Ocimum basilicum var. thyrsiflorum.

Thai basil has narrow leaves, purple stems, and pink-purple flowers. Its sweet, slightly spicy flavor is reminiscent of anise, licorice, and clove, and is more stable under high or extended cooking temperatures than that of sweet basil. Very attractive in cut-flower arrangements. 1-1.5'H x 1-1.5'W.

Basil - Ocimum basilicum var. thyrsiflora 'Siam Queen' (Thai Basil) (michlers.com)