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Soil microorganisms, together with water, play a key role in arid ecosystems, being responsible for the nutrient cycle, facilitating nutrient incorporation into plants, influencing plant drought tolerance, and enhancing their establishment. Therefore, their use for restoration practices is promising. We tested the potential of native strains of Actinobacteria from Monte Desert as growth promoters of native vegetation, isolating them from two substrates from their habitat (bare soil and leaf-cutting ant refuse dumps). Strains were inoculated into the soil where seedlings of three native plant species (Atriplex lampa, Grindelia chiloensis, Gutierrezia solbrigii) were growing. Seedlings were grown following a full factorial design experiment under greenhouse and field conditions comparing native Actinobacteria effects with a known growth-promoting strain, Streptomyces sp. (BCRU-MM40 GenBank accession number: FJ771041), and control treatments. Seedlings survived greenhouse condition but species survival and growth were different among treatments at field conditions, varying over time. The highest survival was observed in a native soil strain (S20) while the lowest in MM40. The low survival in MM40 and in the other treatments may be explained by the higher herbivory observed in those seedlings compared to control ones, suggesting a higher nutritional status in inoculated plants. Strains from refuse dumps were the best at enhancing seedling growth, while strains from soil were the best at maintaining their survival. Native Actinobacteria studied may increase plant species survival and growth by improving their nutritional status, suggesting their potential to facilitate vegetation establishment and, therefore, being good candidates for restoration practices. Furthermore, plant species respond differently to different strains, highlighting the importance of microorganism diversity for ecosystem functioning.

Broom snakeweed (Gutierrezia sarothrae) and threadleaf snakeweed (G. microcephala) are suffrutescent plants found in many parts of western US rangelands and are possibly toxic to grazing livestock. The toxic components are not known, but it has been suggested that the diterpene acids may be both toxic and abortifacient. One hundred sixty-two samples of snakeweed were collected from 55 locations in Colorado, Oklahoma, New Mexico, Texas, Wyoming and Utah and were taxonomically classified. Samples were analyzed by GC-MS in a chemophenetic analysis and grouped into individual chemotypes based on diterpene acid content. The GC-MS profiles were found to be diverse showing at least eight different chemotypes. From each of the chemotypes the major diterpene acids were isolated and characterized by IR, MS and NMR spectroscopy. Twenty-one diterpenoids were identified and found to be a mix of furano, lactone, di-acid and esters of labdane, ent-labdane and chlerodane acids and alcohols. Only four of the 21 compounds isolated had been previously reported as occurring in G. sarathorea or G. microcephala, while another eight compounds were previously reported from other Gutierrezia or related species. Nine of the isolated diterpenoids have not been previously reported and their structure elucidation is reported.

During the revision of South American species of Gutierrezia (Asteraceae, Astereae) taxonomic novelties were established: (1) two new varieties were described, Gutierrezia mandonii var. anomala from northwestern Argentina, and Gutierrezia isernii var. nivea from central and western Argentina; and (2) the species Gutierrezia pulviniformis was included as a new synonym of Gutierrezia spathulata.

Se describen los efectos de la UV-B sobre la síntesis de pigmentos fotosintéticos (clorofila total, clorofila a, clorofila b, carotenoides), protectores (compuestos absorbentes de UV-B) y azúcares solubles (glucosa, fructosa y sacarosa) en cinco variedades de quinoa de diferentes orígenes geográficos. En general, se demuestra que las variedades reaccionan desplegando diferentes estrategias para protegerse de la radiación UV-B. Estas estrategias pueden ser de tipo morfológico, fisiológico y/o bioquímico. Una respuesta común, observada en las cinco variedades fue el incremento en el contenido de compuestos absorbentes de UV-B, lo que puede interpretarse como un “escudo químico” de protección para el aparato fotosintético frente al exceso de energía proveniente de la radiación quese aplica a las plantas.

During the course of the revision of the South American species of Gutierrezia, we have detected names that require typification. After the analysis of the protologues and the herbarium specimens, we designated eight lectotypes and one neotype for nine names of the Gutierrezia genus and we assigned the category of holotype to one specimen. A detailed discussion is provided for each case. Durante el transcurso de la revisión de las especies sudamericanas de Gutierrezia, hemos podido hallar nombres que requieren tipificación. Luego del análisis de los protologos y especímenes de herbario, hemos designado ocho lectótipos y un neótipo para nueve nombres del género Gutierrezia. Además, se asignó la categoría de hólotipo a un especimen. Se provee una discusión detallada para cada nombre. Fil: Ratto, Francisco. Universidad de Buenos Aires. Facultad de Agronomía; Argentina Fil: Schiavinato, Dario Javier. Universidad de Buenos Aires. Facultad de Agronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario; Argentina Fil: Bartoli, Adriana. Universidad de Buenos Aires. Facultad de Agronomía; Argentina

Asteraceae es la familia de plantas vasculares mas diversaa nivel mundial y la mas numerosa de Argentina, incluyendo26% de especies endemicas. Muchas asteraceas son pioneras, facilitandoel establecimiento de otras especies, y varias se han utilizadoen restauracion. Dada la importancia de conocer las caracteristicas delas semillas y de la germinacion para su utilizacion en proyectos derestauracion, se indaga sobre aspectos fisiologicos basicos de la germinacionde Gutierrezia solbrigii Cabrera y Senecio subulatus D. Donex Hook. & Arn. var. erectus Hook. & Arn., arbustos endemicos deArgentina distribuidos en zonas aridas de Patagonia. El material provinode la Reserva Provincial Auca Mahuida (NE de Neuquen), enel Distrito Fitogeografico de Payunia (ecotono Monte-Estepa). Alli,la actividad hidrocarburifera ha generado areas degradadas dondeestas especies podrian utilizarse para revegetacion. Se evaluo el porcentajede germinacion (G), el tiempo medio de germinacion (TMG)y los dias hasta el inicio de la germinacion (IG) de un control y detratamientos pre-germinativos: estratificacion humeda fria de 15 dias(EHF15), escarificacion mecanica con lija (EML) para las dos especies,y estratificacion humeda fria de 30 dias (EHF30) y escarificacionmecanica con bisturi (EMB) para S. subulatus. Para los tratamientos losporcentajes de germinacion fueron elevados (G. solbrigii: 77% EHF15,81% EML; S. subulatus: 88% EHF15, 89% EHF30, 84% EML, 94%EMB) y similares a los controles (G. solbrigii: 82%,S. subulatus: 88%).Solo se registraron diferencias entre EMB y EML para S. subulatus: Ge IG fueron mayores en EMB y el TGM menor, posiblemente porquecon EML las semillas no son escarificadas uniformemente. En conclusion,ambas especies carecen de mecanismos de dormicion bajo lascondiciones experimentales, lo que sumado al hecho de que crecen enambientes disturbados y son endemicas, las hace excelentes candidataspara trabajos de restauracion ecologica.

Gutierrezia leucantha Cabrera, a species previously included in the synonymy of Gutierrezia gillesii Griseb., is reinstated as a distinct species. A morphological description is presented with information on distribution and habitat. A key to distinguish this species from its congeners with white ray florets is provided.

Durante el transcurso de la revisión de las especies sudamericanas de Gutierrezia, hemos podido hallar nombres que requieren tipificación. Luego del análisis de los protologos y especímenes de herbario, hemos designado ocho lectótipos y un neótipo para nueve nombres del género Gutierrezia. Además, se asignó la categoría de hólotipo a un especimen. Se provee una discusión detallada para cada nombre.

Research into plant breeding systems enables the evaluation of whether seed production depends on pollination agents and gene flow mechanisms within and among populations. This aids, in turn, the estimation of the appropriate population sizes needed to maintain both genetic and species' diversity. Little is known about plant reproductive biology in the Monte Desert (Patagonia, Argentina), a habitat threatened by desertification as a result of human impact. The mating systems, flowering phenologies and pollinator networks were studied in five representative plant species of the Monte Desert. The mating systems studied ranged from anemophilous pollen dispersion in the dioecious Atriplex lampa, to a gradient of dependence on pollinators, from the less dependent (facultative self-compatible) Gutierrezia solbrigii and two Larrea spp. (L. divaricata and L. cuneifolia) to the most dependent Grindelia chiloensis (self-incompatible). Flowering phenology was restricted to spring and coincided with pollinator abundance. Solitary bees were the main pollinator group, but beetles, flies and butterflies were also important. The four insect-pollinated species were moderately generalist, but they maintained their own pollinator assemblage. Coleopterans depended more on Grindelia chiloensis and dipterans on Gutierrezia solbrigii. Lepidopterans frequently visited Gutierrezia solbrigii and Larrea divaricata, whereas hymenopterans visited both Larrea spp. more frequently. The studied plant species are ecologically important, not only as resources for a wide range of pollinator species but also for other insects. The Monte Desert is a very disturbance-sensitive environment and, as these plant species hardly show vegetative regeneration, sexual reproduction is essential for their survival. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 161, 190–201.

Increasing wildfire activity is one of the most pressing management concerns in arid lands of the American West. To examine post-fire recovery of perennial vegetation in the Mojave and Sonoran Deserts, I analyzed data systematically synthesized from the literature. Post-fire sprouting by desert perennials is generally limited but varies among species. For example, only 3–37% of Larrea tridentata sprouted compared to 64–86% of Yucca schidigera . Four of five studies measuring recovery of perennial cover reported close relationships ( r 2 = 0.67–0.99) between time since fire (TSF) and cover. In fact, three studies measuring the longest TSF (≥37 years) found that cover had returned to within 10% cover of unburned areas within approximately 40 years. Conversely, post-fire species composition exhibited little convergence with unburned composition in five of six studies even 47 years after fire. Sphaeralcea ambigua , Gutierrezia spp., Achnatherum speciosum , Encelia spp., Hymenoclea salsola , and Baileya multiradiata had the highest burned:unburned abundance ratios, although overall post-fire community composition differed between the Mojave and Sonoran Deserts. Analyzing the literature as a whole suggested some generalities (e.g., that perennial cover reestablishes faster than composition), but more work is required for improving specific knowledge about plant recovery among fires, sites, species, and climates.

Grime’s (1998) ‘‘mass-ratio’’ hypothesis holds that ecosystem processes depend in the short term on functional properties of dominant plants and in the longer term on how resident species influence the recruitment of dominants. The latter of these effects may be especially important among early-successional species in disturbed ecosystems, but experimental tests are few. We removed two groups of early-successional species, an annual forb Gutierrezia dracunculoides (DC.) S. F. Blake and annual species (mostly grasses) that complete growth early in the growing season [early-season (ES) species], from a heavily-grazed grassland in central Texas, USA dominated by a C4 perennial grass. We sought to determine effects of annuals on grassland functioning [productivity, water balance, soil and plant nitrogen (N)] and composition. Removals did not impact N retention in the soil/plant system during the two years of this study, but removing ES annuals increased the amount of water between 30 and 120 cm in the soil profile early in each growing season. Production and N accumulation by vegetation declined following the removal of ES annuals in approximate proportion to the contribution of annuals to aboveground biomass and N, consistent with the mass-ratio hypothesis. By the second year, production and N uptake by initially sub-dominant species increased to fully compensate for the loss of annuals. These results are consistent with the view that ecosystem functions are more strongly linked to species attributes than to diversity per se. Longer-term effects of annuals on grassland composition were evident in a dramatic increase in biomass of perennial forbs after annuals were removed. Because perennial forbs differ from the dominant grass in this grassland in traits that influence ecosystem functioning, ES annuals may affect grassland functioning more by regulating the composition of vegetation than by directly affecting process rates.

Previous molecular investigations of the phylogenetic relationship for Xylothamia employed exemplar taxa and indicated its affiliation is either with the Gutierrezia or the Ericameria alliances. The present 3' ETS and ITS nrDNA gene phylogenies yielded the unexpected result that Xylothamia is polyphyletic. Species within its circumscription are placed into two well-supported evolutionary lineages with other genera of Astereae. Of nine species of Xylothamia, four species plus Gundlachia constitute one clade. The other five species are placed in a sister clade with several other genera including Amphiachyris, Bigelowia, Euthamia, Gutierrezia, and others. Except for X. johnstonii and X. palmeri, these five species of Xylothamia have little affinity for one another or for other genera in the same clade. Morphological similarities in foliar features between certain species in both lineages are possibly from a convergence resulting in adaptation to arid habitats. Such similarities were also the basis, in part, for their taxonomic treatment within Xylothamia or their earlier affiliation with Ericameria, which has similar features. The uncharacteristic leaf form in Xylothamia purpursii has a pattern of adaptation considerably different from its allies. Whether the Xylothamia-containing clades are related to Solidaginineae or represent an independently derived lineage remains equivocal because this outcome rested with the choice of data and optimality criteria.

We examined plant use versus plant availability by a leafhopper guild from a Chihuahuan Desert plant community. Some native woody plants species of the Chihuahua Desert behave as weeds (e.g., Gutierrezia spp.) and could be subjects of augmentative biological control. As a first step, we wanted to know how the leafhopper guild used the woody plant community in the Chihuahua Desert to identify possible candidates to be studied. At least 37 leafhopper species were sampled on 13 woody and perennial plant species. Individual plants were sampled with sticky-traps on nine dates from June 1997 to July 1998. Leafhopper counts and plant availability were used to determine if leafhoppers used plants in proportion to their availability. Analysis of the 13 most abundant leafhopper species indicated differential use of at least one or more plant species in proportion to plant occurrence. Approximately 40% of all possible plant-insect pairs (169 pairs, 13 plants, and 13 insects) demonstrated under-utilization of plants (less than expected) by the leafhoppers. Nearly 50% of the pairs demonstrated plant use in proportion to their availability (random utilization), and in only 10% of pairs, leafhoppers used plants more often than expected. In our study site, 66.7% of the leafhopper species exhibited preference for one or two plant species, whereas the remaining 33.3% exhibited no preference for any studied plant. Our plant utilization results reaffirm published available host plant records for the leafhoppers analyzed. Qualitative temporal patterns in plant utilization were not detected. Specialist species exhibited different host uses in response to increasing leafhopper abundance. At seasonal peak abundance, specialist leafhoppers showed two different strategies: leafhoppers increased their preference toward their preferred host plants, and leafhoppers decreased their preference toward their preferred plants. The possible use of this methodology for augmentative biological control is discussed.

A taxonomic revision of the South American species of Gutierrezia has revealed a new species from Argentina, characterised by its stems with the base prostrate and rooting, turbinate heads and white ray florets. This species, found in the Department of Tunuyán of Mendoza Province (Argentina), is described and illustrated and a key to differentiate it from allied species is given.En el marco de la revisión taxonómica del género Gutierrezia para Sudamérica fue hallada una nueva especie de Argentina, caracterizada por sus tallos con la porción basal postrada, enraizante en los nudos, capítulos con involucro turbinado y flores liguladas blancas. Se describe e ilustra la especie encontrada en el Departamento de Tunuyán de la Provincia de Mendoza (Argentina), y se incluye una clave para diferenciarla de las especies afines.

The Argentine root-boring weevil Heilipodus ventralis (Hustache) is a candidate for biological control of the perennial snakeweeds Gutierrezia sarothrae (Pursh) Britton and Rusby and G. microcephala (DeCandolle) A. Gray, poisonous native weeds of rangelands of the southwestern United States. In Argentina, the weevil occurs in semiarid regions from Tucuman south to Chubut, which are climatically similar to broad areas of the southwestern United States. Laboratory-reared females lived ca. 112 days and laid ca. 117 eggs. The eggs hatched in ca. 15 days. The larvae had eight instars; they required ca. 151 days and pupae ca. 27 days to develop. Adult weevils emerged from the taproots in early summer, fed on the leaves and terminals, and oviposited mostly in the crown near the soil line. The feeding of one or more pairs of caged adults killed medium-sized plants. The larvae tunneled downward to the taproot where they pupated. They overwintered in the taproots of these perennial host plants and pupated in the spring. A generation required 1 year but some individuals probably required two growing seasons. At Peninsula Valdes, Chubut, H. ventralis preferred Gutierrezia solbrigii Cabrera to Grindelia chiloensis (Corn.) Cabrera by a ratio of 1.9 to 1.0. In the field there, crowns of large Gu. solbrigii (average 60 cm canopy diameter) contained an average 5.0 larvae per plant, those of small plants (23 cm diameter) contained 1.1 larvae, and plants smaller than 10 cm rarely contained larvae. No insect parasitoids or predators were found attacking any stage. H. ventralis probably evolved on xerophytic, temperate Astereae, from ancestors of the genus Heilipus that fed on species of ancient, hygrophytic, tropical plant families.

The insecticidal activities of essential oils (EO), the remaining water phase (RW) from the hydrodistillation, and the dichloromethane and methanolic extracts from Gutierrezia repens Griseb. and Gutierrezia mandonii (Sch. Bip.) Solbrig were evaluated. The GC and GC/MS analyses of the oils resulted in the identification of 52 compounds from G. mandonii and 17 compounds from G. repens comprising 88.7% and 98.5% of the oils, respectively. Sabi- nene (0–13.1%), β-pinene (6.4–17.8%) limonene (0.7–13.3%), (E)-β-ocimene (1.3–7.0%), terpinen-4-ol (0.7–4.1%), spathulenol (0–4.1%) and, the isomers (6R,7R)-bisabolone (6.6–58.0%) and (6S,7R)-bisabolone (0–1.6%) were the main components of the oils. Mortality and development delays of Ceratitis capitata larvae, reared using a treated artificial diet, were recorded. Gutierrezia mandonii methanolic extracts and the oil produced lethal effects (p≤0.05). Methanolic and dichloromethane extracts, the oil and the remaining water from distillation (RW) produced sublethal effects. Meanwhile dichloromethane and methanolic extracts, the oil and RW from G. repens resulted in significant mortality (p≤0.05), and all causing also significant development delays. The required concentration of G. repens oil to avoid development in 50% of C. capitata larvae (EC50) was significantly lower than G. mandonii Fil: Clemente, Sandra Viviana. Universidad de Buenos Aires. Facultad de Agronomía; Argentina Fil: Mareggiani, Graciela Silvia. Universidad de Buenos Aires. Facultad de Agronomía; Argentina Fil: Juarez, Berta Estela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo; Argentina Fil: Mendiondo, Maria Elena. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo; Argentina Fil: Van Baren, Catalina Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Metabolismo del Fármaco. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Metabolismo del Fármaco; Argentina Fil: Di Leo Lira, Paola Maria del Rosario. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Metabolismo del Fármaco. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Metabolismo del Fármaco; Argentina Fil: Broussalis, Adriana Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Metabolismo del Fármaco. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Metabolismo del Fármaco; Argentina Fil: Bandoni, Arnaldo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Metabolismo del Fármaco. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Metabolismo del Fármaco; Argentina Fil: Ferraro, Graciela Ester. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Metabolismo del Fármaco. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Metabolismo del Fármaco; Argentina

We hypothesise that genotypic differences in transpiration and root growth in the southern and northern populations of Gutierrezia sarothrae are driven by growing season vapour pressure deficit (VPD) and that ecotypic differentiations are linked to corresponding variations in tissue and leaf water relations. Seedlings from an Idaho (ID) and a Texas (TX) seed source were grown either in an open nursery (full sunlight) or under shade. There were no population differences in transpiration, root growth and tissue water relation parameters when the plants were grown under the shade. However, significant population differences were observed in the plants grown in the open where VPD was substantially higher. Transpiration in the TX population increased twice as rapidly as the ID population in response to rising potential evapotranspiration (PET). In addition, the TX plants grew longer and larger lateral roots than the ID plants when both populations were grown in the open. Moreover, the TX plants had more elastic cell walls (lower bulk cell elastic modulus, E) and were able to maintain leaf turgor at lower relative water content than the ID plants when grown in the open. Similar changes in tissue water relation parameters were observed in the New Mexico (NM) and the ID seedlings subjected to soil water deficit. Cell elastic modulus (E), relative water content at zero turgor (RWC0) and apoplastic water fraction (Wa) were significantly lower in the NM population than in the ID population in response to soil water deficit, suggesting a higher turgor maintenance ability in the NM population. RWC0 was highly correlated with E in the NM (r=0.92, P

A taxonomic revision of the South American species of Gutierrezia has revealed a new species from Argentina, characterised by its stems with the base prostrate and rooting, turbinate heads and white ray florets. This species, found in the Department of Tunuyán of Mendoza Province (Argentina), is described and illustrated and a key to differentiate it from allied species is given. En el marco de la revisión taxonómica del género Gutierrezia para Sudamérica fue hallada una nueva especie de Argentina, caracterizada por sus tallos con la porción basal postrada, enraizante en los nudos, capítulos con involucro turbinado y flores liguladas blancas. Se describe e ilustra la especie encontrada en el Departamento de Tunuyán de la Provincia de Mendoza (Argentina), y se incluye una clave para diferenciarla de las especies afines.

Differences in rhizosphere microbial community function in response to Gutierrezia sarothrae plants grown in elevated CO 2 (750 μl 1 −1 ) and fertilized with nitrogen were studied using the Biolog microplate analysis of sole C substrate utilization. Compared to ambient CO 2 , under elevated CO 2 , polymers were more slowly oxidized by the microbial community, amides showed no change in usage, and all other substrate groups were more rapidly utilized, although there was no significant change in the number of viable bacteria. No microbial community responses to N fertilization were detected. The results indicate that potential functional changes in the soil microbial community in response to elevated CO 2 have to be taken into account in future experiments. Differential use of rhizodeposits in elevated CO 2 may have important consequences for biogeochemistry and plant growth.

Se describe e ilustra Gutierrezia tortosae Ratto & Adr. Bartoli, una nueva especie de Argentina. Se asemeja a Gutierrezia mandonii (Sch. Bip.) Solbrig por presentar xilopodio, por la forma de las hojas y por el color amarillo de las flores liguladas, pero difiere de ella por tener tallos erectos y rígidos, hojas erectas y capítulos menores. Se presenta una clave para diferenciarla de las especies que habitan en el noroeste de Argentina.

A new species, Gutierrezia chubutensis (Asteraceae, Astereae, Solidagininae) from Florentino Ameghino in Chubut Province, Argentina is described and illustrated. It is distinct from its congeners in Patagonia because of its height (over 50 cm), larger elliptical leaves and numerous heads with yellow flowers and involucre terete or terete-turbinate. A key to differentiate the new species from the other Patagonian species of Gutierrezia is provided.

The Argentine root-boring sesiid moth Carmenta haematica (Ureta) is restricted in Argentina to plants of two genera, Grindelia and Gutierrezia (Asteraceae: Astereae). Field examination of 51,622 plants of 67 species of Asteraceae at 286 locations revealed that larvae completed their development only in Grindelia chiloensis (Corn.) Cabrera, Grindelia tehuelches Cabrera, Gutierrezia solbrigii Cabrera, Gutierrezia spathulata (Phil.) Kurtz., and Gutierrezia mandonii (Sch. Bip.) Solbrig. In multiple-choice tests in the laboratory, using cut stems of 37 species in 27 genera and eight tribes of Asteraceae, 93.5% of the neonate larvae that entered stems entered those of 4 species of Grindelia and Gutierrezia and 95.7% entered these plus the 1 other species of the subtribe Solidagininae tested. In no-choice tests using potted plants in the laboratory garden, neonate larvae placed in holes drilled in the stems of 28 species of plants developed to the adult stage only in Gr. chiloensis but reached the fourth instar also in Grindelia pulchella Dun., Gu. solbrigii, and Solidago chilensis Meyen. The no-choice and multiple-choice laboratory tests, interpreted through the three basic elements of host specificity of insects, support the host range observed in the field. C. haematica is the most specific insect yet tested for biological control of snakeweed. It is sufficiently host specific for introduction into quarantine in the United States for further testing and possible future release in the field.

Hydraulic lift occurs in some deep-rooted shrub and herbaceous species. In this process, water taken up by deep roots from the moist subsoil is delivered to the drier topsoil where it is later reabsorbed by shallow roots. However, little is known about the existence of hydraulic lift in shallow-rooted xeric species. The objectives of this study were 1) to ascertain whether hydraulic lift exists in Gutierrezia sarothrae (broom snakeweed), a widespread North American desert species with a shallow root system, grown in pot and field conditions and 2) if it does, how much water can be transferred from the subsoil to the 30 cm topsoil during the night. Snakeweed seedlings were transplanted in buried pots allowing the deeper roots to grow into the subsoil 30 cm below the surface. Soil water content inside and outside of the pot was measured seasonally and diurnally with time domain reflectometry technique (TDR). An increase in water content was detected in the pot after the plant was covered for 3 h by an opaque plastic bag during the day, suggesting hydraulic lift from deeper depths and exudation of water into the drier topsoil. Root exudation was also observed on native range sites dominated by snakeweed. Water efflux in the pot was 271 g per plant per night. which was equivalent to 15.3% of the extrapolated, porometer-derived whole-plant daily transpiration. Hydraulic lift observed in Gutierrezia improved water uptake during the day when evaporative demand is high and less water is available in the topsoil. We concluded that hydraulic lift might help snakeweed to alleviate the effect of water stress.

We hypothesize that predominance of Gutierrezia sarothrae in the rangeland plant community depends on its ability to take up water more effectively from soil depths below 30 cm. Gutierrezia seedlings grown in 30-cm-deep pots were allowed to develop deep lateral roots out of pots into subsoil. The deep laterals were then excised and photosynthesis and stomatal conductance of the test plants measured before and after root pruning. Photosynthesis (A) and stomatal conductance (g) were at least 49% greater (P < .05) before than after root pruning. Photosynthesis and g were more affected by the removal of four deep roots 30 cm below the surface than by the removal of four shallow roots in the top 30 cm of soil. The soil water extraction patterns in Gutierrezia plants grown in 60-cm soil columns were determined for the upper 30 cm and 30 to 60 cm of soil. Water extraction was significantly greater (P < .05) from the wetter, lower section of the soil column than from the drier, upper column. Higher photosynthesis...

Type specimens of two names (Euphorbia sparsiflora A. Heller, Euphorbiaceae, Gutierrezia ionensis Lunell, Asteraceae) have been discovered, superseding recent lecto- and neotypifications.

Snakeweeds, Gutierrezia spp. (Compositae), are native plants that are serious weeds in rangelands of the southwestern United States and northern Mexico. Although the genus apparently originated in North America, 7 species occur in Argentina and 5 in Chile. In Argentina, we found 79 species of insects, 1 mite, and 1 plant pathogen on the 3 species of Gutierrezia most similar to the North American snakeweeds; 33 of these species were observed feeding or had a high probability of feeding on Gutierrezia . Of these, 17 species of insects appear to have narrow host ranges and are possible candidates for biological control of snakeweeds in the southwestern United States. The insects that caused the most obvious damage were 5 species of root borers: the sesiid moth Carmenta haematica (Ureta); the weevil Heilipodus ventralis (Hustache); and 3 buprestids, Dactylozodes alternans Chevrolat, D. okea Gory, and Agrilus leucostictus Klug. Other insects that may have biological control potential were two species that fed on flowers and seed heads, a pyralid moth ( Homoeosoma n. sp.) and a tephritid fly ( Trupanea patagonica (Brethes)); a leaf beetle ( Stolas ingrata (Boh.)); and 2 species of stem-gall formers, an unidentified gelechiid moth and a tephritid fly, Strobelia baccharidis Rondani. The factors that may limit control, the ecosystem effects of controlling these native plants, and the approaches that can be taken are discussed.

The aerial parts of Gutierrezia resinosa gave 15 new diterpenes including 12 labdanes and three nerylgeraniol derivatives. The structures were elucidated by high field NMR spectroscopy.

The genus Gutierrezia (Asteraceae) includes approximately 25 species which occur exclusively in the arid areas of América. Eighth species, Gutierrezia baccharoides Sch. Bip., Gutierrezia gilliesii Griseb., Gutierrezia isernii (Phil.) Phil., Gutierrezia mandonii (Sch. Bip.) Solbrig, Gutierrezia pulviniformis Cabrera, Gutierrezia repens Griseb., Gutierrezia solbrigii Cabrera, and Gutierrezia spathulata (Phil.) Kurtz, grow in Argentina (Freire, 1999). G. mandonii is a resinous shrub which grows naturally in the arid areas of northern Argentina and southern Bolivia (Cabrera, 1978). The aerial parts of G. mandonii were collected during the flowering period in Salta, Argentina, on January 2004. The plant was identified by Ing. Julio Tolaba. A voucher specimen (no 3414) was deposited at the Museo de la Facultad de Ciencias Naturales, Universidad Nacional de Salta. Fil: Alarcón, Silvia Rosana. Universidad Nacional de Salta; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Ocampos, Liliana Soledad Natalia. Universidad Nacional de Salta; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Pacciaroni, Adriana del Valle. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina Fil: Colloca, Cristina Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina Fil: Sosa, Virginia Estela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina

The extract of the aerial parts of Gutierrezia espinosae gave 11 new and two known labdanes as well as five new nerylgeraniol derivatives. The structures were elucidated by high field 1 H NMR spectroscopy. The chemotaxonomic aspects are discussed briefly.

Gutierrezia ameghinoi Speg., a species from the Argentinean Patagonia, is resurrected. Its geographical distribution and habitat are described. A key to distinguish G. ameghinoi from co-occurring relatives is included. The species is illustrated for the first time.

En el marco de la revisión taxonómica del género Gutierrezia para Sudamérica fue hallada una nueva especie de Argentina, caracterizada por sus tallos con la porción basal postrada, enraizante en los nudos, capítulos con involucro turbinado y flores liguladas blancas. Se describe e ilustra la especie encontrada en el Departamento de Tunuyán de la Provincia de Mendoza (Argentina), y se incluye una clave para diferenciarla de las especies afines.

In the past, excessive numbers of livestock on western U.S. rangelands, reoccurring droughts, and lack of management resulted in retrogression of plant communities. Poisonous plants and other less palatable species increased with declining range condition and livestock were forced to eat these poisonous species because of a shortage of desirable forage, resulting in large, catastrophic losses. The level of management on most western rangelands has improved during the last 60 years, resulting in marked improvement in range condition; yet losses to poisonous plants still occur, though not as large and catastrophic as in the past. Some poisonous species are major components of the pristine, pre-European plant communities [tall larkspur (Delphinium barbeyi Huth), Veratrum californicum Durand, water hemlock (Cicuta douglasii (DC.)Coult. &Rose), bracken fern (Pteridium aquilinum (L.) Kuhn), chokecherry (Prunus virginiana L.), Ponderosa pine (Pinus ponderosa Lawson), and various oak species (Quercus spp.)]. Although populations of many poisonous seral increaser species have declined with better management, they are still components of plant communities and fluctuate with changing precipitation patterns [locoweed (Astragalus and Oxytropis spp.), lupine (Lupinus spp.), death camas (Zigadenus spp.), snakeweed (Gutierrezia spp.), threadleaf groundsel (Senecio longolobis Benth.), low larkspur (Delphinium nuttallianum Pritz.), timber milkvetch (Astragalus miser Dougl. ex Hook.), redstem peavine (A. emoryanus (Rydb.) Cory), western bitterweed (Hymenoxys odorata D.C.), orange sneezeweed (Helenium hoopesii Gray), twin leaf senna (Cassia roemeriana Schelle), and white snakeroot (Eupatorium rugosum Houtt)]. Many of the alien invader species are poisonous: [Halogeton glomeratus (Bieb.) C.A. Mey, St. Johnswort (Hypericum perforatum L.), poison hemlock (Conium maculatum L.), tansy ragwort (Senecio jacobaea L.), hounds tongue (Cynoglossum officinale L.), leafy spurge (Euphorbia esula L.), yellow star thistle (Centaurea solstitialis L.) and other knapweeds (Centaurea spp.)]. Poisoning occurs when livestock consume these plants because they are either relatively more palatable than the associated forage, or from management mistakes of running short of desirable forage. DOI:10.2458/azu_jrm_v55i3_ralphs

A colored painting from the Sesse and Mocifio expedition serves as the holotype for the validly published name Grindelia angustifolia DC. ex Dunal, 1819 (= Grindelia dunalii Sprengel, nom. nov., 1825; non Grindelia angustifolia Kunth, in HBK, 1818). The illustration represents the species heretofore identified as Keerlia linearifolia DC., 1836 (= Gutierrezia alamanii A. Gray, nom. nov., 1852; non Gutierrezia linearifolia Lagasca & Segura, 1816), which occurs in the south-central Mexican states of Mexico and Morelos. Gutierrezia dunalii (Sprengel) Nesom, comb. nov., is proposed as the earliest valid name for this species. Gutierrezia megalocephala (Fernald) Nesom is proposed for a closely related entity (Gutierrezia alamanii var. megalocephala (Fernald) Lane = Xanthocephalum megalocephalum Femald). The Sess6 and Mocifio expedition to New Spain (1787-1803) recorded many interesting observations, especially regarding the flora of Mexico. For a description of the expedition and its aims, travels, collections, paintings, and in particular its botanical accomplishments, see articles by McVaugh (1977, 1980, 1987, 1990, 1998) and a recent summary and update by Bartholomew and McVaugh (1997). Plant collections from the expedition are housed at a number of European herbaria as documentation for various early reports and names, but the paintings made in situ by expedition artists also provided the basic information for descriptions of new taxa. A. P. De Candolle and contemporaries proposed approximately 370 new specific names based wholly or in part on these paintings. Considerations regarding the formal typification of these taxa are outlined by Bartholomew and McVaugh (1997) and McVaugh (1998). The original set of paintings is now housed under the name of the Torner Collection of Sesse and Mocifio Biological Illustrations at the Hunt Institute for Botanical Documentation (Carnegie Mellon University, Pittsburgh). Some of these remarkably detailed paintings have remained without corroboration or reevaluation of their initial identifications, if such were ever made. We examined one of them (Torner No. 0884; Fig. 1), which includes on the same sheet two species of Asteraceae tribe Astereae, the left-hand one annotated by De Candolle as "Lemerya anthemoides" and the other as "Grindelia angustifolia." It is assumed that the plants were encountered by the expedition in Mexico, as surmised from the identities of the plants depicted. The Grindelia illustration served as the basis for a formal description of the species in a publication by Michel-Felix Dunal in 1819 (see nomenclature below). The left-hand plant is white-rayed, a species of Aphanostephus. Details at the top of the illustration, showing white ray flowers, disc corollas, and achenes, are from this plant. The slender taproot of annual duration, pinnatifid leaves, basally unexpanded disc corollas, and achenes with a conspicuous coronal pappus are features of A. ramosissima DC. var. ramosus (DC.) Turner & Birdsong (Turner, 1984), which occurs over a wide area of central Mexico, from Durango to San Luis Potosf and south to MichoacAn, Guerrero, Morelos, and Veracruz. The yellow-rayed plant (on the right-hand side) represents the species heretofore identified as Gutierrezia alamanii A. Gray, which is known from the south-central Mexican states of Mexico and Morelos (Lane, 1985). Salient features shown in the illustration are these: a basally ascending stem arising from a fibrous-rooted rhizome; leaves linear-oblanceolate without a well-defined petiolar portion, 1nerved, entire, primarily basally disposed but continuing up the stem; several relatively large heads (compared to other species of Gutierrezia) with conspicuous yellow rays (18, 21, and 23 rays, respecNovoN 10: 67-70. 2000. This content downloaded from 157.55.39.215 on Wed, 31 Aug 2016 04:26:17 UTC All use subject to http://about.jstor.org/terms

Water budget modeling usually requires quantification of all possible processes of the hydrologic cycle. This includes rainfall interception. The purpose of this study was to estimate the potential amounts of water transferred back to the atmosphere from interception for some common plants found in the Chihuahuan desert. Fifty plants of many sizes representing 10 common species of the Chihuahuan Desert were chosen for evaluation. Plants were submerged in a 2 X 2 m tank filled with water. After submersion, the plants were weighed, and the difference in weight was recorded as the maximum water storage capacity of the plant's canopy. Plants were also measured for maximum and minimum crown diameter (cm), height (cm), green weight (g) at time of submersion, and oven-dry weight (g). The forb, grass, and shrub species had different variables included in the prediction equations. Dry and green weight were the 2 variables which appear to have the strongest relationship with the amount of water intercepted for all species. Of the 7 grass species evaluated, dry and green weight were part of all equations, and height was included in only 2 equations.

Restriction site mutations analysis using 18 restriction endonucleases for chloroplast DNA's from North American Gutierrezia has led to a generic circumscription which is somewhat different from those previously proposed. Molecular data agree with a recent taxonomic treatment of Lane (1982, 1985), which transferred the x = 4 species from Xanthocephalum and submerged Greenella into Gutierrezia, but they do not support the submersion of the monotypic genus Thurovia. Thurovia is closely related as a sister group to Amphiachyris and should be resegregated from Gu- tierrezia. The study indicated that Xanthocephalum with x = 6 is very distantly related to Gutierrezia, even though Xanthocephalum has often been treated as part of the Xanthocephalum-Gutierrezia complex. Xanthocephalum is, in contrast, very closely related to Grindelia, which also has a base chromosome number of x = 6. Traditional species of Gutierrezia, G. californica, G. grandis, G. microcephala, G. sarothrae, G. serotina, and G. texana, constitute a closely related cluster and are well-separated from other purported members of the genus. Gutierrezia californica s. str. and G. bracteata should be separated again as distinct species. The herbaceous species, G. sericocarpa and G. sphaerocephala, appear to be the most primitive in the genus.