Cacti escape fire in refugia and in areas with fuels too sparse to carry fire. Although desert vegetation rarely burns completely due to a lack of continuous fuels, unusually heavy winter rains may produce a cover of annual species dense enough to carry a fire when cured. Most desert habitat does not produce enough vegetation to support frequent fires. Succculents in general rarely actually burn, but spines may ignite and carry flames to the apex. The cactus body may scorch and blister without pyrolysis, leaving undamaged parts of the plant alive.
Mortality results from death of the photosynthetic tissue and underlying cambium and phloem.
Cacti may appear completely scorched with no green tissue visible, yet survive fire. Survival of succulents depends primarily on protection of the apical meristem. Two consecutive winters of heavy rain produced enough fuel to carry a fire in a portion of the Sonoran Desert where fire is usually considered ecologically insignificant. Following the Granite Fire in Arizona in June 1979, large-diameter cacti including barrel cactus had the lowest mortality rate of all cacti. Many severely burned plants survived and produced flowers and seeds.