Abstract. Paleoxyela nearctica gen. et sp. nov., is described from the upper Eocene of Florissant Formation in Colorado. We placed nov. subfamily Macroxyelinae and tribe Macroxyelini based on numerous wing venation characters visible specimen. Proxyelia pankowskii lower Fossil Lake deposits Green River Wyoming. Xyeleciini These new records family Xyelidae are particular importance to better und...

Conifers are the most important group of gymnosperms, which include tree species of great ecological and economic importance that dominate large ecosystems and play an essential role in global carbon fixation. Nitrogen (N) economy has a special importance in these woody plants that are able to cope with seasonal periods of growth and development over a large number of years. As N availability i...

In boreal conifers, maximum latewood density (MXD) of annual rings varies in response to warm-season temperatures. Vegetation productivity can be estimated using the Normalized-DiŒerence Vegetation Index (NDVI) calculated from satellite sensor data. Ground measurements related to productivity are required in order to evaluate these estimates. MXD from three boreal sites was compared with estima...

The flora of Carrizo Arroyo is typical of a seasonally moisture-limited environment. Dominant elements were conifers, callipterids and the pteridosperm Sphenopteridium, all plants usually associated with indicators of seasonal moisture regimes. More generally, the Virgilian-Wolfcampian transition was a time of change from dominance of the tropical landscape by floras rich in tree ferns, pterido...

Efficient acquisition, assimilation and economy of nitrogen are of special importance in trees that must cope with seasonal periods of growth and dormancy over many years. The ability to accumulate nitrogen reserves and to recycle N determine to a great extent the growth and production of forest biomass. The metabolic relevance of two key amino acids, arginine and phenylalanine, as well as othe...

Haploids are a valuable tool for genomic studies in higher plants, especially those with huge genome size and long juvenile periods, such as conifers. In these species, megagametophyte cultures have been widely used to obtain haploid callus and somatic embryogenic lines. One of the main problems associated with tissue culture is the potential genetic instability of the regenerants. Because of t...