Half flower, beach naupaka
Native to: southeastern Asia, eastern Africa, Australia and the Pacific Islands, including Hawaii
The salt-tolerant beach naupaka, also known as Hawaiian half-flower, has been available from nurseries since the 1960s. It was promoted in the 1970-80s for use in beach stabilization projects and coastal landscapes. It 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 can be confused with the threatened native inkberry, Scaevola plumieri. The two are easily distinguished by the color of the mature fruit: black in the native inkberry and white in the invasive beach naupaka.
Habit: Large, bushy shrub up to 16 ft. tall, often forming dense hemispherical mounds.
Leaves: Simple, closely alternate, crowded at stem tips; blades thick, shiny green, wider near tips, to 8.3 inches long; glabrous to hairy on both sides, margins revolute, light green becoming yellow with age; leaf axils with tufts of pale hairs.
Flowers: White to pale lilac, several in short clusters at leaf axils; 5 petals, partially fused, split to base on upper side so that petal lobes spread fanlike into a lower lip.
Fruit: A fleshy, sub-spherical drupe, green then white, 0.3–0.5 inches long, with sepal lobes persistent at tip.
Distribution in Florida: the coastal areas of the central to southern peninsula. Isolated individuals have been confirmed on the East Coast in St. Johns and Nassau Counties.
It is spread by both wildlife consuming the fruits and ocean currents where the seeds can remain viable for up to a year. Additionally, branches that contact the ground may develop adventitious roots. This plant forms dense stands displacing native dune vegetation, including sea oats, that help to guard against erosion. It also 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.
Do not plant.
Hand pull seedlings (carefully, soft stems and roots break off and resprout). Remove and dispose of fruits to reduce spread.
Given the sensitive habitats it infests, mechanical treatment is not typically feasible. When done, all plant material including roots must be removed to be effective.
Basal bark: 10% Garlon 4. Cut stump: 50% Garlon 3A or 10% Garlon 4. Foliar (monocultures): 4% Garlon 4.
Monitoring and re-treatment are necessary for at least two to three years.