The morphology, systematics, and ecology of the extinct juglandaceous genus Polyptera are interpreted on the basis of infructescences, fruits, staminate catkins, pollen, and compound leaves from the Paleocene of Wyoming and Montana. The elongate infructescences of Polyptera manningii bear numerous helically arranged sessile fruits. The fruit is a pyramidal nut with a vascularized husk and a mul...

Reports that “own rooted” Chandler walnuts (Chandler clone) out preformed grafted trees stimulated the creation of this replicated trial to investigate the performance of Chandler clone trees, Chandler clone grafted to Chandler clone rootstock, Chandler clone grafted to three selections of paradox rootstock and Chandler clone grafted to a vigorous English rootstock. Rootstock trees were planted...

Phytostabilization aims to immobilize soil contaminants using higher plants. The accumulation of trace elements in Populus alba leaves was monitored for 12 years after a mine spill. Concentrations of As and Pb significantly decreased, while concentrations of Cd and Zn did not significantly over time. Soil concentrations extracted by CaCl2 were measured by ICP-OES and results of As and Pb were b...

Partially expanded male catkins of swamp white oak (Quercus bicolor Willd.) and red oak (Quercus rubra L.) were cultured on Murashige and Skoog (MS) medium supplemented with BA or 2,4-D. Explants on 2,4-D produced a yellow embryogenic callus originating from the junction of the pedicel and peduncle. Subsequent transfers to MS with BA and then MS without growth regulators resulted in callus prol...

Ea~,tern cottonwood (Populus deltoides Bartr.) is the subject of breeding programs designed to develop planting stock with potential for rapid growth, desirable wood properties, and pest resistance (4). Techniques for making controlled crosses within the species are essential to breeding, and their development constitutes an early phase of genetics research. This paper will describe techniques ...

Birch is the most allergenic tree species in Northern and Central Europe. Airborne birch pollen concentrations are observed to be on rise for several decades. Health hazard due grains (BPGs) can worsen particulate air pollution. The prevalence of intimate mixture BPGs with atmospheric matter (APM) at single grain level still unraveled. In this study, APM transfer mechanisms catkins prior pollin...