Canaiolo - (also known as Canaiolo Nero) - is an indigenous Italian red wine grape grown in central Italy, but is most well-known in Tuscany. Other regions with Canaiolo vines include; Lazio, Marche and Sardegna. Together with Sangiovese and Colorino it is often used to create Chianti wine and is an important though small component of Vino Nobile di Montepulciano.
In the history of Chianti it has been a key varietal and during the 18th century may have been the primary grape used even more so than Sangiovese. Required by Italian law to be one of the grapes in every bottle of Chianti - Canaiolo is a high-producer and is very resistant to disease. The best sites can produce a nice combination of very ripe strawberries and leather characters.

 

Another note for its popularity is the grape's ability to partially dry out without rotting for use in the ‘governo’ method of prolonging fermentation.
Ampelographers believe that Canaiolo is most likely native to central Italy and perhaps to the Tuscany region. In the 19th century, the Baron Bettino Ricasoli created the modern Chianti wine recipe that was predominantly Sangiovese with Canaiolo added for its fruit flavours and ability to soften the tannins of Sangiovese.
Wine authority ‘Hugh Johnson’ has noted that the relationship between Sangiovese and Canaiolo has some parallels to how Cabernet Sauvignon is softened by the fruit of Merlot in the traditional Bordeaux style blend.

After the phylloxera epidemic at the end of the 19th century, Canaiolo vines did not take well to grafting onto new American rootstock and the grape began to steadily fall out of favour. As of 2006, total plantings of Canaiolo vines throughout Italy dropped to under 3000ha. Today there are only a few vineyards in the Chianti Classico region specializing in Canaiolo - though there are renewed efforts by Tuscan winemakers to find better clonal selections and re-introduce the variety.