Sea hibiscus is a tropical shrub native to Asia and found widespread across regions like Malaysia. It has been widely naturalized in the tropics of the New World and study suggests it was carried to many Pacific islands by the Polynesians in their peregrinations across the ocean, making it difficult to determine the true natural range of this shrub. Sea hibiscus has a number of uses including traditional medicinal uses and it is also grown as an ornamental in some regions of the world. Gardeners should be aware that it can be invasive.
Known to botanists as Hibiscus tiliaceus, this plant grows on shorelines and in mangrove swamps, and likes salty, wet, humid environments. The sea hibiscus grows best in United States Department of Agriculture (USDA) zones 10 and 11, requiring full sun, and will grow into a large tree in conditions it enjoys. The salt tolerance is an important trait for gardeners in regions where growing plants is difficult due to ocean spray.
This shrub produces large, heart-shaped leaves and big yellow flowers. The flowers appear in the early morning and brown over the course of the day, eventually falling off in the evening. Small brownish fuzzy spherical fruits are produced by the sea hibiscus and used as a source of nutrition by some animals. Humans have historically eaten the leaves during periods of famine and food insecurity.
Medicinally, many different parts of the plant are used in different cultures. The buds are utilized in the treatment of dry throat, while the mature flowers are used in preparations for the treatment of infections and abscesses. The bark is distilled for the treatment of congestion, while the leaves have been used in the treatment of coughs, colds, and fevers in many regions of Asia historically. Sea hibiscus products have not been studied extensively in clinical environments and little information about their efficacy is available.
These plants have also been historically used for timber, as they produce light, strong, durable wood. In addition, sea hibiscus is a source of fiber for the manufacture of rope. Numerous societies have utilized the plant to make rope and related products. As a garden ornamental, sea hibiscus can be grown as a specimen planting to add color to the garden, and can also be used to establish windbreaks and hedges. People growing plants near the ocean can use a sea hibiscus to provide shelter for more delicate plants vulnerable to rough winds and salt spray.