The Lorax's Environment
The "Truffula Trees" may have been large Nanam Rambutan fruits as trees. The Rambutan fruit has a fuzzy top like the Truffula trees and it also comes in pink, red, yellow and green. They grow on thin stems, like the Truffula's thin base, and have large tops that grow in clusters! The only real difference is that the inside of a Rambutan fruit is hollow while the Truffula's are composed entirely of silk.
The "Brown Bar-ba-loots" where very bear-like in stature and appearance. Almost exactly like the Brown Grizzly Bear.