Purple leaves and stems, makes it most appealing for salads and garnishes. Another small difference from regular basil is that Purple basil has a stronger flavour. Evidence of a purple basil dates back to the 1830s, when the English botanist George Bentham first discovered an ‘opal’ strain of the plant. It wasn’t until 1950, however, that a genuine red/purple basil cultivar was created: the Dark Opal.