Wildflower Species Research Articles

Pollination and breeding systems of selected wildflowers in a southern African grassland community

Southern African grasslands harbour diverse plant communities, and recent studies have revealed remarkable plant–pollinator interactions in this biome. However, there has been no attempt to study community-wide patterns in breeding systems or plant–pollinator mutualisms. Here, we present the results of extensive field work on twenty-one wildflower species with large, showy flowers, belonging to a broad range of angiosperm families. Most of the plant species investigated were found to be self-incompatible and therefore completely dependent on pollinators. Based on over 250 h of field observations during which we recorded over 1000 individual insects, 368 of which were examined for pollen loads, we identified pollination systems involving, inter alia, bees and flies (both short- and long-tongued), wasps, butterflies, hawkmoths, beetles, and sunbirds. The most important pollinators of the wildflowers investigated in the community were long-tongued solitary bees. Several plant species appear to be dependent on a single or a few pollinator species, and few are true generalists. This high degree of specialisation indicates a well-structured pollination landscape, suggesting both a history of climatic and ecological stability and potential sensitivity to human disturbance.

The Effects of Climate Change on the Phenological Interactions of Plants and Pollinators

AbstractSymposium title: Interdisciplinary Canary: Linkages between Ecology and Sustainable Decision Making in a Dynamic Environment*1) Background/Question/Methods* The responses of pollinators to climate change could include changes in phenology of migratory pollinators and in the routes or destinations for their migration, changes in the phenology and distribution of non-migratory species, and changes in the host plants they visit for nectar and pollen. Plants face similar challenges with regard to changes in their distributions, their reproductive phenology, and interactions with both co-flowering species and pollinators (competition, facilitation, etc.). Unless pollinators and their host plants are responding similarly to changing environmental cues that affect their phenology, their historical patterns of interaction, both mutualistic and competitive, are likely to change. Long-term data are essential to investigating which if any of these potential outcomes are occurring. A 36-year record of abundance and phenology of flowering of 90+ wildflower species, surveys of the altitudinal distribution of bumble bees in the 1970s and the past few years, and data from a long-term Malaise trap sampling program, all near the Rocky Mountain Biological Laboratory (West Elk mountains, Colorado) are used for this investigation. Results/Conclusions* Although the flowering phenology of all species examined to date is affected by a single environmental event, disappearance of the winter snowpack (range 22 April -19 June since 1975), either their responses to that single cue are not uniform, or different species respond to additional cues in addition to snowmelt (e.g., growing degree days). Thus the community of co-flowering species varies temporally and quantitatively among years; differential sensitivity to frost damage is an example of an environmental variable that generates the quantitative variation among years, and is in turn affected by date of snowmelt. Arrival dates of migratory Broad-tailed Hummingbirds are significantly correlated with the amount of snow remaining on 30 April, and with the day of first flowering of Erythronium grandiflorum (glacier lily), the first flower that they visit at this site in the spring. Altitudinal distributions of at least some bumble bee species, and of the flowers they feed on, are also changing, with one bee species occurring about 600m higher than it did 30 years ago and one wildflower (Mertensia cilata) disappearing from lower altitudes where it was historically common. As these communities of plants and pollinators respond to environmental changes with changes in phenology and distribution, new interactions will be created and old ones will be lost.

Water Deficit Stress Responses of Three Native Australian Ornamental Herbaceous Wildflower Species for Water-wise Landscapes

Perennial wildflower species are important but not well-understood elements in water-wise landscaping that anchors urban water conservation programs in arid climates. Comparative growth and physiological responses to soil substrate drying of three herbaceous Australian ornamental species from habitats of variable moisture regimes were investigated in the context of isohydric and anisohydric behavior. Clonal Orthosiphon aristatus, Dianella revoluta ‘Breeze’, and Ptilotus nobilis plants were container-grown individually and competitively together in two separate studies. In both studies, plants were water-stressed through cyclical dry downs. We measured stomatal conductance (g S), soil water content, and water potential during each study and osmotic adjustment estimated from pressure-volume data and plant biomass at the end of each study. O. aristatus, a rainforest species, fit a general anisohydric model of high water use and more negative water potential during soil drying until stomatal closure and leaf wilting. D. revolata and P. nobilis, indigenous to Australia's dry interior, fit a general isohydric, drought-tolerant model of stomatal closure from water deficits that moderates leaf water potential but through different mechanisms. P. nobilis and D. revolata moderate water use and maintain acceptable aesthetic performance under water stress, suitable for mixed low-water landscape plantings. O. aristatus would not be suitable for low-water urban landscapes, either isolated or in mixed plantings, because of high soil water depletion and wilting.

First Report of Natural Infection of Penstemon acuminatus with Cucumber mosaic virus in the Treasure Valley Region of Idaho and Oregon.

Penstemons are perennials that are grown for their attractive flowers in the United States. Penstemon species (P. acuminatus, P. deustus, and P. speciosus) are among the native forbs considered as a high priority for restoration of great basin rangelands. During the summer of 2008, symptoms of red spots and rings were observed on leaves of P. acuminatus (family Scrophulariaceae) in an experimental trial in Malheur County, Oregon where the seeds from several native forbs were multiplied for restoration of range plants in intermountain areas. These plants were cultivated as part of the Great Basin Native Plant Selection and Increase Project. Several native wildflower species are grown for seed production in these experimental plots. Plants showed red foliar ringspots and streaks late in the season. Fungal or bacterial infection was ruled out. Two tospoviruses, Impatiens necrotic spot virus and Tomato spotted wilt virus, and one nepovirus, Tomato ring spot virus, are known to infect penstemon (2,3). Recently, a strain of Turnip vein-clearing virus, referred to as Penstemon ringspot virus, was reported in penstemon from Minnesota (1). Symptomatic leaves from the penstemon plants were negative for these viruses when tested by ELISA or reverse transcription (RT)-PCR. However, samples were found to be positive for Cucumber mosaic virus (CMV) when tested by a commercially available kit (Agdia Inc., Elkhart, IN). To verify CMV infection, total nucleic acid extracts from the symptomatic areas of the leaves were prepared and used in RT-PCR. Primers specific to the RNA-3 of CMV were designed on the basis of CMV sequences available in GenBank. The primer pair consisted of CMV V166: 5' CCA ACC TTT GTA GGG AGT GA 3' and CMV C563: 5' TAC ACG AGG ACG GCG TAC TT 3'. An amplicon of the expected size (400 bp) was obtained and cloned and sequenced. BLAST search of the GenBank for related sequences showed that the sequence obtained from penstemon was highly identical to several CMV sequences, with the highest identity (98%) with that of a sequence from Taiwan (GenBank No. D49496). CMV from infected penstemon was successfully transmitted by mechanical inoculation to cucumber seedlings. Infection of cucumber plants was confirmed by ELISA and RT-PCR. To our knowledge, this is the first report of CMV infection of P. acuminatus. With the ongoing efforts to revegetate the intermountain west with native forbs, there is a need for a comprehensive survey of pests and diseases affecting these plants.

Assessing Viability of Prevariety Germplasm of Native Coreopsis Species

Dormancy issues and lack of approved protocols have led to increasing use of the pregermination tetrazolium test to assess whether seeds of premium-priced, prevariety germplasm of native wildflower species are living and have the potential to germinate and develop normally under field conditions, that is, whether seeds are viable. A major concern is the limited amount of industrywide training on how to conduct and interpret results of tetrazolium (TZ) tests for the multitude of native species. Precise methods that yield uniform results are especially critical for testing of prevariety germplasm of native species given their high value and economic consequences of inaccurate test results. In preliminary work, we observed that embryos extracted from intact seeds of native Coreopsis species subjected to TZ testing were viable if they were turgid and appeared normal and were stained pink, red, or were pure white with or without the radicle tip stained pink to red. In this study, we conducted an in-depth analysis of TZ testing of intact seeds of prevariety germplasm of four native Coreopsis species to: 1) verify our preliminary conclusions; and 2) to determine if staining could be improved by preconditioning or gibberellic acid (GA3) because relatively low percentages of embryos of intact seeds stained pink or red. In addition, we evaluated two other methods to assess viability: the excised embryo test and emergence tests in soil and a soilless medium under ambient conditions. We confirmed that embryos extracted from intact seeds subjected to TZ testing were viable provided that embryos were turgid and appeared normal and were stained pink, red, or were pure white ± a pink to red radicle tip. Embryo staining was not consistently improved by moist preconditioning or GA3. Results of pregermination TZ tests of intact seeds and/or germination plus postgermination TZ tests of intact, nongerminated seeds were not consistently accurate and/or uniform across all species and seed lots, issues usually encountered in seed lots that were relatively dormant or of poor quality, and in postgermination TZ testing of seed lots with relatively low dormancy. Moreover, these issues are likely to be encountered even with standard TZ testing protocols given the widely accepted challenges of accurately interpreting TZ tests of native species in general. The most precise, uniform method of assessing viability was the excised embryo germination test because all viable seeds germinated, results were easy to interpret so the likelihood of false-positives or -negatives was nil, and results were very uniform across replications. Emergence tests under ambient conditions substantially underestimated viability. In summary, the high cost of prevariety germplasm seeds of native Coreopsis species, inherent genetic and phenotypic variability, and unknown dormancy characteristics warrant the use of the embryo excision test for determining viability and for increased sample sizes, especially for any tests involving TZ.

야생화초지의 조성에 관한 연구

본 연구는 야생화초지 조성을 위한 기초연구로 국내산 야생화초지와 외국산 야생화초지의 2처리를 두어 시험하였다. 공시초종은 기본초종으로 잔디형 목초로 Kentucky bluegrass (Midnight) 를 공시하였고, 국내산 야생화는 패랭이꽃 (Dianthus sinensis L.), 별노랑이 (Lotus corniculatus var. Japonicus Regel), 꼬리풀 (Veronica linariaefolia pallas), 별개미취 (Aster koraiensis Nakai), 부처꽃 (Lythrum anceps Makino), 톱풀 (Achillea sibirica Ledeb), 붓꽃 (Iris nertschinskia Lodd) 및 원추 천인국 (Rudbeckia bicolor Nutt.) 등 8종을 공시하였고, 외국산 야생화는 서양말냉이 (Iberis umbellata), 기생초(Coreopsis tinctoria Nutt), 물망초(Myosotis sylvatica Hoffmann), Baby blue eyes (Nemophila menziesii), 참 제비꽃 (Delphinium ajacis), 아프리칸 데이지 (Dimorphotheca aurantiaca), 왜성 수레국화 (Centaurea cyanus), Dwarf godetia (Clarkia amoena), 왜성 기생초 (Coreopsis tinctoria, dwarf), 왜성 적 기생초(Coreopsis tinctoria, red), Spurred snapdragon (Linaria maroccana), 끈끈이대나물(Silene ameria), 러시안 꽃 무우(Cheiranthus allionii), 캘리포니아 양귀비(Eschscholzia californica Cham), 아이스랜드 양귀비 (Papaver nudicaule), 왜성 제비꽃 (Viola cornuta), Bellflower (Campanula carpatica), Sweet alyssum (Lobularia maritima), 흰 점나도나물 (Cerastium biebersteinii), 큰 달맞이꽃 (Oenothera lamarckiana Ser.), 큰 금계국(Coreopsis lanceolata L.), 각시 패랭이(Dianthus deltoids L.), Baby blue eyes (Nemophila menziesii) 및 참 제비꽃 (Delphinium ajacis) 등 24종을 공시하였다. 시험은 충남대학교 농과대학 초지시험포장에서 2006년 9월부터 2007년 12월까지 수행하였으며, 얻어진 시험결과는 다음과 같다. 야생화초지의 꽃 색깔은 외국산 야생화초지가 국내산 야생화초지보다 다양하였으나 개화가 봄철에 편중되는 등 계절분포 및 영속성이 문제시되었다. 국내산 야생화초지는 꽃 색깔은 다양하지 못하였으나 계절분포 및 영속성이 상대적으로 양호한 것으로 나타났다. 그러나 다년간 식생을 유지하기 위한 야생화 초지의 조성은 기본초종인 잔디형 목초는 물론이고 야생화초종을 지역별로 초기생육 및 개화특성 등을 검토하여 초종을 다양화하는 것이 중요하다고 하겠다. 더욱이 야생화초지를 추파하여 조성할 경우, 외국산 야생화초지는 월동전에는 다양한 식생을 유지하였으나 월동 후에는 내한성의 문제로 식생이 단순화되는 양상을 보였다. 국내산 야생화초지는 내한성에는 문제가 없었으나 식생이 다양화하지 못하였다. 따라서 야생화초지를 다년간 유지할 목적이라면 다년생의 야생화를 중심으로 하되 여기에 단년생을 혼합하여 야생화 초종을 다양화하는 것이 좋을 것으로 사료된다. The purpose of this study was to suggest the basic data for establishment of wildflower pastures. The experimental design includes two treatments: Native wildflower pasture (NWP, Kentucky bluegrass + native wildflower 8 species) and Introduced wildflower pasture (IWP, Kentucky bluegass + introduced wildflower 24 species). The field trials were carried out on the experimental pastures plots at Chungnam National University throughout from Sep. 2006 to Dec. 2007. The results obtained are as fellows: In terms of the flower color in the wildflower pastures, the IWP was found more various than the NWP. But such problems as seasonal distribution and continuity were raised and moreover the time of flowering depended mainly upon the spring season. Even though the flower color in the NWP did not show up its variousness, seasonal distribution and continuity were found comparatively satisfactory. To perennially maintain the botanical composition, the variousness of wildflower species are found important after examining locally the beginning rearing and flowering characteristics of wildflowers as well as the basic turfgrass. Moreover, when the wildflower pastures was constructed in autumn, since most of the introduced wildflower were annuals, it maintained various botanical composition before wintering, but after wintering the botanical composition were found simplified due to the winter tolerance. The NWP did not show any problems in the winter tolerance but it could not make the botanical composition diversified. Accordingly, to maintain the wildflower pasture for many years, diversifying wildflower species based upon perennials including annuals seems to be good.

Is floral diversification associated with pollinator divergence? Flower shape, flower colour and pollinator preference in Chilean Mimulus.

Adaptation to different pollinators is thought to drive divergence in flower colour and morphology, and may lead to interspecific reproductive isolation. Floral diversity was tested for association with divergent pollinator preferences in a group of four closely related wildflower species: the yellow-flowered Mimulus luteus var. luteus and the red-pigmented M. l. variegatus, M. naiandinus and M. cupreus. Patterns of pollinator visitation were evaluated in natural plant populations in central Chile, including both single-species and mixed-species sites. Floral anthocyanin pigments were identified, and floral morphology and nectar variation were quantified in a common garden experiment using seeds collected from the study sites. Mimulus l. luteus, M. l. variegatus and M. naiandinus are morphologically similar and share a single generalist bumblebee pollinator, Bombus dahlbomii. Mimulus cupreus differs significantly from the first three taxa in corolla shape as well as nectar characteristics, and had far fewer pollinator visits. This system shows limited potential for pollinator-mediated restriction of gene flow as a function of flower colour, and no evidence of transition to a novel pollinator. Mimulus cupreus may experience reduced interspecific gene flow due to a lack of bumblebee visitation, but not because of its red pigmentation: rare yellow morphs are equally undervisited by pollinators. Overall, the results suggest that factors other than pollinator shifts may contribute to the maintenance of floral diversity in these Chilean Mimulus species.

EFFECTS OF CLIMATE CHANGE ON PHENOLOGY, FROST DAMAGE, AND FLORAL ABUNDANCE OF MONTANE WILDFLOWERS

The timing of life history traits is central to lifetime fitness and nowhere is this more evident or well studied as in the phenology of flowering in governing plant reproductive success. Recent changes in the timing of environmental events attributable to climate change, such as the date of snowmelt at high altitudes, which initiates the growing season, have had important repercussions for some common perennial herbaceous wildflower species. The phenology of flowering at the Rocky Mountain Biological Laboratory (Colorado, USA) is strongly influenced by date of snowmelt, which makes this site ideal for examining phenological responses to climate change. Flower buds of Delphinium barbeyi, Erigeron speciosus, and Helianthella quinquenervis are sensitive to frost, and the earlier beginning of the growing season in recent years has exposed them to more frequent mid-June frost kills. From 1992 to 1998, on average 36.1% of Helianthella buds were frosted, but for 1999-2006 the mean is 73.9%; in only one year since 1998 have plants escaped all frost damage. For all three of these perennial species, there is a significant relationship between the date of snowmelt and the abundance of flowering that summer. Greater snowpack results in later snowmelt, later beginning of the growing season, and less frost mortality of buds. Microhabitat differences in snow accumulation, snowmelt patterns, and cold air drainage during frost events can be significant; an elevation difference of only 12 m between two plots resulted in a temperature difference of almost 2 degrees C in 2006 and a difference of 37% in frost damage to buds. The loss of flowers and therefore seeds can reduce recruitment in these plant populations, and affect pollinators, herbivores, and seed predators that previously relied on them. Other plant species in this environment are similarly susceptible to frost damage so the negative effects for recruitment and for consumers dependent on flowers and seeds could be widespread. These findings point out the paradox of increased frost damage in the face of global warming, provide important insights into the adaptive significance of phenology, and have general implications for flowering plants throughout the region and anywhere climate change is having similar impacts.

야생화초지 혼파조합을 위한 몇 가지 잔디형 및 야생화 초종의 초기생육과 개화특성에 관한 연구

본 연구는 야생화 초지조성을 위한 잔디형 목초 및 야생화초종의 선정과 혼파조합구성에 대한 기초자료를 탐색하고자 몇 가지 잔디형 목초와 야생화초종을 공시하여 초기생육, 경엽 및 근중, 건물수량, 개화특성 및 기호성 등을 비교분석하였다. 공시초종은 잔디형 목초 5종{Kentucky bluegrass(Midnight), tall fescue(Millennium), perennial ryegrass(Palmer III), redtop(Barricuda) 및 creeping bentgrass(Crenshaw)}과 야생화 11종{Chrysanthemum leucanthemum L., Coreopsis lanceolata L., Rudbeckia bicolor Nutt., Dianthus chinensis L., Chrysanthemum lindicum L., Lotus corniculatus var. Japonicus Regel, Veronica linariaefolia Pallas, Aster koraiensis Nakai., Chrysanthemum zanadskii var. latilobum(Maxim.) Kitamura, Lythrum anceps Makino 및 Iris nertschinskia. Lodd}을 공시하였으며, 충남대학교 농과대학 초지시험포장에서 2005년 1월부터 2006년 12월까지 수행하였다. 공시된 잔디형 목초 중에서 상대적으로 야생화와 혼파가능성이 큰 초종은 Kentucky bluegrass이었으며, Kentucky bluegrass에 비하여 상대적으로 초기생육이 왕성하고 경엽과 근중이 높아 야생화초지를 조성하는 데 유리할 것으로 보이는 야생화는 Chrysanthemum leucanthemum L., Lotus corniculatus var. Japonicus Regel, Chrysanthemum zawadskii var. latilobum (Maxim) Kitamura 및 Lythrum anceps Makino 등으로 조사되었다. 이들 야생화는 꽃색, 개화시기 및 개화지속기간 등이 서로 중복되지 않았으며 가축에 의한 기호성도 대체적으로 양호한 결과를 보였다. 따라서 야생화초지의 조성을 위해서는 잔디형 목초는 야생화와의 경합력이 낮은 초종을, 반대로 야생화는 경합에서 유리한 초종을 선발하되 개화특성이 서로 다른 야생화를 다양화하여 혼파조합을 구성하는 것이 중요하다고 판단된다. The purpose of this study was to compared the early growth pattern, stem, leaf and root weight, DM yield, flowering characteristics and preference for selection of turf type grasses and wild flower species in mixtures combination for wildflower pasture. The experimental design included five species of turf grasses and 11 species of wildflower : turf type grass species{Kentucky bluegrass(Midnight), tall fescue(Millennium), perennial ryegrass(Palmer III), redtop(Barricuda) and creeping bentgrass(Crenshaw)}, wildflower species {Chrysanthemum leucanthemum L. Coreopsis lanceolata L., Rudbeckia bicolor Nutt.., Dianthus chinensis L., Chrysanthemum lindicum L., Lotus corniculatus var. Japonicus Regel, Veronica linariaefolia Pallas, Aster koraiensis Nakai., Chrysanthemum zanadskii var. latilobum (Maxim.) Kitamura, Lythrum anceps Makino and Iris pallassi var. chinensis Lodd}. The field trials were carried out on the experimental pasture plots of Chungnam National University from January 2005 to December 2006. The appropriate species of turf grass which have a mixture possibility with wildflower are thought to be Kentucky bluegrass. Compared with Kentucky bluegrass, on the other hand, species such as Chrysanthemum leucanthemum L., Lotus corniculatus var. Japonicus Regel, Chrysanthemum zanadskii var. latilobum Maxim.) Kitamura and Lythrum anceps Makino have shown advantageous aspects of fast early growth pattern and highly weights of stem, leaf and root. Futhermore, these wild flowers were in harmony and no overlap on flower color, flowering periods and flowering longevity, and highly preference by Korean native goats. For the establishment of wildflower pasture in Korea, therefore, it is important to select the appropriate species of turf glasses, which have a weak competition against wild flowers, and then to make mixture combination of those turf glasses with the various wild flowers which have a strong competition against turf glasses but have a different anthesis characteristics among themselves.

The Effect of Five Pre-Emergence Herbicides on Emergence And Establishment of Four Native Wildflowers

Careful selection of pre-emergence herbicide for control of weeds may improve establishment of native wildflowers grown for seed production. In a 28-d greenhouse herbicide injury experiment, 4 emerging wildflower species were established on soil treated with one of 6 pre-emergence herbicide treatments. No wildflower seedlings survived the atrazine treatment and few survived the sulfentrazone treatment. Of the 5 herbicides tested, DCPA applied at 1100 g active ingredient (ai) per ha (8 lb ai/ac) and trifluralin applied at 184 g ai/ha (2 pt ai/ac) caused the least reduction in wildflower seedling density, height, and shoot dry mass of all species. The densities, however, of <i>Dalea candida</i> Michx. ex Willd. (Fabaceae), <i>Gaillardia aristata</i> Pursh (Asteraceae), and <i>Ratibida columnifera</i> (Nutt.) Woot. &amp; Standl. (Asteraceae) were each reduced in 1 of the 2 experimental runs, whereas the height of <i>D. candida</i> and <i>G. aristata</i> and the shoot dry mass of <i>R. columnifera</i> seedlings were reduced by trifluralin. <i>Liatris punctata</i> Hook. (Asteraceae) densities were reduced only by atrazine and sulfentrazone.

NATURAL VARIATION FOR A HYBRID INCOMPATIBILITY BETWEEN TWO SPECIES OF MIMULUS

Understanding the process by which hybrid incompatibility alleles become established in natural populations remains a major challenge to evolutionary biology. Previously, we discovered a two-locus Dobzhansky-Muller incompatibility that causes severe hybrid male sterility between two inbred lines of the incompletely isolated wildflower species, Mimulus guttatus and M. nasutus. An interspecific cross between these two inbred lines revealed that the M. guttatus (IM62) allele at hybrid male sterility 1 (hms1) acts dominantly in combination with recessive M. nasutus (SF5) alleles at hybrid male sterility 2 (hms2) to cause nearly complete hybrid male sterility. In this report, we extend these genetic analyses to investigate intraspecific variation for the hms1-hms2 incompatibility in natural populations of M. nasutus and M. guttatus, performing a series of interspecific crosses between individuals collected from a variety of geographic locales. Our results suggest that hms2 incompatibility alleles are common and geographically widespread within M. nasutus, but absent or rare in M. guttatus. In contrast, the hms1 locus is polymorphic within M. guttatus and the incompatibility allele appears to be extremely geographically restricted. We found evidence for the presence of the hms1 incompatibility allele in only two M. guttatus populations that exist within a few kilometers of each other. The restricted distribution of the hms1 incompatibility allele might currently limit the potential for the hms1-hms2 incompatibility to act as a species barrier between sympatric populations of M. guttatus and M. nasutus. Extensive sampling within a single M. guttatus population revealed that the hms1 locus is polymorphic and that the incompatibility allele appears to segregate at intermediate frequency, a pattern that is consistent with either genetic drift or natural selection.

Evaluating a Line Source Irrigation System for Determining Water Requirements of Herbaceous Perennials

Abstract We investigated wind effects on the water distribution pattern of a line source irrigation system experimental design that creates a decreasing linear moisture gradient and the growth of twelve perennial wildflower species. Species were randomly assigned to rows perpendicular to a main line of spray irrigation heads, parallel to the decreasing irrigation rates, and irrigated at 110% of evapotranspiration at the heads. At low wind speed (0.44 m/s, 1.4 ft/s), application rates decreased linearly from 50 mm/hr (2 in/hr) for positions closest to the irrigation line to zero at 4 m (12 ft) from the irrigation line. Application rates at positions farthest from the irrigation line were affected by wind speeds as low as 1 m/s (3.3 ft/s). At high wind speeds (3.8 m/s, 12.5 ft/s), application rates at all positions averaged the same across all positions but with extremely high variability. We detected a water stress response in several species known to be drought sensitive. A line source irrigation design offers a potential way to efficiently assess the response of a large number of perennial species to varying irrigation rates by creating a linear moisture gradient, but only when applied under low wind speeds.

Seasonal profiles of leaf ascorbic acid content and redox state in ozone-sensitive wildflowers

Cutleaf coneflower ( Rudbeckia laciniata L.), crown-beard ( Verbesina occidentalis Walt.), and tall milkweed ( Asclepias exaltata L.) are wildflower species native to Great Smoky Mountains National Park (U.S.A.). Natural populations of each species were analyzed for leaf ascorbic acid (AA) and dehydroascorbic acid (DHA) to assess the role of ascorbate in protecting the plants from ozone stress. Tall milkweed contained greater quantities of AA (7–10 μmol g −1 fresh weight) than crown-beard (2–4 μmol g −1 fresh weight) or cutleaf coneflower (0.5–2 μmol g −1 fresh weight). DHA was elevated in crown-beard and cutleaf coneflower relative to tall milkweed suggesting a diminished capacity for converting DHA into AA. Tall milkweed accumulated AA in the leaf apoplast (30–100 nmol g −1 fresh weight) with individuals expressing ozone foliar injury symptoms late in the season having less apoplast AA. In contrast, AA was not present in the leaf apoplast of either crown-beard or cutleaf coneflower. Unidentified antioxidant compounds were present in the leaf apoplast of all three species. Overall, distinct differences in antioxidant metabolism were found in the wildflower species that corresponded with differences in ozone sensitivity.

(61) Pot-in-pot Production of Intermountain West Native Herbaceous Perennials

Low water landscapes are increasing popular and important in the urban areas of the Intermountain West (IMW). Perennial wildflowers are an essential part of low water landscapes, and are a dominant plant type in IMW native habitats. We compared pot-in-pot (PIP) vs. conventional above-ground (CAG) production of six IMW native wildflower species, Mirabilismultiflora, Aquilegia caerulea, Penstemon palmeri, Polemonium foliosissimum, Sphaeralcea grossularifolia, and Penstemonstrictus in #1 (4-L) containers. Media temperature, container-plant water loss, stomatal conductance, and growth were measured during two production cycles per year over 2 years. Growing medium temperatures in the PIP system averaged 10 °C cooler than in the CAG system. Consistent with cooler growing media, overall water loss of PIP-grown plants averaged 10% lower than plants grown in the CAG production system. Lower growing media temperatures apparently affected transpiration, as stomatal conductance was about 60% higher in the PIP system as compared to the CAG-grown plants. The integrated effect of lower growing media temperatures on plant performance resulted in about one-third greater top and root growth for plants growing in the PIP system compared to those in the CAG system. Pot-in-pot production may be an economically suitable nursery system for producing IMW native perennial wildflowers by reducing water loss and enhancing growth.

Native Wildflower Seed Production Techniques inMississippi

Abstract Techniques using little hand labor to plant, manage, harvest, and clean seeds of 5 native wildflower species in Mississippi are presented.

Effects of Drought and Competition by a Ryegrass Sward on the Seedling Growth of a Range of Grassland Species

AbstractIn de‐intensified grassland where an increased seedling recruitment is seen as a prerequisite to enhance plant species diversity, establishment success of introduced seeds of wildflower species is often poor. Outshading by the existing sward and dry weather spells when seedlings are at an early stage of development are major reasons for a low seedling establishment. The effects of drought and competition by an existing Lolium perenne sward on the growth of seedlings of seven wildflower species were investigated under standardized environmental conditions. Without competition (control), the relative growth rate of the wildflower seedlings varied between 103 (Tragopogon pratensis) and 184 mg g−1 day−1 (Leontodon autumnalis). Species differed in the extent of growth reduction by competition. Compared with the control, reduction of seedling dry weight ranged from 45 % (Trifolium pratense) up to 88 % (Daucus carota). The time range between onset of desiccation and first effects on growth varied between species, with T. pratense showing early and strong growth reduction in contrast to D. carota being least affected. It can be concluded, that those species which maintain a comparatively high growth rate supported by adapted shoot‐root allocation are most promising for establishment in grassland as they can exploit profiles of higher resource availability.

Species Composition Changes in a Rooftop Grass and Wildflower Meadow: Implications for Designing Successful Mixtures

Daniel W Dewey, Paul G Johnson and Roger K Kjelgren

Seedling recruitment on agriculturally improved mesic grassland: the influence of disturbance and management schemes

AbstractQuestion: Are the recruitment patterns of deliberately introduced wildflower species influenced by cutting frequencies and disturbance treatments? To what extent do these different treatments affect productivity and sward structure of an agriculturally improved grassland?Location: A mesic lowland grassland near Göttingen, Lower Saxony, Germany.Methods: Recruitment success of eight sown wildflower species was studied in a permanent grassland treated by a factorial combination of different pre‐sowing cutting intervals (1, 3 or 9 wk), post‐sowing cutting intervals (1,3 or 9 wk) and disturbance (control, harrowing, removal of sward). Seedling emergence and survival, biomass production and sward structure were followed over two years.Results: For most species seedling emergence was highest in the harrowing treatment. The complete sward removal did not further increase seedling emergence. Seedling survival was strongly influenced by the post‐sowing cutting frequency with highest mortality in the 9 wk cutting interval compared to one and 3 wk cutting intervals. Annual dry matter yield varied between 4.4, 5.9 and 9.4 t.ha‐1 in the 1,3 and 9 wk pre‐sowing cutting treatment, respectively. In June, when the seeds were sown, the tiller number of the 1 wk cut plots was twice as high as for the 9 wk cut plots and five times higher than in the harrowing treatment.Conclusions: Disturbance by harrowing provided the optimal environmental cues to trigger germination, whereas seedling survival was facilitated by increased light penetration due to frequent cutting. The investigation revealed the overriding importance of frequent standing crop removal in the early phase of seedling establishment on agriculturally improved grassland.

Seedling recruitment on agriculturally improved mesic grassland: the influence of disturbance and management schemes

Question: Are the recruitment patterns of deliberately introduced wildflower species influenced by cutting frequencies and disturbance treatments? To what extent do these different treatments affect productivity and sward structure of an agriculturally improved grassland? Location: A mesic lowland grassland near Göttingen, Lower Saxony, Germany. Methods: Recruitment success of eight sown wildflower species was studied in a permanent grassland treated by a factorial combination of different pre-sowing cutting intervals (1, 3 or 9 wk), post-sowing cutting intervals (1,3 or 9 wk) and disturbance (control, harrowing, removal of sward). Seedling emergence and survival, biomass production and sward structure were followed over two years. Results: For most species seedling emergence was highest in the harrowing treatment. The complete sward removal did not further increase seedling emergence. Seedling survival was strongly influenced by the post-sowing cutting frequency with highest mortality in the 9 wk cutting interval compared to one and 3 wk cutting intervals. Annual dry matter yield varied between 4.4, 5.9 and 9.4 t.ha-1 in the 1,3 and 9 wk pre-sowing cutting treatment, respectively. In June, when the seeds were sown, the tiller number of the 1 wk cut plots was twice as high as for the 9 wk cut plots and five times higher than in the harrowing treatment. Conclusions: Disturbance by harrowing provided the optimal environmental cues to trigger germination, whereas seedling survival was facilitated by increased light penetration due to frequent cutting. The investigation revealed the overriding importance of frequent standing crop removal in the early phase of seedling establishment on agriculturally improved grassland.

Species Composition Changes in a Rooftop Grass and Wildflower Meadow: Implications for Designing Successful Mixtures

Based on our observations of a grass and wildflower meadow growing in 7 radiation zones on the roof of The Church of Jesus Christ of Latter-day Saints Conference Center in Salt Lake City, Utah, we identified 21 species that should be considered for future grass/wildflower mixture studies. We also found a single wildflower species and 1 grass species that were too aggressive for mixtures, and 4 wildflower species and 3 species of grass that were not aggressive enough. Mixtures of grasses and wildflowers can be aesthetically appealing, water-conserving, low-maintenance alternatives to conventional turfgrass.