To be fair Carrie (preview chapter spoilers, since you're not reading them):
"Lemon Trees don't grow in Bravos but we're told they do" comes up in a bit of dialogue in the Mercy chapter. In the form of one of the soldiers looking for Lemons and not finding any.
“Seven hells, this place is damp,” she heard her guard complain. “I’m chilled to the bones. Where are the bloody orange trees? I always heard there were orange trees in the Free Cities. Lemons and limes. Pomegranates. Hot peppers, warm nights, girls with bare bellies. Where are the bare-bellied girls, I ask you?”
edit:
He's even answered with
“Down in Lys, and Myr, and Old Volantis,” the other guard replied. He was an older man, big-bellied and grizzled. “I went to Lys with Lord Tywin once, when he was Hand to Aerys. Braavos is north of King’s Landing, fool. Can’t you read a bloody map?”
Also,
CarrieVS wrote:Plenty of families besides the Targaryens have Valyrian blood and the accompanying tendency to white hair and purple eyes. (Notably the Daynes, and one of my wilder theories was that Ashara and Ned's baby was not actually stillborn, which has the pleasing symmetry, if R+L=J, that the boy believed to be Ned's son is Rhaegar's and the boy believed to be Rhaegar's son is Ned's.)
If there's one thing I agree with Preston Jacobs on* it's the importance of Ashara Dayne to the story of R+L and J. All the evidence points to Ned having a real bastard, no matter how much people paint him as the only uncomplicated character in GRRM's books, or as a gullible foil to the scheming.
His theory is that R+L = D and Ned's kid is Jon Snow, but he also thinks it's a completely irrelevant question given inheritance in aSoIaF doesn't matter because of how intrigue and the fog of war works, and this by far is GRRM's view on the subject as well, as far as his writing shows.
By the end of the War of Five kings, the common folk believe that Cersei is incestous and not, that Joffrey was a bastard and the true king, that the Lions and Wolves are both terrible for the country and respectively the righteous people who want to save the country from the usurpers, that the Targaryens weren't all that bad (There aren't many who seem to think they were for some reason). So in the end, lines of inheritance in aSoIaF are irrelevant. So in his opinion, R+L=? just sets up a minor irony and doesn't do much more than that. So if it was D it would fit better with Ned's insistence that Dany not be killed off, as well as explain the Dayne and Red Door mysteries, while if it was J, it would fit into the Aragorn RIGHTFUL KING plot, something GRRM doesn't want to do. Of course, that's not to say R+L=J isn't an aragorn subversion too. It's just not as strong a one as Dany (someone the plot is building up to be the greater scope villain for the Westerosi) being the rightful ruler of Westeros.
*-(there's a lot. He's really good at making GRRM's books coherent and the only issue I have with him is how he seems to think the Sci Fi equivalent of magic is more legitimate than the fantasy equivalent of magic when they're both the same thing, to the extent that one of his theories is basically "Danaerys can't control fire, she has pyrokineses" WHICH GODDAMNIT)