If a simple explanation is what you’re looking for, then yes, the Roots are a hip-hop band. But one listen to any of their 10 albums shows that they’re much more than that — a little soul here, some classic rock there, even bits of punk thrown in for good measure. The Philadelphia-based group, set to play at 8 p.m. Saturday at the Field House on the University of Maine campus in Orono, is a band that defies genres. Sure, there’s founding member Black Thought, who raps. But then there’s the full band, comprising Kamal Gray, F. Knuckles, Captain Kirk Douglas, Owen Biddle and the instantly recognizable drummer Questlove, with his iconic afro. There’s even a sousaphone player, known as Tuba Gooding Jr. Ranging from the band’s early, hit-making albums “Do You Want More” and “Illadelph Halflife” to the dark, complex, political recent albums “Game Theory” and “Rising Down,” the Roots have progressed from style to style over their nearly 20-year history. After all that, they joined the ranks of television history as the house band for “Late Night with Jimmy Fallon.” Their appearance this Saturday at UMaine will be their second, after a February 2001 concert at the Alfond Arena. Tickets are $20 for the general public, $15 for UM students, and are available at 581-1706 or www.umainetix.com.