this meyer lemon from costco has a rootstock tag that says IMMFDG, which translates to improved meyer lemon on flying dragon rootstock. The contorted close crossing upper root knuckle for lack of a better term (I planted high?) is extremely thick. but I'm having difficulty believing that this is actually flying dragon and not some other trifoliate relation based on its size. Isn't flying dragon painfully slow growing? The root stalk is an inch thick easy.

I mean to produce this grafted tree would take how long just to get the rootstock that big?