White Kryptonite

WHITE KRYPTONITE

This scarce form of kryptonite, which is harmless to Superman and all other Kryptonian survivors but emits a radiation that “destroys all plant life,” was brought into being when a flock of green-kryptonite meteors passed through a weird “space cloud” somewhere in the vast reaches of interstellar pace. Supergirl uses a chunk of white kryptonite to destroy the diabolical extraterrestrial “plant intelligence” Xasnu in July 1961 (Act No. 278: “The Super Powers of Perry White!”).[[]]