The best Argentinian white white is made from a sub-variety of the Torrontés grape - Torrontés Riojano, which is grown in the La Rioja region of Argentina and also in the Mendoza region.
The Torrontés grape is believed to be a hybrid of Muscat of Alexandria and Criolla Chica, and does particularly well in the dry climate of Argentina. It's the closest you can get to a national Argentinian grape.
It produces a dry white wine with a rich bold flavour and is often drunk as an aperitif.