There are many different types of basil, however the succulent, large-leaved, sweet basil is by far the most popular variety for culinary use. Basil's refreshing, clove and anise-like aroma conjures p memories of summer, hardly surprising when one considers how this warmthloving annual thrives in the heat and expires with the first chills of winter. Sweet basil plants grow to around 20 in. (50 cm) high and even more in ideal conditions. The stems are tough, grooved and square with dark-green, oval, crinkly leaves from 1 in. (30 mm) to 4 in. (100 mm) long. The tiny, white, long-stamened flowers should be nipped off to prevent the plant from going to seed and finishing its life cycle. This will also encourage thicker foliage and hence more abundant harvests for the basil-loving cook.
The taste of sweet basil is far less pungent than the permeating, heady aroma of the freshly picked leaves would suggest, thus large quantities can be used with safety. Dried sweet basil leaves are quite different from the fresh, and although the fragrant, fresh-smelling top notes disappear upon drying, a concentration of volatile oils in the cells of the dehydrated leaves give a pungent clove and allspice bouquet. This is matched by a faint rninty, peppery flavor that is ideal for long, slow cooking.
Other varieties of basil are bush basil which has small leaves 1/3 -1/2 in. (10-15 mm) long. It grows to about 6 in. (150 mm) high and the foliage has a less pungent aroma and lower flavor-strength than sweet basil. The two types of purple basil, serrated leaved 'purple ruffle' and the smoother 'dark opal basil' mainly grown for decorative purposes, have a mild pleasing flavor and look attractive in salads and as a garnish. 'Hairy basil' or 'Thai basil' has slender oval leaves with deep serrations on the edges and a more camphorous aroma than sweet basil. Although the seeds of this variety (referred to as subja in India) have no distinct flavor, they swell and become gelatinous in water and are used in Indian and Asian sweets, drinks and as an appetite suppressant.
Holy basil or tulsi as it is called in India, has mauve-pink flowers, is perennial and is lightly lemon scented. Cinnamon basil has a distinct cinnamon aroma, with long, erect flower heads. It is also an attractive plant and its leaves complement Asian dishes. The perennial camphor basil (O. kilimanscharicum) is not used in cooking, but its distinctive camphorous aroma makes it a pleasant decorative herb to have in the garden.