Being a bit pedantic (and possibly ignorant) here, but surely like Jake says Salix alba grown in England is English White willow, but Salix alba grown in India is Indian white willow.
But I guess where it could get confusing is if the IWW is grown from saplings raised in England brought over to India, then it could be English willow nurtured in India. But is there a point in its life where it becomes Indian willow - What would the export information say if they sold it as felled trees and shipped it to another country?
Stretching this a bit with an alternative example - if you bought a whole load of italian olive saplings, shipped them to the UK, planted, and a few years later produced some olive oil from the olive crop, would it be called Italian olive oil, English olive oil, or Italian olive oil nurtured in England?