It is found in many guises: Johannisberger, Weisser Riesling, Rhine Riesling, Ryzlink Rýnský or, in its spiritual homeland of Germany, simply as Riesling. It is the world's most highly rated white grape variety.

Riesling's origins suggest it may have descended from the original wild grape Vitis Silvestris. It has long been the pride of vineyards lying more or less along the latitude of Alsace in eastern France, into the Rhineland and on to Saxony, deep in former East Germany. That line extends into the Czech Republic, with the best Riesling sites lying along the Elbe valley in areas such as Roudnice, Melník and Zernoseky. In Moravia, it gives a very different expression: floral with slightly mineral undertones.

The Riesling vine grows vigorously, with wood tough enough to resist the most extreme conditions of cold and frost - which is as well, since it is a late ripener - making it eminently suited to extreme conditions on the edge of wine regions. But it demands the best of these sites, the precipitous south-facing slopes in the Rhine and Mosel valleys being prime examples.  

Typical Riesling lends amazing, steely wine with high acidity and noticeable mineral qualities. Pronounced notes of petroleum come to the fore, especially as the wine matures. Late-harvest versions are full of peach and apricot tones, while wines with special attributes (Prädikat or jakostní víno s prívlastkem in Czech) can be packed with spiciness and have great aging potential.

As a point of interest, the oldest Riesling in the world is dated 1540, from a barrel that was hidden from the marauding Swedish Army in Würzburg. Noted authority Hugh Johnson describes being taken to a tasting of this wine, by then in bottle, as a young man in the 1960s. The wine was extremely deep in color, with a pronounced nose that, after half a minute, completely disintegrated, just like Tutankhamen's mummy when it was exposed to sunlight. Two bottles still remain - one in a German museum, the other in the care of the cellarmaster of Queen Elizabeth II of England.  

For those interested in this variety, the annual Riesling Gallery exhibition takes place in Prague March 7 and 8 at the National House of Wine, a new four-story establishment dedicated to local wines, on Mostecká street (between Charles Bridge and Malostranská). Also, every August a Riesling tasting is organized in the south Moravian town of Bzenec. Although most entries were local, last year saw a noticeable increase in wines from Austria, Germany and Alsace. Medal winners are available for sampling throughout the show. (For more information, check www.galerierr.info.)