Ask Mr. Smarty Plants

Cupressus glabra, smooth bark cypress is not listed as such in our Native Plant Database. It is, however, a synonymn for Cupressus arizonica ssp. arizonica (Arizona cypress), - which is also called smooth bark cypress. In the information we could find about this tree there was no mention of exploding tree bases to extinguish fires from lightning, nor of toxic smoke from berries. Actually, the Cupressus does not have berries, but cones. The base of a tree is part of the anchoring system of the tree, and also part of the transportation system, carrying minerals and water from the soil to the rest of the tree, and returning the food manufactured by the leaves for the continued nutrition of the tree. There really is no place there for storage of water, although, of course, water is stored in the roots. Perhaps some of this slighty skewed information may have come from the fact that the seed-bearing cones often remain on the tree for many years, and the seeds may be finally released by fire. 

In fact, in Yellowstone in the terrible fires of 1988, a species of pine, Pinus contorta (lodgepole pine), helped to reforest the hillsides because of the fire dependency of the seeds in the cones.  This variety is adapted to forest fires, often with cones that remain tightly closed on the trees many years until a fire destroys the forest. When the heat causes the cones to open, the seeds fall to the bare ground to begin a new forest. This variety is also able to reproduce without fire, and in some areas most of the trees release their seeds without the heat of fire. Pinus and Cupressus genuses are related insofar as both belong to the Order Pinales, and both are cone-bearing. 

So, sorry, we couldn't substantiate this story. Possibly when lightning hits a cone-bearing tree, the heat generated by the electricity could cause some of those cones to explode or flare up suddenly, and perhaps that's where the story came from.

Pictures of Cupressus arizonica (Arizona cypress) and its cones.

Pictures of Pinus contorta (lodgepole pine) and its cones.