The water hawthorn, also known as Aponogeton distachyos and Cape Pond Weed, is an aquatic plant that is native to South Africa, and cultivated as a decorative pond and aquarium plant in other parts of the world. In some cases, as in Australia, it has become naturalized in the wild. The plant is notable for its small white and purple flowers that have a delicate vanilla-like scent. The flowers and the tuber roots are edible.
The plant grows from underwater tuberous rhizomes that send out long petioles to the water surface. These petioles can grow up to 20 feet (6.096 meters) in length. The leaves float on the water, and are dark green and often mottled with brown.
The water hawthorn flowers, which generally appear between May and September, are produced on Y-branched spikes which are held above the water. The flowers are small, with waxy petals and black anthers. They are scented, as mentioned, and rather attractive with their white and purple coloring. The water hawthorn generally stops flowering in summer months.
These deciduous plants are propagated by tuber division and by seeds. The seeds, which are produced quite prolifically, can be found floating on the water surface. They can be collected and planted in about three inches (7.62 cm) of water. The water hawthorn tuber can be planted in about an inch (2.54 cm) of soil at a depth of around 18 inches (45.72 cm). It's best to sow seeds and tubers in individual pots and transfer to a deeper depth once the plant has developed sufficiently.
Water hawthorns are pond plants that are quite easy to care for. They can be planted in still ponds as well as in slow-moving streams. These aquatic plants require full sun to thrive, but they can grow well in partial shade as well. The plant grows fast and can spread at least three feet (0.91 meters) across. It is often planted in conjunction with water lilies. In the natural state, the water hawthorn grows in the rainy season and the tubers remain dormant in the dry months when the pond dries up or in the cold months when the pond freezes over.
In South Africa, the water hawthorn roots, young shoots and flowers are considered quite a delicacy. The tuber roots are roasted and eaten. The flowers are pickled or are used to flavor waterblommetjie stews, roasts and salads. The young shoots can be cooked as a vegetable.