Ocimum

A tender warm-season culinary herb native to tropical Africa and Asia; grown as an annual in most US climates for fragrant edible leaves and as a kitchen-garden staple. Sweet basil is the species behind Genovese, Thai, and most ornamental purple basils.

Holy basil, or tulsi, is an aromatic basil from tropical and subtropical Asia with hairy stems, often purple-tinged leaves and a spicy taste that NC State Extension describes as a mix of clove, mint and basil. Outside frost-free zones 10 to 12 it is a warm-season annual, best grown in a pot or a herb bed and set out only once the weather is warm. It is sacred in Hinduism, and its leaves are cooked and brewed as tea. NC State Extension warns that it seeds itself readily and can be an aggressive weed outside its native range, so keep it in a container or a confined bed. Japanese beetles are its main pest, and cool, damp weather brings grey mould.