Cygne blanc

Cygne blanc is a white Australian wine grape variety that is a seedling of Cabernet Sauvignon that was discovered in 1989 in Western Australia. Unlike Cabernet blanc, which was a crossing of Cabernet Sauvignon and Resistenzpartner, and Shalistin which is a white-berried color mutation of Cabernet Sauvignon, Cygne blanc is a selfling that sprang from a seed of a Cabernet Sauvignon berry that fell on the ground and took root.

Indigenous to Australia, Cygne blanc has been touted as the "first truly Australian grape variety".

Cygne blanc, from the French term for white swan, is named after the Swan Valley where it was discovered in 1989 growing in a garden in Baskerville, Western Australia by Sally Mann, wife of winemaker Dorham Mann and daughter-in-law of Jack Mann, who noticed that the stray vine had leaves similar to Cabernet Sauvignon. The garden was planted next to one of the family's Cabernet Sauvignon vineyard and likely arose from a chance dropping of Cabernet Sauvignon seeds, either from dropped clusters and berries that decomposed, leaving behind the seeds, or from the droppings of birds or other wildlife which previous consumed the seeds and berries of the vine.

Unlike vine cuttings which are clones of the parent vines and color mutations which are mutated vines derived from cuttings, vines propagated from seedlings are distinct varieties with diverse genetics that can lead to the offspring having very different traits from the parent vine, even if the original seed was the result of self-pollination. In the case of Cygne blanc, the grape vine likely inherited its white berried trait from its grandparent, Sauvignon blanc, that crossed with Cabernet Franc to produce the red berried Cabernet Sauvignon.

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Wikipedia