ʻŌpelu in cultivation. The leaf shapes and degree of white undersides and flower colors vary from island to island or even specific locations on an island. The origin of this particular form (in these photographs) was from near the summit in the central Koʻolau Mountains, Oʻahu.

Growth Requirements

General

    I (Eickhoff) have found that ʻōpelu are relatively easy to grow and flower successfully in containers at a lower altitude (c. 300 ft) than its natural elevation of nearly 2,000+ ft. Perhaps with the good trade winds, it helped keep it a bit cooler. And, in fact, ʻōpelu is often found on open, windswept areas. A well-drained equal mixture of peat, perlite, and black cinder has done well for me. I also add "native compost" containing mycorrhizal fungi, which helps plants to take up water and nutrients and is beneficial to a plant’s resistance against pathogens [Koko 2021]. (See Soils & Media Native Soils). Watering may depend on the origin of the plants, but it appears to be rather adaptable. Still, it may be best to keep the soil on the moist side. ʻŌpelu seems to do best with full to partial sun on the north and east sides of the property, or with some shading on the west and south sides. 

    However, ʻōpelu may not be a plant for the beginner. For one thing, young plants will not likely survive even a brief dry spell in containers or in the ground if left unwatered! Secondly, one needs to keep an eye out for pests. (see Pests and Diseases below). 

Pests and Diseases

    ʻŌpelu is very prone to attacks by red spider mites, and snails and slugs can destroy a plant in a short time. Therefore, you need to be vigilant and check your plants daily. A single lapse in attention can result in disaster for all your hard work to grow these beautiful plants. Too, an unknown caterpillar (species?) can devastate plants, especially seedlings, within a very short period of time. Undetected caterpillars may also be in the cocoon stage and rolled up in leaves. Once noticed, treat plants as soon as possible with a systemic insecticide and destroy leaves with cocoons. Refer to the Pests & Diseases page for ways to battle these pests.

Special Features and Information

General

    ʻŌpelu (Lobelia spp.) are members of the Bellflower family (Campanulaceae). There are 14 species of Lobelia found exclusively in the Hawaiian Islands, eight of which are found on Oʻahu, with five species endemic to this island alone [Flora of the Hawaiian Islands]!

    Other family members include endemic species in Brighamia, Clermontia, Cyanea, Delissea and Trematolobelia — all but Lobelia are endemic genera.

    Lobelia hypoleuca is the most widespread of Hawaiian Campanulaceae, occurring on the six largest islands and is extremely variable morphologically, especially in size and shape of leaves [Wagner et al. 1990]. 

    Hawaiʻi Botanist Joel Lau notes the following observations of Lobelia “green hypoleuca-like” (Oʻahu, Waiʻanae Mts., northern part) on Flickr® (an online photo and video hosting service):

    "Lobelia “green hypoleuca-like” is known from three areas in the northern Waiʻanae Mountains, Oʻahu: at a spot along the ridge that extends from Kaʻala to Puʻupane (a small number of plants), in the Kalena area (a small number of plants), and on ʻŌhikilolo Ridge (the ridge between Mākua and Mākaha Valleys) (Only a single plant has been observed here; it died years ago.). It is a rare and endangered plant.

    "This entity appears to be a taxon distinct from L. hypoleuca. It occurs in mesic habitats, whereas L. hypoleuca in the Waiʻanae Mountains occurs only in wet habitats on the sides of Kaʻala. Lobelia hypoleuca in the Koʻolau Mountains also occurs only in wet habitats and it seems to be morphologically indistinguishable from the L. hypoleuca plants in the Waiʻanae Mountains. Lobelia “green hypoleuca-like” and Oʻahu L. hypoleuca differ in the size and shape of their leaves, the hairiness of the lower leaf surfaces, the venation of their leaves, and the shininess of the upper leaf surfaces. The two appear also to differ in the color of their flowers." 

Hawaiian Name

    While many native lobelioids may not have a single known name, this native Lobelia species to has four! The complete meaning of Kuhiʻaikamoʻowahie is not yet known. However, the names Moʻowahie literally means "fragment of wood for burning" and Liua (Nuia) means "dizzy" [Hawaiian Dictionaries].

    It is perhaps ʻŌpelu, however, that is the most commonly used name for this species, for the supposed resemblance of its leaf to the fish, Mackerel scad (Decapterus macarellus), of the same name [Hawaiian Dictionaries].

Etymology

    The generic epithet Lobelia is named for Matthias de l’Obel (1538–1616), Flemish renaissance pioneer of botany and herbalist to James I of England, author of Plantarum seu stirpium historia (Lobeliaceae) [Gledhill 2008].

    The specific Greek epithet, hypoleuca [hypoleucas], whitish below, is in reference to the white tomentose (woolly) undersides of the leaves of this species [Gledhill 2008].