Foliage Type Research Articles

Foliage type specific susceptibility to ozone in Picea abies, Pinus cembra and Larix decidua at treeline: A synthesis

Cumulative ozone uptake (COU, mmolm−2) and O3 flux (FO3, nmolm−2s−1) were related to physiological, morphological and biochemical characteristics of field-grown mature evergreen Norway spruce [Picea abies (L.) Karst.], Cembran pine [Pinus cembra L.], and deciduous European larch [Larix decidua Mill.] trees at treeline. The threshold COU causing a statistically significant decline in photosynthetic capacity (Amax) ranged between 19.6mmolm−2 in current-year needles of evergreen conifers and 22.0 6mmolm−2 in short-shoot needles of deciduous L. decidua subjected to exposure periods of ≥84 and ≥43 days, respectively. The higher O3 sensitivity of deciduous L. decidua than of evergreen P abies and P. cembra was associated with differences in FO3 and specific leaf area (SLA), both being significantly higher in L. decidua. FO3 was 5.9nmolm−2s−1 in L. decidua and 2.7nmolm−2s−1 in evergreen conifers. Species-dependent differences were also related to detoxification capacity expressed through total surface area based concentrations of reduced ascorbate and α-tocopherol that both increased with SLA. Findings suggest that differences in O3 sensitivity between evergreen and deciduous conifers can be attributed to foliage type specific differences in SLA, the latter determining physiological and biochemical characteristics of the treeline conifers.

Dietary mixing within the crown of a deciduous conifer enhances the fitness of a specialist sawfly

Dietary mixing is an important adaptation used by many animals to account for nutritional heterogeneity in their environment, but it remains largely unstudied for specialist insects within crowns of deciduous hosts. We carried out field and laboratory studies to explain dietary mixing by larvae of the larch sawfly, Pristiphora erichsonii (Hartig) (Hymenoptera: Tenthredinidae) of dimorphic foliage types (i.e. long shoots versus fascicles) within a deciduous conifer, Larix kaempferi (Lamb.) Carr. First-instar larvae fed mainly on long shoots, and late instars fed mainly on fascicles; however, during all instars, some individuals could be observed feeding on long shoots or fascicles. A mixed diet yielded higher overall survival due to benefits accrued during both early and late instars. Late instars had similar prepupal mass and developmental rate when provided a mixed or fascicle-only diet, but they suffered significant reductions in both performance parameters when forced to feed exclusively on long shoots. Overall fitness of females was 15–22% higher for larvae provided a mixed diet than for larvae provided one foliage type. Our results support the ‘ontogeny’ hypothesis, which attributes dietary mixing to changes in nutritional needs of larvae over the course of development, as well as the ‘complementary diet’ hypothesis, which contends that mixing of different foliage types is associated with nutrient balancing or toxin dilution. Our results suggest that architectural patterns of growth and nutritional quality within crowns of deciduous conifers exert selective pressure similar to that of evergreens on insect herbivores to diet-mix during juvenile development.

Review: Variety, Archaeology, and Ornament: Renaissance Architectural Prints from Column to Cornice

Variety, Archaeology, and Ornament: Renaissance Architectural Prints from Column to Cornice . University of Virginia Art Museum. 26 August–18 December 2011. This genesis of this compelling exhibition is a collection of twenty-three mid-sixteenth-century architectural prints acquired by the University of Virginia some thirty years ago. The prints are of various capitals and bases, some quite elaborate but matching none of the canonical orders with which we are most familiar. While several can be linked to known ancient monuments, others are from sources unknown, and some appear to be inventions. Their engraver is identified only by the initials G.A., with a tiny image of a caltrop (a small spiked weapon spread on the ground to inhibit the advance of mounted troops). Master G.A. may be Giovanni Agucchi, a mid-sixteenth-century Italian engraver, but the attribution remains conjectural. The prints are a reminder of how single-leaf architectural prints accelerated the spread of information on classical architecture during the formative years of the Italian Renaissance. The printed image was just then coming into its own and made knowledge of Roman antiquity widely accessible to an eager audience as never before. Moreover, the prints are evidence of how this particular master, along with numerous others, quickly absorbed and shared the richness and variety of the wealth of ancient architectural details scattered about. Using Master G.A. prints as a foundation, the …

Effects of Havardia albicans supplementation on feed consumption and dry matter digestibility of sheep and the biology of Haemonchus contortus

This study evaluated effects of Havardia albicans foliage intake on sheep dry matter digestibility (DMD) and included post-mortem evaluation of Haemonchus contortus infection (i.e., worm burdens, worm female length, fecundity). Fifteen hair sheep (16±4.2kg live weight (LW)) raised free of gastrointestinal nematodes were used. Sheep were fed a basal diet: grain based concentrate and Pennisetum purpureum grass (900 and 100g/kg DM, respectively) and were infected on day 0 with 3000 H. contortus infective larvae. On day 28 post-infection (PI) sheep were distributed to three groups being: Control (100g/kg DM of basal diet), HA group (basal diet 600+H. albicans 400) and the HA+PEG group (basal diet 600+H. albicans 400)+Polyethylene glycol (PEG). The H. albicans foliage was supplied for 13d including 7d of adaptation (i.e., day 28–40 PI). The content of condensed tannins (CT), total polyphenols (TP) and total tannins (TT) was determined in the foliage. Concentrate, grass and H. albicans intake (g DM/kg LW0.75), DMD and H. contortus egg excretions were determined. Sheep were slaughtered at day 41 PI to assess adult worm burdens, female worm lengths and fecundity (i.e., eggs in utero). Foliage had (g/kg DM): 71.5 CT, 61.3 TP and 66.9 TT. Experimental groups had similar feed intakes, and intake of H. albicans was not affected by PEG. The DMD of HA+PEG and HA groups was lower than Control (P<0.05). Post-mortem worm burdens were similar in all groups, but the H. contortus females in the HA group were shorter and had reduced fecundity (P<0.05). Adding PEG (HA+PEG) eliminated the effect of H. albicans intake on worm length. A short period of H. albicans intake affected the DMD of sheep and reduced the H. contortus female worm length and fecundity. The use of this type of tannin-rich foliage could bring nutritional and anti-parasitic benefits to the ruminants which consume them.

Leaf evolution in Southern Hemisphere conifers tracks the angiosperm ecological radiation.

The angiosperm radiation has been linked to sharp declines in gymnosperm diversity and the virtual elimination of conifers from the tropics. The conifer family Podocarpaceae stands as an exception with highest species diversity in wet equatorial forests. It has been hypothesized that efficient light harvesting by the highly flattened leaves of several podocarp genera facilitates persistence with canopy-forming angiosperms, and the angiosperm ecological radiation may have preferentially favoured the diversification of these lineages. To test these ideas, we develop a molecular phylogeny for Podocarpaceae using Bayesian-relaxed clock methods incorporating fossil time constraints. We find several independent origins of flattened foliage types, and that these lineages have diversified predominantly through the Cenozoic and therefore among canopy-forming angiosperms. The onset of sustained foliage flattening podocarp diversification is coincident with a declining diversification rate of scale/needle-leaved lineages and also with ecological and climatic transformations linked to angiosperm foliar evolution. We demonstrate that climatic range evolution is contingent on the underlying state for leaf morphology. Taken together, our findings imply that as angiosperms came to dominate most terrestrial ecosystems, competitive interactions at the foliar level have profoundly shaped podocarp geography and as a consequence, rates of lineage diversification.

Modeling Jack Pine (Pinus banksiana) Foliage Density Distribution

Abstract The vertical distribution of foliage biomass is important because it is associated with photosynthesis and is closely related to some wood quality attributes such as branch diameter and sapwood content. In this article we propose a model to predict foliage biomass distribution within the crown for jack pine trees in Eastern Canada. This model has two parts. The first one distinguishes the proportion of nodal (formed at the end of each yearly shoot) and internodal (formed during the growing season) foliage biomass. The second part of the model predicts the distribution of the biomass depending on the type of foliage (nodal or internodal). This second part is based on a two-parameter beta cumulative distribution function (cdf). The parameterization of this cdf was performed using a mixed-effects nonlinear regression. The proportion of foliage biomass found in the nodal whorls is proportional to dbh and age and inversely proportional to total height. The distribution of the foliage biomass in the nodal whorls is dependent only on tree-level variables whereas the internodal foliage biomass is influenced by both tree- and stand-level variables. The internodal foliage biomass maximum is closer to the crown base than that of nodal foliage biomass. Decomposing the distribution into whorl types leads to a better description of crown characteristics.

Photosynthetic characterization of Australian pitcher plant Cephalotus follicularis

Australian carnivorous pitcher plant Cephalotus follicularis Labill. produces two types of leaves. During the spring time, the plant produces a foliage type of noncarnivorous leaf called lamina. Later, the second type of leaf is produced — carnivorous pitcher. Using simultaneous measurements of gas exchange and chlorophyll (Chl) fluorescence photosynthetic efficiency of these two distinct forms of leaves were compared. In addition stomatal density, an important component of gas exchange, and Chl concentration were also determined. Pitcher trap had lower net photosynthetic rate (P N) in comparison to noncarnivorous lamina, whereas the rate of respiration (R D) was not significantly different. This was in accordance with lower stomatal density and Chl concentration in the pitcher trap. On the other hand maximum quantum yield of PSII (Fv/Fm) and effective quantum yield of photochemical energy conversion in PSII (ΦPSII) was not significantly different. Nonphotochemical quenching (NPQ) was significantly higher in the lamina at higher irradiance. These data are in accordance with hypothesis that changing the leaf shape in carnivorous plants to make it a better trap generally makes it less efficient at photosynthesis. However, the pitcher of Cephalotus had much higher P N than it was expected from the data set of the genus Nepenthes. Because it is not possible to optimize for contrasting function such as photosynthesis and carnivory, it is hypothesized that Cephalotus pitchers are less elaborated for carnivorous function than the pitchers of Nepenthes.

Diversity of Shrub-Dwelling Arthropods to Thinning of Young Douglas-Fir Forests in the Pacific Northwest, USA

Abstract We examined an unthinned control stand and three different thinning intensities in 40- to 60-year-old Douglas-fir forests in western Oregon to assess the effects of thinning on the abundance, species richness, and diversity of shrub-dwelling arthropods. Shrub-dwelling arthropods, collected with a bagging technique, decreased significantly as thinning intensity increased in deciduous foliage (vine maple, Acer circinatum Pursh), but arthropods showed no response to thinning on the two types of conifer foliage (Douglas-fir, Pseudotsuga menziesii [Mirb.] Franco and western hemlock, Tsuga heterophylla [Raf.] Sarg.). The species richness and diversity of shrub-dwelling arthropods showed significantly higher values on the coniferous branches than on the deciduous foliage. Functional group composition for the two foliage types revealed consistently different proportions. Deciduous branch supported a higher proportion of sapsuckers and leaf chewers, and conifer branch hosted a higher proportion of predators and detritivores. Nonmetric multidimensional scaling ordination showed a distinct difference between the species assemblages inhabiting the deciduous and conifer branches. The effects of thinning on the arthropods were complex. Seasonal effects on arthropods exceed treatment effects because the species composition in the dry season was very different from that in the wet season. The shrub-dwelling arthropod community reveals little seasonal difference on coniferous branch, but significant differences occur on deciduous branch. In this study, treatment effects were very limited, but our results indicate that as thinning increased, the response of arthropod community on deciduous branch increased more. This large-scale experiment provided an opportunity to assess responses of shrub-dwelling arthropods to levels and patterns of forest management.

Growth architecture and silhouette of Jurassic conifers from La Matilde Formation, Patagonia, Argentina

Simple morphological traits are used to describe the architecture of a tree: the growth and branching process, the morphological differentiation of the axes and the position of reproductive structures. The main purpose of this contribution is to describe the growth architecture of the Jurassic conifer trees present at the most basal part of the La Matilde Formation in the locality of Monumento Natural Bosques Petrificados, Patagonia, Santa Cruz province, Argentina, and to compare it with that of extant and fossil conifers. This study is based on a large number of in situ petrified trunks, impressions and external molds of leafy branches and female cones in intimate association or organic connection with the trunks. The cones were assigned to Araucaria cf . A. mirabilis (Speg.) Windhausen emend. Calder (Araucariaceae) based on morphological and anatomical characters. The “ Araucaria mirabilis” trees had 3 branching categories, corresponding to the typical pattern in extant Araucariaceae, although 4 branching categories cannot be completely discarded. The main, orthotropic stem (TA1) had rhythmic growth and branching, bearing 3–4, probably up to 6–7 plagiotropic branches in pseudowhorls. The lower part of the trees shows no branch-scars; therefore, self-pruning would have been present. Lateral branches (A2) had rhythmic branching: the branchlets (A3) were distributed regularly on the leading branch, with an alternate arrangement, conforming two orthostichies on the same horizontal plane. The female cones were borne terminal at the tip of peduncles, but lateral in position with respect to A2 branches. Reiteration patterns are present: total reiterations (bifurcated trunks and big, orthotropic branches in trunks with normal plagiotropic branches) and partial reiterations (epicormic branching) were observed. The root system consisted of 6 horizontal roots, no tap root was observed. Two architectural patterns or “morphotypes” were recognized at one of the forest levels studied, in keeping with other pieces of evidence (type of wood, foliage, and cones). The “Araucarioid morphotype or morphotype A” includes most of the studied specimens (i.e. “ Araucaria mirabilis” trees); showing pseudowhorls of plagiotropic branches. These characters correspond to Massart's model, with certain modifications in the adult trees due to reiteration processes. Morphotype B was observed in bigger trunks with a distinctive costulated surface, which bear only orthotropic branches irregularly arranged, and without reiteration evidences; they could be assigned to Attim's model and possibly represent a different conifer taxon, though subrepresented. Partial and total reiteration patterns are described for the first time for Jurassic, Gondwanic conifers. Moreover, Massart's model can be followed from Upper Palaeozoic Walchiaceae to Mesozoic Araucariaceae.

Taste receptor activity and feeding behaviour reveal mechanisms of white spruce natural resistance to Eastern spruce budworm Choristoneura fumiferana

The pattern of feeding of Eastern spruce budworm Choristoneura fumiferana (Clem.) (Lepidoptera, Tortricidae) is compared on foliage from white spruce Picea glauca (Moench) Voss. (Pinaceae) trees previously determined to be susceptible and resistant to defoliation by budworm. No differences are observed in electrophysiological responses from taste sensilla to aqueous extracts of the two foliage types, nor is there a preference for either extract type in a choice test. Acetone extracts from the two foliage types are both preferred to a control sucrose solution, although neither elicits a preference relative to the other. These results suggest that there is no difference in phagostimulatory power of internal leaf contents of the two foliage types. Longer‐term observation of feeding behaviour in a no‐choice situation shows no difference in meal duration, confirming the lack of difference in phagostimulatory power. However, on average, intermeal intervals are twice as long on the resistant foliage, leading to an overall lower food consumption during the assay. This result suggests an anti‐digestive or toxic effect of the resistant foliage that slows behaviour and limits food intake. Previous research has shown that waxes of the resistant foliage deter initiation of feeding by the spruce budworm and that this foliage contains higher levels of tannins and monoterpenes. The data suggest that the resistant foliage contains a post‐ingestive second line of defence against the spruce budworm.

Host Plant Phenology Affects Performance of an Invasive Weevil,Phyllobius oblongus(Coleoptera: Curculionidae), in a Northern Hardwood Forest

We investigated how host plant phenology and plant species affected longevity, reproduction, and feeding behavior of an invasive weevil. Phyllobius oblongus L. (Coleoptera: Curculionidae) is common in northern hardwood forests of the Great Lakes Region. Adults emerge in spring, feed on foliage of woody understory plants, and oviposit in the soil. Preliminary data indicate that adults often feed on sugar maple, Acer saccharum Marshall, foliage early in the season, then feed on other species such as raspberry, Rubus spp. Whether this behavior reflects temporal changes in the quality of A. saccharum tissue or merely subsequent availability of later-season plants is unknown. We tested adult P. oblongus in laboratory assays using young (newly flushed) sugar maple foliage, old (2-3 wk postflush) sugar maple foliage, and raspberry foliage. Raspberry has indeterminate growth, thus always has young foliage available for herbivores. Survival, oviposition, and leaf consumption were recorded. In performance assays under no-choice conditions, mated pairs were provided one type of host foliage for the duration of their lives. In behavioral choice tests, all three host plants were provided simultaneously and leaf area consumption was compared. Adults survived longer on and consumed greater amounts of young maple and raspberry foliage than old maple foliage. P. oblongus preferred young maple foliage to old maple foliage early in the season, however, later in the growing season weevils showed less pronounced feeding preferences. These results suggest how leaf phenology, plant species composition, and feeding plasticity in host utilization may interact to affect P. oblongus population dynamics.

A seed-bearing lobatopterid frond segment from the Westphalian D (Upper Pennsylvanian) of south-central Germany

Abstract The Pennsylvanian foliage morphogenus Lobatopteris is commonly referred to the marattialean ferns based on the presence of synangia in fertile specimens. This paper reports on a seed-bearing frond segment from the Westphalian D (Upper Pennsylvanian) of the Zwickau–Oelsnitz Basin, Germany, that corresponds to Lobatopteris with regard to gross morphology and venation. Seeds are ovoid and occur in place of basiscopic pinnules positioned proximally on the ultimate pinnae. Lateral extensions of the seed integument appear to form two wings in a primary plane. Discovery of a seed-bearing lobatopterid reveals that this type of foliage was not exclusively produced by ferns, but also by seed plants.

Repetibilidade e importância de caracteres para avaliação de coleção ativa de germoplasma de batata

Como a base genética da batata cultivada Solanum tuberosum L. é estreita, torna-se importante a utilização do germoplasma existente nos programas de melhoramento, associada a um eficiente método de caracterização. O objetivo foi verificar a repetibilidade, o número de avaliações necessárias e a importância relativa de caracteres fenotípicos na caracterização de uma coleção ativa de germoplasma de batata. Um conjunto de 77 cultivares e clones elite de batata foi cultivado no campo experimental da Embrapa Clima Temperado, nas primaveras de 1999, 2000, 2001, 2002 e 2003, em parcelas de fileira simples de 15 plantas, espaçadas de 0,30 x 0,80 m, dentro e entre fileiras, respectivamente. Foram avaliados 31 caracteres nas plantas e nos tubérculos, os quais fazem parte dos descritores mínimos da batata. Os dados foram submetidos à análise de variância, de repetibilidade e de importância de caracteres. Concluiu-se que os caracteres com maior importância na caracterização do germoplasma avaliado são pigmentação da haste e intensidade de coloração da base do broto, tanto pela porcentagem de contribuição quanto pela repetibilidade da expressão nos diferentes anos de cultivo, refletindo no reduzido número de avaliações necessárias. Os caracteres coalescência da folha e pigmentação da nervura, presença de asas, tipo de folhagem, inserção da folha, largura dos folíolos, tamanho dos folíolos, cor da película, freqüência de flores, pubescência da base do broto, pigmentação do pedúnculo e pigmentação externa da corola, aspecto do ápice e aspereza da película, por apresentarem menores repetibilidades e/ou menores contribuições para a dissimilaridade, podem receber menos ênfase nas avaliações

Response of pea (Pisum sativum L.) cultivars and lines to seed infection by Ascochyta blight fungi

Seeds collected from 10 cultivars and lines of Pisum sativum of both ‘afila’ and normal foliage type, inoculated in field by Mycosphaerella pinodes and Phoma pinodella, were evaluated for incidence of fungi responsible for Ascochyta blight. Also seed germination and contamination by other fungi were considered. Surface sterilized seeds were plated on Coon agar medium. A sample contains 50 seeds. Data were taken after 8 days of incubation. Frequency of species occurrence depended not only on characters of cultivars and lines, weather conditions during 1998-2001, but on inoculation treatment. Clear response between cultivars and lines to tested factors was noted. Seeds of normal leaved line 344/87/3 and cv. Rubin were the most inhabited by all fungi, and germinated very poorly. Seeds of eight cultivars and lines, including cvs: Kwestor, Agra, Miko, were less infected and better germinated. Almost 40% of non-germinated seeds were inhabited by various fungi, but cultivars and lines differences were not clear. Seed infection by ascochyta blight fungi was rather low, reaching from 2.26 - 11.34 percent, a mean 4.81, but always the highest for M. pinodes. Percentage of contaminated seeds by other fungi, mainly saprobic, was always higher, even 5 times, with an average 16.73%. The best for seed germination was growing season of 2000, while for seed infestation, non-germinated and germinated, 2001.

Leaf nutrient content and host plant selection by leaf‐cutter ants, Atta laevigata, in a Neotropical savanna

AbstractThe selection of nutrient‐rich leaves by leaf‐cutter ants (Atta spp.) is thought to be of indirect benefit to these ants by promoting the growth of their symbiotic fungus. However, relatively few studies have analyzed the influence of leaf nutrient content on host plant selection by leaf‐cutter ants, and conflicting results have been found. We compared the content of eight nutritional elements plus the non‐nutrient aluminum between leaves harvested by colonies of Atta laevigata (Smith) (Hymenoptera: Formicidae: Attini) and leaves collected randomly within their foraging areas. In addition, we evaluated whether leaf nutrient content explained the frequency with which these ants attacked and defoliated some of the tree species found in the study area. For 2 years, we monitored 17–26 trees from 15 species and determined the number of times each plant was attacked and the amount and type of foliage removed. Leaves harvested by A. laevigata presented significantly higher concentrations of N, P, K, Zn, and Cu than those collected randomly. This result is likely to reflect the foraging pattern presented by these ants, which were selective both in terms of the plant species and age of leaves most commonly attacked. Young leaves were the only or the main leaf type exploited in many species, and in comparison to mature leaves these presented significantly higher concentrations of P and K. Large differences in the mean number of ant attacks on the tree species studied were also observed, and those presenting more leaf N tended to be the most frequently attacked.

Variation of defence-related metabolites in the foliage of adult beech and spruce: a conceptual approach to approximating traded-off carbon

To prevent carbon (C) loss to consumers, trees need to defend their primary production. The tree-internal conflict in resource allocation between growth and defence demands has been the subject of various hypotheses but still requires quantification. A conceptual approach to approximating the C amount dispensable in favour of primary production at the expense of defence is demonstrated which is based on nine defence-related metabolite groups. Quantification is exemplified at the level of sun and shade leaves of adult Fagus sylvatica and Picea abies trees, two species contrasting in foliage type, under oxidative stress as induced by ozone exposure. The difference between maximum and minimum metabolite levels sampled several times throughout four consecutive growing seasons were conceived as dispensable between growth and defence-related metabolism and expressed in proportion of the mean annual gross primary production (GPP) of the foliage. In both species, this proportion amounted to between 2 and 5% of GPP (on a molar C basis). Remaining uncertainties are discussed as concerning functional overlap of substances between growth and defence-related metabolism, estimated classification of metabolite turnover rates and “third-party” trade-offs across C demands. Given the complexity of plant defence, simplification is needed for modelling allocation trade-offs in plants. The presented conceptual approach meets this need in approximating C transfer capacities between competing physiological demands and in stimulating empirical assessments towards mechanistic understanding.

Credneria and Platanus (Platanaceae) from the Late Cretaceous (Santonian) of Quedlinburg, Germany

Foliage and reproductive structures of Platanaceae from the Upper Cretaceous (Santonian) of Quedlinburg, Central Germany, were comparatively studied and their systematic affinities established. One type of foliage preserved in sandstone and rarely in clayish siltstone belongs to the extinct genus Credneria. The leaves are typically obovate with a pinnate-actinodromous venation and distinct suprabasal veins. In addition, a substantial number of leaves preserved in siltstone and rarely in sandstone are identical to modern Platanus based on leaf architecture and epidermal features. As in modern Platanus leaf margin and size were found to be of no systematic significance in both fossil leaf types. Further, staminate flower heads preserved as cleavage compressions in siltstone were found in association with Platanus leaves; they contain pollen that is identical to modern Platanus in size and type of tectum. In addition, a few three-dimensionally preserved staminate flower heads with ca. 50 flowers on a receptaculum are described. Each flower appears to have a two-whorled perianth and six or seven stamens. The organs of the outer perianth whorl show a distinct epidermal cell pattern different from the inner ones. All perianth organs have the same length as the stamens. Stamens are bithecate and contain pollen identical to that found in compression fossils. Pistillate heads preserved in siltstone consist of numerous achenes with persistent styles, which show close similarity to modern Platanus. It remains unclear, whether additional inflorescence heads of uncertain sex found in sandstone that are slightly larger than those preserved in siltstone belong to the leaves of Credneria. Association evidence links vegetative and reproductive structures preserved in siltstone and indicates the presence of the modern genus Platanus in the Santonian.

When is a Vase Solution Biocide not, or not only, Antimicrobial?

The vase life of cut flowers and foliage is often shortened by vascular occlusions that constrict vase solution supply. Reductions in stem conductivity are typically caused by blockage of cut stem ends and xylem conduits by microbes, physiological plugging, and disruption of water columns in xylem vessels by cavitation and air emboli. Cut flower and foliage longevity can be greatly affected by the chemical composition of the vase solution. Provision of biocides prolongs the vase life of numerous species. A broad range of biocides has been suggested to prevent the proliferation of microorganisms in vase solutions; however, their assumed antimicrobial action may be confounded by their other physicochemical effects. In this context, the response of cut stems to biocides may also vary according to the cut flower or foliage type, the specific microorganisms involved, and other vase solution ingredients. This paper explores the efficacy and multifunctional roles of vase solution biocidal agents used in industry and by researchers for cut flowers and foliage.

HORSETAILS AND SEED FERNS FROM THE MIDDLE TRIASSIC (ANISIAN) LOCALITY KÜHWIESENKOPF (MONTE PRÀ DELLA VACCA), DOLOMITES, NORTHERN ITALY

Abstract: Well‐preserved floras from the Alpine Early–Middle Triassic are rare, and thus our understanding of the vegetation in this area during this period of time continues to be incomplete. As a result, every new find represents a significant piece of information that deserves thoughtful consideration. Anisian (Middle Triassic) sphenophytes and pteridosperms have recently been recovered from the Kühwiesenkopf locality (Monte Prà della Vacca) in northern Italy. The sphenophytes are represented by stem fragments, strobili and isolated sporangiophore heads of Equisetites, as well as by a few specimens of Neocalamites sp. and Echinostachys sp. The pteridosperms include abundant remains of the peltasperm foliage type Scytophyllum bergeri. A second Scytophyllum species in this flora, S. apoldense, is regarded as conspecific with S. bergeri based on epidermal anatomy; the two morphotypes are interpreted as sun and shade leaves of a single biological species. The seed‐bearing disc Peltaspermum bornemannii sp. nov. probably represents the female reproductive structure of S. bergeri. Additional pteridosperm remains include foliage assignable to Sagenopteris sp. and Ptilozamites sp., in both cases perhaps the earliest records of these genera.

MAGNETOBIOSTRATIGRAPHY OF THE STURA DI LANZO FOSSIL FOREST SUCCESSION (PIEDMONT, ITALY)

Along the Stura di Lanzo River, 20 km north of Turin (Italy), several large mummified stumps in growth position crop out, thus providing a well-preserved example of fossil forest. This is formed by conifers which bear the Glyptostrobus europaeus type of cone and foliage as well as the Glyptostroboxylon rudolphii wood-type. Stratigraphic and plant taphonomic analyses of the outcropping succession clearly indicate that the palaeoenvironment was a densely-vegetated swamp, laying nearby one or more active fluvial/deltaic channels, in which coarse cross-bedded sands were deposited. The fossils are embedded in fine-grained continental sediments referred to the «Villafranchiano» unit, a term used in the Piedmont region (north-western Italy) to designate coastal to continental deposits which conformably overlay Pliocene marine successions. In this paper we present new data which better characterize the chronostratigraphy of the Stura di Lanzo Fossil Forest (FF) succession and similar deposits studied at the Front Canavese (FR) site, 10 km to the NE. The integrated magnetobiostratigraphic approach, applied to both outcropping sections and subsurface deposits, permits to attribute the FF to the subchron Kaena. On the basis of these new magnetobiostratigraphic data, a strongly supported correlation between the FF and the Villafranchian type-section of Villafranca d'Asti is proposed. Furthermore, the well-constrained FF chronostratigraphy adds new data to the Middle Pliocene vegetation history, since an adequate palaeofloral documentation for the time interval corresponding to subchron Kaena was still lacking in Italy.