The Wangadi tree grows in the scrubland on the very edge of The Diamond Desert, a twisted, gnarled tree with iron-hard bark to protect it from browsing creatures, leaves that fold up into the branches when a browsing animal comes along, and large, tasty looking purple fruits. In most years, these fruits taste delicious and there is no danger to those animals and humans who eat them. The tree gets it's seeds spread, and those who spread the seeds get a tasty meal.
But there are years of deep drought where there is so little water to be found in the earth that the Wangadi tree is in danger of dying of thirst. When that happens, although the fruit looks the same from the outside, the tree makes it become explosive when the skin is pierced. Highly explosive. So the animal or human who eats one of these fruits will literally get his or her head blown off. If this happens close to the tree, the tree will send out roots through the ground that reach the body within a matter of hours, and grow up into the body so that the tree can suck out the moisture and nutriants to be found in the corpse.
This can provide the tree with just enough to keep it going until the rains arrive to give it water. Should a human take the fruit far from the tree before eating it, a seed or two always survives the explosion and a new Wangadi tree will start growing, fed well on the decomposing body beneath it, which it's roots will colonise within days, pinning the corpse to the ground.
Someone worth his or her salt who lives in this area knows when the fruit can be safely eaten and when it can be used as a grenade. Get it wrong, and you could either get your head blown off or pelt someone in a life or death fight with a soft,pulpy and totally harmless fruit.