ETA.... while this premise was 'onto something', a decent conclusion was only reached in-thread. To save reading through the thread i have summarized the most plausible conclusion here....
Throughout the books, Dany thinks of the one place she was truly happy.
"That was when they lived in Braavos, in the big house with the red door. Dany had her own room there, with a lemon tree outside her window"
This place is supposed to represent the lost notion of 'home' for Dany. However, there's one problem...
There are no lemon trees in Braavos.
Lemons are now cultivated widely and freely in our World, due to advances and needs, but in medieval times, in the western World, lemon orchards were cultivated only in Mediterranean areas. The lemons could be preserved to be sent afar, and even frozen. This explains how, in Westeros, we see lemon cakes in Winterfell and lemon slices at the frozen Wall. However, lemon trees only grow in the correct climate - and the only correct climate in Westeros is likely to be Dorne.
Anguy and Sharmas' conversation highlight this point, when considering if he can have lemon with his duck supper:
“Hang this,” she said, handing him the duck. Anguy shuffled his feet. “We were thinking we might eat it, Shama. With lemons. If you had some.”
“Lemons. And where would we get lemons? Does this look like Dorne to you, you freckled fool? Why don’t you hop out back to the lemon trees and pick us a bushel, and some nice olives and pomegranates too.”
No other places are mentioned to be growing citrus, and whenever we're in Dorne we're continuously reminded of citrus smells in the air, oranges, lemons etc.
Dorne has two things vital for lemon trees. Copious sunshine, and fresh water irrigation.
"Beyond a line of stony hills the grass grew greener and more lush, and there were lemon orchards watered by a spider’s web of old canals."
Braavos has neither the sunshine, nor the freshwater needed to grow lemon trees.
Braavos is a collection hundreds of Islands sitting at sea level in a vast lagoon. The purity of the water and soil is a problem - there's a big chance it could be very infertile for plant and tree growth in general. Also, the canals are not freshwater like in Dorne, Sam has to boil it before drinking (indicating likely brackish water).
"the water from the lagoon is brackish, briny and unfit for drinking".
GRRM reminds us again and again, via Arya and Sam, that trees rarely grow in Braavos. The soil could be poisonous to most plant-life, and lemon trees are far more demanding than a standard tree. There's no grass!
Braavos, devoid of grass and trees
They have no trees, she realized. Braavos is all stone, a grey city in a green sea.
In the forest, they see all. but there are no trees here
"There's no more wood." Dareon had paid the innkeep double for a room with a hearth, but none of them had realized that wood would be so costly here. Trees did not grow on Braavos, save in the courts and gardens of the mighty."
ETA - see a much better conclusion put forth in the in-thread discussion
Edited by yolkboy, 28 March 2014 - 09:13 AM.