Gynerium Sagittatum Research Articles

Herbaceous angiosperms, pteridophytes and shrubs cocktail for rapid ground cover for soil and water bioengineering in the Caribbean

Among the Nature-based Solutions currently spreading worldwide, soil and water bioengineering techniques, are used to stabilize hill slopes, earth embankment, and riverbanks. They consist in the use of living plants, sometimes coupled with dead materials, to control erosion and restore ecosystems.These approaches remain to be adapted to Neotropics and particularly to the Caribbean Islands biodiversity hotspot. The success of soil and water bioengineering designs depends on the selection of suitable native plant species and considering the hydrodynamic and geotechnical processes. In the Caribbean, data are available concerning woody species but are still lacking for the other constitutive components of riparian plant communities. The objective of this study was to identify the riparian forest understory species best suited for use in SWBE at their establishment phase. In a three-month ex situ experiment, we measured the survival rate, biomass production and root growth of propagules (cuttings and bulbils) of eleven native Caribbean species (5 herbs, 4 pteridophytes, 2 shrubs) occurring naturally in a variety of riparian environments. All the herb and shrub species studied displayed growth vigour adequate for a successful inclusion in soil and water bioengineering techniques. Among herbs, Commelina diffusa, Hymenachne amplexicaulis and Sphagneticola trilobata performed the best. Gynerium sagittatum and Dieffenbachia seguine, despite their slower growth and root development, remain suitable. Regarding the two shrubs, Ludwigia octovalvis gave better results than Clidemia hirta. Among the pteridophytes, Adiantum latifolium, Thelypteris reticulata and particularly Lycopodium cernuum appeared poorly suited to soil and water bioengineering. Acrostichum danaeifolium was the best-performing pteridophyte. These first experimental results focusing on the propagation and establishment of native herbs, pteridophytes and shrubs, allowed to identify a diversity of species of interest as cuttings for soil and water bioengineering and practical clues for their use in the Neotropics.

Effect of Gynerium sagittatum methanol extract on testosterone-induced benign prostatic hyperplasia in rats compared with finasteride.

Effect of Gynerium sagittatum methanol extract on testosterone-induced benign prostatic hyperplasia in rats compared with finasteride.

Biotechnology on arrow cane (<em>Gynerium sagittatum</em>Aubl.). A plant of cultural interest.

Arrow cane (Gynerium sagittatum Aubl.) is a Poaceae associated to human development of the ancient Zenú culture present nowadays in the flat lands of Córdoba and Sucre department in the Colombian north Coast. Despite its importance, arrow cane is not cultivated in large scale and extraction from natural populations is the most common way for plant exploitation with negative environmental and economic consequences for the aboriginal communities. A research program based on biotechnology was implemented to generate information related to plant genetic diversity, plant propagation and genetic resource conservation in order to provide knowledge to contribute to implement technical crop development to minimize the impact of artisans´ activity on the environment and increase sustainability on fiber source for craftsmanship. Accessions from different zones of the Colombian territory were characterized using morphological and molecular markers founding low genetic diversity. Cultivars UC121, “Criolla”, “Criolla 1”, Costera and “Martinera” were in vitro established and micropropagation results indicated that large quantities of high quality, fully adapted, homogeneous plants can be produced from any cultivar. In vitro cultured arrow cane plants can be stored by means of slow growth or modified structures such as micro rhizomes developed in vitro.

Micropropagation of arrow cane, Gynerium sagittatum (Aubl.) P. Beauv. cv. Criolla, Criolla 1, and Martinera, in a double-phase medium

To evaluate the micropropagation response of arrow cane, Gynerium sagittatum (Aubl.), plants using a double-phase medium in the multiplication stage, explants consisting of stem sections with axillary meristems from cultivars Criolla, Criolla 1, and Martinera were established in vitro in a semisolid medium. Then, they were multiplied using a double-phase medium supplied at several Benzylaminopurine (BAP) concentrations (0.0, 0.5, 1.0, 1.5, and 2.0 mg/L), followed by rooting in a culture medium supplied at several Naphthaleneacetic acid (NAA) concentrations (0.0, 0.5, 1.0, 1.5, and 20 mg/L). Both multiplied unrooted and rooted microshoots were transferred ex vitro. Treatments were distributed with a completely randomized design; data were analyzed with an ANOVA and means separated with Tukey’s test. Explants from Criolla and Martinera cultured with 0.5 mg/L BAP resulted in higher multiplication rates. All microshoots transferred to the rooting medium rooted, although NAA significantly increased the number of roots and reduced root length. Plants from all three cultivars, in vitro rooted or unrooted transferred to ex vitro conditions, showed 100 % survival and adaptation. For Criolla and Martinera, 0.5 mg/L BAP statistically increased shoot multiplication rates and NAA increased adventitious root formation and reduced root length. Plants of all cultivars survived and adapted 100 % to ex vitro conditions.

DNA barcoding for molecular identification of Gynerium sagittatum (Poales: Poaceae): genetic diversity in savannah genotypes from Córdoba, Colombia

ABSTRACT. Introduction: The fiber of the Gynerium sagittatum Aubl. P. Beauv is raw material for the elaboration of several handcrafts, which are symbols of Colombian cultural identity. In the manufacture process, different genotypes are used according to the fiber quality and the type of craftsmanship, but it is believed that Gynerium is a complex species, and to date, there is no agreement on whether these genotypes belong to the same species or to different species. Objective: The aim of this study was to quickly and accurately identify wild cane plants using the nuclear ribosomal internal transcribed spacer (ITS1+ITS2), three chloroplast regions (matK, rbcL, ycf1), and their combinations. Methods: Different tests were used for discrimination: (1) inter and intraspecific distances, (2) Best Match (BM), Best Close Match (BCM), and tree-based method (3) Neighbor Joining (NJ) and (4) maximum likelihood and bayesian inference in molecular data. Results: The results showed that BM and BCM approaches revealed the low rate of correct species identification for ITS+matK (33.3 %) and ITS (28.6 %) loci, showing similarity among sequences. These results were further supported by tree-based analyses, where all individual regions and the different gene combinations had a zero discrimination rate. Conclusions: all genotypes belong to the same species of wild cane, therefore existing morphological differences can be related to phenotypic plasticity.

ADSORPTION OF CRUDE OIL IN AQUEOUS ENVIRONMENT USING WILD CANE FIBER: EQUILIBRIUM AND KINETIC STUDIES

This work evaluates the adsorption capacity of the wild cane fiber (Gynerium Sagittatum) in crude oil. Both untreated biomass and treated with ionic liquid [2HEA][Ac] and acetylated were studied for oil spill cleanup in aqueous environment. Crude oil adsorption tests were performed in a thermostatic bath, varying the time for the kinetic study and the amount of oil for isotherm model. Kinetic study of oil adsorption allowed us to identify that the untreated fiber reached saturation in 90 minutes, while the fiber treated with acetylated and ionic liquid reached saturation in 30 minutes. In equilibrium, the total amount of oil adsorbed by the untreated fiber was 3.8g, whereas in acetylated and ionic liquid treated fiber, the obtained maximum adsorption capacity was 4.4 and 3.7 g, respectively. The remediation process using wild cane fiber followed a second order kinetic rate and Sips and Toth isotherm models provided the best fit to experimental data.

Diseño y artesanado: una mirada contemporánea

Resumen
 El escaso reconocimiento de la identidad y estética presentes en el artesanado y uso de la Caña flecha (Gynerium Sagittatum) de las culturas indígenas Zenú, plantea la necesidad de indagar sobre cómo entender el diálogo entre el diseño, el artesanado y procesos de producción industrial orientados hacia la innovación de procesos y productos en un contexto de sustentabilidad. Mediante una revisión bibliográfica organizada en dos fases, la primera consistente en la búsqueda de artículos científicos y libros y la segunda en el análisis, permitió clasificar la información en dos categorías: 1) Design, Handcraft y nuevas tendencias y 2) Design y Decolonization. Como resultado se muestran aspectos críticos en la relación entre diseño, artesanado y conocimiento indígena. En esta búsqueda se discute sobre el potencial que, desde el diseño, hace posible generar procesos de innovación y se presenta el diseño contemporáneo como una disciplina de síntesis que responde a un enfoque culturalista o esencialista del diseño con grandes capacidades de empoderamiento y emancipación en contextos periféricos. Esto permitió cuestionar sobre cuáles metodologías permiten acercarse a la comprensión del legado de las culturas y los procesos de artesanado.
 Palabras clave: Artesanía; diseño centrado en el sujeto; diseño sustentable; humanismo proyectual; materiales tradicionales; tradiciones indígenas;
 
 AbstractThe low recognition of the identity and aesthetics present in the craft and use of the cane arrow (Gynerium Sagittatum) of the Zenú indigenous cultures, propose the need to inquire about how to understand the dialogue between design, craftsmanship and industrial production oriented processes towards the innovation of processes and products in a context of sustainability. Through a bibliographic review organized in two phases, the first consisting of the search for scientific articles and books and the second in the analysis, allowed the classification of information into two categories: 1) Design, Handcraft and new trends and 2) Design and Decolonization. As a result, critical aspects are shown in the relationship between design, crafts and indigenous knowledge. This search discusses the potential that, from design, makes it possible to generate innovation processes and presents contemporary design as a discipline of synthesis that responds to a culturalist or essentialist approach to design with great empowerment and emancipation capabilities in contexts peripherals This allowed us to question which methodologies allow us to approach the understanding of the legacy of cultures and craft processes.
 Keywords: Crafts; subject-centered design; sustainable design; projective humanism; traditional materials; indigenous traditions;

Estandarización de la técnica de AFLPS para la caracterización de germoplasma de caña flecha (Gynerium sagittatum Aubl.)

La caña flecha (Gynerium sagittatum (Aubl.), especie originaria de la India, constituye la materia prima esencial para la elaboración de artesanías típicas en la Costa Norte Colombiana. Conocer la variabilidad genética de esta especie permite diseñar e implementar estrategias de mejoramiento y conservación de los recursos genéticos. El objetivo del estudio fue desarrollar un protocolo para caracterizar 25 accesiones de caña flecha con AFLPs. El análisis permitió detectar 223 loci que se extendieron desde 43 (E-ACC/M-CAG) hasta 72 loci (E-ACA/M-CTA) con un promedio de 55,75 loci por combinación de iniciadores. La combinación de iniciadores E-ACC/M-CAG generó el mayor porcentaje de polimorfismo (39,53%). Los diferentes perfiles de locus para todos los individuos indicaron un buen escrutinio del genoma para el análisis de la variabilidad y la estructura genética de la especie. El presente protocolo muestra por primera vez la caracterización genética a nivel molecular en caña flecha

Ecology and Behavior of Alder Flycatchers (Empidonax alnorum) On Their Wintering Grounds In Argentina

ABSTRACT The Alder (Empidonax alnorum) and Willow (E. trailli) flycatchers are cryptic species, and their distribution outside the breeding season is poorly known, owing mostly to identification difficulties. Our new records suggest that large numbers of Alder Flycatchers overwinter in rivers crossing the Chaco region and in the foothill forests of the Yungas of Argentina, significantly increasing their southern wintering range. Records in northern Argentina span 3 November to 23 March. Key habitat for overwintering Alder Flycatchers in Argentina included stands of palo bobo (Tessaria integrifolia) along the Rio Bermejo and tributaries, either in association with sparse shrubs of chilca (Baccharis salicifolia) or more rarely with canebrake (Gynerium sagittatum). Other habitats used were old shrubby ‘madrejones' with Tessaria scrub and sacha cafe (Sesbania virgata), very dense Baccharis salicifolia scrub next to flowing creeks in foothill Yungas and dry Chaco, and riparian forests dominated by palo flojo (...

Tratamiento de lixiviados de relleno sanitario por medio de humedales construidos sembrados con policultivos de plantas nativas

Use of constructed wetlands for wastewater treatment (domestic, storm water, landfill leachate, acid drainage mine) has increase since the mid 90´s. This paper presented the results of the study at pilot scale of constructed wetland (CW) for landfill leachate (LL) treatment planted with polycultures of tropical species Gynerium sagittatum (Gs), Colocasia esculenta (Ce) and Heliconia psittacorum (He). The CW cells were operated during 7 months at continuous gravity flow (Q=0.5 m3 d-1). Three CWs were divided into three sections, and each section (5.98 m2) was seeded with 36 cuttings of each species. The other unit was planted randomly. The final distribution of plants in the CW cells was: CW-I (He- Ce-Gs), CW-II (randomly), CW-III (Ce-Gs-He) and CW-IV (Gs-He-Ce). All CW cells received pre-treated LL from a high-rate anaerobic pond (BLAAT®) operating as primary treatment. Influent and effluent from each CW cell were analysed for total and filtered COD weekly and heavy metal (HM) (Cd, Pb and Hg) fortnightly. Flowering, stem length, Chlorophyll and photosynthetic rates in plants were measured fortnightly. The removal efficiencies were good; with better performances in CW-IV (60-90%) for all parameters, indicating that plant distribution may affect the removal capacity of CW cells. All plants presented a good physiological response and constant growth along the research period. The native plants thus demonstrated their suitability for phytoremediation of LL and all could be categorized as HM accumulators.

CARACTERIZACIÓN SOCIAL Y ECONÓMICA DEL OFICIO ARTESANAL ZENÚ Y CARACTERIZACIÓN AGRONÓMICA DE BANCOS DE GERMOPLASMA DE CAÑA FLECHA EN EL DEPARTAMENTO DE ANTIOQUIA, COLOMBIA

ResumenLa artesanía Zenú, cuya pieza icónica es el Sombrero Vueltiao, es un oficio ancestral derivado de la caña flecha Gynerium sagittatum, planta asociada a fuentes hídricas y a diversidad de especies tintóreas que sirven para dar color a sus artículos. Esta actividad (la artesanía) necesita fortalecerse en Antioquia debido a que la variedad criolla; utilizada en la artesanía denominada “fina”, planta que domesticaron en sus antiguos territorios (Córdoba y Sucre) no se encontraba en Antioquia. Pero el desplazamiento por la violencia y la búsqueda de tierras, hizo que los zenúes llegaran a este territorio donde no encontraron las condiciones apropiadas de la relación co-evolutiva que se ha dado entre la planta, el oficio y su identidad, esto representa la cuenta regresiva de su cultura en la región. La caña flecha más que una planta es base de materias primas para el oficio artesanal. La artesanía Zenú es un esfuerzo por tener mejores alternativas económicas y por seguir siendo zenúes. Ante esta problemática, el Jardín Botánico de Medellín estableció con tres comunidades zenúes unos Bancos de Germoplasma con caña flecha en campo (BGC) a partir de rizomas de la variedad criolla, como material de propagación para establecer cultivos como fuente de materia prima para la elaboración de la artesanía, que son la base de desarrollo del proyecto del cual, en esta publicación se presentan los resultados de las fases iniciales. Hoy, el pueblo Zenú sufre muchas carencias en materia de salud, agua, saneamiento básico, alternativas laborales e incluso alimento en contextos ecológicamente valiosos y amenazados por la minería y cultivos ilícitos. La intención de las caracterizaciones que se presentan aquí es para abordar y empezar precisamente por medio del oficio artesanal a construir soluciones a problemas sociales y ambientales que serán detallados en el contenido de este texto.Palabras claves: Etnia Zenú, Plantas tintóreas, Agroambiental.

Production and quality analysis of pellets manufactured from five potential energy crops in the Northern Region of Costa Rica

Modifications to a pellet manufacturing process must be made based on the characteristics of raw material used. The purpose of this work was to determine the alternations required to a wood pellet manufacturing process and the quality of the pellets produced using this process from five energy crops. Quality measurements include: the caloric value, the loss of moisture content in each production stage, the efficiency index of particle-pellet, ash content and quality as defined using the quantity of cracks and the transversal density and longitudinal density determined using X-ray radiography. The crops analyzed were rhizomatous plants, with caloric values ranging between 17.1 and 20.3 MJ kg−1. This work determined that it was possible to produce pellets with Gynerium sagittatum and Phyllostachys aurea using the same production process for wood; however, Arundo donax and Pennisetum purpureum needed pre-air-drying and the Sorghum bicolor required mechanical dewatering before drying. A. donax, P. purpureum and G. sagittatum provided the highest efficiency index. When evaluating the pellet quality P. aurea and G. sagittatum hard a large quantity of cracks, unlike A. donax, P. purpureum and S. bicolor. The transversal and longitudinal pellet density varied from 1129 to 1294 kg m−3. The highest values of bulk density were obtained in A. donax and P. purpureum, followed by G. sagittatum and P. aurea, and the lowest bulk density was obtained in S. bicolor. Althogh out, some species produced cracks and high ash content, this work demonstrated that it is possible to produce pellets with moderate quality.

Pellets Evaluation Made from Tropical-Climate Agricultural and Forestry Crops of Costa Rica with a Domestic Stove

The present study shows the results of the evaluation of the pellets made from two forestry crops and eight agricultural crops in Costa Rica by employing a 50 kW domestic stove. The following variables were evaluated: flame outlet and flue gas temperatures and emissions (CO2, CO, NO, NO2, NOx and SO2). It was found that the pellet consumption varies from 2.5 to 3.4 kg/h, where the former corresponds to Tectona grandis and the latter to the mesocarp oil palm fruit. Flame outlet temperature varied from 400 to 623 °C and flue gas temperature varied from 205 to 322 °C, where the lowest temperature corresponds to Phyllostachys aurea and the highest to the oil palm residue. T. grandis showed the highest variation in temperature, while Cupressus lusitanica showed the lowest variation. A result that stands out in the measurement of emissions is that the two forestry crops show the lowest values. Different type of pellet produces different behaviour in domestic stove. Gynerium sagittatum and C. lusitanica were with greater heat generation and Pennisetum purpureum and T. grandis with the lowest heat generation.

Quality of Pellets Made from Agricultural and Forestry Crops in Costa Rican Tropical Climates

Pellets may be produced with different types of agriculture or forestry crops in Costa Rica. This work evaluated the energy, physical, and mechanical properties of pellets fabricated from 12 types of agricultural and forestry crops (Ananas cumosos, Arundo donax, Coffea arabica, Cupressus lusitanica, empty fruit bunch and oil palm mesocarp fiber of the fruit of Elaeis guineensis, Gynerium sagittatum, Pennisetum purpureum, Phyllostachys aurea, Saccharum officinarum, Sorghum bicolor, and Tectona grandis), and similarities among these crops were established by multivariate principal component analysis. High variation was found in the pellet properties. The energy evaluation revealed that C. lusitanica and P. aurea are the crops with the best qualities for fuel use because of their high calorific values (from 16807 kJ/kg and 19919 kJ/kg, respectively) and low ash content (1.03% and 3.39%, respectively). As for physical properties, most crops exhibited values within the range noted by several authors and standards. All 12 pellet crops displayed high durability (from 72.12% to 92.98%) and compression force (from 295.18 N to 691.86 N). Moreover, the evaluation of crop similarities allowed the determination of four group combinations. Within these groups, C. lusitanica, P. aurea, and G. sagittatum had similar energy qualities and the best caloric characteristics.

Cr(VI) and COD removal from landfill leachate by polyculture constructed wetland at a pilot scale.

Four subsurface horizontal-flow constructed wetlands (CWs) at a pilot scale planted with a polyculture of the tropical plants Gynerium sagittatum (Gs), Colocasia esculenta (Ce) and Heliconia psittacorum (He) were evaluated for 7months. The CW cells with an area of 17.94m(2) and 0.60m (h) each and 0.5m of gravel were operated at continuous gravity flow (Q = 0.5m(3)day(-1)) and a theoretical HRT of 7days each and treating landfill leachate for the removal of filtered chemical oxygen demand (CODf), BOD5, TKN, NH4 (+), NO3 (-), PO4 (3-)-P and Cr(VI). Three CWs were divided into three sections, and each section (5.98m(2)) was seeded with 36 cuttings of each species (plant density of six cuttings per square metre). The other unit was planted randomly. The final distributions of plants in the bioreactors were as follows: CW I (He-Ce-Gs), CW II (randomly), CW III (Ce-Gs-He) and CW IV (Gs-He-Ce). The units received effluent from a high-rate anaerobic pond (BLAAT®). The results show a slightly alkaline and anoxic environment in the solid-liquid matrix (pH = 8.0; 0.5-2mgL(-1) dissolved oxygen (DO)). CODf removal was 67%, BOD5 80%, and TKN and NH4 (+) 50-57%; NO3 (-) effluents were slightly higher than the influent, PO4 (3-)-P (38%) and Cr(VI) between 50 and 58%. CW IV gave the best performance, indicating that plant distribution may affect the removal capacity of the bioreactors. He and Gs were the plants exhibiting a translocation factor (TF) of Cr(VI) >1. The evaluated plants demonstrated their suitability for phytoremediation of landfill leachate, and all of them can be categorized as Cr(VI) accumulators. The CWs also showed that they could be a low-cost operation as a secondary system for treatment of intermediated landfill leachate (LL).

Phytoremediation of Landfill Leachate with Colocasia esculenta, Gynerum sagittatum and Heliconia psittacorum in Constructed Wetlands

This study assessed the accumulation of Cd (II), Hg (II), Cr (VI) and Pb (II) in Gynerium sagittatum (Gs), Colocasia esculenta (Ce) and Heliconia psittacorum (He) planted in constructed wetlands treating synthetic landfill leachate. Sixteen bioreactors were operated in two experimental blocks. Metal concentrations in the influent and effluent; root, stem, branch and leaves of plants were analysed, as well as COD, N-NH4+, TKN, T, pH, ORP, DO, and EC. Average removal efficiencies of COD, TKN and NH4+-N were 66, 67 and 72%, respectively and heavy metal removal ranged from 92 to 98% in all units. Cr (VI) was not detected in any effluent sample. The bioconcentration factors (BCF) were 100 -102. The BCF of Cr (VI) was the lowest: 0.59 and 2.5 (L kg−1) for Gs and He respectively; whilst Cd (II) had the highest (130–135 L kg−1) for Gs. Roots showed a higher metal content than shoots. Translocation factors (TF) were lower, He was the plant exhibiting TFs >1 for Pb (II), Cr (T) and Hg (II) and 0.4–0.9 for Cd (II) and Cr (VI). The evaluated plants demonstrate their suitability for phytoremediation of landfill leachate and all of them can be categorized as metals accumulators.

Flavonoids and isoflavonoids from Gynerium sagittatum

Four flavonoids namely (2 R,3 R)-2,3- trans-7,4′-dimethoxydihydroflavonol, (2 R,3 S,4 S)-2,3- trans-3,4- cis-7,4′-dimethoxy-3,4-flavandiol, 6-hydroxy-7,4′-dimethoxyflavone, 6,7,4′-trimethoxyflavone, along with the known isoflavonoids ferreirin, dihydrocajanin, dalbergioidin, dihydrobiochanin A and biochanin A and other 11 known compounds were isolated from the roots of Gynerium sagittatum. The structural characterization of these compounds was carried out via one- and two-dimensional NMR experiments in combination with ESI-MS. Finally a quantitative analysis of the isoflavones of the methanolic extract was performed by LC-ESI-MS. The high quantity of isoflavonoids found in G. sagittatum makes this plant a good natural source of isoflavonoids.

An experimental study of bamboo ants in western Amazonia

Numerous ant taxa naturally inhabit stems of live and dead Guadua bamboo (Bambusoidea, Poaceae) in western Amazonia. In an experiment at the onset of the wet season in Peru’s Manu National Park, we augmented potential nest sites in stems of live bamboo, dead bamboo and dead cana brava (Gynerium sagittatum, another woody grass) at five stations within each of ten bamboo patches and ten control areas outside those patches. Each experimental stem possessed three vacant and available internodes, pre-drilled with, respectively, large, small and linear holes, mimicking the range of forms of surveyed natural entrances. After 24 days, approximately 13% of 798 available internodes had been colonized, the majority by fragments of existing colonies. Ignoring entrance type, which did not affect colonization for any species or species group, and censoring non-independent internodes of the same stem, we used individual stems as independent sample units in other tests. One specialist in live bamboo (Camponotus longipilis), and a likely specialist in dead bamboo (Camponotus depressus), were identified based on overrepresentation in bamboo habitat and disproportionate occurrence in live or dead bamboo stems. A third species, Camponotus (Pseudocolobopsis sp.) was more abundant in bamboo areas but colonized both dead bamboo and dead cana. Relatively high abundance of standing dead stems in Guadua forests may account for the presence of a dead stem specialist. The experiment missed detecting specialization in one live culm specialist (Camponotus mirabilis), likely due to its failure to simulate conditions required for the species’ unique modes of colony establishment and spread into new culms. Most opportunistic stem nesters colonized dead bamboo at significantly greater rates than dead cana, but were either equally well represented in bamboo and control areas, or underrepresented in bamboo habitat. Given low colonization rates overall, underrepresentation in bamboo cannot be attributed to competition from bamboo specialists for nesting space. Rather, it may be due to combined effects of seasonal flooding of bamboo habitat, and greater importance of food limitation, relative to nest site limitation, in that habitat.

The Neotropical species Askalaphium depressum (Bates): Larval description, first diagnosis and illustrations of immature Ctenodactylini, with natural history notes on the genus and tribe (Coleoptera: Carabidae)

Adults and larvae of Askalaphium depressum (Bates) live in association with hispine chrysomelid beetles of the genus Cephaloleia Chevrolat, in the appressed leaf axils of the riverside reed, Gynerium sagittatum (Aubl.) P. Beauv. This reed is locally known in Amazonian Perú as Caña Brava. Both adult and larval A. depressum eat larvae of Cephaloleia species and larvae of an unidentified dipteran, and perhaps other insects living in the confines of the leaf sheaths of that plant species. The geographic range of Caña Brava reed extends from subtropical South America northward to México (and Florida), but A. depressum has been found thus far at only three Amazonian localities, probably indicating its cryptic microhabitat and lack of collecting, therein. Likely, the range of this commensal carabid species is more extensive and may approach the range of its host plant and hispine food. Structural features of second and third instar larvae of A. depressum are described for the first time. Larval character states that are shared with a related ctenodactyline, Leptotrachelus dorsalis (Fabricius), provide a basis for characterization of the tribe Ctenodactylini.

Shoot dynamics of the giant grass Gynerium sagittatum in Peruvian Amazon floodplains, a clonal plant that does show self-thinning.

The giant rhizomatous grass Gynerium sagittatum is an early successional species that forms dense monocultures in Peruvian Amazon floodplains. We studied the shoot population structures by recording shoot densities and shoot heights. Leaf areas and stem volumes were allometrically estimated. Stands of two varieties of G. sagittatum were examined that differ in height and in the degree of shoot branching. In stands of increasing age, marked decreases in shoot densities were accompanied with an increase in mean shoot size. Self-thinning was indicated by the negative correlation between log stem volume per unit ground area and log shoot density, significant at least for one of the two varieties. The difference in thinning slope between the varieties could be largely accounted for by their different shoot geometry, as was revealed by calculations based on the allometric model of Weller (1987b). The relationship between log leaf area per shoot and log shoot density was significantly negative with slopes close to -1. Shoot size inequalities decreased with increasing mean stem volume per shoot, probably as a result of density-dependent mortality of the smaller shoots. All of these results accord with expectations for shoot self-thining. Gynerium sagittatum is the first clear example of a clonal plant species that exhibits self-thining in natural monospecific stands. It is argued that self-thinning occurs in this giant tropical grass because its shoots are perennial and do not experience seasonal die-back (periodic density-independent mortality), in contrast to many of the clonal plant species that have been studies so far.