Bright green leaves with a low creeping habit and white flower spikes. This mint is much less invasive than most. It is toxic if consumed in large quantities. We used to suggest planting it around areas where pets live since pennyroyal is used to repel fleas, but after many reports of animals eating pennyroyal and getting quite ill or dying we don't think this is a very good idea.
It prefers a shady, moist location to grow, however once established it can take dry shade very well. Plant it around shady moist walking areas. It may become more invasive if planted in very rich soil.