August is peak season at farmers markets. The best of summer -- stone fruit and corn -- lingers while crunchy grapes and apples start their comeback. But the quintessential comer in August is the tomato.

Hillbillies, Mortgage Lifters and Green Zebras fill the stands. My Brandywine tomato plant on the deck is not disappointing me, either -- rich tomato flavor, sweet, juicy and a good balance of acid. These heirloom varieties are favorites, but only the tip of the tomato world.

There are more than 100 California tomato growers producing tomatoes on approximately 37,000 acres, making the state the second largest tomato producer in the United States. And tomatoes are the fruit of choice for almost 90 percent of the 30 million or so home gardeners out there.

Any type of tomato left on the vine to ripen is a guarantee of optimum flavor. Other factors affecting flavor are in the fruit's genes, including acid, sugar and water content, and the texture of the skin and flesh. The closer you look, the bigger the differences become.