vascular features, though these are not the same as the discontinuity plate found in Amorpheae. Psoralea, Otholobium, and all New World genera of Psoraleeae have simple delayed maturation of xylem through the receptacle. Some species of Tephrosia (Tephrosieae) were found to have a similar development. Cullen and Bituminaria (Psoraleeae) have delayed maturation of xylem with an inverted cone‐like structure developing in early fruit. A similar structure was found in species of Desmodium (Desmodieae). Because the discontinuity plate is shown to comprise more than one phenomenon, and since these vascular irregularities are now known in four tribes, the discontinuity plate does not necessarily indicate a close relationship between the tribes Psoraleeae and Amorpheae. Furthermore, the phenomena cannot be assumed to be homologous. More complete developmental studies and a larger survey of the Papilionoideae is needed before the vascular features can be confidently used in systematic hypotheses.
CHANGE IN DORMANCY STATUS OF FRASERA CAROLINIENSIS SEEDS DURING OVERWINTERING ON PARENT PLANT
Authors: Baskin Jerry M. , Baskin Carol C.
Published: January 2018

Seeds of the monocarpic perennial Frasera caroliniensis ripen in late summer, and most of them are dispersed in late autumn and winter. However, some viable seeds may remain undispersed for more than a year. Embryos are underdeveloped (ca. 1.1–1.3 mm long) at seed maturity and do not grow while seeds remain on plants in the field. Dormancy in freshlymatured seeds was broken by 12 to 14 weeks of cold stratification at 5 C, during which the embryos elongated. On the other hand, seeds collected in January and March required a period of warm stratification followed by a period of cold stratification to germinate. Seeds collected in September and sown in a nonheated greenhouse germinated to 83% the first spring after maturation, whereas those collected and sown in January and March did not germinate until the second spring. Thus, seeds that remained on plants in the field until winter entered a deepened state of dormancy, and a warm (summer) followed by a cold (winter) stratification period was required to overcome it.
REPRODUCTIVE BIOLOGY OF ASCLEPIAS EXALTATA
Authors: Shannon T. Randolph , Wyatt Robert
Published: January 2018

An analysis of the relationships between plant size and survivorship and reproductive success was carried out by sampling four populations of the herbaceous perennial milkweedAsclepias exaltatain Virginia from 1980 to 1982. The annual survivorship rate (about 65%) is the lowest measured for any species ofAsclepias.Survivorship was strongly size‐dependent but showed no clear relationship with previous history of fruit production. Non‐flowering plants were significantly smaller than flowering plants and showed very strong (r > 0.87) correlations between root dry weight and stem or leaf dry weight. Flowering plants were similar to nonflowering plants in root: shoot ratio (approximately 1:1) but differed in that root dry weight was not strongly correlated with stem or leaf dry weight. Components of inflorescence size were strongly correlated within a given level of comparison (e.g., stems per plant with flowers per plant) but less strongly correlated between levels (e.g., stems per plant with flowers per stem). Number of fruits per plant and percentage fruit‐set were positively correlated with every component of inflorescence size. Although overall fruit‐set was low (about 2%), fruits that were initiated had a high probability of surviving to maturity. There was no evidence of an early period of high fruit abortion: a relatively constant proportion of fruits aborted between each age class.
CHROMOSOME COUNTS OF LATIN AMERICAN COMPOSITAE
Authors: Sundberg Scott , Cowan Clark P. , Turner Billie L.
Published: January 2018

Chromosome numbers are reported for 111 species of Compositae from Argentina, Chile, Costa Rica, Guatemala, Mexico, Paraguay, and Peru. These include first reports for 46 taxa, including 3 genera (Kyrsteniopsis K. & R.: N = 10, Eupatoriastrum Greenman: N = 16, and Piptothrix B. L. Robins.: N = ca. 17). The new combination, Decachaeta pyramidalis (B. L. Robins.) Sundberg, Cowan, & Turner, based on Piqueria pyramidalis B. L. Robins. is proposed.
RELATIONSHIP BETWEEN OIL DUCTS AND VOLATILE TERPENOID CONTENT IN CARROT ROOTS
Authors: Senalik Douglas , Simon Philipp W.
Published: January 2018

The number of oil ducts in freehand sections of roots of eight carrot (Daucus carota L.) genetic lines was compared to the levels of major volatile terpenoids. There was a high correlation (0.79) between number of ducts per unit area and total terpenoid amount. Individual compounds exhibited varying degrees of correlation, probably due to genetic difference between lines. Oil ducts often exhibited distinct patterns of concentric rings or radial lines, but this feature was not closely related to duct number. Oil ducts are present only in the phloem, and can form a highly interconnected network.
THE ROLE OF ETHYLENE IN COROLLA UNFOLDING IN IPOMOEA NIL (CONVOLVULACEAE)
Authors: Koning Ross E.
Published: January 2018

The roles of ethylene in corolla growth and senescence have been extensively studied; light, temperature, and abscisic acid (ABA) have already been implicated in rapid corolla opening (unfolding) in morning glory. In the present study, a possible interaction between ABA and ethylene production was examined. While applied ABA promoted corolla unfolding, it also promoted ethylene production. Furthermore, the effect of ABA could be eliminated by the ethylene biosynthesis inhibitors, aminoethoxyvinyl glycine (AVG) and cobalt ions. Simultaneously applied aminocyclopropane carboxylic acid (ACC) augmented the ABA response, but ACC applied alone promoted corolla unfolding as effectively as ABA alone. Measurements of ethylene production during eight successive stages of flower opening showed that the ethylene burst widely reported to occur in opened flowers prior to corolla senescence actually begins before the corolla unfolds. Ethylene production seems to be a later part of the sequence of biochemical events that leads to both corolla unfolding and synchronized inrolling and senescence.
AMYLOPLAST SEDIMENTATION AND ORGANELLE SALTATION IN LIVING CORN COLUMELLA CELLS
Authors: Sack Fred D. , Suyemoto M. Mitsu , Leopold A. Carl
Published: January 2018

Amyloplast sedimentation during gravistimulation and organelle movements was studied in living central rootcap cells of Zea mays L. cv. Merit. Cells from sectioned roots were viewed with a horizontally‐mounted videomicroscope. The kinetics of gravity‐induced amyloplast sedimentation were comparable to those calculated from experiments using fixed material. Individual amyloplasts fell at an average velocity of 5.5 μm min‐1; the maximal velocity of fall measured was 18.0 μm min‐1. Amyloplasts often rotated, sometimes rose in the cytoplasm, and occasionally underwent sudden rapid movements as fast as 58 μm min‐1. Saltations of other organelles were frequently observed. This appears to be the first report of cytoplasmic streaming in the presumptive statocytes of roots.
STIGMA OF NICOTIANA: ULTRASTRUCTURAL AND BIOCHEMICAL STUDIES
Authors: Cresti M. , Keijzer C. J. , Tiezzi A. , Ciampolini F. , Focardi S.
Published: January 2018

The aim of the present study has been to elucidate further the cytology of the glandular stigma of Nicotiana tabacum, the mechanism of the secretory process during stigma development and the biochemical composition of the exudate. The stigma consists of two distinct zones: a glandular zone formed by the papillae and 2–3 layers of cells (basal cells) immediately below them, and a non‐glandular region formed by vacuolated cells which are in continuity with the transmitting tissue. The stigmatic exudate is a complex mixture of different chemical compounds such as proteins, saccharides, fatty acids and phenols. The role of stigma secretion is discussed in relation to pollen activation, recognition and pollen tube growth.
GENDER VARIATION IN A RED MAPLE POPULATION (ACER RUBRUM; ACERACEAE): A SEVEN‐YEAR STUDY OF A “POLYGAMODIOECIOUS” SPECIES
Authors: Primack Richard B. , McCall Claire
Published: January 2018

Red maple trees have been described as having a complex breeding system, categorized as “polygamodioecious.” However, the seven‐year, quantitative investigation of 79 trees presented here shows that the breeding system is relatively simple, using the gender equations of Lloyd (1980). Out of the entire maple population, 55 individuals are constant males while 4 individuals are inconstant males that on occasion produce some female inflorescences. Twelve individuals are constant females and 6 individuals are inconstant females that on occasion produce some male inflorescences. Only 2 of the plants have a functional gender which fluctuates dramatically in successive years between maleness and femaleness. It might be predicted that maple plants may specialize in one gender at a small size and switch over to produce both pollen and ovules at a larger size. However, these data show that plants of inconstant gender are not larger than plants of constant gender. Further, the inconstant plants actually appear to have a lower mean fitness than plants of constant gender. These results suggest that inconstancy in red maple gender does not increase fitness and may be an example of an imperfectly developed canalization process.
SPORE TETRAD STRUCTURES OF POSSIBLE HEPATIC AFFINITY FROM THE AUSTRALIAN LOWER CARBONIFEROUS
Authors: Satterthwait Donna F. , Playford Geoffrey
Published: January 2018

Palynological studies of Early Carboniferous (Viséan) sediments of the Bonaparte Gulf Basin, northwestern Australia, reveal the presence of intact tetrahedral spore tetrads (here described as Sagenotetradites gen. nov.) and, more usually, of their disjunct spore portions which had previously been interpreted as dispersed whole‐miospore species. Two species of the new tetrad genus are recognized: S. bonapartensis (Playford) comb, nov., as type species; and S. spiritensis (Playford) comb. nov. The species are distinguished, as originally, on the basis of sculptural attributes of their distal exoexines. When intact, both species share a common internal “binding” element (“Cadiospora abrupta” Playford, 1971) composed of the fused proximal exoexinal faces of all four spores of a given tetrad. Morphological comparisons with modern hepatic spores suggest an alliance of the microfossils with the order Sphaerocarpales. The occurrence of Sagenotetradites in exclusively marine sediments suggests that its parent plants grew in close proximity to the marine depositional basin. Moreover, the morphological attributes of the tetrads would appear to have facilitated dissemination by water.
GENETIC DIFFERENTIATION IN LEAF AND WHOLE PLANT PHOTOSYNTHETIC CAPACITY AND UNIT LEAF RATE AMONG CLONES OF PHLOX PANICULATA
Authors: Garbutt K.
Published: January 2018

A model population comprising five genotypes of Phlox paniculata was used to investigate differentiation in carbon assimilation amongst those genotypes. Three methods were used to measure carbon assimilation, single leaf photosynthetic capacity, whole plant photosynthetic capacity and unit leaf rate (ULR). Genotypes displayed no significant differences in single leaf photosynthetic capacity and that character did not have a detectable genetic component. However, genotypes showed significant differences in both whole plant photosynthetic capacity and unit leaf rate, and significant genetic components were found for both characters. The differences in whole plant photosynthetic capacity and unit leaf rate are related to differences in plant architecture and modular demography. Erect, self‐shading morphs had lower whole plant photosynthetic capacity and unit leaf rate than prostrate morphs. The results suggest that the better measures of physiological parameters for use at the population level will be those which integrate over the whole plant rather than those which only measure performance of parts.
CHROMOSOME NUMBERS IN SPHAERALCEA SECTION FENDLERIANAE
Authors: Duke John C. La
Published: January 2018

Chromosome numbers are reported for ten taxa in Sphaeralcea section Fendlerianae (Malvaceae). New ploidy levels are reported for six taxa, with one species not previously reported, and extensive polyploidy at all taxonomic levels is documented. The geographic and taxonomic distribution of polyploids suggests that polyploidy arose many times in the taxa of Sphaeralcea. Sphaeralcea fendleri var. venusta, S. polychroma, and S. wrightii populations have yielded exclusively tetraploid counts. Tetraploidy is correlated with taxa having lavender petals. Polyploidy has also allowed the taxa to expand their distributions without resulting in speciation.
REPRODUCTION IN POLEMONIUM: PATTERNS AND IMPLICATIONS OF FLORAL NECTAR PRODUCTION AND STANDING CROPS
Authors: Zimmerman Michael , Pyke Graham H.
Published: January 2018

Patterns of floral nectar production and standing crop were measured in four populations of the herbaceous perennial plant species Polemonium foliosissimum. Contrary to prediction (Pleasants, 1983), individual flowers in this mass‐flowering species were found to produce equivalent nectar volumes every day of their lives. Alternative methods of increasing the reward variability presented to pollinators are evaluated for P. foliosissimum and the relationship between that variability and risk‐aversive foraging by pollinators is discussed. Significant spatial and temporal variability in rate of nectar production was found. Populations separated by approximately 200 m exhibited different rates. Nectar production declined significantly as a function of time of the flowering season in two populations but not in a third. In spite of such variability, individual plants showed consistency in production both within a single blooming season and across successive seasons. Because of the variability found in the present study, care should be taken to design appropriate sampling protocols in future nectar studies. Patterns of standing nectar crop were consistent with those expected if pollinators were using an area‐restricted searching pattern.
PINUXYLON WOOLARDII SP. NOV., A NEW PETRIFIED TAXON OF PINACEAE FROM THE MIOCENE BASALTS OF EASTERN OREGON
Authors: Tidwell William D. , Parker Lee R. , Folkman Vaughn K.
Published: January 2018

Specimens of the new species Pinuxylon woolardii have been collected from Miocene strata near Durkee, OR. These petrified specimens are unique in that, due to weathering, individual tracheids and ray cells can be separated for detailed SEM studies. This species is characterized by its high number of ray cells; numerous rays; large resin ducts which are commonly paired; primarily uniseriate pitting, two to five (usually three) small, oval or circular pinoid pits per crossfield; and smooth walls on its transverse (ray) tracheids. The latter character relates this species to taxa in the subgenus Haploxylon of Pinus. Pinuxylon woolardii is most similar to the fossil species Pinuxylon parryoides and the extant species Pinus aristata, P. cembroides, P. edulis, P. monophylla and P. balfouriana. These modern species live in dryer environments and at higher elevations than that suggested by the Miocene leaf floras which occur near the locality of P. woolardii.
POLLEN MORPHOLOGY OF AMPHIANTHUS, ARTANEMA, CURANGA, GLOSSOSTIGMA, AND PEPLIDIUM (SCROPHULARIACEAE‐GRATIOLEAE)
Authors: Argue Charles L.
Published: January 2018

Pollen of the scrophulariaceous genera Amphianthus, Artanema, Curanga, Glossostigma, and Peplidium was examined by light and scanning electron microscopy. All have single, isopolar, radially symmetrical pollen grains with equally spaced meridional colpi and columellate exines. Intergeneric differences are established mainly on the differential correlation of colpus number, colpus morphology, and sculpturing of the mesocolpium. The colpi vary in length and range in number from 3 to 6. The colpus membrane can be variously granular, verrucate, rugulate, or spinulose. The exine varies from semitectate and microreticulate or reticulate to tectate and sparsely perforate. It may be psilate or ornamented with supratectal processes ranging from small granules to relatively long spinules or bacules. All the genera examined, with the possible exception of Artanema vs. Amphianthus, are distinguished from one another by pollen morphology, and the grains of both Curanga and Glossostigma have morphotypes not previously reported in tribe Gratioleae. Final taxonomic assessment of the pollen data in the genera examined must await further comparative studies in the Gratioleae and other tribes, but the morphological diversity observed is clearly of potential significance in evaluating specialization levels and clarifying current conflicting interpretations of relationships in these taxa.
ORNITHOPHILY AMONG THE HAWAIIAN LOBELIOIDEAE (CAMPANULACEAE): EVIDENCE FROM FLORAL NECTAR SUGAR COMPOSITIONS
Authors: Lammers Thomas G. , Freeman C. Edward
Published: January 2018

Data on the sugar compositions of floral nectars were used to test the hypothesis that the Hawaiian Lobelioideae (Campanulaceae) were pollinated by nectarivorous passerine birds (Fringillidae subfam. Drepanidinae, Meliphagidae) prior to widespread extinctions among the native avifauna. Nectars from 24 individuals (representing different taxa [three genera, ten species, and three interspecific hybrids], different conspecific populations, and different individuals within a population) were analyzed via high‐performance liquid chromatography (HPLC). Mean percentages (±one S.D.) and ranges (parenthetically) for each sugar were: fructose, 43.5 ± 2.8% (37.2%–48.3%); glucose, 54.5 ± 3.1% (47.2%–62.8%); and sucrose, 2.0 ± 1.6% (0.0%–5.3%). These nectars are thus hexose‐dominant (mean sucrose‐hexose ratio of 0.019 ± 0.017), the type preferred by passerine birds.
VASCULARIZATION OF A MULTILACUNAR SPECIES: POLYSCIAS QUILFOYLEI (ARALIACEAE) I. THE STEM
Authors: Larson Philip R.
Published: January 2018

The odd‐pinnate leaves of Polyscias quilfoylei have a sheathing leaf base that completely encircles the stem. At each node, many traces depart the vascular cylinder and traverse an obliquely upward course through the leaf base before aggregating in the rachis. Lateral traces diverge from parent traces in the stem vasculature at variable times relative to the leaf they serve, from variable positions in the vascular cylinder and from parent traces of variable ages. The stem vasculature is formed by the coalescing of leaf traces from as many as five leaves. All bundles departing the vascular cylinder at a node to serve a leaf are true leaf traces originating independently in the stem. Leaf traces develop acropetally from their positions of origin on parent traces. Primordial leaves are first served by the median trace and later by lateral traces. Many traces were recognized in the internodes subtending embryonic leaves, but they could not be related either to a specific leaf or to a specific position within a leaf. Because these traces had not yet achieved contact with a primordial leaf site, they were assumed to be in the process of developing acropetally at the time of sampling. Observations suggest that the multiple traces in this species might perform a similar function of integrating the vascular cylinder that subsidiary bundles perform in certain uni‐ and trilacunar species.
THREE NEW GENERA OF FOSSIL NONCALCAREOUS ALGAE FROM VALMEYERAN (MISSISSIPPIAN) STRATA OF ILLINOIS
Authors: Leary Richard L.
Published: January 2018

Three previously unknown algal forms are preserved as carbonaceous residue and impressions in basal St. Louis Formation (Valmeyeran Series) of Jersey County, Ill. On the basis of morphologic similarities the algae are considered to belong to Rhodophyta and Phaeophyta. The algae are associated with conularia. The algae and conularia probably lived in shallow marine water on the eastern flank of the Ozark Dome and southern margin of the Illinois Basin. This region would have been at approximately 20 south latitude during the Visean.
REPRODUCTIVE BEHAVIOR OF AMPHICARPAEA BRACTEATA (LEGUMINOSAE), AN AMPHICARPIC ANNUAL
Authors: Schnee Bradley K. , Waller Donald M.
Published: January 2018

Amphicarpaea bracteata, an annual legume common in woodland communities in the eastern United States, produces three distinct types of flower: subterranean cleistogamous (SCL), aerial cleistogamous (ACL), and aerial chasmogamous (ACH). We sought to quantitatively describe the growth and reproduction of four diverse A. bracteata populations in an effort to explain the adaptive significance of this species’ variable reproductive modes. Virtually all plants develop 1 to 3 SCL seeds on subterranean cotyledonary shoots, starting in late July. Larger plants produce additional SCL seeds later from the tips of axillary shoots which bury. Seeds produced by SCL flowers are large (39 to 134 mg), have restricted dispersal, lack dormancy, have high germination , and produce relatively vigorous seedlings. ACL flowers develop from early August through plant senescence in early October, while ACH flowers appear in a pulse in late August. The number of each aerial flower type was positively correlated with plant size. The ACL flowers take significantly less time to develop mature fruits than do ACH flowers. Both aerial seeds are smaller than the subterranean (mean weights: ACL 12.1, ACH 8.7 mg), have lower germination (ACL 20.2%, ACH 15.3%), appear relatively resistant to environmental extremes, and have the potential for more widespread dispersal. Plants derived from subterranean seeds are much larger than plants derived from aerial seeds, which makes them more likely to produce axillary SCL and aerial seeds. Only larger plants derived from subterranean seeds and growing in favored sites produce ACH flowers. This imposes an alternation of selfing with outcrossing generations. This pattern of reproductive behavior in A. bracteata is similar to that found in several other amphicarpic species.
CLADISTIC TESTS OF HYPOTHESES CONCERNING EVOLUTION OF XEROPHYTES AND MESOPHYTES WITHIN TILLANDSIA SUBG. PHYTARRHIZA (BROMELIACEAE)
Authors: Gilmartin Amy Jean , Brown Gregory K.
Published: January 2018

Tillandsia L. Subg. Phytarrhiza (Visiani) Baker (Bromeliaceae) is a distinctive group of about 35 epiphytic species. These exhibit a range of habits from xeric to mesic. The evolutionary relationships of the contrasting adaptations need to be established here as well as in the subfamily as a whole. Relations between the subgenus and other tillandsioids are problematical and phylogenetic reconstruction of its member‐species would be facilitated by identification of Phytarrhiza's relative (sister taxon) sharing the same most recent common ancestor with Phytarrhiza. This paper examines the two most likely sister taxa, Subg. Pseudo‐Catopsis Baker and Subg. Diaphoranthema (Beer) Baker. Diaphoranthema is rejected as sister taxon. The accepted evolutionary tree, rooted by Pseudo‐Catopsis, indicates that most habital evolutionary changes in Phytarrhiza have been between mesic and semi‐mesic forms and from mesic to xeric forms. Methods developed for testing specific evolutionary hypotheses are broadly applicable.
CALCIUM MOVEMENT, GRAVIRESPONSIVENESS, AND THE STRUCTURE OF COLUMELLA CELLS IN PRIMARY ROOTS OF AMYLOMAIZE MUTANTS OF ZEA MAYS
Authors: Moore Randy
Published: January 2018

Primary roots of Zea mays cv. Amylomaize were less graviresponsive than primary roots of the wild‐type Calumet cultivar. There were no significant differences in: 1) the partitioning of volume to organelles in columella cells, 2) the size or density of amyloplasts, or 3) rates and overall patterns of organelle redistribution in horizontally‐oriented roots of the two cultivars. Amyloplasts and nuclei were the only organelles whose movement correlated positively with the onset of root gravicurvature. However, the onset of gravicurvature was not directly proportional to the average sedimentation rate of amyloplasts, since amyloplasts sedimented at equal rates in columella cells of both cultivars despite their differences in root gravicurvature. The more graviresponsive roots of Calumet seedlings were characterized by a more strongly polar movement of 45Ca2+ from the upper to lower sides of their root tips than the less graviresponsive roots of Amylomaize seedlings. These results suggest that the decreased graviresponsiveness of horizontally‐oriented roots of Amylomaize seedlings may be due to a delay in or decreased ability for polar transport of calcium rather than to smaller, more slowly sedimenting amyloplasts as has been suggested for their less graviresponsive coleoptiles.
EFFECTS OF BURIAL BY SAND ON SEED GERMINATION AND SEEDLING EMERGENCE OF FOUR DUNE SPECIES
Authors: Maun M. A. , Lapierre J.
Published: January 2018

On the beach strand, seedlings of Cakile edentula, Elymus canadensis, and Corispermum hyssopifolium emerged from mean depths of 3.4, 3.5 and 3.0 cm, respectively. The frequency distribution of the depth of seedling emergence was 1) significantly leptokurtic for C. edentula and slightly platykurtic (not significant) for C. hyssopifolium and E. canadensis, and 2) significantly skewed to the right for C. edentula and E. canadensis but not for C. hyssopifolium. The total germination was not influenced by the burial of seeds at 2, 4, 6, 8, 10 and 12 cm depths except in Ammophila breviligulata in which the germination decreased with increasing depth of burial. The rate of emergence and total emergence decreased with increased sowing depth for all four plant species. Species with larger seeds emerged from deeper burial treatments than those with small seeds. The order of ED50 (the planting depth from which 50% of the seedlings emerged) and EDmax (the maximum depth from which a seedling emerged) was C. edentula (upper seeds) > E. canadensis > C. edentula (lower seeds) ≖ C. hyssopifolium > A. breviligulata and it coincided with weight per seed.
DEVELOPMENT AND EVALUATION OF A FREEZE‐ETCH, FREEZE‐FRACTURE TECHNIQUE APPLIED TO DEVELOPING WHEAT ENDOSPERM
Authors: Bechtel D. B. , Barnett B. D.
Published: January 2018

A technique was developed and evaluated whereby differentiating wheat endosperm tissue could be processed for the freeze‐etch, freeze‐fracture technique without the use of chemical fixatives. Field grown, developing hard red winter wheat (cv. Newton) caryopses were infiltrated with glycerol prior to freezing in liquid nitrogen‐cooled Freon‐22. Frozen samples were placed in cryogenic vials and stored in liquid nitrogen until needed. Freeze‐fracture was carried out under standard conditions. Evaluation of replicas from glycerol‐imbibed endosperm was made by comparing them to replicas obtained from freshly frozen untreated endosperm, and endosperm that had been prefixed in glutaraldehyde and paraformaldehyde. Other evaluations were made by comparing replicas of glycerol‐treated endosperm to thin sections obtained from wheat that had been imbibed with glycerol, fixed, dehydrated, and infiltrated and embedded in epoxy resin for routine electron microscopy. The results indicate that if the unfixed glycerol‐treated wheat endosperm is handled carefully, replicas can be obtained which show few artifacts due to glycerol and freezing. Typical artifacts such as vesiculation of RER, ice crystal damage, production of fusion intermediates, and membrane particle segregation can be nearly eliminated when this technique is applied to developing wheat endosperm.
ANTHECOLOGY AND POLLINATOR EFFICACY OF STYRAX OFFICINALE SUBSP. REDIVIVUM (STYRACACEAE)
Authors: Sugden Evan A.
Published: January 2018

Styrax officinale subsp. redivivum is a homogamous, xenogamous shrub of the California foothill chaparral. Its floral biology, breeding system, and pollination ecology are presented. A summarizing model of pollinator efficacy, EP, describes the relative potential of pollinator species based on behavioral, morphological, and ecological variables. The EP can be expressed as the product of pollinator density (number per flower per minute) and individual pollinator efficacy. By this analysis, the most individually efficacious pollinator of S. o. redivivum is the papilionid butterfly Battus philenor. Pollen forager honey bees, Apis mellifera, are important on a population level but, on an individual basis, are less efficacious than queens of the bumble bee Bombus vosnesenskii. Nectar foraging honey bees, Bombus edwardsii workers, and females of the carpenter bee Xylocopa tabaniformis have intermediate values. The halictid bee Halictus ligatus has little importance as a pollinator and syrphid flies have almost no potential.
TWO NEW GENERA OF BRAZILIAN BAMBOOS RELATED TO GUADUA (POACEAE: BAMBUSOIDEAE: BAMBUSEAE)
Authors: Soderstrom Thomas R. , Londoño Ximena
Published: January 2018

Of all the genera of woody bamboos described from America, only three have pseudospikelets—Atractantha, Elytrostachys, and Guadua. The former two have pseudospikelets with an elongated rachilla internode that precedes the floret, making it pedicellate; they also share a type of leaf anatomy that separates them from the latter. The two new genera herein described, Criciuma and Eremocaulon, show most similarity to species of Guadua, both in spikelet morphology and in leaf anatomy. The study of these new taxa has helped to clarify the limits of New World genera with pseudospikelets and strengthened the case for maintaining Guadua as a genus distinct from its Old World counterpart, Bambusa. We are now able to discern a New World line of bamboos that includes Criciuma, Eremocaulon, and Guadua, separate from an Old World line that includes Bambusa, Dendrocalamus, and several other genera.
EFFECT OF DENSITY ON SECONDARY SEX CHARACTERISTICS AND SEX RATIO IN SILENE ALBA (CARYOPHYLLACEAE)
Authors: Doust J. Lovett , O'Brien G. , Doust L. Lovett
Published: January 2018

A field survey of plant and flower sex ratio and secondary sex characteristics was made in Silene alba. Female‐biased plant sex ratios were found, as seems typical for the species. Sex ratio distribution correlated with a gradient of soil moisture (with the more moist area having a more female‐biased ratio) and with changes in the density of Silene (intermediate and higher density areas having greater female bias). The floral sex ratio was significantly female‐biased only at the site that was most female‐biased in terms of plant sex ratio. Otherwise the population of flowers was significantly male‐biased. Male and female plants harvested from the field differed in secondary sexual characteristics. Males had more flowers and invested proportionately more biomass in leaf, but less in root, stem and reproductive tissue than did females. Although both males and females were larger in terms of total dry weight at the moist site, males produced more flowers at the driest (high density) site. Here the female bias in plant sex ratio was intermediate, but the floral sex ratio was significantly male‐biased.

A glasshouse experiment was performed in which plants were grown at four densities. Density significantly influenced plant survivorship and the probability of flowering, and increased female bias in the pots, but it did not affect patterns of biomass allocation in flowering plants. Patterns of male and female biomass allocation did not differ in the experiment, except in terms of reproductive allocation (greater in females) and allocation to leaf, greater in males, but only at the lowest density. This work urges caution in interpreting differences between males and females in the field as secondary sex characteristics, since we find such properties to be overlapping under experimental conditions. It supports the idea that males and females of a species may sustain different reproductive output under differing conditions.
FINE STRUCTURE OF EPITHELIAL CANAL CELLS IN PETIOLES OF XANTHIUM PENSYLVANICUM
Authors: Maksymowych R. , Ledbetter M. C.
Published: January 2018

Secretory canals, lined with an epithelium, occur in many families, e.g., Umbelliferae, Compositae. These canals are said to extend continuously through the root and shoot systems and are known, in some cases, to secrete resins, essential oils, etc. In Xanthium the canals arise schizogenously from cells derived from canal initials. Subsequent divisions lead to a ring of 7–12 epithelial cells surrounding a central cavity. During maturation the epithelium becomes crushed and obliterated. Canals were examined in petioles of Xanthium pensyhanicum (Cocklebur) grown under long day illumination to maintain vegetative growth. The fine structure of the canal and its epithelium was studied by electron microscopy of thin sections cut transverse to the principal axis of petioles from leaves in an early stage of development. The canal proper is delimited by walls of epithelial cells which protrude into a scallop shaped cavity. In comparison to the surrounding parenchyma, the epithelial cells are smaller, cytoplasmically more dense, and less vacuolate. The epithelium contains pleomorphic starch‐free plastids with planar thylakoids frequently stacked into grana; thus, the plastids are presumed photosynthetically active. Mitochondria are abundant and often dense. The cytoplasm is rich in free polysomes, and smooth endoplasmic reticulum predominates over the rough form. Spheroidal granules averaging about 530 nm in diameter are numerous in the epithelium and appear at lower concentration in neighboring cells. Many features of fine structure of the epithelial cells suggest that a high metabolic activity is present in this tissue during this early stage of development. A possible function of the canals is defense against insect predation and animal grazing.
INSECT POLLINATION IN THE CYCAD ZAMIA PUMILA (ZAMIACEAE)
Authors: Tang William
Published: January 2018

A wind and insect exclusion pollination experiment was conducted in a wild population of the cycad Zamia pumila L. in Florida. Cones from which insects but not wind were excluded produced no viable seeds, while cones from which wind but not insects were excluded produced abundant viable seeds. Two beetle species have been identified which may be effecting pollination. Adults and larvae of both beetles are found abundantly on the male cones, and adults of both species and larvae of one species are found occasionally on female cones. Z. pumila produces sugar and amino acid‐rich micropyle droplets which may serve as pollinator rewards. Mimicry of resource‐rich male cones by female cones and the use of cones as refuges between mating and feeding bouts may account for beetle movement from male to female cones.
NUCLEAR GENE‐INDUCED PLASTOME MUTATIONS IN OENOTHERA HOOKERI. II. PHENOTYPIC DESCRIPTION WITH ELECTRON MICROSCOPY
Authors: Epp Melvin D. , Parthasarathy M. V.
Published: January 2018

The nuclear gene pm of Oenothera hookeri T. & G. strain Johansen increases the frequency of plastome mutations. These plastome mutations are visible because they form variegation sectors. A distinctive feature of the pm system is the large number of different phenotypes induced by the plastome mutator. The fine structure of four plastome mutants has been studied using electron microscopy. Each of the four mutants had a unique phenotype which was characterized by the amount of thylakoid development, the number of plastoglobuli, and the dilation of thylakoids with age. The developmental sequence of the phenotype of one of the mutants was studied by following plastid development in progressively larger leaves. The phenotypes of the pm‐induced mutants are generally similar to those of spontaneous plastome mutations described in the literature.
REPRODUCTIVE BIOLOGY OF PETAL COLOR VARIANTS IN WILD POPULATIONS OF RAPHANUS SATIVUS: II. FACTORS LIMITING SEED PRODUCTION
Authors: Stanton Maureen L.
Published: January 2018

Wild radish (Raphanus sativus) populations in California contain several conspicuously different petal color morphs. Pollinators are known to discriminate among color variants, and this study was done to determine whether such discrimination influences seed and fruit production. Seed set potential, as determined by total flower production and the number of ovules per flower, did not vary among color morphs. Total fruit set was high in these populations, ranging from 60% to 80%, and did not vary significantly among common petal colors in any site. The number of seeds per fruit did vary among color morphs, but the pattern was different in 1983 and 1984 and did not correspond to concurrent patterns of pollinator visitation. Hand pollination studies showed that pollen limitation is not a major factor influencing seed production; in 1984, addition of pollen to flowers failed to enhance fruit or seed set, while in 1983, addition of pollen slightly increased the number of seeds per fruit. Additional experiments demonstrated that all petal color morphs were mostly self‐incompatible. Resource limitation appeared to be a major force regulating seed production. Despite consistently high pollinator visitation rates, flower production rate, fruit set, and seeds per fruit all declined markedly through the five wk flowering season. Pollinator discrimination among colors is likely to have its greatest impact on paternity success rather than maternal fecundity.
INFLUENCE OF MICROGRAVITY ON ROOT‐CAP REGENERATION AND THE STRUCTURE OF COLUMELLA CELLS IN ZEA MAYS
Authors: Moore Randy , McClelen C. Edward , Fondren W. Mark , Wang Chia‐Lien
Published: January 2018

We launched imbibed seeds and seedlings of Zea mays into outer space aboard the space shuttle Columbia to determine the influence of microgravity on 1) root‐cap regeneration, and 2) the distribution of amyloplasts and endoplasmic reticulum (ER) in the putative statocytes (i.e., columella cells) of roots. Decapped roots grown on Earth completely regenerated their caps within 4.8 days after decapping, while those grown in microgravity did not regenerate caps. In Earth‐grown seedlings, the ER was localized primarily along the periphery of columella cells, and amyloplasts sedimented in response to gravity to the lower sides of the cells. Seeds germinated on Earth and subsequently launched into outer space had a distribution of ER in columella cells similar to that of Earth‐grown controls, but amyloplasts were distributed throughout the cells. Seeds germinated in outer space were characterized by the presence of spherical and elipsoidal masses of ER and randomly distributed amyloplasts in their columella cells. These results indicate that 1) gravity is necessary for regeneration of the root cap, 2) columella cells can maintain their characteristic distribution of ER in microgravity only if they are exposed previously to gravity, and 3) gravity is necessary to distribute the ER in columella cells of this cultivar of Z. mays.
FLOWER AND FRUIT DEVELOPMENT IN WIGANDIA CARACASANA (HYDROPHYLLACEAE)
Authors: Hilger Hartmut H.
Published: January 2018

In contrast to previous descriptions, which only state the bicarpellate, syncarpous gynoecium of Wigandia caracasana is superior, this paper demonstrates that it is half inferior and zygomorphic. The abaxial carpel is initiated before the adaxial and constitutes the major part of the ovary. The ovarial chamber is divided at the bottom by both a cross zone and false septa, and at the top by apical septa. The dehiscence tissue of the loculicidally opening capsule develops through the median carpel bundles and the small false septa. The sclerified endocarp, consisting of both inner epidermis and adjacent subepidermal layer, acts as opening tissue. From an entire circular stele that enters the receptacle, ten vascular strands originate from ten gaps. They alternatingly diverge either into the dorsal bundle of a sepal and the single trace of the adjacent stamen, or into the single petal trace and two branches supplying adjacent sepals as marginal bundles. The stele itself vascularizes the gynoecium. Half inferior ovaries seem to be more frequent in the Hydrophyllaceae than previously assumed.
FOSSIL FLORAL EVIDENCE OF MALPIGHIACEAE AND AN EARLY PLANT‐POLLINATOR RELATIONSHIP
Authors: Taylor David Winship , Crepet William L.
Published: January 2018

Fossil flowers with affinities to Malpighiaceae have been discovered in the Middle Eocene Claiborne formation of northwestern Tennessee. The new taxon Eoglandulosa warmanensis gen. et sp. nov. Taylor and Crepet, has paired glands on the five sepals, clawed petals and tricolporate pollen with reticulate ornamentation and an unusual infratectal wall structure of anastomosing elements. The fossil is similar in wall structure to some extant species of Malpighiaceae. Glandular floral morphology in extant species is associated with specific anthophorid bee pollinators and the fossil evidence suggests that such specific plant‐pollinator relationships existed during the Eocene. This fossil species also suggests that by the Eocene, South American floral elements had migrated to North America via island pathways, and that the Mississippi embayment was nearly frost‐free.
BREEDING SYSTEM OF THE FERN DRYOPTERIS EXPANSA: EVIDENCE FOR MIXED MATING
Authors: Soltis Douglas E. , Soltis Pamela S.
Published: January 2018

The levels and distribution of genetic variation within and among populations of the homosporous fern Dryopteris expansa were assessed using enzyme electrophoresis. Twelve loci representing six enzymes were examined in 502 sporophytes from nine populations. Values of P, H, and mean number of alleles per locus are much lower in D. expansa compared to values for other fern species. Values of F varied from –0.014 to 0.745 with an average F of 0.335. There was also considerable population to population variation in F. In three populations the observed heterozygosity closely approximated that expected at Hardy‐Weinberg equilibrium, whereas in the remaining populations observed heterozygosity was significantly lower than the expected heterozygosity. In D. expansa the major component of FIT is FIS; the relatively high FST value suggests a high degree of interpopulational differentiation. Electrophoretic data suggest that this species possesses a mixed mating system. This study, in conjunction with other investigations, indicates that just as in angiosperms, a variety of breeding systems operates in homosporous ferns, ranging from extreme inbreeding, through mixed mating to outcrossing.