bluuebunny/crossref_metadata_2025 huggingface dataset:
Evolutionary implications of substitution patterns in prolamin genes of Oryza glaberrima (African rice, Poaceae) and related species
Authors: Hilu Khidir W. , Sharova Lioudmila V.
Published: February 2008

Patterns of sequence variation of nuclear genes encoding 10‐kDa and 16‐kDa prolamin seed storage proteins were examined in Oryza glaberrima (African rice, Poaceae) and O. barthii and compared to available sequences for the genus to assess potential application of these gene families in evolutionary studies. Sequence variation among species in 10‐kDa genes was very low. In contrast, the 16‐kDa genes have undergone rapid evolution, displaying a larger number of length and point mutations that in some cases result in frame shift or produce truncated protein or pseudogenes. The proportion of nonsynonymous substitution is high in both genes. Although nonsynonymous mutations did not alter the overall profile of the protein, pronounced shifts in proportions of some amino acids were evident and could have systematic application. The data provide support for a proposed direct evolution of the Asian (O. sativa) and African rice from O. rufipogon and O. barthii, respectively. Patterns of amino acid frequencies of the 10‐kDa genes show the distinctness of O. rufipogon and O. longistaminata from the other species. The study underscores the potential application of the prolamin genes as markers from the nuclear genome for evolutionary studies in grasses at different taxonomic levels.
The role of autonomous self‐pollination in floral longevity in varieties of Impatiens hypophylla (Balsaminaceae)
Authors: Sato Hisashi
Published: February 2008

The floral longevity of unpollinated, hand self‐, and hand cross‐pollinated flowers was compared in two varieties of Impatiens hypophylla, which contrasts with their mating systems. When flowers were emasculated and hand‐pollinated every day after anthesis, their longevity was reduced. In the absence of emasculation and hand pollination, the staminate phase of the flowers of both varieties was 1 d longer. After the staminate phase, flowers of the outcrossing variety dropped their androecium, exposing the stigma and initiating the pistillate phase, which lasted for ∼2 d. In contrast, flowers of the mixed‐mating variety self‐pollinated autonomously and then terminated their flowering. Under great seasonal variation in the pollinator visitation rate, which was observed in their natural populations, the outcrossing variety should maximize expected outcross success through the phenology of floral sex phases, whereas the mixed‐mating variety self‐pollinated ovules that were not outcrossed within the staminate phase. Based on these results, I suggest that the autonomous self‐pollination in I. hypophylla induced differences both in the selfing coefficient and in floral longevity between the varieties.
A systematic analysis of Heliotropium, Tournefortia, and allied taxa of the Heliotropiaceae (Boraginales) based on ITS1 sequences and morphological data
Authors: Diane Nadja , Förther Harald , Hilger Hartmut H.
Published: February 2008

The relationships of Heliotropium, Tournefortia, Schleidenia, Ixorhea, and Ceballosia of the Heliotropiaceae (Boraginaceae in the traditional sense, Boraginales) are investigated using molecular data (ITS1). These genera form a monophyletic group. Five clades can be distinguished on the basis of molecular data, morphological traits, and distribution. In their current circumscription, Tournefortia is polyphyletic and Heliotropium is paraphyletic. Tournefortia section Cyphocyema is the sister group to all other ingroup taxa. Heliotropium section Orthostachys including Schleidenia sensu lato is the well supported sister group of a clade comprising the other species of Heliotropium sensu stricto (s.s.), Tournefortia section Tournefortia, and Ceballosia. Heliotropium s.s. forms two clades: one clade includes all species of the Old World and represents the only monophylum of Heliotropium s.s. The other clade consists of all Heliotropium s.s. species of the New World but also includes Tournefortia section Tournefortia and Ceballosia. The results suggest that taxonomic changes are inevitable.
Phylogenetic relationships within the blueberry tribe (Vaccinieae, Ericaceae) based on sequence data from MATK and nuclear ribosomal ITS regions, with comments on the placement of Satyria
Authors: Kron Kathleen A. , Powell E. Ann , Luteyn J. L.
Published: February 2008

The blueberry tribe (Vaccinieae) is a large and morphologically diverse group that is widespread in the temperate and tropical zones of most continents. The greatest species diversity is in the tropics, where Vaccinieae are a major component of montane cloud forests. Generic limits are poorly understood, and many of the characters traditionally used fail to adequately distinguish among taxa. This study analyzed sequence data from the chloroplast matK gene and the nrITS region for 93 species of Vaccinieae, representing 28 genera, and 16 sections (of the ∼33 currently recognized) of Vaccinium. Results indicated that, in general, traditional generic circumscriptions were not corroborated, but several well‐supported clades were found: an Andean clade (including at least some members of 18 of the 23 Neotropical genera sampled), a Meso‐American/Caribbean clade, an East Malesian clade (including the Old World taxa Paphia and Dimorphanthera), an Agapetes clade comprised of some Asian Vaccinium and Agapetes, and a Bracteata‐Oarianthe clade (Vaccinium spp.). This study is the first to address phylogenetic relationships among members of Vaccinieae on a worldwide basis and the results indicate that the large genus Vaccinium is not monophyletic, but likely represents a grade group out of which several more specialized clades evolved.
Mycorrhizal dependency of some endemic and endangered Hawaiian plant species
Authors: Gemma J. N. , Koske R. E. , Habte M.
Published: February 2008

Four endemic species of Hawaiian plants were tested for their response to inoculation with a Hawaiian isolate of Glomus aggregatum (an arbuscular mycorrhizal fungus [AMF]) when grown in a native soil with or without P added to achieve different soil‐solution P levels. The endangered species (Sesbania tomentosa [Fabaceae] and Colubrina oppositifolia [Rhamnaceae]) and two nonendangered species (Bidens sandvicensis and B. asymmetrica × sandvicensis [Asteraceae]) were tested. When soil‐solution P levels in greenhouse trials were similar to unfertilized field soils (e.g., 0.005–0.020 mg P/L), shoots of inoculated plants were 2.1 to 7.0 times larger than noninoculated plants. Leaf tissue P levels and root biomass in these species showed similar responses to inoculation. Mycorrhizal dependencies ranging from 44 to 88% were measured when plants were grown in low‐P soils and were −4–42% in soil with P levels typical of highly productive agricultural soils. A survey of P levels in a variety of native (nonagricultural) Hawaiian soils indicated the widespread occurrence of P‐limited sites (mean = 0.010 mg P/L, range = <0.001–0.030 mg P/L; N = 41). The terms “ecological mycorrhizal dependency” (EMD) and “agricultural mycorrhizal dependency” (AMD) are introduced to refine the concept of mycorrhizal dependency.
Fringe Science: are the corollas of Nymphoides (Menyanthaceae) flowers adapted for surface tension interactions?
Authors: Armstrong Joseph E.
Published: February 2008

Attractive features of flowers are adaptations for biotic interactions, and a few floral adaptations are for interactions with the physical environment. Marginal corollar appendages of Nymphoides (Menyanthaceae) can be membranous, a fringe of trichomes, or a ruffle. Although clearly enhancing display, a fringed corollar margin might function by generating a significant upward force through surface tension, an interaction adaptive in an aquatic environment. The force needed to dunk flowers with an intact corollar fringe and those whose fringe had been trimmed showed a significant difference. The fringe added a mean of 10.4% to the floral mass, but the upward force generated increased by nearly 50%, a significant difference from the predicted change based upon buoyancy alone. A correlation between plant form and type of corolla margin supports the surface‐tension hypothesis. The membranous and ruffled corollar margins were found in species whose flowers had less risk of contacting the water's surface.
Thigmo responses in plants and fungi
Authors: Jaffe Mordecai J. , Leopold A. Carl , Staples Richard C.
Published: February 2008

Thigmo mechanisms are adaptations that permit a plant to alter growth rates, change morphology, produce tropisms, avoid barriers, control germination, cling to supporting structures, infect a host plant, facilitate pollination, expedite the movement of pollen, spores, or seeds, and capture prey. Through these varied functions, plant thigmo systems have evolved impressive controls of cell differentiation, localized growth rates, regulated synthesis of novel products, and some elegant traps and projectile systems. For most thigmo events, there will be a dependence upon transmission of a signal from the cell wall through the plasmalemma and into the cytoplasm. We propose the possible involvement of integrin‐like proteins, Hechtian strands, and cytoskeletal structures as possible transduction components. Many thigmo mechanisms may use some modification of the calcium/calmodulin signal transduction system, though the details of transduction systems are still poorly understood. While transmission of thigmo signals to remote parts of a plant is associated with the development of action potentials, hormones may also play a role. Thigmo mechanisms have facilitated an enormous array of plant and fungal adaptations that make major contributions to their success despite their relatively sessile or immobile states.
Comparative anatomical analysis of the cotyledonary region in three Mediterranean Basin Quercus (Fagaceae)
Authors: Pascual Gemma , Molinas Marisa , Verdaguer Dolors
Published: February 2008

Anatomical changes at the cotyledonary node from the embryo to the seedling stage in Quercus coccifera, Q. ilex, and Q. humilis were investigated by light and scanning electron microscopy techniques. Mature embryos of Q. humilis possess 2–3 pairs of leaf primordia and a pair of cotyledonary buds, whereas in Q. coccifera and Q. ilex there are two incipient primordia, and cotyledonary buds are not observed until 1 wk after germination. In all three species the cotyledonary buds multiply, forming bud clusters, and a vascular connection is well established within 5–6 wk after germination. As development proceeds, the cotyledonary region becomes woody, but buds, which are exogenous in origin, never become embedded in the periderm. In comparison with Q. suber, another native Mediterranean Basin oak, the cotyledonary node is short and axillary buds are not present below the insertion of cotyledons. In addition, starch accumulation in the cotyledonary region is not observed from histological analysis in the three oaks. Therefore, in Q. coccifera, Q. ilex, and Q. humilis seedlings the cotyledonary node can be considered to be an important regenerative structure enabling them to resprout after the elimination of the shoot above the cotyledons, despite the absence of a lignotuberous structure.
Probability of tree seedling establishment changes across a forest–old field edge gradient
Authors: Meiners Scott J. , Pickett Steward T. A. , Handel Steven N.
Published: February 2008

Forest edges affect many aspects of plant communities, causing changes in microclimate, species composition, and community structure. However, the direct role of edges in regulating forest regeneration is relatively unknown. The pattern of tree establishment across a forest–old field edge was experimentally examined to determine the response of three tree species to the edge gradient. We placed 100 1‐m2 plots in a 90 × 90 m grid that began 30 m inside the forest, extended across the edge, and ended at 60 m into the old field. Into each plot, we planted seeds of Acer rubrum, Acer saccharum, and Quercus palustris. Emergence increased with distance into the field for both A. saccharum and Q. palustris. Emergence for A. rubrum increased from forest to field, reaching a maximum near 20 m into the field, and then declined with further distance. Nearly all A. rubrum seedlings died shortly after emergence. Survival of A. saccharum increased with distance into the old field, while survivorship of Q. palustris did not respond to the edge gradient. Establishment probabilities increased with distance into the old field for both A. saccharum and Q. palustris. Growth of Q. palustris and allocation patterns of A. saccharum also varied across the edge gradient. These results suggest that edges have complex, species‐specific effects on tree establishment and growth that can influence the spatial pattern and species composition of regenerating forests.
Floral longevity in Campanula americana (Campanulaceae): a comparison of morphological and functional gender phases
Authors: Evanhoe Laurelin , Galloway Laura F.
Published: February 2008

Plastic responses to pollination and/or pollen removal may shift a flower's realized longevity closer to an optimal longevity that maximizes reproductive output per unit resource input. In particular, conditional responses to pollen removal and pollen deposition are expected in flowers of protandrous species in which the lengths of the male and female phases may be adjusted independently. We investigated plasticity in floral longevity in Campanula americana, a protandrous, insect‐pollinated herb. In greenhouse studies, we found that the longevity of the morphological male phase was shortened by pollen removal and that the longevity of the morphological female phase was shortened by pollen deposition. In a natural population, male and female sexual functions saturated within a few hours of morphological gender phase onset. In contrast to theory, morphological gender phases did not terminate immediately upon saturation of sexual function. These findings are discussed in the context of current floral longevity theory.
Genetic variation inBromus tectorum(Poaceae): differentiation in the eastern United States
Authors: Bartlett Elizabeth , Novak Stephen J. , Mack Richard N.
Published: February 2008

Bromus tectorum, a devastating plant invader in western North America, had entered Pennsylvania by 1790. Although rare, or extirpated, in the east until the 1850s, it was collected with increasing frequency after 1859 from Vermont to Virginia. Using enzyme electrophoresis, we analyzed 38 populations of this grass in the eastern U.S. to determine their genetic variation and structure as well as assess their relatedness to populations in the west. Genetic variation among eastern U.S. populations is low: mean number of alleles per locus (A), percent polymorphic loci per population (%P), and expected heterozygosity (Hexp) are 1.01, 1.05%, and 0.002, respectively. No heterozygotes were detected. The eastern populations are genetically similar: mean genetic identity for all populations was 0.990 with values among population pairs ranged from 0.913 to 1.000. Thirteen populations in eastern and western North America sharedPgm‐1aandPgm‐2a,while eight populations sharedMdh‐2bandMdh‐3b.Other alleles detected in western North America (Got‐4c, Got‐4d,andPgi‐2b) were not, however, found in eastern U.S. populations. The invasion of North America byB. tectorumoccurred through multiple introductions on both coasts; results from historical and genetic evidence suggest that eastern populations stem from a minimum of two introductions. The 19th century westward spread ofB. tectorumfrom the East appears to be plausible.
Induction of vivipary in Arabidopsis by silique culture: implications for seed dormancy and germination
Authors: Raghavan Val
Published: February 2008

Culture of excised fruits (siliques) of different ages of Arabidopsis thaliana in a solidified mineral salt medium supplemented with vitamins, myo‐inositol, and 3% sucrose induces vivipary. Whereas early stage and immature embryos complete their full development before germinating viviparously in seeds enclosed in the silique, mature green embryos enclosed in green ovules germinate without further growth in culture. Vivipary is not observed in cultured siliques enclosing brown ovules with yellowish mature embryos inside. Suggestive of a role for abscisic acid in preventing vivipary on the mother plant, addition of the hormone to the culture medium is found to inhibit vivipary in cultured siliques. Although dried green ovules enclosing mature embryos require a cold treatment for germination, undried ovules of the same age do not germinate even after a cold treatment. This indicates that mature embryos enclosed in green ovules that germinate viviparously are cold resistant and have not become dormant at the time of culture of siliques. The circumvention by silique culture of a cold treatment and light exposure normally required for germination of isolated seeds of A. thaliana provides new possibilities to study the molecular biology of vivipary and seed germination in this model plant.
Chromosome‐specific desynapsis in the n = 2 race of Haplopappus gracilis (Compositae)
Authors: Jackson R. C. , Ngo Ngan , Ngo Hao
Published: February 2008

During cytological screening for pollen sterility in a wild population of Haplopappus gracilis (n = 2), several partially sterile plants were found that had good pachytene pairing but varying numbers of univalents. Some plants had chromosome A bivalents or A univalents, while in the same cells chromosome B had only bivalents. In other plants the reverse condition occurred; the B chromosome had B bivalents or B univalents and only A bivalents. This demonstrates a chromosome‐specific effect for the desynapsis genes. Hybridization between the two homozygous mutant genotypes produced only normal bivalents; this indicates the two mutants are not alleles and each is recessive. An F2 generation showed independent assortment of the desynaptic mutations. The chromosome A bivalent is the larger of the two and normally has one or two chiasmata; the B bivalent normally has a single chiasma. Chiasmata distribution was tested in the desynaptic mutant A bivalents and showed an acceptable fit to a binomial distribution. This occurs also in heterozygous, asynaptic pairing control gene mutations. Analysis of the NOR bivalent in two hologenomic desynaptic mutations in tomato also showed a good fit to a binomial distribution of chiasmata. This indicates the same methods are applicable to diverse species.
Isozyme variability of the wetland specialistSwertia perennis(Gentianaceae) in relation to habitat size, isolation, and plant fitness
Authors: Lienert Judit , Fischer Markus , Schneller Jakob , Diemer Matthias
Published: February 2008

We examined the effects of size and spatial isolation of fens on the isozyme variability of 17 populations ofSwertia perennis. This long‐lived perennial is a locally abundant fen specialist in Switzerland, where wetlands have been strongly fragmented. Isozyme variability was comparable to other outcrossing plants (A= 1.53,APp= 2.01,Pp= 42.5,Ho= 0.113,He= 0.139).Fstatistics indicated both inbreeding within and differentiation between populations (FIS= 0.076,FIT= 0.194,FST= 0.128), with moderate gene flow between populations (Nem= 1.703). Populations in small, isolated fens had reduced genetic variability and the highest within‐population inbreeding coefficients (FIS). Isozyme variability was significantly associated with vegetative fitness traits (MANOVA), and the magnitude of leaf herbivory decreased as the percentage of polymorphic loci increased. These data suggest that the reduced genetic variability ofS. perennisin small, isolated populations may reduce plant fitness, thereby increasing susceptibility to herbivore damage. Our study also shows that habitat fragmentation can reduce the genetic variability of populations of fairly common habitat specialists, which so far have attracted less conservation attention than rare species.
First comparative phenetic studies of Argentinean species of Acacia (Fabaceae), using morphometric, isozymal, and RAPD approaches
Authors: Casiva Paola V. , Saidman Beatriz O. , Vilardi Juan C. , Cialdella Ana M.
Published: February 2008

Morphological and genetic diversity among Acacia aroma, A. macracantha, A. caven, and A. furcatispina were studied with morphometric, isozymal, and RAPD approaches. The analysis of seven isozyme systems revealed 21 loci, and RAPD analysis showed 34 loci. Most of these loci allowed us to differentiate the species, with the exception of A. aroma and A. macracantha, the two most similar species. The levels of genetic variability estimated by isozymes were higher than those obtained from RAPD analyses. Morphometric characters showed highly significant differences among the species, although A. aroma and A. macracantha are differentiated only by thorn length. The phenogram obtained from isozyme data is consistent with morphological data. The RAPD phenogram based on allelic frequencies showed agreement with morphological and isozymal approaches only at the intraspecific levels, while the RAPD phenogram based on Nei and Li's similarity measures agreed with the phenograms constructed from isozyme and morphological data. High similarities and high indirect gene flow were found between A. aroma and A. macracantha, results that call the relationship between them into question.
Comparative floral ontogeny in Detarieae (Leguminosae: Caesalpinioideae). 1. Radially symmetrical taxa lacking organ suppression
Authors: Tucker Shirley C.
Published: February 2008

Flowers in detarioid legume taxa (Isoberlinia angolensis, Microberlinia brazzavillensis, M. bisulcata, Hymenostegia klainii) initiate all 21 floral organs, are radially symmetrical, and have little or no organ suppression. All share a narrow, “Omega”‐shaped floral apex and massive bracteoles at initiation. All have helical sepal initiation, starting abaxially. They differ in whether the first sepal initiates medianly (Microberlinia brazzavillensis, M. bisulcata) or nonmedianly (Isoberlinia angolensis, Hymenostegia klainii), and in petal order: helical (I. angolensis) or unidirectional (M. brazzavillensis, M. bisulcata, H. klainii). Stamens initiate in unidirectional order in each whorl except in M. brazzavillensis, which has a bidirectional outer whorl. An unusual feature is the ring meristem in M. bisulcata, on which petals and stamens are initiated. Overlap in time of organ initiation between whorls occurs in I. angolensis, M. brazzavillensis, and M. bisulcata but not in H. klainii. The carpel initiates concurrently with petals in all except H. klainii, in which it initiates with the outer stamens. The carpel remains open at ovule initiation in both species of Microberlinia. These detarioid taxa represent elements of the tribe having essentially radially symmetrical flowers, with all organs initiated and persisting to anthesis, but their specialized “Omega” character‐state complex is shared with specialized taxa that have zygomorphic flowers and some organs suppressed.
Phylogeny of Chloranthus (Chloranthaceae) based on nuclear ribosomal ITS and plastid TRNL‐F sequence data
Authors: Kong Hong‐Zhi , Chen Zhi‐Duan , Lu An‐Ming
Published: February 2008

The internal transcribed spacers (ITS) of the nuclear ribosomal DNA and trnL‐F region of the chloroplast DNA were sequenced for all ten species of Chloranthus and the outgroup Sarcandra (Chloranthaceae). Parsimony analyses of separate and combined data sets strongly suggest that Chloranthus is monophyletic and can be divided into two major clades: one containing C. erectus, C. spicatus, C. serratus, C. henryi, C. sessilifolius, and C. oldhamii (Clade A), and the other comprising C. angustifolius, C. fortunei, C. nervosus, and C. japonicus (Clade B). Taxonomically, these two clades correspond to Bentham and Hooker's sections Euchloranthus and Tricercandra. Within Clade A, two subclades, corresponding to Solms‐Laubach's sections Triandri and Brachyuri, can be recognized. Solms‐Laubach's subgenera Fruticosi and Herbacei, however, were resolved as paraphyletic, and thus the traditional division of Chloranthus on the basis of growth habit was not supported. Evidence from ITS and trnL‐F sequences, in agreement with morphology, anatomy, and cytology, strongly suggest that Chloranthus consists of two groups that morphologically may be distinguished by their androecial characters. The present study also supports the hypothesis that the tripartite androecium of Chloranthus may have arisen by splitting of a single stamen with two marginal thecae.
Reclassification of landrace populations of cultivated potatoes (Solanum sect. Petota)
Authors: Huamán Zósimo , Spooner David M.
Published: February 2008

Cultivated potatoes have been classified as species under the International Code of Botanical Nomenclature (ICBN) and as cultivar‐groups under the International Code of Nomenclature of Cultivated Plants (ICNCP); both classifications are still widely used. This study examines morphological support for the classification of landrace populations of cultivated potatoes, using representatives of all seven species and most subspecies as outlined in the latest taxonomic treatment. These taxa are S. ajanhuiri, S. chaucha, S. curtilobum, S. juzepczukii, S. phureja subsp. phureja, S. stenotomum subsp. stenotomum, S. stenotomum subsp. goniocalyx, S. tuberosum subsp. andigenum, and S. tuberosum subsp. tuberosum. The results show some phenetic support for S. ajanhuiri, S. chaucha, S. curtilobum, S. juzepczukii, and S. tuberosum subsp. tuberosum, but little support for the other taxa. Most morphological support is by using a suite of characters, all of which are shared with other taxa (polythetic support). These results, combined with their likely hybrid origins, multiple origins, evolutionary dynamics of continuing hybridization, and our classification philosophy, leads us to recognize all landrace populations of cultivated potatoes as a single species, S. tuberosum, with the eight cultivar‐groups: Ajanhuiri Group, Andigenum Group, Chaucha Group, Chilotanum Group, Curtilobum Group, Juzepczukii Group, Phureja Group, and Stenotomum Group. We defer classification of modern cultivars, traditionally classified in Tuberosum Group, to a later study.
Origins of domestication and polyploidy in oca (Oxalis Tuberosa: Oxalidaceae). 2. Chloroplast‐expressed glutamine synthetase data
Authors: Emshwiller Eve , Doyle Jeff J.
Published: February 2008

In continuing study of the origins of the octoploid tuber crop oca, Oxalis tuberosa Molina, we used phylogenetic analysis of DNA sequences of the chloroplast‐active (nuclear encoded) isozyme of glutamine synthetase (ncpGS) from cultivated oca, its allies in the “Oxalis tuberosa alliance,” and other Andean Oxalis. Multiple ncpGS sequences found within individuals of both the cultigen and a yet unnamed wild tuber‐bearing taxon of Bolivia were separated by molecular cloning, but some cloned sequences appeared to be artifacts of polymerase chain reaction (PCR) recombination and/or Taq error. Nonetheless, three classes of nonrecombinant sequences each joined a different part of the O. tuberosa alliance clade on the ncpGS gene tree. Octoploid oca shares two sequence classes with the Bolivian tuber‐bearing taxon (of unknown ploidy level). Fixed heterozygosity of these two sequence classes in all ocas sampled suggests that they represent homeologous loci and that oca is allopolyploid. A third sequence class, found in eight of nine oca plants sampled, might represent a third homeologous locus, suggesting that oca may be autoallopolyploid, and is shared with another wild tuber‐bearing species, tetraploid O. picchensis of southern Peru. Thus, ncpGS data identify these two taxa as the best candidates as progenitors of cultivated oca.
Vulnerability and determinants of reproductive success in the narrow endemic Antirrhinum microphyllum (Scrophulariaceae)
Authors: Torres Elena , Iriondo José M. , Pérez César
Published: February 2008

The breeding system and flowering phenology of the narrow endemic Antirrhinum microphyllum (Scrophulariaceae) were studied in order to assess the main factors affecting female reproductive success and to identify existing or potential threats to the viability of its populations. Hand‐pollination experiments showed that A. microphyllum is an allogamous self‐incompatible species. In both populations studied, the flowering season was 4 mo long and mean flowering duration per plant was about 1 mo. Peak flower production took place between mid‐April and mid‐May and overlapped with the period of activity of the main pollinator, Rhodanthidium sticticum (Megachilidae). Estimated mean number of seeds produced per plant was 9391, showing that population viability is not presently limited by seed output. The study of the direct and indirect effects of plant size, phenological traits (first flowering date, flowering duration, and flowering synchrony), and distance to neighbor plants on reproductive success was performed using structural equation modeling (SEM). In both populations, number of flowers and plant size were the main factors that determined the total number of fruits produced by a plant. First flowering date and flowering synchrony also affected fruit production. Multisample comparison of path coefficients for the two populations rejected the possibility that reproductive patterns could be described by one single model.
Root starch storage and allocation patterns in seeder and resprouter seedlings of two Cape Erica (Ericaceae) species
Authors: Verdaguer Dolors , Ojeda Fernando
Published: February 2008

Post‐fire sprouting of dormant buds in resprouter plants is facilitated by stored carbohydrate reserves, with starch being the critical reserve. Starch is mainly stored in xylem parenchyma ray tissue of woody underground organs, such as burls, lignotubers, and roots. We carried out a comparative analysis of the pattern of starch storage and the proportion of parenchymatic ray tissue in the upper root or cotyledonary region of seedlings from seeder and resprouter forms within two Cape Erica (Ericaceae) species: E. coccinea L. and E. calycina L., which were raised in the greenhouse under controlled irrigation. We also explored the root‐to‐shoot allocation patterns of seeder and resprouter seedlings in these two species. Resprouter seedlings of both species showed higher relative amounts of upper‐root starch and upper‐root storage tissue as well as a higher root‐to‐shoot allocation than their seeder counterparts. Pronounced swelling of the upper root region suggests ontogenetic development of a lignotuber in the resprouter forms of the two Erica species. The distinct allocation of starch in roots seems to be genetically determined and would account for the apparent differences in the root‐to‐shoot allocation patterns between both regeneration forms from the early seedling stage.
Frequency of spontaneous amphiploids in Gilia (Polemoniaceae) hybrids
Authors: Grant Verne
Published: February 2008

This paper reports the frequency of spontaneous amphiploids or neopolyploids in experimental interspecific hybrids in two annual sections of Gilia (Polemoniaceae, sects. Arachnion and Gilia, x = 9). In each section the species were intercrossed in numerous hybrid combinations to obtain an array of F1 hybrid types; seven of the hybrid types spontaneously produced new amphiploid progeny in F2. In sect. Arachnion the parental species and F1s were all diploids and the amphiploids were tetraploid; in sect. Gilia the parental species were diploids or tetraploids and the amphiploids were tetraploid or hexaploid. Two measures were used to express the frequency of spontaneous amphiploid formation. The first is the proportion of the F1 hybrid combinations that yielded any amphiploid progeny at all. In sect. Arachnion this proportion is 3/39 or 7.7%; in sect. Gilia it is 4/16 or 25%. A second measure is needed to express the variation in productivity among the seven amphiploid‐producing hybrid types. The measure adopted is the mean number of new amphiploids per single F1 hybrid plant. The productivity numbers for the three hybrid combinations in sect. Arachnion are 0.25, 0.67, and 2.0; and those for four hybrid combinations in sect. Gilia are 0.15, 0.62, 2.25, and 12.62. There are large differences from one hybrid combination to another in rate of amphiploid formation, and the rate is quite high in some hybrids. The factors affecting these differences are discussed.
The effects of stigma age on receptivity in Silene alba (Caryophyllaceae)
Authors: Young Helen J. , Gravitz Lauren
Published: February 2008

Silene alba, a perennial, dioecious plant, produces flowers that open in the evening and can remain open and receptive to pollination for up to 5 d, though in hot and dry conditions the flowers will wilt during the day only to reopen night after night. In the field, it is visited by two different kinds of pollinators with differential success: moths visit the flowers at night, and their movements result in broad pollen dispersal and large seed production, whereas bees, wasps, and flies visit the flowers in the mornings and have decreased pollination effectiveness. However, this differential success may be due to a decrease in stigmatic receptivity soon after the flowers open. We performed controlled pollinations to determine the effect of stigma age on pollen germination and seed set. We pollinated flowers at 12‐h intervals up to 120 h and divided these into two sets: from one set, we removed stigmas 24 h after pollination to examine percentage of pollen germination. The second set of flowers was allowed to produce fruits, and the seeds were counted and weighed. Pollen germination declined significantly with stigma age, but there was no significant effect of stigma age at pollination on the number or mass of resulting seeds. Thus, the decreased pollination success of bees is not due to a decrease in stigmatic receptivity but is most likely a result of pollinator inefficiency.
Evolutionary maintenance of stigma‐height dimorphism in Narcissus papyraceus (Amaryllidaceae)
Authors: Arroyo Juan , Barrett Spencer C. H. , Hidalgo Rosario , Cole William W.
Published: February 2008

Stigma‐height dimorphism is a sexual polymorphism in which plant populations are composed of two floral morphs that differ significantly in style length but not anther position. The morphs exhibit approach and reverse herkogamy, floral designs that in most species typically occur as monomorphic conditions. We investigated the floral biology of stigma‐height dimorphism in the Mediterranean geophyte Narcissus papyraceus (Amaryllidaceae) in an effort to understand the evolutionary forces maintaining stylar polymorphism. Our survey of 66 populations in Spain, Portugal, and Morocco indicated that 56% were dimorphic with the long‐styled morph at an average frequency of 0.79. The remaining 44% of populations sampled were monomorphic for the long‐styled morph. In dimorphic populations there was a significant positive relation between population size and the frequency of the short‐styled morph. Controlled pollinations demonstrated that N. papyraceus is self‐sterile with no significant differences in female fertility between intra‐ and intermorph crosses. Prior self‐pollination reduced seed set in flowers that were subsequently cross‐pollinated. Estimates of mating patterns using allozyme markers in eight populations indicated that N. papyraceus is largely outcrossing (mean tm = 0.81) with no significant differences between monomorphic and dimorphic populations or style morphs. Stigma‐height dimorphism in N. papyraceus is maintained in populations by insect‐mediated cross‐pollination with biased morph ratios and stylar monomorphism likely resulting from the combined influence of the inheritance of the polymorphism, morph‐specific differences in assortative mating and founder effects.
A chloroplast DNA phylogeny of easternPhlox(Polemoniaceae): implications of congruence and incongruence with the ITS phylogeny
Authors: Ferguson Carolyn J. , Jansen Robert K.
Published: February 2008

The comparison of independent phylogenies is a valuable approach to the study of evolutionary pattern and process. Available data on eastern North AmericanPhlox, including our recent ITS phylogeny, suggest that relationships are complicated in the group and that hybridization may have been a contributing factor. We used restriction site data from the chloroplast genome to develop a second phylogeny for easternPhlox. Sampling was the same as that for the ITS study and consisted of 79 samples (including all 22 easternPhloxspecies and most eastern subspecies, as well as multiple populations of many taxa). The resulting cpDNA phylogeny agrees with the ITS phylogeny in many respects, strengthening earlier conclusions. Nevertheless, incongruence between the trees is noteworthy: many samples, particularly of members of theP. pilosaandP. glaberrimacomplexes, are placed in different clades. A variety of tests were carried out to assess congruence in terms of topological patterns, character congruence, and homogeneity of data sets. Significant conflict between the phylogenies is discussed in light of the hypothesis that hybridization has affected relationships in this genus.
Genetic and environmental effects on morphology in clonal sedges in the Eurasian Arctic
Authors: Stenström Anna , Jónsdóttir Ingibjörg S. , Augner Magnus
Published: February 2008

We studied the variation in morphological characters of importance for resource acquisition and storage in 21 populations of four clonal sedge taxa in arctic Eurasia, Carex bigelowii, C. ensifolia subsp. arctisibirica, C. lugens, and C. stans, and the response to transplantation to a common garden in Tromsø, Norway. The morphology of C. stans was distinct from the other three taxa, all of which belong to the C. bigelowii species complex. However, differences among populations within taxa were even greater than differences among taxa, and environmental variables explained 40–50% of the among‐population variation in the morphological characters. Stomatal size decreased with temperature while stomatal density increased. Shoot height and leaf width were smaller at peak lemming population phase, while rhizome length was shorter at higher longitudes. Transplantation to a common garden affected stomatal density in all taxa, stomatal size and shoot height only in some taxa, while leaf width was not affected. We found a weak, but highly significant correlation between geographical, morphological, and genetic distances. We concluded that although genotypic differentiation in arctic rhizomatous Carex species is reflected in their morphology, they are also capable of plastic morphological responses to the environment and that these responses are specific for each taxon.
Anatomically preserved Cycadeoidea (Cycadeoidaceae), with a reevaluation of systematic characters for the seed cones of Bennettitales
Authors: Rothwell Gar W. , Stockey Ruth A.
Published: February 2008

Four anatomically preserved ovulate cycadeoid cones have been recovered from three localities in Upper Cretaceous (Turonian/Coniacian‐Late Campanian) sediments of Vancouver and Hornby Islands, British Columbia, Canada. All of the specimens are preserved by calcareous cellular permineralization and are quite similar to seed cones described as several species of Cycadeoidea and Bennettites. These cones, described as Cycadeoidea maccafferyi sp. nov., consist of tightly packed interseminal scales and ovulate sporophylls with terminal ovules. Two specimens also preserve remains of a small receptacle. Interseminal scales and ovulate sporophylls are oriented parallel to one another. Ovules are distinctly stellate at the base of the micropylar tube, and the sarcotesta consists of both longitudinally oriented tubular cells and large radially elongated cells attached to the sclerotesta. The vascular strand below each ovule is highly contorted in a pattern that is characteristic of contractile tissue in the roots of living plants. These specimens are the most recent anatomically preserved cycadeoid cones yet discovered, revealing details of the reproductive biology shortly before extinction of the clade. Superb preservation of the British Columbia cones confirms that Bennettitales lack a cupule, have radial seeds, and have a vascularized nucellus (but no integumentary tracheids), and that no pollen chamber is produced. Together with a new species of Williamsonia preserved at one of the same localities, these specimens reveal a clear set of contrasting systematic characters for differentiating between isolated seed cones of Williamsoniaceae and Cycadeoidaceae.
Rediscovery of Pedilanthus coalcomanensis (Euphorbiaceae), a threatened endemic Mexican species
Authors: Lomelí‐Sención José Aquileo , Sahagún‐Godínez Eduardo
Published: February 2008

Pedilanthus coalcomanensis was described from specimens collected by George B. Hinton in 1941 but was not collected again until 1999, when we found it in a tropical deciduous forest near Tehuantepec, in Chinicuila, Michoacán, Mexico. After analyzing Hinton's original collection notes, we concluded that this is the type locality. Based on the reduced geographic distribution presently known for this species (11 km2), the level of disturbance of its habitat, and the use of the method for the assessment of extinction risk in Mexican wild species (MER), we propose that P. coalcomanensis be covered by the appropriate Mexican legislation as a threatened species and be included in the Red List of Threatened Plants of the International Union for the Conservation of Nature. Our results help justify and delimit a local biosphere reserve in northwestern Michoacán, an area that is considered a center of endemism and that has largely been deforested. Our findings have implications for research on other historical specimens collected by Hinton in this region.
Phenetic and phylogenetic analysis of Reinhardtia (Palmae)
Authors: Henderson Andrew J.
Published: February 2008

Principal component analysis and cluster analysis of morphometric data divide specimens of Reinhardtia into six groups, corresponding to the six species recognized in the most recent revisions. Discriminant analysis classifies specimens into these six species with 100% success. Five species occur in lowland to montane moist forests in Central America, from Mexico to Panama, and just reach Colombia; one species occurs in montane moist forests in Hispaniola. Three species have large stems and are rare, patchily distributed, and seldom collected. The other three species have small stems, are common and frequently collected, but also patchily distributed. One species of small plants, R. gracilis, exhibits considerable variability. Within this species, seven distinct groups can be recognized, although sample size is limited. Among species, there is a phyletic decrease in size of plants, from the basal species with large stems to derived species with small stems. For leaves and inflorescences there is also an associated decrease in size, but one species does not follow this trend. In this species, R. latisecta, there is evidence of a large ontogenetic change in leaf development. Phyletic decrease in size corresponds to a latitudinal and elevational gradient suggesting speciation has taken place from north to south and from high to low elevation. However, this pattern is obscured disjunct distributions in some species.
Evidence of Carpinus (Betulaceae) in the Late Tertiary (Pliocene) of Alabama
Authors: Stults Debra Z. , Axsmith Brian J. , Haywick Douglas
Published: February 2008

Carpinus is a common and widespread element of the modern North American forest vegetation, but its scant fossil record on the continent is perplexing, especially considering the abundant and relatively continuous record of the genus in the Tertiary of Europe and Asia. Despite earlier claims of Tertiary Carpinus remains, recent reviews have indicated that a definitive post‐Eocene Tertiary record of the genus in North America is lacking. Therefore, it remains uncertain if Carpinus was present but left no clear fossil record or if the genus became extinct in North America and migrated back to the continent more recently. A reinvestigation of the Citronelle Formation paleoflora has yielded conclusive evidence for the presence of Carpinus in the Gulf Coastal Plain of Alabama during the Pliocene based upon the discovery of a nutlet bract. Carpinus bracts are distinctive and consist of a central bract fused basally with two lateral bractlets. This specimen provides proof of the existence of Carpinus on this continent by the Pliocene Epoch, and any future research on the biogeography of the genus must consider this as the earliest, post‐Eocene record of the genus in North America based on unequivocal reproductive structures.
The origin and evolution of Eragrostis tef (Poaceae) and related polyploids: evidence from nuclear waxy and plastid rps16
Authors: Ingram Amanda L. , Doyle Jeff J.
Published: February 2008

Tef (Eragrostis tef; Poaceae) is an allotetraploid (2n = 4x = 40) cereal crop whose origin within the large genus Eragrostis is unknown. Previous studies have suggested a total of 14 wild Eragrostis species as potential progenitors. Phylogenetic analysis of sequence data from the nuclear gene waxy and the plastid locus rps16 strongly supports the widely held hypothesis of a close relationship between tef and E. pilosa, a wild allotetraploid. Eragrostis heteromera, another previously proposed progenitor, is shown by the waxy data to be a close relative of one of the tef genomes. Other putative progenitors included in the taxon sample are not supported as closely related to tef. Plastid sequences from five varieties of tef and four E. pilosa accessions are identical and therefore are uninformative with respect to the question of multiple origins of these polyploids. The waxy phylogeny also resolves the relationships among other allopolyploids, supporting a close relationship between the morphologically similar allotetraploids E. macilenta, E. minor, and E. mexicana. Eragrostis cilianensis, another morphologically similar allopolyploid, appears to have shared one diploid progenitor with these species but derived its other genome from an unrelated diploid.
Spatial pattern of allozyme variation in a contact zone of Pinus Ponderosa and P. arizonica (Pinaceae)
Authors: Epperson Bryan K. , Chung Myong Gi , Telewski Frank W.
Published: February 2008

The spatial distribution of genotypes for nine polymorphic allozyme loci was examined in a contact zone between Pinus ponderosa var. scopulorum and another tree regarded as either a separate species, Pinus arizonica, or variety, Pinus ponderosa var. arizonica, in southern Arizona. Previous work had identified a steep elevational cline for a key taxonomic trait, number of leaf‐needles per fascicle, on the south slope of Mt. Lemmon. The present results indicate that the taxa are not fully interbreeding in this contact zone, because allozyme genotypes are considerably more spatially structured than expected for the dispersal characteristics of pines. The amount of spatial differentiation is also much less than that observed for needle number. It appears that this is due to the lack of differentiation for allozyme gene frequencies for the two types of trees, which is further evidenced by analysis of samples from two other populations away from the contact zone. It is likely that if the two taxa were isolated in the past, it was not for long enough nor complete enough to allow mutation‐drift to create substantial differentiation between them. Another possible explanation is that introgression after recontact is so advanced that any differences have been erased throughout the Santa Catalina mountain range.