Basil Amethyst : "Ocimum Basilicum" A almost-black basil with nice, large, thick, turned-down leaves. Amethyst Basil is the only purple variety of Genovese-type basil. This basil can be used in any sweet basil recipe just remember, it can turn your dish a darker color. Also great in flower arrangements and as a garnish. Plant grows 18 to 24" tall and is a annual.