Basil (Ocimum spp.) is a member of the mint family. There are several species and numerous interspecific hybrids. The most common culinary type is sweet basil, O. basilicum, which also has purple and lemon-scented cultivars.  Specialty types include Thai (O. tenuiflorum), lemon (O. americanum X O. citridorum) and small-leaved bush types of various species and crosses. Basil seed is not always true to type. Try to obtain high quality seed that is uniform with a high germination percentage (New England Vegetable Management Guide.)