Beach Naupaka: Scaevola taccada

Appearance:

There are two varieties of beach naupaka. The common S. taccada var. sericea has silky plant hairs on the stem and leaves, and the less common S. taccada var. taccada, appears to be smooth, lacking plant hairs.

Look for first:

• rounded shrub
• white "half-flower"
• white clusters of fruit
• large, mostly erect leaves, with wavy margins and small indentations at the apex

	Leaves: Blades 4 to 21 cm long, 1.8 to 9 cm wide, appearing elliptic to spoon-shaped; leaf edges sometimes curved downward, somewhat succulent, but not stiff or thickskinned; broad apex often having shallow indentations.
	Flowers: Dense axillary clusters emerge in groups of three, all flowers stalked. Five white petals (about 2 cm long) extend halfway around the flower, like a semi-circle, resulting in the name "half-flower;" sometimes appear pinkish violet.
	Fruits: Round to elliptical drupes measure about 1 to 1.7 cm, white to yellowish-white. Plants can produce fruits within their first or second year.

Beach naupaka is also known as Hawaiian half-flower. Its distinctive flower makes it easy to identify; however, it can be confused with the native inkberry (Scaevola plumieri), whose flowers look similar. Inkberry has black fruits, and its leaves are stiffer, smaller (to 10 cm long), with a smooth, entire leaf margin. By contrast, the beach naupaka has white fruits and leaves that grow to about 21 cm in length and often have a few shallow indentations along its
broad apex.

Habitat:

Beach naupaka is a large bushy shrub native to southeastern Asia, eastern Africa, Australia and the Pacific Islands, including Hawaii.  The salt-tolerant beach naupaka has been available from nurseries since the 1960s. It was promoted in the 1970s and 1980s for use in beach stabilization projects and coastal landscapes - a practice that continues, but is now discouraged.  Beach naupaka escaped cultivation by the early 1980s and now forms dense stands on many beach dunes, coastal rock barrens, coastal strands, along saline shores, including mangroves, and in coastal hammocks.

Beach naupaka has been offered and planted as inkberry by the nursery trade, resulting in accidental and intentional introductions in natural areas.

Distribution

Frost sensitive. Now found escaped in coastal habitats of Central and South Florida, through the Keys. It is also naturalized in the Bahamas and possibly in other parts of tropical America.

Behavior:

The seeds are dispersed by birds and by water. Fruits may float for up to one year, and can be spread along wrack lines of the coast, canal banks, mangroves and inland shorelines.

Why beach naupaka must be managed

Shrubs of beach naupaka produce copious fruit clusters and can grow to heights of 5 meters (16 feet). They displace native dune vegetation, including sea oats, that helps to guard against erosion. This shrub consumes open spaces on the dune that are important for the endangered sea lavender (Argusia gnaphalodes), beach peanut (Okenia hypogaea), beach clustervine (Jacquemontia reclinata), and threatened inkberry. Because of its rapid growth and expansion, some municipalities have authorized the removal of beach naupaka within 10 years of planting.  Beach naupaka is difficult to control. The fleshy branches are easy to handpull, but broken underground stem segments readily resprout if not completely removed. Herbicides have been effective in the dry dunes, but removal and treatment of beach naupaka in tidal mangrove areas requires more careful treatment. Monitoring and re-treatment are necessary for at least two to three years after removal, to weed out new seedlings and stem sprouts.

Additional Information:

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Beach naupaka (Scaevola taccada)

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Image Credit: W. Jurgens, courtesy of Fairchild Tropical Garden