That Picasso story sounded vaguely familiar to me, so I looked through my rose books and found it in one that I had devoured with such enthusiasm and speed that I apparently didn't retain enough of the information in my mind.
When Mike was here last year, he gave me a great book for my birthday, "A Rose by Any Other Name," by Douglas Brenner and Stephen Scanniello. It's full of fascinating tidbits about rose names. Anyway, according to those authors, Picasso didn't really want to be paid for having the rose named after him. What happened was that Sam McGredy wanted to name the rose "Picasso" and wrote to Picasso to ask him for a signed letter of permission, because he needed to show it to the patent office. Picasso refused, saying that his autograph was worth $10,000 on the international market and he didn't want to give it away. His manager signed the letter of permission instead. It's still a good story, but not quite as smarmy as the first one.