Lemon basil, Thai lemon basil or Lao basil (Ocimum × citriodorum) is a hybrid between basil (Ocimum basilicum) and African basil (Ocimum americanum).The herb is grown primarily in northeastern Africa and southern Asia for its strong fragrant lemon scent, and is used in cooking.Lemon basil stems can grow to 20–40 cm tall. It has white flowers in late summer to early fall. The leaves are similar to basil leaves, but tend to be narrower.