To understand Caricature Carving you must start with the most commonly used wood, Basswood. Basswood is of the tree genus Tilia, or as it is most frequently called, the Linden tree. To us woodcarvers it supplies us with Basswood. This tree is found across North America and Europe and in the states is most likely planted as a specimen such as the gorgeous tree shown in my neighbor's yard. The tree grows in a triangular shape. This tree was photographed today and is showing the stress of the approach of fall as we are experiencing nightly lows in the lower 40's. To better understand the tree there are actually 30 trees in the genus, that's a lot of flavors and I can't begin to understand what grows where. For more information check out the Wikipedia link http://en.wikipedia.org/wiki/Tilia
Not that we really need to know which of the trees supply the best wood, there is already a preferred origin of what is commonly thought the best, that being the far north of Wisconsin and Minnesota. The wood emanating from this region in some fashion benefits from cold weather as it easily distinguishable from others with its white color and clear grain(block shown on left). Wood from other regions tend to be yellow in color and harder to carve. The lesser woods also have streaks and defects within the grain (block shown on right).
The alternative to Basswood is Butternut, which due to a disease affecting this species is becoming rare. Butternut is considered an excellent carving wood as well, however, it is seen in the Caricature category less frequently than seen in Realistic or Relief carving.
No matter what, the best advice when it comes to wood is to buy the best you can get. Over time you will be able to distinguish the difference and get more enjoyment from carving.