I am a giant, intelligent, fortress-like, plant-based organism, able to forge many structures, defenses and organisms from my flesh by altering my own DNA and rapidly growing new constructs whenever and wherever I please. I have recently developed a new way to fend off the humans trying to kill me: a large (about the size of an exercise ball), hollow, melon-based fruit filled with multiple volatile chemicles. The melon is hurled sling-like by a large vine arm into the enemy. When the melon breaks, the chemicals mix, causing a sizable explosion.
My question is, are there chemicals found in plants (or able to be aquired by plants) that would serve this purpose? I'm looking for two (or more) volatile chemicals that violently combust when they come in contact with eachother.