Some of the Magic Trees listed in the Illustrated Book don't have Recipes. How do I grow these trees? Are there secret combinations to grow each one?
You have to combine three seeds of quality AAA, AAB or ABB, mixing them will result in a random magic tree from a selection of trees you can't get by recipe. The seeds can be in any order. I have no yet confirmed if including more A rank seeds means you get different trees.
Because A and B rank seeds create magic trees, I'd recommend only using C rank seeds to mix for other seeds (you can get random seeds above C rank this way). Consult this forum post for some more information:
http://126.96.36.199/forum/showpost.php?s=598202cf987e014ad56f937b296e0c0a&p=380378&postcount=33 (Can't linkify the URL)