When cast, this spell transforms the caster's bare feet into roots that burrow deep into the ground. By absorbing nutrients from the soil, the caster can go without regular food or drink for one day for every two levels of the caster. Therefore, a 6th-level priest could go without eating for three days. It takes 1 hour to absorb a day's worth of nourishment, so that same priest must stay rooted for 3 hours for the spell to work.
This spell goes unnoticed in areas with rich soil (such as forests or swamps), but it severely depletes barren areas (such as scrub plains or savannahs). Therefore, druids use the spell sparingly.