Shore plants, like watermint, are important for erosion control, food sources, animal habitat and simple waterline beauty. What is watermint? Growing watermint around the pond will add fragrance in the summer blooming season and attract butterflies and pollinating insects. The midsummer blooms are caps of tiny florets amassed into a larger flower in deep hues of purple to blue, creating a beautiful effect. Watermint has thick dark green leaves tinged with purple, deeply veined and slightly hairy. Like all mints, this plant spreads with long runners, which root at nodes and create daughter plants. It has the tendency to become invasive, so plant in a container to prevent invasive growth.