Pennyroyal (Mentha pulegium), also know as Pudding grass, is a lovely creeping British native plant which is great for wildlife that has strong peppermint scented leaves. It produces whorls of pretty tiny lilac flowers from July right through to October. It is less vigorous and smaller than its relative the Water mint, so is ideal for smaller ponds, and like Water mint it is also a good water conditioner. Note can be harmful if foliage eaten in large quantities but you would have to scoff 10kg of the stuff to be dangerous.
All of the mint family is a valuable source of nectar for bees and butterflies and the foliage provides food for a variety of caterpillars.
Planting position: Pond marginal shelf up to 15cm deep or very wet soil