If you don't have access to a plant, you can actually buy very large individual leaves of the stuff at Publix and other grocery stores. Slice it open, scoop out the slime, and apply it to your burned skin. Works great on any burn really, especially if you can put it on the affected skin quickly, the sooner after burning the better.
My wife also uses a Limelife product that works really well, she gave me some after I got burned a few weeks ago and the redness remained but it didn't hurt anywhere nearly as bad. Good stuff, expensive, but good.