The TSA released the following guidance:
Religious Holiday of Sukkot
The travel period for the Jewish holiday of Sukkot is from September 19 through October 4, 2010.
Observant Jewish travelers may carry four plants – a palm branch, myrtle twigs, willow twigs, and a citron – in airports and through security checkpoints. These plants are religious articles and may be carried either separately or as a bundle. Jewish travelers may be observed in prayer, shaking the bundle of plants in six directions.
TSA’s screening procedures do not prohibit the carrying of such agricultural items through the airport or security checkpoints, or on airplanes. These plants are not on TSA’s Prohibited Items List. And, as always, TSA is committed to treating all passengers, including passengers who may be observing Sukkot, with respect and dignity during the screening process.