A friend of mine shared a mind-blowing theory with me: all plants and trees are trying to kill us. They're just moving too slowly.
Next time you're near a plant, really look at that plant. Note how it's reaching out for you, no doubt in the hopes of suffocating you with leaves, or strangling you with twisted vines. Note how their roots are trying to ensnare you, or rip up the concrete where you stand. Note how they're storing ammunition to fire at you, like acorns or pollen. Think about it.
That's why whenever I see leaves on the ground, I look up to the nearby branches and shout "is that the best you got, mother fucker?"