Before my next group of posts about these grapes, a bit of background may be needed. I know, it sounds like work. All the heavy lifting is over though, you just have to read.
Jancis Robinson's brilliant Vines, Grapes and Wines proclaims them the same grape. The Oxford Companion to Wine lets on that they are essentially identical but leaves a little wiggle room. At the most extreme, cynthiana appears to be a mutation of norton.
The major difference appears to be local names for them. Dr. Norton cultivated the grape in Virginia where it remains best known as norton. Arkansas and Missouri also have significant plantings and pay homage to it as their state grape. Missouri as norton/cynthiana and Arkansas as cynthiana. At one time, according to Leon Adams' The Wines of America, it was called "Virginia Seedling" in Missouri. Clearly that moniker had to change.
The grapes make a serious wine that some describe as resembling zinfandel and others called claret, after the British term for Bordeaux. They are dry and do not exhibit the "foxy" aroma associated with many other native varieties. No, not like sexy, slinky or "She/he is foxy," this term refers to the aroma of a wine and likens it to an animal mustiness. Not appealing.
A norton wine from Missouri won a gold medal in Vienna in 1873. Of course, winning medals at wine competitions does not mean you have actually produced a great wine, just that you produced one better than the other dreck being judged.
Then Prohibition came along and essentially wiped out production. Since then a revival has occurred and more and more impressive versions continue to emerge. Riedel has even designed a glass specifically for norton wines. Norton glass Reidel is completely out of control about the variety of glassware offered in their catalog, so wild excitement about the recognition should be tempered.
I enjoy the grape a lot and need to read The Wild Vine by Todd Kliman, which tells the story of Dr. Norton and his grape from the early days until the recent resurrection. My next couple of posts will focus on this/these grape(s).
If you want to read more history, explanation, etc. this is a great spot to continue.
More on norton and Missouri