Gwäss is indeed a rare grape. In 1994 a mere 1.35 hectares were cultivated commercially in the Valais. Gwäss is the name given in Haut-Valais, Switzerland, for Gouais Blanc, also known as Président in France. Confusingly, it has a second Valasian name – Noir Valais.
Light yellow in colour, it has a lemon scented nose with grapefruit and green apple on the palate with some herbal notes and potentially high levels of acidity. It can age very well and the maturity acts to soften the acidity. Chanton’s 1991 is a particularly good example. Unfortunately, you will have to visit their vineyard to beg a sample!
Gwäss is a white grape variety that is believed to have originated in Croatia and which is important as the ancestor of many modern French and German wine varieties. This may have been the grape given to the Gauls by Probus (Roman Emperor 276-282), who overturned Domitian's decree banning grape growing north of the Alps. By the Middle Ages it was the most widely grown white grape in north east France and in central Europe. Gouais blanc was the grape of the peasantry - indeed the name Gouais derives from the old French ‘gou’, a term of derision befitting its traditional status as the grape of the peasants. Normally growing on flat land next to the better slopes where the nobility grew Pinot.
Having been widely grown in proximity to Pinot, the two varieties had many opportunities to cross and Gwäss is the parent to over eighty other varieties, the better known of which are modern day Chardonnay, Aligoté, Auxerrois, Gamay, Colombard and Riesling. The name Gwäss was first recorded in 1823. It's a vigorous high-yielding variety and traditionally produced wines with high acidity. Some stories tell that the Gwäss vines were planted around the edges of fields with other vines to protect them from thieves, the grapes being so acidic it put them off!