Ral Benem came to Earth in the latter half of the 30th Century from his native world of Mardru to apply for membership in the Legion of Super Heroes. His power to stimulate plant growth, acquired when he accidentally fell into a tank of hydroponic serum as a child, was pronounced inadequate and he was rejected.
Disappointed and uneager to return to life as the governor's gardener on Mardru, Ral stayed in Metropolis looking for work. It was there that he was contacted by Polar Boy, who asked him to join the Legion of Substitute Heroes. Ral happily joined the Subs, but also kept working as a consultant at several Metropolis area arboretums and garden shows.
Ral has faithfully served on the Subs for most of their existence, taking a break only once when he developed a weight problem.
Chlorophyll Kid has the ability to super-accelerate the gestation and growth of any plant life. He does this by casting radiation from his hands that can make plants grow to unbelivable sizes almost instantly. He can also control the growth patterns of the plants.
Ral also claims that he has the ability to communicate with plants, but no one believes him.