Ok so they're not actual truffula trees. They're the seed heads of Sugarbowl Clematis (Clematis hirsutissima var. scottii), which look like this when in bloom:
Sugarbowl Clematis is native to Wyoming, Colorado, South Dakota, Utah, Oklahoma, New Mexico and western Nebraska, and grows in the foothills of the mountains as well as woodlands and mountain meadows. Not exactly the same habitat as truffula trees.
But couldn't you just imagine the Lorax wandering about the garden, singing and jumping and being his jovial little self?
Well, it was fun to dream. Here's to the inner child in each of us!
Written by Brenna Marsicek, UW Biodiversity Institute