Delissea kauaiensis slightly curved and tubular flowers are believed to be adapted to match the beaks of Hawai‘i's endemic honeycreepers. A cultivated plant with flowers and immature fruits. Delissea kauaiensis often has colorful red and green leaves. A cluster of cultivated mature plants. (Header, flowers, and mature plants photographs courtesy of Forest & Kim Starr CC BY 2.0).

Growth Requirements

General

    Growing and maintaining Hawai‘i's endemic lobelioids [WikipediA;Hawaiian lobelioids] is not for beginners. It's not that they are impossible to grow. Rather, it's that all of them require vigilant monitoring for pests, diseases, or other problems, and swift action by the grower to remedy the situation quickly (and, sometimes, repeatedly). For example, all the Hawaiian lobelioids we have ever grown have been attacked by spider mites (with different species being more vulnerable than others). If left untreated, the mites will infest and destroy all the plant's leaves and eventually kill the plant. Despite this discouraging preface, we still encourage you to grow one or more of these beautiful plants when you feel you have the experience and dedication to "put in the work." This large group of Hawaiian bellflowers is found nowhere else in the world, and, without exception, all of them are incredibly beautiful, with some being truly spectacular!

    Given the above caution, Delissea kauaiensis is one of the easiest of the Hawaiian lobelioids to grow and maintain. Use it as an accent planting or in clusters to protect more sun-sensitive plants like ferns. It does well at low elevations in the ground or in a container, provided the site or pot has good drainage. ʻOha grows best in partially sunlit sites (but can tolerate full sun) and organic or cinder-rich soils or media. Keep the soil or media anywhere from dry to moderately wet. ʻOha is intolerant of salt spray, and its stem(s) can snap in strong winds. While it is okay to remove dead leaves, spent flowers, or fruit, avoid pruning any of its stem(s).

    ʻOha is a great indoor plant (and, one can argue, maybe easier to keep inside than outside). Place it near a window to provide it with bright but filtered light or full-morning sun, or keep it under full-spectrum lamps (LEDs work well). Keep the potting media moist, and drench fertilize (with a standard organic or inorganic fertilizer) once a month or apply a slow-release balanced fertilizer every six months. Though the plant will escape most pests indoors, keep a close lookout for spider mites. ʻOha can get tall, but normally takes several to many years before bumping up against your ceiling.

Pests and Diseases

    Outside, Delissea kauaiensis is attacked by spider mites, aphids, mealybugs, ants, slugs, snails, mice, and rats. Snails, slugs, mice, and rats are the most deadly pests because they can girdle or severely damage the basal stem of the plant and kill it (sometimes in a single night!). Inside, spider mites are generally the pest to worry about most because they will distort the leaves or make them look spotty and/or crinkly. Ultimately, the leaf dies, and any new leaves the plant tries to produce are also attacked. Refer to the Pests & Diseases page for ways to battle these pests. In the wild, entire ʻoha are sometimes eaten by a goat or rat. 

Special Features and Information

General

    The Bellflower family (Campanulaceae) is a large family of mostly herbaceous plants with about 2,400 species within 84 genera with a worldwide distribution and a wide diversity of habitats. Plants often have a milky sap [WikipediA;Campanulaceae].

    There are over 100 endemic Hawaiian species of Campanulaceae. Delissea is an endemic Hawaiian genus with about 15 species; there is still some taxonomic debate on the exact number. (Until recently, Delissea kauaiensis was informally lumped in with Delissea rhytidosperma [Lammers 2005]). The overwhelming number of Delissea species are extinct, with the remaining handful either extinct in the wild or critically endangered.

Hawaiian Name

    ʻOha appears to be a recently-adopted Hawaiian name for this species and the name we will use within this website. It may have originated from ‘ōhā, a Hawaiian name used for members of the endemic genus Clermontia, a closely related species group to Delissea.

Etymology

    Delissea is named after Jacques Delisse (1773–1856), a Frenchman who joined the Baudin expedition to Australia that sailed from Le Havre in October 1800, as a botanist-pharmacologist. Suffering from scurvy, he left the ship when it reached Mauritius the next year, and set up as a pharmacist in Port Louis [WikipediA;Jacques Delisse]. The species name, kauaiensis, refers to the island of Kauaʻi, where this species is endemically found. The suffix -ensis was added to Kauaʻi to Latinize the name [Gledhill 2008].