The lettered edition of THE PLANT, PART 1 was clearly an afterthought. On the limitation page "and 26 lettered copies" is written in by hand along with the letter. But Parts 2 & 3 have the lettered limitation printed so they were clearly thought out beforehand.
THE EYES OF THE DRAGON limitation page makes no mention of a lettered state but there are apparently 26 red lettered copies and 26 black lettered copies. Regardless of the original intent, where the heck did they all go?