Scaevola taccada var. taccada
Goodeniaceae or Goodenia or Fanflower family
Synonyms: Scaevola fauriei, Scaevola frutescens, Scaevola frutescens f. moomomiana, Scaevola plumerioides, Scaevola sericea, Scaevola sericea var. fauriei, Scaevola sericea f. moomomiana, Scaevola sericea f. saintjohnii, Scaevola taccada, Scaevola taccada var. bryanii, Scaevola taccada var. sericea
Naupaka kahakai
Aupaka, Huahekili, Naupaka, Naupaka kai
Beach cabbage, Beach naupaka, Fan flower, Sea lettuce
Natural Range & Environment
Scaevola taccada var. taccada is a very wide-ranging species being found in tropical and subtropical coastal areas and beaches of the Indian and Pacific Oceans and is considered indigenous to Hawai‘i. In Hawai‘i, it grows on most of the Northwestern Hawaiian Islands (i.e., Kure, Midway, Pearl & Hermes, Lisianski, Laysan, French Frigate Shoals) as well as all the main Hawaiian Islands [Flora of the Hawaiian Islands].
In recent times, Scaevola taccada var. taccada was introduced to tropical and subtropical regions of the Americas where it has become an invasive species, often displacing native plants including the threatened Scaevola plumieri (inkberry) [Florida Department of Agriculture and Consumer Services].
While all naupaka kahakai flowers have the same unusual "half-flower," the flower's petals can vary in size and color; here and in the header are just two examples. Naupaka kahakai is the only native Hawaiian Scaevola species with white fruits. Two examples of naupaka kahakai in its natural coastal habitat: in the sandy dunes at Ka‘ena Point, O‘ahu, coexisting with the endangered ‘ohai (Sesbania tomentosa), and emerging from lava rock at Punalu‘u Black Sand Beach Park, Hawai‘i Island (Hawai‘i Island photograph courtesy of Scott Zona CC BY-NC 2.0.). Note how both wild plants maintain a low stature in these windy coastal locations. Two examples of cultivated naupaka kahakai: a manicured hedge along Waikiki Beach (Photograph courtesy of Kathy Keeler ©.), and a prostrate variegated form recently developed by Dr. Orville Baldos and his team at the University of Hawai‘i at Mānoa (Photograph courtesy of Orville C. Baldos ©.).
Description
Naupaka kahakai is a large shrub with a lifespan exceeding five years. Wild plants are rarely more than three feet (1 m) tall, while cultivated plants can sometimes exceed ten feet (3 m) in height. Its stems have a thin gray bark and soft white wood. While the stems are flexible to a point, capable of withstanding strong winds, they can be broken by careless hands.
The light green oval to spoon-shaped leaves of naupaka kahakai are 2 to 8 inches (5 to 20 cm) long with slightly inrolled margins. Margins are also sometimes (barely) toothed and purple. The leaves' surfaces can be anywhere from nearly hairless to densely covered with very short white hairs (see Scaevola taccada versus S. sericea discussion below) but seem to always have tufts of silky white hairs at their axils (attachment to the stem). Recently, two variegated cultivars of naupaka kahakai have been developed and promoted by Dr. Orville Baldos and his team at the University of Hawai‘i at Mānoa.
Naupaka kahakai produces clusters of perfect (bisexual) "half-flowers," typically with five (rarely 4 or 6) petals all positioned like a hand with a curved style opposite the petals. The corolla is mostly white but often has a yellow throat with purple streaks extending out to the distal end of the petals. Flowering is continuous (or nearly so) in both wild and cultivated plants.
Pollinated flowers develop into green turning to white (when ripe) grape-sized round fruits with a soft mealy pulp and a corky endocarp surrounding one (occasionally two) seeds. Naupaka kahakai is the only native Hawaiian Scaevola species with white fruits; the others all have dark purple to black fruits.
Scaevola taccada or Scaevola sericea?
This species name debate/confusion started in 1788 when Joseph Gaertner first applied the name Lobelia taccada to a plant found in its eastern range. William Roxburgh then indirectly referred to this name when transferring it to the genus Scaevola in 1788. Later, and separately, Martin Vahl described and named Scaevola sericea in 1791, based on a specimen from Niue, a small island in the Southern Pacific Ocean. In recent times (i.e., since 1980), there has been debate on which species name should be valid, whether there should be one or two species, and, if classified as a single species, should the one species have two formal varieties. Additionally, another species, Scaevola plumieri, has recently been added to the debate to further confuse the taxonomy [WikipediaA;Scaevola taccada]. (All of this is not totally unexpected given the very wide geographic range of this/these species.) For now, we will adhere to the classification given in Flora of the Hawaiian Islands, but also recognize that, in Hawai‘i, you can see plants with very fuzzy leaves (the origin of the name sericea which means “with silky hair”), plants with shiny hairless leaves (typically considered species or subspecies taccada), and some plants that have leaves with intermediate pubescence.
A shiny-leafed naupaka kahakai (Photograph courtesy of Forest & Kim Starr CC BY 3.0 US.).
A naupaka kahakai with fuzzy leaves (Photograph courtesy of Forest & Kim Starr CC BY 3.0 US.).
Growth Requirements
General
When it comes to the future of native Hawaiian plants, there is only a handful of species I (Koebele) don’t worry about. Naupaka kahakai is one of these. One reason I am not worried is because this coastal plant is today found around the world, naturally in tropical and subtropical regions of the Old World, and unnaturally (i.e., introduced and frequently invasive) in tropical and subtropical areas of the Americas. Second, naupaka kahakai is probably the most common native Hawaiian plant used by professional landscape companies in Hawai‘i, with pōhinahina (Vitex rotundifolia) likely tied or a close second. Sometimes I wish it was just a little less popular and these companies would opt for one of the other eight native (and endemic) species of naupaka found in Hawai‘i, but it just isn’t so (today). (When you can just poke a naupaka kahakai cutting into the ground and water it daily to establish a new plant, it’s tough to get a landscaper to switch to something a bit more difficult!) In any case, naupaka kahakai is likely to remain for some time one of the few native Hawaiian plants most tourists visiting Hawai‘i will likely see without trying. And, I guess, that’s a good thing.
Napaka kahakai has been used in landscapes as an accent, a formal or informal hedge or screen, and as a windbreak. Prostrate forms have been planted as a groundcover (see examples above). It can also be kept in a container for those without a yard or the space for a large plant. Rick Barboza, co-owner of Hui Kū Maoli Ola, notes that many people plant naupaka kahakai on the makai (ocean-facing) side of their house and naupaka kuahiwi on the mauka (mountain-facing) side in recognition of their natural origins [Hui Kū Maoli Ola].
Naupaka kahakai does best in a site that receives full sunlight for all or most of the day. While it can tolerate some shading, shaded plants tend to become lanky and have less succulent leaves and fewer flowers.
Once established in the ground (in about a month), naupaka kahakai requires little to no watering. In fact, watering your naupaka kahakai too often is likely to turn it into a "monster" that will grow unnaturally tall, lanky, and overwhelm any nearby plants.
Two of the traits that make naupaka kahakai a favorite among professional landscapers are its tolerance to harsh environments (i.e., drought, extreme heat, strong winds, salt spray, and salty soil) and its ability to grow in just about any type of soil, even those it is not naturally found (e.g., clay or organic-dominant).
In-the-ground naupaka kahakai typically grow fast, and you should have a plant three or more feet (1 m) in diameter in one to two years. Plants also begin flowering early. If your plant was propagated from a cutting, expect to see flowers almost immediately; if it was grown from seed, you should see the first flowers in less than a year. Planted naupaka kahakai normally do not require any fertilization. However, if your plant is in a container, you may want to apply a balanced controlled-release fertilizer once a year, or use a foliar organic or inorganic fertilizer at half the recommended strength every few months. Avoid applying too much fertilizer or your plant will become lanky with abnormally large and floppy leaves.
If you are using naupaka kahakai as a formal hedge, while time-consuming, it's best to prune by hand, cutting off each stem with its attached leaves, since both manual and power hedgers slice the plant’s leaves and stems in a non-targeted way, leaving a ragged and unattractive shrub.
Pests and Diseases
Naupaka kahakai is rarely afflicted by pests or diseases. The most common pest we've encountered is spider mites, particularly on plants in windless locations. The mites can distort the growth of young leaves and cause older leaves to turn yellow and die. Refer to the Pests & Diseases page for ways to deal with spider mites.
While none of our cultivated naupaka kahakai have become diseased, Scot Nelson and others have reported that the Cucumber mosaic virus (CMV) can cause ringspots on naupaka kahakai. For more information, visit Cucumber Mosaic Virus in Hawai‘i.
Ringspot likely caused by Cucumber mosaic virus (Photograph courtesy of Scot Nelson Public Domain.).
Uses
Ancient Hawaiian
According to Krauss [1993], naupaka kahakai fruits were eaten as a refreshment on journeys but became more important as food during times of famine.
Ka‘aiakamanu, in one account, states that the bark of the roots, when pounded with salt, is "good for cuts" and "skin diseases" [Ka‘aiakamanu & Akina 1922]. In another, he states that the "fruit and skin," mixed and pounded with salt, should be used to treat ‘eha moku hau (cuts) and ‘eha ulia (accidental sores or wounds) [Ka‘aiakamanu & Chun 2003].
While there are no written records, McDonald & Weissich [2003] have suggested that naupaka flowers were likely used in lei.
Modern
Naupaka kahakai has been used to make fabric dyes [Krohn-Ching 1980]. Flowers and fruits are strung into lei [McDonald & Weissich 2003]. Fruits and leaves are used as sunscreen and to prevent fogging inside a diver's mask. Check out the great Instagram video by nattybynature808 on some modern uses of naupaka kahakai.
Outside Hawai‘i, Scaevola taccada has a multitude of traditional uses. For a good summary of most (but not all) of these uses, check out Useful Tropical Plants.
Special Features and Information
General
Goodeniaceae is a family primarily found in Australia in arid and semi-arid sites, except for the genus Scaevola, which is pantropical. It contains about 400 species within 12 genera [WikipediA;Goodeniaceae].
Scaevola is the only genus in the Fanflower family (Goodeniaceae) native to the Hawaiian Islands. There are nine extant and one likely extinct species of naupaka (Scaevola spp.) native to Hawai‘i, with all but one (Scaevola taccada) being endemic [Flora of the Hawaiian Islands]. Scaevola taccada is also the only Hawaiian naupaka without a black fruit.
Genetic analysis suggests three independent colonizations of Scaevola to Hawai‘i. One, represented by naupaka kahakai, likely arrived via its buoyant fruits floating to the Islands, while the other two, represented by the black-fruited Scaevola species, were probably brought to Hawai‘i as seeds in the gut of birds [Howarth et al. 2003].
Hawaiian Origin Stories for the Naupaka Flower
Today, there are several origin stories or legends about the naupaka flower. Nearly all of them are of recent origin and are romantic stories of some type of forbidden or thwarted love between a young man and woman. The number of naupaka stories and their elaborations has grown significantly in the past 30-plus years I (Koebele) have been learning about native Hawaiian plants, with most now ending with a call to have the reader add a happy ending to the story by hiking up into the mountains, pick a flower from a naupaka kuahiwi, then quickly hiking back down to the ocean, picking a flower from a naupaka kahakai, and pressing the two flowers together to symbolically rejoin the young lovers. Since all these stories are of recent origin, I'm not certain how much they communicate ancient Hawaiian beliefs or culture; therefore, I will not retell any of them here. If you are interested, a simple online search will yield most of these stories for your enjoyment and critique. Instead, after conducting an online search for the "oldest story of the naupaka flower," I found The Story of Naupaka and ‘Ōhikimakaloa as told by Leilehua Yuen on the website kaahelehawaii.com. I encourage you to read this account since it reveals the origins of many of the elements of the later stories.
Hawaiian Name
Kahakai means "beach" or "seashore;" therefore naupaka kahakai is "the naupaka on the beach or seashore." Similarly, kai can mean "sea" or "near the sea" [Pukui & Elbert 1986].
Aupaka is the name for this species on Ni‘ihau, as well as being the Hawaiian name for members of the endemic genus Isodendrion [Pukui & Elbert 1986].
Huahekili translates to "thunder fruit" and means "hail" [Pukui & Elbert 1986], possibly referring to the white fruits of naupaka kahakai looking like hailstones.
Etymology
Scaevola is derived from the Greek word, scaevus, meaning "left-handed" or "awkward," likely referring to its unusual half-flower appearance [Wagner et al. 1990].
The species names taccada and sericea seem to go back and forth in taxonomic revisions. Therefore, we have included the etymology for both. The species name, taccada, is from the Sinhala name for this species, takkada, in Sri Lanka [Oxford English Dictionary;taccada], while the species name, sericea, is Latin for "with silky hair" or "like silk" (coming from the Ancient Greek word sērikós), likely referring to the short hairs found on the foliage [Gledhill 2008].
BPK