A. aborescens spines are soft. It’s endlessly tolerant, a friendly aloe. In the terrible rash of forest fires in 2008-09, photos showed a succulent fence of aloes could actually serve as a firebreak. The water stored in the leaves turned out to be astonishingly effective in slowing down or stopping the fires. The plants melted, released their water, looked terrible afterwards, but survived. Since a happy a. aborescens can easily top 5 -10 feet and have many spirals 5 feet across, a significant amount of water is stored in a living fence of these aloes. Planted as brakes to slow a fire, A. arborescens and opuntias can save homes.
http://www.gardeninggonewild.com/?p=7205#more-7205 http://www.insidesocal.com/uplandnow/2008/11/cal-poly-pomona-professor-give.html (more about opuntias later. )