Cir-cen are squat cactus-like plants, and the predominant form of desert plant life on Vulcan.
Virtually all types of cir-cen have a tough outer protective skin that can be penetrated only by a laser or sharp knife. This skin shields the plant from the worst ravages of the searing heat and is often covered by thorns or spines to protect it from animal predators.
The interior layers of the plant store water, and when sucked upon can provide a brief respite to those whose supplies have run low. Certain varieties of the plant, referred to in some parts of Vulcan as nor-cen, are characterized by an outer coating of sharp crimson spines; the pulp-like interior of this subspecies not only holds water but offers a tasty and nourishing repast as well. (Last Unicorn RPG module: The Way of Kolinahr: The Vulcans)