Last week I bought some unidentified tropical lumber that was imported from Paraguay in the 1980's.  The seller mentioned that the US Forest Service has a wood identification service. Here are the address and the form that has to accompany each 1 X 3 X 6" sample.

Individuals can submit up to three samples and the service is free.

Wood Identification Public Service  
Center for Wood Anatomy Research  
USDA Forest Service, Forest Products Laboratory  
One Gifford Pinchot Dr.  
Madison, WI 53726-2398