Thai Basil

What it is: A member of the ocimum basilicum family, which includes the bright green varieties used for pesto. With its purple stems and blossoms, the striking Thai basil has an effusive clove scent. Using Thai basil instead of regular basil is like playing a chord versus a single note, says South Dartmouth grower Eva Sommaripa of Eva's Garden.

How to use it: ''You don't want to put it in a soup and cook it for three hours," advises Beth Jensen, herb product manager for Johnny's Selected Seeds, a Maine-based farm and garden supply company. The plant's essential oils will break down with prolonged exposure to heat, says Jensen. Thai cooks call the plant bai horata and add the herb uncooked to dishes at the last minute.

At the Belmont restaurant Patou Thai, says co-owner Dan Tanabat, Thai basil is an important ingredient. ''We throw Thai basil into red and yellow curries at the end for the aroma. It's important to keep it fresh and see that bright green color." The basil also finds its way into garden rolls, which are made with rice paper and fresh vegetables.

Where to buy it: With the same growing season as other basil varieties, Thai basil might turn up at farmers' markets. It is also available at Asian specialty stores such as Super 88. If you can't find it, other varieties will do in a pinch. And if you have an abundance of the Thai type, ''you can use it to make pesto," says Jensen. -- LEIGH BELANGER