Plectranthus neochilus or Dogbane is a fast growing perennial herbaceous plant that makes a low mat of musky scented foliage that is often used to repel dogs - as they dislike the odour intensely. Hence the common name of 'DogBane'.
Their pretty mauve flowers, that appear in short dense spikes, do however attract pollinators to your garden - so this is a double delight sort of plant.
This is a very effective companion plant especially in vegetable gardens as it repels, snakes, mosquitos, flies and many garden pests.