Sproutling, A.K.A. Experiment 509-A, is the son of Sprout. He was the genetic experiment born from Sprout's molecules. Like his father, it became a killer plant. Sproutling's experiment pod didn't have any number because he was born via Sprout.
Although Sprout reappeared in the Japanese version of the Stitch! anime and was mentioned by Jumba who still lives on Kauai, he instead has a son named Sproutling, codename: Experiment 509-A. He first appeared in "Son of Sprout", because he was born via Sprout planting to the meteor. Following his birth, Sproutling carried out his father's original programming before eventually being neutralized.
Sproutling reappeared in "Sprout 2.0" where he was captured by Gantu, who used him to genetically enhance the DNA of none other than Experiment 627. He was returned back to his normal state after 627's DNA was gone.
- Because the Japanese version of Stitch! is non-canon when Sprout still existed, Sprout stays in Hawaii. Thus, the English dub of the anime turns out to be canon to the TV series.