There have been a couple of posts in the past week on what exactly "petite sirah" is. The following is by Sean Thackrey, who probably knows more about the subject than any other winemaker:
"... They brought back what was considered to be the great clone for planting on any of the favored sites on the hill at Hermitage, and that clone was called, as it still is, 'Petite Syrah.' That's the origin of 'Petite Sirah' as a name in California. It was originally real Syrah from Hermitage and from a particularly good clone of Syrah and was sold and planted as such. The hard part to pin down is how the name came gradually to be applied (as it now is) as a grab-bag for virtually any otherwise unidentified black grape in any old vineyard. It’s just incredible, the amount of stuff that's called Petite Sirah. I’ve harvested at least four different varieties myself that were called (and still are by the people who own the vineyards) 'Petite Sirah,' and in fact bear no relation to each other."