• Aspen clonesaspen grove image by Carbonbrain from Fotolia.com
  
  Two common types of aspens are the quaking aspen and the bigtooth aspen. Aspens are deciduous hardwood trees that grow to heights of 40 to 70 feet and are distributed widely in North America. The tough pulpwood is used by farmers for floors, posts and horse stalls. Its primary use is for paper because it is inexpensive, easy to peel and bleach and the pulp, when mixed with additional strong fibers, produces quality paper products. These trees are short-lived and survive about 40 to 60 years.
  
  

Identifying Characteristics

• The smooth greenish-white trunks of aspen trees have a diameter of one to two feet. The bark of older aspen trees will split repeatedly and the furrows will become a dark gray. Aspen trees will self-prune lower branches and leave behind eye-shaped black scars. The bright green, simple, toothed, round leaves turn yellow in the fall and produce a characteristic fluttering. The undersides of the leaves are a contrasting silver color. The fluttering is attributed to having long flat leaf stems instead of round stems that are attached to the blades at right angles. Shade-intolerant, aspen trees have a sun seeking canopy and a luxuriant understory and generally grow in evenly-aged pure stands.
  
  

Flowers and Seeds

• There are female and male aspen trees. The male trees are found at higher, harsher elevations while the female trees tend to grow in protected, moist pockets. The male flowers appear earlier than the female flowers. During flower development, the male anthers and female stigmas both have a red color. As the female flowers mature, the catkins become longer and the capsules expand. The seeds within the capsules are considered mature when they are pink or brown.
  
  Aspen trees can reproduce from seeds but the mature seeds are only viable for two to three weeks. The seeds require a moist environment and need full sunlight. Fields with compacted, moist and bare mineral soil or banks are good spots for seed germination. The seeds are dispersed by wind or hand.
  
  

Regeneration

• Aspen trees usually reproduce asexually by producing clones or suckers from the roots. If a grove is clear cut or disturbed by environmental causes, a mature root system, according to Douglas Johnson from San Francisco State University, can send up 400,000 to 1 million shoots per acre.
  
  

Fire

• Fire has a dual effect on aspens. Historically, fire has been the catalyst for regeneration and cloning, however, aspen trees don't burn easily. Nicknamed the asbestos tree, when a grove does burn, the roots put energy into sprouting suckers.
  
  

Bark

• With its white bark and black markings aspen trees may be confused with birch trees. However, the bark of aspen trees does not peel like birch bark. The outer white layer of aspen trees is its living layer and is capable of photosynthesis. Consequently, when scratched or carved, the wounds will turn black.