Lindsay Lohan & Family Christmas Photo -- Guess Who's Missing?

The Lohans came together for a traditional family Christmas photo on Sunday -- but one person was conspicuously missing ...

While Ali, Dina, Mike Jr., Lindsay, and Cody chowed down in Long Island to commemorate the birthday of Jesus -- Michael Lohan was stuck in Florida ... completing his court-ordered 4-month stint at a treatment center, which includes a domestic violence intervention program.

Sources close to the Lohans tell us, it was pretty joyous -- lots of gifts, delicious food, and no one jumping off a 3-story balcony.