This is the story of a successful native. Beach lettuce, fan flower, Scaevola taccada, grows on beaches across the Pacific Ocean. Called beach naupaka in Hawaii, it is one of about 600 species of plants native to Hawaii, having reached the islands, the most remote in the world, without human help. Since it is found on beaches all over the Pacific, Hawaiians call it indigenous rather than endemic. It is a conspicuous plant to beach-goers, growing abundantly just above the tide line.
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| beach naupaka Scaevola taccada, Honolulu |
I want to praise it for its role as an ornamental.
Visiting tropical holiday sites, such as Hawaii, one is bombarded with gorgeous tropical plants--hibiscus, spider lilies, bougainvilleas, plumerias, orchids, bromeliads. In Hawaii, those are not native plants. The bounty of Hawaii seen by tourists features ornamentals native all over the world but not to Hawaii. Beach naupaka is an important exception. (There are native Hawaiian hibiscus species, but they are rare as tourist area ornamentals). |
| hibiscus |
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| bromeliads and ferns |
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| Waikiki Beach, Honolulu, Hawaii (compare beach to sidewalk) |
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| beach naupaka Scaevola taccada, bordering Waikiki Beach |
That is very sensible. Beach naupaka is tolerant of salty sand and salt spray. Few plants are. Probably without caring that it is native, developers and land owners incorporatedit into their landscaping. But native status is important. Native plants need conservation.
Sure, beach naupaka is common on beaches across Hawaii, but, truly, development that rips out what is there for something it prefers can make common plants rare. In this case, that didn't happen. Beach naupaka was useful and they kept it. So it has abundant stable populations along the coast where it always grew.
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| beach naupaka, Scaevola taccada, flowers and small fruits |
The genus Scaevola has more than 130 species, with a center of diversity in Australia. From there, two species, S. taccada (previously called S. sericea) and S. plumieri, became widespread coastal species, S. taccada in the Pacific and Indian Oceans, S. plumieri in the Atlantic and Indian Oceans. Other Scaevola species are endemic species found on only one island, both in the Atlantic and Pacific. Many more species are confined to inland areas in Austalia. DNA analysis shows three quite different colonizations of Hawaii by Scaevola lineages, a remarkable record, given that Hawaii is more than 1,000 miles from land of any kind. Scaevola is well-adapted to long-distance dispersal. The white fleshy fruits are often eaten by sea birds. The fruits float in sea water, and the seeds inside are not killed by months of soaking in sea water. Seedlings are less resistant to salt water and salt spray than older plants, but more tolerant than most other species.
Experts hypothesize that, in a rainy period, with heavy rain rinsing the soil, seeds lying on the beach germinated and grew in areas that might otherwise be too salty and, once their roots reached groundwater, survived in the severe conditions of the beach edge.
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| Here you can see why it has common names of beach cabbage and sea lettuce. |
The genus name Scaevola means "left-handed" a reference to the hand-like shape of the flowers. The species epithet taccada is a Latinization of its common name in Sri Lanka. Beach naupaka is its Hawaiian name, beach cabbage and sea lettuce are two English common names. It is in the plant family Goodeniaceae, a family common in Australia and surrounding areas. Note that the name sea lettuce is used for the seaweed (green alga), Ulva (sea lettuce family Ulvaceae) and an unrelated beach plant in California Dudleya caespitosa (stonecrop family, Crassulaceae).
The flowers of beach naupaka are very distinctive "half flowers" with the petals only on the lower side. In beach naupaka they are white, but other species of Scaevola have lavender and purple flowers and are popular ornamentals in Australia and other warm climates. As a widespread beach plant, beach naupaka can be pollinated by a variety of generalist pollinators. It probably was pollinated by native Hawaiian animals, but those are rare to extinct today. I saw numerous fruits, so it is successfully reproducing.
Across the Pacific, beach naupaka was used in traditional medicine, for example for eye infections. The root was taken as an antidote after eating a poisonous fish or crab and for indigestion and dysentery. Young leaves, chewed or as a tea, treated a cough. The leaves were applied directly to sooth stings and to treat skin problems, or to the forehead to cure a headache. The pith was used to make paper and the twigs served as nails in traditional boats. The fruits and leaves can be eaten by people but the taste is quite unpleasant.
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| beach naupaka |
The curious half flowers of all the Hawaiian species of Scaevola (there are nine endemic species) led to a variety of legends. They tell of forbidden lovers who, fleeing a death penalty, went one along the beach and the other toward the mountains. Both were killed, and a goddess (versions vary as to which goddess) created beach naupaka, naupaka kahakaki and mountain naupaka, naupaka kuahiwi (Scaevola procera if the island was Kauai or Molokai) each with half flowers, remembering them. Hawaiian legends rarely have happy endings for those who break taboos, but see Some Majestic Island Plants link, for a gentle version of the legend.
Hawaii evolved a unique flora and fauna in its isolation, which human colonization has removed and replaced. Since the 1980s when I spent a sabbatical year doing research in Hawaii, Hawaiians have embraced their natives, planting and using them instead of tropical generalist ornamentals. However, the tourist areas are still dominated by pantropical ornamentals with nary a native in sight. So beach naupaka stands out.
Meanwhile, halfway across the world, somebody thought Floridians would like beach naupaka and introduced it. Of course they pitched it as great for beaches and salty locations. Beach naupaka liked Florida and is now listed as a noxious weed in Florida. Scaevola plumieri, the other widespread Scaevola, called beachberry, inkberry, and gullfeed, was already in Florida, that is, is native there, but it is now quite rare. Florida sites prohibit the sale of beach naupaka and caution people to get and plant beachberry, not beach naupaka. This highlights the importance of regionalism: one location's native is another's weed.
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| south Florida beach; this is beach naupaka the noxious weed |
Beach naupaka is easy to recognize and grows along popular Hawaiian beaches. Stop to see the big round leaves, half flowers, white fruits, and give it credit as an attractive, adaptable, salt-tolerant native.
Comments and corrections welcomed.
References
Alpha, C. G., D. R. Drake and G. Goldstein. 1996. Morphological and physiological responses of Scaevola sericea (Goodeniaceae) seedlings to salt spray and substrate salinity. American Journal of Botany. 83 (1): 86-92.
Florida Department of Agriculture and Consumer Services. (no date given) Scaevola taccada Beach Naupaka. Noxious Weeds. link (Accessed 4/30/23).
Goldstein, G., D. R. Drake, C. Alpha, P. Melcher, J. Heraux and A. Azocar. 1996. Growth and photosyntetic responses of Scaevola sericea, a Hawaiian coastal shrub, to substrate salinity and salt spray. International Journal of Plant Sciences. 157 (2):171-179.
Hall, J. B. 2004. A Hiker's Guide to Trailside Plants in Hawai'i. Mutual Publishing. Honolulu, HI.
Howarth, D. G. , M. H. G. Gustafsson, D. A. Baum and T. J. Motley. 2003. Phylogenetics of the genus Scaevola (Goodeniaceae): Implications for dispersal patterns across the Pacific Basin and colonization of the Hawaiian Islands. American Journal of Botany. 90 (6): 915-923.
Planetnet Scaevola taccada (PROSEA). link (Accessed 4/29/23).
Scaevola taccada (Gaertn.) Roxb. 20174. Some Majestic Island Plants. somemajesticislandplants.com link (Accessed 4/30/23).
State of Hawaii. 2023. Rising Sea Level link (Accessed 4/29/23).
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