Sea purslane (Sesuvium portulacastrum) is a common native plant — found just above the high tide line — that helps build the dunes on our Lowcountry beaches.
Although superficially resembling the colorful purslanes (Portulaca spp.) sold in garden stores, sea purslane is more closely related to a large family of succulent plants called stone plants or carpet weeds. Most are native to southern Africa. Sea purslane, however, is widely distributed in coastal areas throughout much of the world.
Like garden purslanes, sea purslane grows as a sprawling mat of thick, juicy stems and succulent green leaves. During warmer months it produces pinkish-purple flowers that are pollinated by bees and other insects. The flowers give rise to capsules containing tiny black seeds. Some scientists have suggested that the seeds are dispersed by adhering to the bodies of shorebirds, or by lodging in cracks of wood or other objects carried by ocean waves.
Studies have shown that even after 56 days of immersion in seawater, sea purslane seeds can still germinate. But it’s probably through vegetative reproduction that sea purslane has spread so widely around the world. Its buoyant, salt-tolerant stems break off easily, and many are swept up by the sea. Bits and pieces of sea purslane may travel far and wide via waves and storms, washing up on other beaches.
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Once deposited on land, these stem fragments send out tiny roots and eventually give rise to spreading masses of new plants. Sea purslane tolerates, even thrives in, habitats that are inhospitable to most other plants. It’s resistant to salty substrates, high surface temperatures, low nutrient levels, and changing moisture conditions. Its waxy stems and leaves retard water loss and stand up to wind and salt spray. The plant can even survive temporary burial by wind-blown sand. In fact, mats of sea purslane trap sand particles, helping dunes to grow.
Ecologically, sea purslane plays an important role as a “pioneer” species on beaches, and it’s currently used extensively in dune restoration projects.
The species also has a long history of culinary and medicinal use. Leaves, stems, flowers, and fruits are all edible and can be added raw to salads, where they reportedly give a crunchy, if salty, flavor. Cooking the stems and leaves in several changes of water helps remove some of the salt and turns the plant into a basic boiled green vegetable. In folk medicine, sea purslane has been used to treat a variety of conditions and disorders, from fever and kidney problems to leprosy, toothaches, and scurvy. Studies are underway to further investigate therapeutic uses of this species.
Future research may also focus on the molecular basis of the high stress tolerance shown by sea purslane to the extreme environmental conditions under which it survives. Such knowledge may have far-reaching effects on the development of more stress-resistant crops.