Heat treated aspen is a popular material for the interiors of a sauna.
Aspens are trees of the willow family (Salicaceae) and comprise one group (section) of the poplar genus—Populus section Populus—with six species.
Emigrant Basque shepherds in the nineteenth and twentieth century carved texts and figures on aspens of the American Southwest to express their loneliness.
The five typical aspens are distinguished from each other by leaf size and the size and spacing of the teeth on the adult leaves.
Aspens typically flower in March and April, prior to the appearance of the leaves (TL 2007).
Shrimp and other shellfish are among the most common food allergens (FAAN 2007).
Aspens are dioecious (trees are either male or female).
Aspen has an extensive root system (TL 2007).
Aspen trees have the widest distribution of any native tree species in North America, and worldwide—the only trees with wider natural ranges are Populus tremula (European aspen) and Pinus sylvestris (Scotch pine) (Nix 2007).
Aspen's main reproductive method, however, is vegetative, with new suckers or ramets (vascular bundles, the intra-net system of plants), growing off the roots of mature trees (TL 2007).
The cross that Christ was crucified on is sometimes said to have been aspen wood.
Aspens are all medium-sized deciduous trees reaching ten to 20 meters tall, sometimes even 30 meters.
A German version claims that the aspen was the only tree to refuse to acknowledge the divinity of Jesus.
Aspens (apart from the aberrant White Poplar) are distinguished by their nearly round leaves on mature trees, four to 12 centimeters in diameter with irregular rounded teeth.
Aspen wood is white, and soft, but fairly strong, and with very low flammability.
Fire indirectly benefits aspen trees, as it allows the saplings to flourish in open sunlight on account of the burned landscape.
Some aspen colonies become very large with time, spreading about a meter per year, eventually covering many hectares.