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Two new species of Macrosiphum are described, both of which live in similar dry forest habitats of the inland northwestern U.S.A.: Macrosiphum dewsler n. sp. from Linum lewisii (Linaceae), and Macrosiphum garyreed n. sp. from Geum triflorum (Rosaceae). Information is presented about the habitats, host plant biology, distribution, and taxonomy of both species.

Extensive areas of the northern mixed grass prairies of North America require restoration and reclamation as they have been extensively disturbed by agricultural, mining and oil and gas related activities. Amending seedbeds with mulch may avoid soil erosion and help both plant recruitment and early vegetation development in these water limited landscapes. A field experiment was established to determine if straw and hay mulch facilitate early revegetation. The site is an abandoned irrigation area in southern Alberta, Canada. Soil was tilled and the seedbed prepared through manual harrowing, then plots were broadcast seeded with Elymus trachycaulus, Bouteloua gracilis, Astragalus canadensis and Linum lewisii. Hay and straw mulch were applied at two rates (300 and 600 g m−2). Plant recruitment and cover were assessed through the first four years. Mulch had a positive impact on recruitment of all species planted except Bouteloua gracilis. While a thinner material like hay proved to be most effective at high rates (600 g m−2), a thicker material like straw encouraged quick recruitment for these species only at low application rates (300 g m−2). However, these early differences among mulch treatments did not show an impact in either recruitment or cover during subsequent years. Bouteloua gracilis, whose recruitment and growth were broadly impaired by mulch, showed an abundant and constantly increasing cover in the bare ground control and in plots with low application rates of hay. Both recruitment and cover per species indicate that plots are following two different trajectories that show some degree of resilience; the bare ground treatment is dominated by Bouteloua gracilis whereas the mulch treatments are characterized by vegetation dominated by Elymus trachycaulus, Linum lewisii and Astragalus canadensis. Fil: Mollard, Federico Pedro Otto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina. University of Alberta; Canadá Fil: Naeth, M. Anne. University of Alberta; Canadá Fil: Cohen Fernández, Anayansi. University of Alberta; Canadá. Coastal Raintree Consulting; Canadá

Premise of research. Dust particles and pollen grains are similar in size. Dust deposition might therefore influence the pollination and reproduction of flowering plants. Little is known about such effects, however, despite more general interest in ecological effects of dust.Methodology. We used observational and experimental methods to explore whether dust generated by traffic on unpaved roads affects the amounts of pollen received and numbers of seeds produced by four species of native wildflowers in the western United States.Pivotal results. Flowers of Nuttall’s larkspur (Delphinium nuttallianum), scarlet gilia (Ipomopsis aggregata), Lewis flax (Linum lewisii), and sulphur paintbrush (Castilleja sulphurea) growing 1–2 m from a road received substantially more dust and less pollen than those growing 40–50 m away. We observed the same pattern when we transplanted individuals of the first two species into pots and placed pots near to compared with far from a road. Experimental “hand dusting” of scarlet gi...

Seedling establishment in semiarid prairie sites under reclamation can be facilitated by mulch due to its effects on seedbed conditions. Effects on plant recruitment can also be inhibitory, as mulch can filter out or attenuate environmental signals that break seed dormancy and can negatively affect early seedling performance. A manipulative field experiment was established to determine if straw and hay mulch facilitate seedling emergence and establishment. The reclamation site is an abandoned irrigation area in the mixed grass prairie of southern Alberta, Canada. Soil was tilled and the seedbed prepared through manual harrowing, then plots were broadcast seeded with Elymus trachycaulus, Bouteloua gracilis, Hesperostipa comata, Astragalus canadensis and Linum lewisii. Hay and straw mulch were applied at two rates (300 and 600 g m−2). Seedling emergence and survival were assessed through the first growing season. Both hay mulch rates increased E. trachycaulus and L. lewisii seedling emergence relative to bare ground. A. canadensis seedling emergence was more than ten times higher with low straw and both hay rates than with bare ground. Straw mulch facilitated seedling emergence at a low rate but had a neutral effect at high rates. Effects of low straw and both hay mulch rates on seedling establishment were facilitative for E. trachycaulus and L. lewisii and neutral for B. gracilis. Effects of high straw rates were neutral for E. trachycaulus and L. lewisii and hindered B. gracilis seedling establishment. These results clearly show that low mulch rates can increase native plant establishment during the critical first year of prairie reclamation as they were able to overcome microsite limitations.

The availability of soil and pollination resources are main determinants of fitness in many flowering plants, but the degree to which each is limiting and how they interact to affect plant fitness is unknown for many species. We performed resource (water and nutrients) and pollination (open and supplemental) treatments on two species of flowering plants, Ipomopsis aggregata and Linum lewisii, that differed in life-history, and we measured how resource addition affected floral characters, pollination, and reproduction (both male and female function). We separated the direct effects of resources versus indirect effects on female function via changes in pollination using a factorial experiment and path analysis. Resource addition affected I. aggregata and L. lewisii differently. Ipomopsis aggregata, a monocarp, responded to fertilization in the year of treatment application, increasing flower production, bloom duration, corolla width, nectar production, aboveground biomass, and pollen receipt relative to control plants. Fertilization also increased total seed production per plant, and hand-pollination increased seeds per fruit in I. aggregata, indicating some degree of pollen limitation of seed production. In contrast, fertilization had no effect on growth or reproductive output in the year of treatment on L. lewisii, a perennial, except that fertilization lengthened bloom duration. However, delayed effects of fertilization were seen in the year following treatment, with fertilized plants having greater aboveground biomass, seeds per fruit, and seeds per plant than control plants. In both species, there were no effects of resource addition on male function, and the direct effects of fertilization on female function were relatively stronger than the indirect effects via changes in pollination. Although we studied only two plant species, our results suggest that life-history traits may play an important role in determining the reproductive responses of plants to soil nutrient and pollen additions.

This article summarizes information on the taxonomy of 'Appar', a perennial blue flax cultivar ( Linum perenne L. [Linaceae]), and characteristics that distinguish it from native Lewis flax ( Linum lewisii Pursh [Linaceae]). 'Appar' apparently originated as a European flax that escaped from garden cultivation. Randomly amplified polymorphic DNA (RAPD) analysis places 'Appar' with other collections of European Linum perenne and separates it from native North American collections of Lewis flax. Morphologically, 'Appar' differs from Lewis flax in having an intense blue petal color, shorter internodes, leaves that point upward along the stem, and multiple slender stems suffused with red near the base. The heterostylous reproductive system, which it shares with its European cousins, keeps 'Appar' reproductively isolated from native populations of Lewis flax. All available data indicate that 'Appar' is not invasive and does not pose a threat to native flax populations. Ease of establishment, seed production, and showiness of the abundant flowers recommend 'Appar' for use in xeriscape plantings. Alternatively, the recent germplasm release of Lewis flax, 'Maple Grove', also establishes readily from seed and can be effectively used when objectives dictate the exclusive use of native germplasms.

The ‘Appar’ flax germplasm was originally released by the USDA Soil Conservation Service as a cultivar of Linum lewisii. The observation that ‘Appar’ is heterostylic, a key taxonomic character distinguishing Lewis flax from other members of the Linum perenne complex, created a need for further study in order to resolve the taxonomic position of both Lewis flax and the ‘Appar’ cultivar. We grew 10 plants each of nine European, nine North American, and three putative ‘Appar’ seed sources, measured 18 morphologic variables on each plant, and examined genetic variation using randomly amplified polymorphic DNA (RAPD). We also performed self‐ and cross‐pollinations within and among source groups. North American collections differed from European collections for 12 of the 18 morphologic variables. ‘Appar’ collections were morphologically similar to European collections and differed from North American collections for 13 of the 18 variables. RAPD data also showed that ‘Appar’ sources clustered with European, and ...

Arsenic (As) contamination is widespread in the industrial areas of northwest Ohio. Plant species that both take up As and are appropriate for the climate and growth conditions of the region are needed for phytoremediation to be successfully employed. Actively growing plants from 22 species of native genera were exposed to As in hydroponics systems (either 0, 10, or 50 mg As L−1; 1 week) and commercially available potting mix (either 0, 10, 25, 100, or 250 mg As L−1; 2 weeks), depending on their growth conditions. Aboveground plant tissues were harvested and digested, and concentrations of As were determined by inductively coupled plasma–optical emission spectrometry. The highest tissue concentrations of As (mg As kg−1 dw) were recorded in seven plant species: Rudbeckia hirta (661), Helenium autumnale (363 in tissues formed after exposure to As), Lupinus perennis (333), Echinacea purpurea (298), Coreopsis lanceolata (258), Lepidium virginicum (214), and Linum lewisii (214). These seven species ar...

Steppe communities of interior Alaska are restricted to steep, generally southfacing bluffs. Two competing hypotheses explain this distribution: (1) steppe taxa are restricted to bluffs by their requirements for the abiotic conditions of these sites, and (2) steppe taxa have broader physiological ranges than expressed in nature, but are restricted to bluff sites by competition with other plants. We addressed these hypotheses using correlative and experimental methods to identify controls over the distribution of steppe and forest understory species on Eagle Bluff, Alaska. We developed a causal model and used path analysis, a correlative method, to estimate strengths of hypothesized causal relationships. Based on the results of path analysis we hypothesized that light intensity and soil moisture were important controls over the composition of the vegetation and species distributions. We tested this hypothesis by examining the responses of two species native to steppe (Linum lewisii and Potentilla hookeriana) and two species native to forest (Moehringia lateriflora and Pyrola secunda) to manipulation of light intensity, soil moisture, and soil type. The forest species had reduced survival and biomass when grown in the high light and dry soil moisture characteristic of steppe environments. Conversely, survival of steppe taxa was independent of treatments, and the response of survivors to treatments differed between species. Linum had higher seed production with higher soil moisture than it normally experiences and grew less under lower light intensity. Potentilla responded positively to higher moisture and had weakly negative (but not significant) response to reduced light levels. Our experiments confirmed the importance of light and soil moisture to vegetation on Eagle Bluff, but revealed the individualistic nature of species response to environment.

Flower-visiting Diptera are abundant in montane and Arctic areas. This research, conducted on the western slope of the Colorado Rocky Mountains: (1) characterizes the predominant anthophilous fly taxa in comparison with other high-elevation and highlatitude sites; (2) examines changes in fly abundance with elevation, and (3) examines the potential of flies as pollinators by examining quality and quantity of pollen loads. Flies collected from 66 flowering species were identified to species to produce a data base containing taxonomic information, elevation and floral records. Malaise trap censuses were conducted in three elevational zones. Pollen carried by flies and pollen in their guts were quantified and examined to determine the number of plant species represented. Proportional representation of dipteran families changed in a similar manner in different mountain systems and the Arctic. The predominance of flies on flowers at high elevations appears to be due to a decrease in representation of other orders of insects. Most fly taxa fed at multiple plant species, but gut contents indicated that individual flies fed largely on a single pollen type. Total pollen loads of flies and solitary bees were similar although flies collected on Linum lewisii carried less pollen than bees.

Variation patterns and interpopulational relationships were examined in Linum lewisii Pursh and L. pratense (Norton) Small, the two native North American blue-flowered flax species. The two principal evolutionary trends in the North American populations have been toward self-pollination and an annual life habit. A third trend, toward greater outcrossing, is considered probable. Hybridizations between and within species indicate that evolution has occurred mainly by the accumulation of small genic changes in geographically isolated populations. The buildup of sterility barriers between populations regardless of species has not been extensive and in no case do hybrids have less than 30% good pollen. In general, morphological evolution has occurred independently of the buildup of sterility barriers. A new taxonomic combination, L. lewisii ssp. lepagei (Boivin) Mosquin, is adopted.

IN the Proceedings of the Academy of Natural Sciences of Philadelphia for 1902, pp. 33–36, is a very interesting paper by the late Mr. Thomas Meehan, treating of some points in the life-history of certain plants. On p. 36, Mr. Meehan says:—“Mr. Darwin once stated that one might as well use organic dust as to endeavour to get seeds of Linum pereune by the aid of its own pollen. I found Linum pereune of our Rocky Mountains abundantly fertile with own-pollen, and said so in one of my papers.” As some anti-Darwinian will probably make much of this statement, it is as well to say that the Rocky Mountain plant is a distinct species, Linum lewisii, Pursh.

Flower behavior, particularly petal abscission,, of Linum lewisii was observed in the field and laboratory of the Rocky Mountain Biological Laboratory, Crested Butte, Colorado. Flower opening is primarily a response to light but is slower when temperatures are low. Normally the flowers open until the petals form an angle of 180?. If cut flowers are desiccated slowly, the distal 1/3 of the petals recurve strongly beyond 180?. Flowers close during the afternoon of the day of anthesis. Petals are weakly attached and can be readily dislodged by mechanical factors. Petal abscission occurs sporadically from midafternoon of the day of anthesis through the following morning; and can be hastened by wind or rain. Petal abscission is sensitive to temperature and moisture supply. It is accelerated by abscisic acid and retarded by indoleacetic acid. The evidence indicates petal abscission in L. lewisii involves the synthesis of hydrolytic enzymes in the abscission zone in a manner similar to? that of leaf abscission.