Plectranthus is a large genus, with approximately 325 annuals or subshrub species. These are characterised by toothed, herbaceous, semi-succulent or succulent foliage. Plants produce spike-like inflorescences, with flowers arranged in whorls or cymes. In cymes, a central stem produces a flower at its growing tip first, followed by flowers from the ends of subsequent lateral shoots. Flowers are 2-lipped and showy with attractive patterning, coloured a shade of white or purple to blue.