Cactus

Though Cosmos atrosanguineus (Chocolate Cosmos) is Tyson’s favourite flower, he honestly adores cacti.

There is a tiny cactus in his apartment living room, which despite his only green-ish thumb Tyson has managed to keep alive, and the wrap-around patio of his army home in all applicable verses is completely covered in various types of cacti.

From a mathematical standpoint cactus plants are rather interesting showcasing many different forms of geometry, and he finds that aesthetically pleasing in general. 

More accurately, Tyson just likes prickly things. He had a bad habit of collecting things with sharp edges, metaphorical or physical, and then taking care of them regardless of consequences. Cacti, at least, are content to be spiky without hurting him.