johnp -- I knew my forestry education would come in handy some day...
The wood pictured is one of over a dozen species of genus Populus common to North America, infected by fungus during the dying process - aka 'spalted'.
There are about 25 species of poplar/cottonwood in the genus Populus - in several categories : White and Black Poplars, eastern & western Poplars, Aspens, Balsam Poplars, Bigleaf Poplars, etc.
Liriodendron tulipifera has a name that for some reason has tickled my fancy since I learned it over 40 years ago. Common names include Tulip Tree, Tulip Poplar, Whitewood, Fiddlewood, and Yellow Poplar. It is NOT a poplar, but rather a unique member of the Magnoliaceae family. Like the Magnolias they produce large pinkish-white flowers in the spring. They are one of the largest North American trees, being known up to 190 ft tall and over 10 ft in diameter. Thirty years ago in Ohio I personally surveyed a 20 acre section of bottom land that had only 46 trees, each at least 150 ft tall and 8 ft in diameter with clear trunks at least 70 feet before the first branch. Absolutely magnificent trees!
The tree is called "tulip" because, of course, of the distinctive shape of the leaf, which appears something like a tulip in profile, as does the Liriodendron flower itself: