Sémillon

Sémillon is a grape of two entirely separate reputations, and both of them are unusual.

In Bordeaux it is primarily a sweet-wine grape. Its thin skin makes it exceptionally receptive to Botrytis cinerea, and in Sauternes and Barsac it is the backbone of the world's benchmark botrytised wines. Blended with Sauvignon Blanc and fermented in barrel it also makes the long-lived dry whites of Pessac-Léognan, where it supplies the waxy, lanolin texture that lets those wines age for twenty years.

In Australia's Hunter Valley it does something no other grape does. Picked early at around ten or eleven per cent alcohol, unoaked, it produces a wine that is thin, neutral and frankly unremarkable on release — lemon juice and not much else. Left in bottle for a decade or more it transforms completely, developing toast, honey, buttered brioche and lanolin with no oak involved at all. The change is dramatic and remains only partly explained. Hunter Semillon was for years mislabelled Hunter Riesling, which confused matters further.

The grape's own character is low-key: lemon, apple, a waxy, faintly lanolin texture and moderate acidity. It is not aromatic and is generally at its best either blended or transformed.

South Africa has old plantings, and it was once the most planted white grape there.

It is a wine that rewards patience more reliably than almost any other white, and is priced as if it did not.

The Hunter Valley phenomenon deserves more attention than it gets, because it contradicts almost everything the wine trade believes about ageing. The wine is picked at very low sugar, sees no oak, undergoes no malolactic fermentation, and is bottled within months. On release it is thin and neutral. At ten to fifteen years it has developed toast, honey and buttered brioche with no external input whatsoever, which remains only partly explained.

In Bordeaux the grape's thin skin is what makes Sauternes possible, and the same thinness makes it vulnerable to grey rot in a wet year — the difference between a great vintage and a total loss can be a fortnight of weather.

It is also a superb blending partner for Sauvignon Blanc, adding waxy texture and ageing capacity to a grape that has neither, and the white Bordeaux blend is one of the most durable combinations in wine.