What is main herb in pesto sauce?

Ingredients
MAKES ABOUT 1 CUP
1 1/2tcups (lightly packed) fresh basil leaves
1/2 cup pine nuts, toasted
1/2 cup freshly grated Parmesan cheese
1/4 cup (packed) fresh Italian parsley leaves
1/4 cup fresh tarragon leaves
2 garlic cloves, peeled
1/3 cup extra-virgin olive oil

Preparation
Combine first 6 ingredients in processor. Blend until herbs are finely chopped. Add oil and blend to coarse puree. Season pesto to taste with salt and pepper. Transfer to small bowl. DO AHEAD Can be made 1 day ahead. Press plastic wrap directly onto surface of pesto and chill.