The white tree was a symbol of renewal descended, as it was, from Nimloth the Fair the tree of Númenor and before that from Galathilion of Telperion in the Deathless Lands. Thus there remains a link between the peoples of Gondor and the Valar and High Elves but it is a link contained in something that is dead.
Also question is, what kind of tree is the white tree of Gondor?
Silver Tree of Valinor
In respect to this, what country does Rohan represent?
Rohan and Gondor
Despite this, many academics link Rohan to one of the most powerful kingdoms of Anglo-Saxon England – Mercia, which was based in the Midlands where Tolkien spent much of his youth. Some also say the riders’ names are rooted in the Mercian dialect.