"I will teach you how to grow a Void Sequoia tree, but not an ordinary one. I will teach you how to grow a rarer, more ancient variant called Void Stabilisation Sequoia tree, and from that I will require some sap and its first seed. That will be the payment after the fact.
"Before that, I will require a Genesis Oak seed and an Eternal Autumn Persimmon seed. When you have both, I will teach you what you need."
Lex was unfamiliar with the Void Stabilisation Sequoia tree, as well as the others mentioned by the turtle. Even though he had recently done a lot of research on trees, it made sense that information on rarer species was not so easily available. Since the turtle knew about them, they must exist. He was curious about them though.
"I'll see if I can get my hands on them, though I'll admit I've never heard of them before. Can you tell me a bit about them? That might help me find them."