bluuebunny/crossref_metadata_2025 huggingface dataset:
Treaty of 1989 between Australia and Indonesia concerning the “Timor Gap”—existence of legal dispute between Portugal and Australia—objections to jurisdiction—effect of Court ruling on absent third parties—right to self-determination as right erga omnes —status of East Timor as non-self-governing territory: East Timor (Port. v. Austl.). 1995 ICJ Rep. 90
Authors: Bello Judith Hippler , Bekker Peter H. F.
Published: April 2006

International Court of Justice, June 30, 1995.

Portugal submitted an Application instituting proceedings against the Commonwealth of Australia before the International Court of Justice on February 22, 1991. Both Portugal and Australia had made declarations accepting the compulsory jurisdiction of the Court pursuant to Article 36, paragraph 2 of the ICJ Statute. Portugal sought a declaration from the Court that Portugal's status with respect to East Timor and the rights of the people of East Timor to self-determination, territorial integrity and unity, and permanent sovereignty over its wealth and natural resources were opposable to Australia. Portugal also sought a declaration that Australia had incurred international responsibility and had caused damage for which it owed reparation to both the people of East Timor and Portugal. Portugal alleged that Australia had incurred this responsibility mainly by negotiating and concluding—not with Portugal, but with Indonesia—a treaty on December 11, 1989, creating a “Zone of Cooperation” in an area of the undelimited continental shelf between East Timor and northern Australia known as the “Timor Gap.”
Free International Trade and Protection of the Environment: Irreconcilable Conflict?
Authors: Schoenbaum Thomas J.
Published: April 2006

States should cooperate to promote a supportive and open international economic system that would lead to economic growth and sustainable development in all countries, to better address the problems of environmental degradation. Trade policy measures for environmental purposes should not constitute a means of arbitrary or unjustifiable discrimination or a disguised restriction on international trade. Unilateral actions to deal with environmental challenges outside the jurisdiction of the importing country should be avoided. Environmental measures addressing transboundary or global environmental problems should, as far as possible, be based on an international consensus.

Principle 12 Rio Declaration on Environment and Development

The global multilateral trading system and its centerpiece, the General Agreement on Tariffs and Trade (GATT), are facing a new challenge from a quite unexpected quarter. The GATT is under attack by some in the environmental community who charge that international free trade blindly fosters the exploitation of natural resources. The GATT is depicted as a sinister charter that allows “big business” a free hand to plunder the bounty of the natural world. In certain environmentalists’ view, “free trade can destroy the environment.” Thus, a segment of the large and influential environmentalist lobby has joined the growing coalition of interests seeking to scuttle what is left of international free trade.
International Law and International Relations Theory: A Dual Agenda
Authors: Burley Anne-Marie Slaughter
Published: April 2006

Writing in 1968 on the “relevance of international law,” Richard Falk described his efforts as part of the larger endeavor of “liberating the discipline of international law from a sense of its own futility.” In 1992 that task appears to have been accomplished. International legal rules, procedures and organizations are more visible and arguably more effective than at any time since 1945. If the United Nations cannot accomplish everything, it once again represents a significant repository of hopes for a better world. And even as its current failures are tabulated, from Yugoslavia to the early weeks and then months of the Somali famine, the almost-universal response is to find ways to strengthen it. The resurgence of rules and procedures in the service of an organized international order is the legacy of all wars, hot or cold.
Rules, Sanctions and Enforcement Under Section 301: At Odds with the WTO?
Authors: Puckett A. Lynne , Reynolds William L.
Published: April 2006

Section 301 of the Trade Act of 1974 permits the United States Trade Representative (USTR) to investigate and impose sanctions on countries whose trade practices are found to be unfair to U.S. interests. It reaches beyond the General Agreement on Tariffs and Trade (GATT), to give the United States unilateral power to penalize countries that threaten American interests. Section 301 can be used to enforce United States rights under multilateral and bilateral trade agreements, as well as to remedy unreasonable, unjustifiable or discriminatory foreign trade practices that restrict or burden U.S. trade. It contains both mandatory and discretionary provisions and specific timetables for action by the USTR.
The Forty-Fifth Session of the International Law Commission
Authors: Rosenstock Robert
Published: April 2006

The International Law Commission of the United Nations held its forty-fifth session from May 2 to July 23, 1993, under the chairmanship of Ambassador Julio Barboza of Argentina. The Commission elaborated a substantially complete draft statute of an international criminal court in a working group, considered aspects of state responsibility, commenced drafting articles on liability for injurious consequences arising out of acts not prohibited by international law, began its second reading on non-navigational uses of international watercourses, and made recommendations for its future work. The Commission continued its innovative use of working groups and subgroups to expedite its work and, consequently, had a highly productive session.
Civitas Maxima: Wolff, Vattel and the Fate of Republicanism
Authors: Onuf Nicholas Greenwood
Published: April 2006

For more than two decades, historians of the United States have energetically debated the relative importance of liberalism and republicanism in the 1770s and 1780s. Was the late eighteenth century a time of progress, and events culminating in the ratification of the Constitution a triumph for individual rights and liberal society, as convention held? Or was it a time of decay, and the events of the founding a renewal of citizen virtue in defense of the common good? Political theorists and constitutional scholars joined the debate, extending it beyond the founding and noting its relevance to our own time. Everyone agreed that liberalism eventually prevailed, more or less completely, for better or for worse. Just when it did so, and why, were questions always asked but never satisfactorily answered as the debate ran its course.
The Relationship between the International Court of Justice and the Security Council in the Light of the Lockerbie Case
Authors: Gowlland-Debbas Vera
Published: April 2006

The relationship between the International Court of Justice and the Security Council may be approached from the perspective of the United Nations Charter and the way it delimits competences between two principal UN organs and regulates the exercise of their concurrent powers. The Court, however, has a dual, ambivalent role. It is not only the principal judicial organ of the United Nations under Article 92 of the Charter; it is also an autonomous adjudicative body with the function, under Article 38 of its Statute, of applying international law to such disputes between states as are brought before it. Viewed in the light of Questions of Interpretation and Application of the 1971 Montreal Convention Arising from the Aerial Incident at Lockerbie, the relationship between the judicial and political organs raises some fundamental questions of general international law that go beyond UN constitutional issues.
U.S. Provisional Application of the 1994 Deep Seabed Agreement
Authors: Charney Jonathan I.
Published: April 2006

On July 28, 1994, the United States voted at the United Nations General Assembly in favor of a resolution endorsing the new Agreement that essentially amends the deep seabed regime (Part XI) of the 1982 Convention on the Law of the Sea and calls on states to ratify the Convention. Shortly thereafter, it signed the new Agreement. Plans call for the Convention to be submitted to the Senate for its advice and consent to ratification in October 1994 and for hearings to be held during the next Congress in the spring of 1995. By signing the Agreement, the United States will provisionally apply the deep seabed regime, as amended, until the United States becomes a party to the Convention or decides not to do so. In this paper I examine whether such provisional application is appropriate under the U.S. system of government.
Contemporary Practice of the United States Relating to International Law
Authors: Nash Marian
Published: April 2006

On June 20, 1994, Ambassador Harriet C. Babbit, the U.S. Permanent Representative to the Organization of American States, deposited on behalf of the U.S. Government the instrument of ratification of the “Protocol of Washington,” adopted on December 14, 1992, by the Sixteenth Special Session of the General Assembly of the Organization of American States and signed by the United States on January 23, 1993, and the “Protocol of Managua,” adopted by the Nineteenth Special Session of the OAS General Assembly on June 10, 1993, and signed that day by the United States. The U.S. Senate had given its advice and consent to ratification of the Protocols on May 17, 1994, with two-thirds of the Senators present and concurring.
Using restriction‐site variation of PCR‐amplified cpDNA genes for phylogenetic analysis of Tribe Cheloneae (Scrophulariaceae)
Authors: Wolfe Andrea D. , Elisens Wayne J. , Watson Linda E. , dePamphilis Claude W.
Published: April 2006

Data from restriction‐site variation of three PCR‐amplified chloroplast genic regions (trnK, rps2, and rbcL) were used to assess the utility of PCR‐based methodology for phylogenetic reconstruction. Seventeen genera from tribe Cheloneae s.l. (Scrophulariaceae), and one genus each from Solanaceae, Acanthaceae, and Bignoniaceae, representing 32 taxa, were sampled. Phylogenetic reconstruction, based on a combined data set of 138 variable restriction sites, revealed a monophyletic clade of North American Cheloneae, which were not inconsistent with a polyphyletic Scrophulariaceae. Separate analyses of individual genic regions were unable to completely resolve the phylogeny, but were adequate for resolving relationships of major clades among the taxa sampled. We suggest that analysis of PCR‐product restriction‐site variation is useful for phylogenetic reconstruction above the species level.
Cotton fibers can undergo cell division
Authors: Hof Jack Van't , Saha Sukumar
Published: April 2006

Ovular culture was used to determine the cell cycle aspects of cotton fiber cells. Each ovule (Gossypium hirsutum, cultivar, MD51 ne) grown under the conditions used has ~10 000 fiber cells at 4 d postanthesis. About 25% of these cells divide when ovules are cultured at 34°C. Mitosis occurs after fiber cells differentiate, producing multicelled fibers. The basal and tip cells of multicelled fibers have the same characteristics as the polar ends of single‐celled fibers. Most cell division occurs in ovules cultured at 2–3 d postanthesis. Multicelled fibers are rare in ovules cultured at 1 d postanthesis and absent if cultured at 7 d postanthesis. No multicelled fibers are detectable on ovules sampled from the plant regardless of age. Fiber cell division occurs in the absence of exogenous hormones. The addition of IAA and GA3 to the medium lowers the frequency of multicelled fibers. IAA alone further reduces their frequency, while GA3 by itself has no effect. The number of fiber cells per cultured ovule ranges between 9462 and 11 087 and is not significantly different from the 9892 seen in the plant at 4 d postanthesis. These findings show that a subpopulation of fiber cells, fully differentiated in appearance, retain cell cycle functions up to 4 d postanthesis.
Quantitative analyses of the genetic Structure of Closely Related Conifers with Disparate Distributions and Demographics: The Cupressus Arizonica (Cupressaceae) Complex
Authors: Rehfeldt Gerald E.
Published: April 2006

Seedling populations of seven Cupressus taxa were compared in common gardens to assess relationships among taxa and to elucidate the genetic structure of three taxa with different distributions and demographics. Discriminant analyses of 15 quantitative traits separated C. sargentii and C. forbesii from taxa within the C. arizonica complex (C. arizonica, C. glabra, C. stephensonii, C. nevadensis, and C. montana); aligned a population of C. arizonica from Sierra de Arteaga, Mexico, with families of the same taxon from southwestern United States; and described a close relationship between C. nevadensis and C. glabra, but nevertheless separated taxa within the C. arizonica complex. Analyses of wind‐pollinated progenies of single trees showed the narrow endemic, C. glabra, to have a greater degree of population differentiation than the more broadly dispersed C. arizonica. In addition, genetic variances within the numerically small populations of C. arizonica were about the same as in the much larger populations of C. glabra. The results also suggested that genetic variability in C. stephensonii, a taxon occurring in a single population, may occur primarily among inbred lines. While the genetic structures of C. arizonica and C. glabra have counterparts among broadly dispersed conifers, that of C. stephensonii appears to be unique. Together, the results support the view that genetic structure primarily reflects the uncertain, chance events that are interspersed throughout evolutionary history.
Contrasted pollen capture mechanisms in Phyllocladaceae and certain Podocarpaceae (Coniferales)
Authors: Tomlinson P. Barry , Braggins John E. , Rattenbury Jack A.
Published: April 2006

Comparative study shows that Phyllocladus and representative Podocarpaceae differ in the mechanism by which pollen is introduced into the pollen chamber and onto the apex of the nucellus (“pollen capture”). Both types involve a pollination drop, but only in Podocarpaceae is it consistently inverted and in contact with adjacent surfaces. Phyllocladus has functionally nonsaccate pollen (although a vestigial saccus has been claimed); its pollen is wettable and sinks in water. Podocarpaceae (except Saxegothaea) have saccate pollen, which is nonwettable and floats on water. In Phyllocladus the pollination drop receives the pollen directly and presence of pollen stimulates complete drop withdrawal, which may be a metabolic process. Once pollinated, an ovule does not resecrete a pollination drop. In Podocarpaceae the drop usually receives the pollen indirectly via pollen scavenging and saccate pollen is preferentially captured. The retraction of the drop appears to be the result of evaporation and is presumably nonmetabolic. Drop secretion can be repeated in the presence of pollen. A major consequence of these contrasted mechanisms is that in Phyllocladus the entire contents of the pollination drop are ingested, whereas in Podocarpaceae only that part of the drop that includes saccate pollen is ingested. Because of differences in repeatability of the secretion process, Podocarpaceae are likely to capture more pollen. In neither mechanism does the process favor “own” pollen, but in Podocarpaceae all but saccate pollen is excluded. We thus have further evidence for differences in pollen capture mechanisms in conifers with a pollination drop, and differences in the behavior of the pollination drop itself.
Developmental analysis of Teosinte glume architecture1: a key locus in the evolution of maize (Poaceae)
Authors: Dorweiler Jane E. , Doebley John
Published: April 2006

A key event in the evolution of maize from teosinte was a reduction in the cupulate fruitcase and softening of the glumes, which increased the accessibility of kernels for harvest. The teosinte glume architecture1 (tga1) locus largely controls this difference between maize and teosinte, and thus may have played a pivotal role in maize evolution. The teosinte allele (tga1+teosinte) lengthens inflorescence internodes, shortens rachillae, and makes glumes longer, thicker, and harder. Developmental characterization of morphometric traits reveals that differences among genotypes are apparent early in female inflorescence development. Increased hardening in glumes homozygous for tga1+teosinte is correlated with a thicker abaxial mesoderm of lignified cells. Silica deposition in the abaxial epidermal cells of the glumes is also affected. In the maize background, glumes homozygous for tga1+teosinte deposit silica in both the short and long cells of the glume epidermis, whereas glumes homozygous for the maize allele (Tga1+Maize) concentrate silica only in the short cells. Silica deposition also appears to be affected by genetic background. The effects of tga1 appear largely to explain the differences in glume induration between maize and teosinte. The diverse pleiotropic effects of tga1 suggest that it is regulatory in nature.
A new microphyllous plant from the Lower Devonian of Yunnan Province, China
Authors: Li Cheng‐Sen , Edwards D.
Published: April 2006

Sterile and fertile shoots of a microphyllous vascular plant are described from the Lower Devonian Posongchong Formation (? upper Siegenian), Yunnan Province, southern China and placed in the new taxon Halleophyton zhichangense gen. et sp. nov. The sterile axes are characterized by conspicuous, contiguous swollen rhomboidal to hexagonal leaf bases and relatively broad spatulate laminae. The relief of the leaf bases is not so pronounced in the fertile areas, which bear numerous cauline sporangia with two equal valves. In vegetative characters the new fossils, although smaller and more fragmentary, resemble Drepanophycus gaspianus but in the absence of information on the fertile parts of the latter and because of the controversy surrounding the concept of the genus Drepanophycus, we decided to erect a new genus. Its relationship to the lycophytes sensu stricto is equivocal as exact details of the relationship of sporangium with leaf and sporangium vascularization remain unknown.
Comparative pollination biology of Venezuelan columnar cacti and the role of nectar‐feeding bats in their sexual reproduction
Authors: Nassar Jafet M. , Ramírez Nelson , Linares Omar
Published: April 2006

The floral biology, reproductive system, and visitation behavior of pollinators of four species of columnar cacti, Stenocereus griseus, Pilosocereus moritzianus, Subpilocereus repandus, and Subpilocereus horrispinus, were studied in two arid zones in the north of Venezuela. Our results support the hypothesis that Venezuelan species of columnar cacti have evolved toward specialization on bat pollination. Additional information on the floral biology of a fifth species, Pilosocereus lanuginosus, was also included. All species showed the typical traits that characterize the pollination syndrome of chiropterophily. All species but Pilosocereus moritzianus were obligate outcrossers. Nectar and pollen were restricted to nocturnal floral visitors. Two species of nectar‐feeding bats, Leptonycteris curasoae Miller and Glossophaga longirostris Miller, were responsible for practically all the fruit set in these cacti. Frequency of bat visitation per flower per night was highly variable within and between species of cactus, with average frequencies varying between 27 and 78 visits · flower−−1 · night−−1. In general terms, the pattern of floral visitation through the night was significantly correlated with the pattern of nectar production and nectar sugar concentration for all species of cactus. Under natural pollination, fruit:flower ratios varied from 0.46 in Subpilocereus repandus to 0.76 in Stenocereus griseus. The efficiency of bat pollination in terms of seed:ovule ratio was high in all species, varying between 0.70 and 0.94.
A cyanolichen from the Lower Devonian Rhynie chert
Authors: Taylor Thomas N. , Hass Hagen , Kerp Hans
Published: April 2006

The 400 million‐year‐old Rhynie chert has provided a wealth of information about various types of fungal interactions that existed in this Early Devonian paleoecosystem. In this paper we report the first unequivocal evidence of a lichen symbiosis from the Rhynie chert. Specimens of a new genus, Winfrenatia, consist of a thallus of superimposed layers of aseptate hyphae and, on the upper surface, numerous uniform depressions. Extending into the base of each depression are hyphae that form a three‐dimensional netlike structure. Enclosed within each of the net spaces is a coccoid cyanobacterium, each cell of which is surrounded by a thick sheath. These photobiont cells divide in three planes, resulting in cell clusters of up to perhaps 64 individuals. The photobiont is parasitized by the fungus in the base of each net as new cyanobacterial cells are formed distally. Reproduction is by endospores and soredia. Affinities of the mycobiont appear closest to members of the Zygomycetes, while the photobiont is most similar to coccoid cyanobacteria of the Gloeocapsa and Chroococcidiopsis types. We speculate that this cyanobacterial symbiosis was well adapted to exploit and colonize new ecological niches, especially in the periodically desiccated environment postulated for the Rhynie chert paleoecosystem.
The methionine‐rich low‐molecular‐weight chloroplast heat‐shock protein: evolutionary conservation and accumulation in relation to thermotolerance
Authors: Downs Craig A. , Heckathorn Scott A. , Bryan John K. , Coleman James S.
Published: April 2006

The evolutionary conservation of the low‐molecular‐weight chloroplast‐localized heat‐shock protein (LMW chlpHsp) in vascular plants was examined using immunological methods. An antibody (Abmet) specific to the LMW chlpHsp was produced using a synthetic 28‐residue peptide containing the most conserved elements of its unique “methionine‐rich domain” as an antigen. This antibody detected a heat‐inducible low‐molecular‐weight chloroplast protein in plants of six divergent Anthophyta species, including C3, C4, CAM, monocot, and dicot species. Abmet also detected a LMW chlpHsp in species from the Divisions Psilotophyta, Equisetophyta, Polypodiophyta, and Ginkgophyta. A preliminary examination of the relationship between accumulation of the LMW chlpHsp and habitat was also conducted. Seven Anthophyta species originating from both warm‐ and cool‐temperature habitats were grown at 28°C and then heat stressed at 40°C. A positive qualitative relationship between the accumulation of the LMW chlpHsp and organismal thermotolerance in these species was observed; similar results were obtained separately with four nonAnthophyta species. The strong evolutionary conservation of this LMW Hsp and its localization to the chloroplast, and the correlation between production of this protein and plant thermotolerance, suggest that the LMW chlpHsp plays an important role in adaptation to heat stress.
Sex differential nectar secretion in protandrous Alstroemeria aurea (Alstroemeriaceae): is production altered by pollen removal and receipt?
Authors: Aizen Marcelo A. , Basilio Alicia
Published: April 2006

We examined diurnal and nocturnal nectar secretion across sexual stages in protandrous Alstroemeria aurea, a bumble bee‐pollinated herb with long‐lived flowers native to the southern Andes. We found the following patterns: (1) most nectar was produced diurnally and (2) three times more sugar was secreted during the male than female phase, not only because the male phase lasted longer but also because the rate of nectar production was higher. This 3:1 ratio in nectar production matched the ratio of the minimum number of bumble bee visits required on average to saturate male (pollen removal) vs. female (seed set) functions. Standing crop of nectar, on the other hand, did not differ greatly between male‐ and female‐stage flowers left open to visitors, because the high‐production male‐phase flowers were visited more frequently than female‐phase flowers. In an experiment concurrent with the repeated nectar sampling of individual flowers over their life‐span, we removed pollen from anthers or deposited pollen on stigmas by hand. Neither treatment, designed to mimic effects of visits by Alstroemeria’s native bumble bee pollinator, affected nectar production. The absence of plasticity in nectar secretion in relation to pollination events may reflect a low cost of nectar production, or may result from developmental constraints related to the evolution of the synchronous protandry that characterizes A. aurea.
Ovule and seed development of Lacandonia schismatica (Lacandoniaceae)
Authors: Vázquez‐Santana Sonia , Engleman E. Mark , Martínez‐Mena Alejandro , Márquez‐Guzmán Judith
Published: April 2006

Ovule and seed development is described for Lacandonia schismatica, a species whose androecium is surrounded by the gynoecium. The ovule in each carpel is basal, anatropous, tenuinucellate, and bitegmic. The female gametophyte is formed by the micropylar megaspore cell, after a coenocytic stage of the four megaspore nuclei. The mature female gametophyte has the normal complement of seven cells and eight nuclei. We propose a new type of female gametophyte development on the basis of the coenocytic stage of the tetrad, the cellularization of the tetrad, and the survival of the micropylar spore. At seed dispersal time, the embryo has ~10–20 cells. Endosperm development is of the nuclear type. At maturity, endosperm cells show starch and protein inclusions as well as polysaccharides in their thick walls. The seed coat is formed from the outer integument; the inner one disappears. The exotesta contains tannin. The fruit (achene) wall is two‐layered. The maturation of the fruits in a flower is synchronous, and they separate from the receptacle for dispersal.
Susceptibility of pollen to UV‐B radiation: an assay of 34 taxa
Authors: Torabinejad Javad , Caldwell Martyn M. , Flint Stephan D. , Durham Susan
Published: April 2006

Much of the ultraviolet‐B radiation (UV‐B) research on plants has concentrated on vegetative plant parts, and only a small fraction has dealt with the reproductive system. The present study analyzed pollen grains of 34 taxa germinated and grown under two levels of UV‐B radiation (187 and 460 mW/m2) or no UV‐B (control group). Visible radiation at 260 µmol·m−−2.s−−1 was present in all treatments. Taxa included those with binucleate and trinucleate pollen types. We detected differences among species. A significant reduction in pollen germination occurred in only five species. Pollen tubes of >50% of the species showed significant reduction in length. Trinucleate pollen types were more likely to exhibit tube length reduction than the binucleate types. Proportionately more monocotyledonous species were sensitive to UV‐B treatment than dicotyledonous species, and proportionately more wild species were sensitive than cultivated species and pollen collected from plants growing in the field were somewhat more sensitive than pollen collected from plants grown in the greenhouse. Species in which pollination occurred earlier in the season were more likely to be susceptible to UV‐B radiation than those for which anthesis took place later in the season, suggesting a possible adaptation to UV‐B radiation.
Chloroplast DNA characters, phylogeny, and classification of lathyrus (Fabaceae)
Authors: Asmussen Conny B. , Liston Aaron
Published: April 2006

Mapped cpDNA restriction site characters were analyzed cladistically and the resulting phylogenetic hypotheses were used to test monophyly and relationships of the infrageneric classification of Lathyrus (Fabaceae) proposed by Kupicha (1983, Notes from the Royal Botanic Garden Edinburgh 41: 209–244). The validity of previously proposed classification systems and questions presented by these classification schemes were explored. Two cpDNA regions, rpoC (rpoC1, its intron, part of rpoC2, and their intergenic spacer) and IR−− (psbA, trnH‐GUG, part of ndhF, and their intergenic spacers), were analyzed for 42 Lathyrus and two Vicia species. PCR (polymerase chain reaction) amplified rpoC and IR−− products digested with 31 and 27 restriction endonucleases, respectively, resulted in 109 potentially informative characters. The strict consensus tree suggests that several of Kupicha's sections may be combined in order to constitute clades. The widespread section Orobus and the South American section Notolathyrus should be combined. Section Lathyrus, characterized by a twisted style, should either include sections Orobon and Orobastrum or be redefined as three sections, one of which is characterized by a 100 base pair deletion in the IR−− region. Finally, a weighted parsimony analysis positions sections Clymenum (excluding L. gloeospermus) and Nissolia, both with phyllodic leaves, as sister sections. The affiliation of Lathyrus gloeospermus (section Clymenum) remains problematic.
Monophyletic subgroups of the tribe Millettieae (Leguminosae) as revealed by phytochrome nucleotide sequence data
Authors: Lavin Matt , Eshbaugh Elisa , Hu Jer‐Ming , Mathews Sarah , Sharrock Robert A.
Published: April 2006

Phylogenetic analysis of phytochrome (PHY) genes reveals the identity and relationships of four PHY loci among papilionoid Leguminosae. A phylogenetic analysis of loci combined according to species suggests that most of the tribe Millettieae belongs to one of two monophyletic clades: the Derris–Lonchocarpus or the Tephrosia clade. Together these two form a monophyletic group that is sister to a lineage represented by Millettia grandis of Millettia sect. Compresso‐gemmatae. Collectively, this large monophyletic group is referred to as the Millettieae‐core group, which based on our sampling, includes species of Millettieae that do not accumulate the nonprotein amino acid canavanine and that mostly have pseudoracemose or pseudopaniculate inflorescences. This new phylogenetic framework assists in targeting additional taxa for future sampling. For example, the “American Derris” (Deguelia), which accumulate canavanine, might not be members of the Millettieae core group. Afgekia is also predicted not to be a member because it accumulates canavanine and has an inflorescence of terminal racemes. PHY gene analysis specifically reveals that certain genera traditionally classified in Millettieae are actually distantly related to the Millettieae core group, such as Austrosteensia, Callerya, Craibia, Cyclolobium, Fordia, Platycyamus, Poecilanthe, and Wisteria.
Stem biomechanics of three columnar cacti from the Sonoran Desert
Authors: Molina‐Freaner Francisco , Tinoco‐Ojanguren Clara , Niklas Karl J.
Published: April 2006

The allometric relationship of stem length L with respect to mean stem diameter D was determined for 80 shoots of each of three columnar cactus species (Stenocereus thurberi, Lophocereus schottii, and S. gummosus) to determine whether this relationship accords with that predicted by each of three contending models purporting to describe the mechanical architecture of vertical shoots (i.e., geometric, stress, and elastic similitude, which predict L ∞ Dα with α = 1/1, 1/2, and 2/3, respectively). In addition, anatomical, physical, and biomechanical stem properties were measured to determine how the stems of these three species maintain their elastic stability as they increase in size. Reduced major axis regression of L with respect to D showed that α = 2.82 ± 0.14 for S. thurberi, 2.32 ± 0.19 for L. schottii, and 4.21 ± 0.31 for S. gummosus. Thus, the scaling exponents for the allometry of L differed significantly from that predicted by each of the three biomechanical models. In contrast, these exponents were similar to that for the allometry previously reported for saguaro. Analyses of biomechanical data derived from bending tests performed on 30 stems selected from each of the three species indicated that the bulk stem tissue stiffness was roughly proportional to L2, while stem flexural rigidity (i.e., the ability to resist a bending force) scaled roughly as L3. Stem length was significantly and positively correlated with the volume fraction of wood, while regression analysis of the pooled data from the three species (i.e., 90 stems) indicated that bulk tissue stiffness scaled roughly as the 5/3‐power of the volume fraction of wood in stems. These data were interpreted to indicate that wood served as the major stiffening agent in stems and that this tissue accumulates at a sufficient rate to afford unusually high scaling exponents for stem length with respect to stem diameter (i.e., disproportionately large increments of stem length with respect to increments in stem diameter). Nevertheless, the safety factor against the elastic failure of stems (computed on the basis of the critical buckling height divided by actual stem length) decreased with increasing stem size for each species, even though each species maintained an average safety factor equal to two. We speculate that the apparent upper limit to plant height calculated for each species may serve as a biomechanical mechanism for vegetative propagation and the establishment of dense plant colonies by means of extreme stem flexure and ultimate breakage, especially for S. gummosus.
Applications of the compensating pressure theory of water transport
Authors: Canny Martin J.
Published: April 2006

Some predictions of the recently proposed theory of long‐distance water transport in plants (the Compensating Pressure Theory) have been verified experimentally in sunflower leaves. The xylem sap cavitates early in the day under quite small water stress, and the compensating pressure P (applied as the tissue pressure of turgid cells) pushes water into embolized vessels, refilling them during active transpiration. The water potential, as measured by the pressure chamber or psychrometer, is not a measure of the pressure in the xylem, but (as predicted by the theory) a measure of the compensating pressure P. As transpiration increases, P is increased to provide more rapid embolism repair. In many leaf petioles this increase in P is achieved by the hydrolysis of starch in the starch sheath to soluble sugars. At night P falls as starch is reformed. A hypothesis is proposed to explain these observations by pressure‐driven reverse osmosis of water from the ground parenchyma of the petiole. Similar processes occur in roots and are manifested as root pressure. The theory requires a pump to transfer water from the soil into the root xylem. A mechanism is proposed by which this pump may function, in which the endodermis acts as a one‐way valve and a pressure‐confining barrier. Rays and xylem parenchyma of wood act like the xylem parenchyma of petioles and roots to repair embolisms in trees. The postulated root pump permits a re‐appraisal of the work done by evaporation during transpiration, leading to the proposal that in tall trees there is no hydrostatic gradient to be overcome in lifting water. Some published observations are re‐interpreted in terms of the theory: doubt is cast on the validity of measurements of hydraulic conductance of wood; vulnerability curves are found not to measure the cavitation threshold of water in the xylem, but the osmotic pressure of the xylem parenchyma; if measures of xylem pressure and of hydraulic conductance are both suspect, the accepted view of the hydraulic architecture of trees needs drastic revision; observations that xylem feeding insects feed faster as the water potential becomes more negative are in accord with the theory; tyloses, which have been shown to form in vessels especially vulnerable to cavitation, are seen as necessary for the maintenance of P, and to conserve the supplementary refilling water. Far from being a metastable system on the edge of disaster, the water transport system of the xylem is ultrastable: robust and self‐sustaining in response to many kinds of stress.
Mentor effects in wild species of Helianthus (Asteraceae)
Authors: Desrochers Andrée M. , Rieseberg Loren H.
Published: April 2006

Self‐incompatibility (SI) is an effective method for limiting self‐fertilization in flowering plant species, but there are circumstances in which an otherwise functional SI system may fail. One of the most intriguing of these is the induction of selfing by mixed loads of self and heterospecific pollen (the mentor effect) because it is likely to occur under natural conditions, such as in hybrid zones. Here we conducted a series of controlled crosses to determine whether mentor effects operate in two SI annual species, Helianthus annuus and H. petiolaris, and whether the failure of SI results in a decrease in the frequency of hybridization between these two species. Of the 1396 achenes examined from pollen mixtures that included varying ratios of self, intraspecific compatible, and interspecific pollen, 71 (5.1%) were selfed. Selfing frequencies were significantly less than expected based on pollen ratios, except when the proportion of intraspecific compatible pollen was low. Hybridization frequencies from these same pollen ratios averaged 41.8% with H. annuus as the maternal species and 13.3% with H. petiolaris as the mother. Analysis of 1404 achenes from pollen mixtures that excluded self pollen resulted in hybridization frequencies for H. annuus (42.2%) and H. petiolaris (18.2%) that do not differ significantly from those including self pollen. Thus, mentor effects do not appear to play an important role in reproductive isolation between these species. On the other hand, even a modest increase in self‐fertilization in hybrid populations, such as that due to mentor effects, could enhance the probability of hybrid species establishment.
The cashew nut, Anacardium occidentale (Anacardiaceae), and its perennial association with ants: extrafloral nectary location and the potential for ant defense
Authors: Rickson Fred R. , Rickson Melinda M.
Published: April 2006

Cashew nut trees are consistently ant‐visited throughout the year, with the ants attracted to a large number of extrafloral nectaries on the leaves, inflorescences, flowers, and developing nuts. The commercial production of cashew nut, for example, in India, Brazil, and east Africa, consistently applies pesticides, especially insecticides, in large monoculture plantings. Each year prophylactic spraying begins with the first flush of new leaves, continues through flowering, ending at about mid‐nut development. We surveyed for ant diversity in sprayed and unsprayed cashew monocultures of various sizes and ages in Sri Lanka, India, and Malaysia to document the ant‐cashew relationship and to explore the potential of ants replacing chemical pesticides in insect control. Using for‐profit, commercial‐size plantations as examples, we present information that cashew has a strong potential for arthropod‐dependent protection from pests and suggest important habitat considerations for encouraging ants within cashew plantings.
The colorless flavonoids of Arabidopsis Thaliana (Brassicaceae). I. A model system to study the orthodihydroxy structure
Authors: Sheahan John J. , Cheong Hyeonsook , Rechnitz Gary A.
Published: April 2006

The orthodihydroxy structure may mediate flavonoid coloration or antioxidant activity, making it of interest to floral or health food industries, respectively. In the first of two companion papers, the authors demonstrate a model system to study the orthodihydroxy structure in colorless flavonoids of Arabidopsis, with tools similar to those used upon the colored flavonoids. The system includes a fluorescent staining procedure to visualize colorless orthodihydroxy flavonoids at a subcellular level and to screen seedlings for rare genetic recombinants. The system also includes mutant lines to study the synthesis of colorless orthodihydroxy flavonoids, their potential role as antioxidants, and their potential risk as oxidative mutagens.
Postpollination nectar reabsorption in the African epiphyte Aerangis verdickii (Orchidaceae)
Authors: Koopowitz Harold , Marchant T. Alejandro
Published: April 2006

Nectar reabsorption in flowering plants seems to be a rare phenomenon and to our knowledge it has not been reported previously in the Orchidaceae. In this study we present data that show statistically significant differences in nectar sugar concentrations before and after pollination. Virgin flowers of the African epiphytic orchid Aerangis verdickii showed mean sugar concentrations in the nectar of 14.4 and of 18.3% in 1994 and 1995, respectively (sucrose mass by mass equivalent). Sugar concentration in nectar from naturally pollinated flowers had a mean of 3.2 and of 8.7% for the same period. In an experiment in the wild 60 flowers were protected against nectar theft by the ants. Half of those flowers were hand‐pollinated. Control (virgin) flowers had nectar with a mean value of 13.8%, while flowers measured 48 h after pollination had a mean sugar concentration of 4.3%. The mean volume of nectar based on measurements of 23 virgin flowers from nine different plants was 19 µL. We estimated an average energy value for the nectar produced of 684 J per plant per season. At the study site, over 60% of the unmanipulated flowers were robbed of all their nectar by arboreal ants, Polyrachis spp. (Formicinae). The adaptive significance of nectar reabsorption for A. verdickii is probably a function of the environmental stresses to which it has been exposed and the relative costs of nectar production.
First report of oil cavities in Scrophulariaceae and reinvestigation of air spaces in leaves of Leucophyllum frutescens
Authors: Lersten Nels R. , Beaman Jeffrey M.
Published: April 2006

Conspicuous air spaces in Leucophyllum (Scrophulariaceae; Leucophylleae) leaves have been suggested to be developmentally transformed secretory cavities. We reinvestigated air space development in Leucophyllum frutescens, using freehand sections of mature fresh leaves and paraffin sections of several leaf stages. Each of the numerous air spaces per leaf forms because greater separation occurs within a local group of spongy mesophyll cells than in the developing spongy mesophyll elsewhere. We found no anatomical evidence of transitory epithelial cells or lysis of cells in developing air spaces, thus the hypothesis that air spaces are transformed secretory cavities is not supported. However, an important finding was that all leaves had one pair of conspicuous true secretory cavities flanking the midvein at the apex, each lined by an epithelium and filled with oil. We also found conspicuous apical cavities in freehand sections of herbarium specimens of this and three other Leucophyllum species. Cavities were not seen in L. revolutum or in the related Eremogeton grandiflorus. This is the first report and description of a true internal secretory cavity in Scrophulariaceae. In the related family Myoporaceae, we found epithelium‐lined cavities scattered abundantly in leaves of cleared samples of three genera.
Does seed dispersal limit initiation of primary succession in desert playas?
Authors: Fort Kevin P. , Richards James H.
Published: April 2006

To investigate the initiation of primary succession in a cold‐desert playa‐dune complex, we studied the large‐scale (2000 m) seed (diaspore) dispersal patterns at Mono Lake, California. Seeds of seven of the ten species reaching the barren playa had wind‐dispersal adaptations. Rates of dispersal (numbers of seeds per square metre per day) were as much as three orders of magnitude lower on the playa than in the diverse dune vegetation. However, seed input appeared sufficient to reach potential safe sites on the playa, with a peak input of 66 ± 8 total seeds·m−2·d−1. The smooth playa surface, the virtual absence of aboveground barriers, and the high windspeed environment promote the long‐distance dispersal of seeds (at least 1300 m for Chrysothamnus spp. and at least 700 m for Sarcobatus vermiculatus). The large spatial scale of sampling revealed a relatively high seed input onto the playa by the dominant pioneer species S. vermiculatus, despite the low abundance of parent vegetation in this region. All of these results implicate low rates of seed entrapment as an obstacle to establishment on this desert playa, rather than a lack of seed input.
Phylogenetic relationships of conifers inferred from Partial 28S rRNA gene sequences
Authors: Stefanović Saša , Jager Muriel , Deutsch Jean , Broutin Jean , Masselot Monique
Published: April 2006

The conifers, which traditionally comprise seven families, are the largest and most diverse group of living gymnosperms. Efforts to systematize this diversity without a cladistic phylogenetic framework have often resulted in the segregation of certain genera and/or families from the conifers. In order to understand better the relationships between the families, we performed cladistic analyses using a new data set obtained from 28S rRNA gene sequences. These analyses strongly support the monophyly of conifers including Taxaceae. Within the conifers, the Pinaceae are the first to diverge, being the sister group of the rest of conifers. A recently discovered Australian genus Wollemia is confirmed to be a natural member of the Araucariaceae. The Taxaceae are nested within the conifer clade, being the most closely related to the Cephalotaxaceae. The Taxodiaceae and Cupressaceae together form a monophyletic group. Sciadopitys should be considered as constituting a separate family. These relationships are consistent with previous cladistic analyses of morphological and molecular (18S rRNA, rbcL) data. Furthermore, the well‐supported clade linking the Araucariaceae and Podocarpaceae, which has not been previously reported, suggests that the common ancestor of these families, both having the greatest diversity in the Southern Hemisphere, inhabited Gondwanaland.
Analysis of form and function in North American columnar cacti (tribe Pachycereeae)
Authors: Cornejo Dennis O. , Simpson Beryl B.
Published: April 2006

Simple and multivariate linear models were used to demonstrate the influence of mechanical design and climate on stem morphology and branching architecture in 25 species of North American columnar cacti. The effect of phyletic inertia was tested by the method of independent contrasts. Stem girth was found to increase significantly slower with increased height within taxa (cross‐sectional stem area ∝ [plant height]0.603), than across taxon (cross‐sectional stem area ∝ [plant height]1.451). Juveniles are shown to be mechanically overbuilt and subsequently grow into more slender adult forms determined in part by structural limitations and the optimization of other stem functions. We make a structural analogy of relatively rigid columnar cacti to concrete columns and compare plants and models with similar growth forms lacking woody skeletons (barrel cacti). Taxa with woody support achieved a surface‐to‐volume ratio six times greater than taxa without woody support. Across taxon, cooler winter temperatures were associated with larger stem girths, and greater annual precipitation was associated with less frequent branching. The relationship between total plant surface and volume approaches isometry within taxa, but across taxon average individuals are scaled replicates. We hypothesize that architecture and average plant height are adjusted, in an evolutionary sense, to maintain geometric similitude between surface and volume along a climatic gradient.