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Abstract Reforestation and restoration efforts have traditionally relied on "local" seed sources as planting stock. The term "local" has different meanings in different locales, since no single set of seed-collection zones has yet been widely adopted across the eastern United States. Given concerns about mitigating the effects of climate change, forest managers are increasingly seeking to move seed sources in a process called assisted migration, which would be facilitated if a common set of seed-collection zones were available. We developed a map of 245 seed-collection zones for 37 states by combining two ecologically important layers: plant hardiness zones and ecoregions. These new seed-collection zones should be used by seed collectors and nurseries to describe the origin of seed for plants and trees in the eastern United States. Common garden studies remain the gold standard for determining how far to move seed from any particular seed-collection zone. For species that have not been field-tested, seed movement that is limited either within a seed-collection zone or between adjacent seed-collection zones is a reasonable general guideline. [ABSTRACT FROM AUTHOR]

Inconsistent soybean [Glycine max (L.) Merr.] seed yield response to plant density has been previously reported. Moreover, recent economic and productive circumstances have caused interest in within-field variation of the agronomic optimal plant density (AOPD) for soybean. Thus, the objectives of this study were to: (i) determine the AOPD by yield environments (YE) and (ii) study variations in yield components (seed number and weight) related to the changes in seed yield response to plant density for soybean in North America. During 2013 and 2014, a total of 78 yield-to-plant density responses were evaluated in different regions of the United States and Canada. A soybean database evaluating multiple seeding rates ranging from 170,000 to 670,000 seeds ha-1 was collected, including final number of plants, seed yield, and its components (seed number and weight). The data was classified in YEs: low (LYE, <4 Mg ha-1), medium (MYE, 4-4.3 Mg ha-1), and high (HYE, >4.3 Mg ha-1). The main outcomes were: (i) AOPD increased by 24% from HYE to LYE, (ii) per-plant yield increased due to a decrease in plant density: HYE > MYE > LYE, and (iii) per-plant yield was mainly driven by seed number across plant densities within a YE, but both yield components influenced per-plant yield across YEs. This study presents the first attempt to investigate the seed yieldto- plant density relationship via the understanding of plant establishment and yield components and by exploring the influence of weather variables defining soybean YEs. [ABSTRACT FROM AUTHOR]

Conservation assessments present a formidable challenge for regions of the developing world such as the Lesser Antilles. Of the 2652 seed plant taxa recorded from this archipelago (Acevedo-Rodríguez & Strong, 2012, 2016), only 150 taxa (including 14 endemics) are listed in the IUCN Red List. Using only herbarium data, we carried out a preliminary conservation assessment of the 263 seed plant taxa unique to these islands by two methods. Using the algorithm originally developed to assess the Hawaiian flora (Krupnick et al. in Biodiversity and Conservation 18: 1459-1474, 2009), 8% of the taxa were deemed to be Potentially Extinct and 62% Potentially Threatened while 30% were assessed as Not Threatened. Using a Red List criteria approach, 70% were deemed Threatened (Critically Endangered, Endangered and Vulnerable), while 30% were assessed as Near Threatened, Least Concern or Data Deficient. The congruence between the assessments by these distinct methods and for the 14 Red Listed species validate this approach as a first step in prioritising plant conservation efforts. [ABSTRACT FROM AUTHOR]

The gigantopterids are a poorly understood group of plants defined primarily on the basis of a particular type of reticulate leaf venation in combination with stratigraphic distribution. It is generally agreed that many, if not all, are seed plants. A new genus of gigantopterid, Euparyphoselis gen. nov., is described from foliage only, derived from the Middle Permian of the southwestern United States and eastern China. One species occurs in each area: Euparyphoselis gibsonii sp. nov. in the United States and Euparyphoselis marginervum (Yao and Liu) comb. nov. in China. The most significant characteristic of the new genus is a marginal vein. The foliage displays three and occasionally four orders of venation, with a variably distinct suture vein between second-order veins, formed by the fusion of tertiary veins from adjacent secondaries. The leaves are obovate in shape and unforked, tapering toward the base. Leaf margins are smooth or bluntly toothed with broad, shallow sinuses between the teeth. Secondary veins end or dissipate into the teeth, where present. Leaves are amphistomatic; stomatal complexes are haplocheilic and monocyclic. The two species differ mainly in the characteristics of the epidermal surfaces, including the shape and size of the epidermal and subsidiary cells, stomatal complexes, number of subsidiary cells, orientation of the stomatal complexes, and secretory structures. Euparyphoselis marginervum was originally described as a species of Gigantopteridium, with which it shares certain characteristics of venation. However, it clearly differs from Gigantopteridium in the details of venation and in leaf architecture. It is argued that leaf venation should not be given primacy over all other characteristics when assessing gigantopterid relationships and therefore as a basis for taxonomy. As previously suggested, the gigantopterids, as presently construed, may not be a monophyletic group. [ABSTRACT FROM AUTHOR]

Most recent studies describing pollination networks are based on observed flower visits, and few have explicitly tested if the floral visitors actually carry pollen. Since floral visitors can vary in their ability to remove and transfer pollen, it is important to show that visitation patterns reflect effective pollination. Given the difficulty of measuring per-visit pollen deposition at the community scale, a first step is to examine the amount of conspecific pollen carried by insect visitors. Here I compared the plant–animal visitation network with the pollen-transport network, estimated from insect pollen loads, for a montane meadow community from southern California, USA. Visitation and pollen-transport networks were positively associated with each other in both 2001 and 2002. However, the exclusion of visitors that do not carry any conspecific pollen reveals that pollen-transport networks are more specialized from the plants’ perspective and that species are involved in fewer mutualistic interactions compared with estimates derived from visitation frequencies. Although conspecific pollen loads were smaller in 2002, bees tended to carry the largest conspecific loads in both years and were responsible for transporting the most pollen. These results suggest that, although visitation networks are suitable first-order approximations of pollination networks, information on which visitors carry conspecific pollen, and in what amounts, is crucial for distinguishing between antagonistic and mutualistic interactions. [ABSTRACT FROM AUTHOR]

Comparison of the common floristic elements between the West Indies and the surrounding continents shows a mosaic of affinities that are stronger to Central America and South America as a whole than with either one of them separately or with North America. However, since only 28% of the total West Indian seed plant flora is shared with other geographic regions of the world, the referred exercise is of limited value. Numerous tables are provided to show the distribution of genera throughout the archipelago. The application of phylogenetic studies into the service of biogeography is herein regarded as the next necessary step in elucidating the origins and affinities of the West Indian flora. [ABSTRACT FROM AUTHOR]

Aim In this paper, we explore the relationship between pollen concentration in surface soil and extant perennial vegetation across a rapidly urbanizing arid ecosystem along with its surrounding agricultural and native Sonoran Desert land. We also investigate whether taxa behave as expected from known pollination characteristics (e.g. anemophilous vs. zoophilous) and whether the pollen–plant relationship differs between the undeveloped desert and agro-urban regions. Location We used a probability-based sampling scheme at 200, 900-m2 sites across the Central Arizona–Phoenix region, a 6400-km2 area of the south-western USA. Methods Pollen–plant abundances were mapped across the study area using interpolation techniques, summary bar charts and scatterplots, then two statistical approaches were applied to examine the data quantitatively. Firstly, we used regression analysis of paired pollen concentration and plant cover data; secondly,pc-ord was used on a cross-matrix (contingency table) containing the presence/absence scores of both pollen and plants for each taxon at each site. Results Mapping and quantitative analysis revealed that pollen–plant relationships do vary both between anemophilous and zoophilous groupings and by individual taxon. They also revealed that distribution patterns of both pollen and plant abundance vary consistently across the three main landscape types (desert, urban, agricultural) and that pollen taxa groupings are consistent with pollination method and source plant distribution regardless of landscape type. Main conclusions These findings provide a broad range of comparative data to facilitate palynological reconstruction of past vegetation and aid in assessing types of prehistoric impacts on this vegetation. They also document that significant variation can occur in pollen rain across a city, even for taxa with widely distributed pollen, leading to the conclusion that forecasting pollen distribution patterns for allergy-related pollen types using only one or a few pollen traps is likely to entail substantial error. [ABSTRACT FROM AUTHOR]

Nonhost angiosperm volatiles and verbenone were tested for their ability to disrupt the response of western pine beetle, Dendroctonus brevicomis LeConte (Coleoptera: Scolytidae), to attractant-baited multiple funnel traps. Verbenone significantly reduced attraction; however, no difference was observed between 4 and 50 mg/24-h release rates. Combinations of six bark volatiles (benzyl alcohol, benzaldehyde, trans-conophthorin, guaiacol, nonanal, and salicylaldehyde), three green leaf volatiles [(E) -2-hexenal, (E) -2-hexen-1-ol, and (Z) -2-hexen-1-ol], and the nine compounds combined did not significantly reduce D. brevicomis response to attractant-baited traps. However, a significant effect was observed when the bark and green leaf volatiles were combined with verbenone. The nine nonhost angiosperm volatiles (NAys) significantly augmented the effect of both release rates of verbenone, reducing trap catches to levels significantly below that of either release rate of verbenone alone, trans-Conophthorin, a compound reported to have behavioral activity in a number of other scolytids, was not critical to the efficacy of our NAV blend. Our results suggest that the addition of nonhost angiosperm volatiles to verbenone could be important for developing successful semiochemical-based management techniques for D. brevicomis. [ABSTRACT FROM AUTHOR]

Niger [Guizotia abyssinica (L. f.) Cass.] is imported into the USA for use as birdseed. An early maturing niger cultivar, 'EarlyBird' may have the potential to be grown in the northern Great Plains. This study evaluated the effect of different EarlyBird niger seeding rates on seed yield, test weight, plant height, and pest incidence. Eight to ten seeding rates, ranging from 0.56 to 16.8 kg ha[sup -1], or 15 to 465 pure live seeds m[sup -2], were evaluated in seven environments: Red Lake Falls (RLF) and Kennedy (Ken), MN, in 2000 and 2001, and Carrington (Car), Langdon (Lan), and Prosper (Pro), ND, in 2001. Mean yield across the seven environments was 355 kg ha[sup -1]. At RLF00 and RLF01 (Red Lake Falls, MN, 2000 and 2001) the mean yield was 535 and 580 kg ha[sup -1], respectively. Maximum yields across all environments corresponded to a seeding rate of 284 seeds m[sup -2] and a plant stand of 157 plants m[sup -2], or approximately 10.0 kg seed ha[sup -1], whereas 90% of the maximum yields corresponded to a seeding rate of 127 seeds m[sup -2] and a plant stand of 72 plants m[sup -2], or the planting of slightly under 6.7 kg seed ha[sup -1]. Plants at the lowest seeding rate had more heads and higher aboveground biomass per plant than the other seeding rates evaluated; however, individual head weight did not differ. For production purposes, a seeding rate of 6.7 kg ha[sup -1] provided high yields with early canopy closure and uniform seed maturation. [ABSTRACT FROM AUTHOR]

Reports the discovery of a compound pollen cone among a walchian conifers in Pennsylvania. Description on the pollen cone; Axillary structures; Implications of the discovery.

Describes anatomically preserved vojnovskyalean seed plants in Upper Pennsylvanian marine shales of North America. Lengths of individual cones; Occurrence of scales in the basal region of the cone; Sporophylls; Ovules; integument histology; Vascular tissue distribution.