Nanea produces clusters of bright yellow pea-like flowers that are often partially hidden by its leaves. Pollinated flowers develop into long dry brown to black pods when ripe. Nanea has compound leaves with three leaflets. Note the leaf damage caused by nanea's numerous pests (Photograph courtesy of bluerockbotanicals CC BY-NC 4.0.). Wild nanea in their typical coastal habitat (Photograph courtesy of Forest & Kim Starr CC BY 3.0 US.). And, two cultivated nanea outside their normal habitat, one far inland in non-sandy soil, and the second climbing up and covering a couple of palms (Climbing nanea photograph courtesy of obsidiann CC BY-NC 4.0.). Header photograph of nanea seeds courtesy of Edward Rau CC BY-SA 4.0. 

Growth Requirements

General 

    Unfortunately, nanea lacks the persistence of some other native Hawaiian vines like ʻāwikiwiki, hunakai, and pā‘ū-o-Hi‘iaka. Rather, in cultivation (and seemingly in the wild), this native pea goes through approximately annual cycles of appearance, rapid growth and site domination, decline (because of pests and diseases), and disappearance from a landscape. The cycles are initiated by either the revitalization of an existing vine(s) or the sprouting of one or more of the many seeds produced by the former generation. Therefore, consider nanea an unexpected but welcome visitor to your landscape. Because of its temporary nature, nanea is a poor choice as a weed-suppressing or erosion-control groundcover. However, it can temporarily dominant the ground in a landscape, or, if given something to climb, will quickly cover a trellis, fence, or nearby tree or shrub. Unsurprisingly, nanea is a great choice for sunny seaside landscapes with their constant sea breezes and salt spray, and less so for inland sites where they are more prone to attack by pests and diseases.  

    Nanea does best in a site that receives full sunlight for all or more of the day. It can tolerate some shading, but shaded vines typically do not produce as many flowers.

    Immediately after planting, water your nanea about once a week until it is established and actively growing. Then, cut back on your watering to near zero. Wild nanea grow in quite dry places. Therefore, it's unlikely you will need to water your established nanea — unless you see signs of water-stress such as wilted leaves. While nanea grows best in sandy soils, we have also grown it successfully in coralline and organic dominate soils, as well as lava/cinder and clay. However, whatever the soil type, it should drain water quickly because nanea will die in waterlogged soil. Nanea can tolerate extreme heat, drought, strong winds, and salt spray.

    Nanea, like many Fabaceae, is a nitrogen-fixer and can actually improve the fertility of the soil over time. Therefore, it's normally not necessary to fertilize your in-the-ground plant(s) unless the soil is lacking some other essential mineral or nutrient. Potted nanea, because their media over time can become depleted of other macronutrients or micronutrients (see Fertilizers), should receive a foliar feeding of either an organic or inorganic water-soluble fertilizer at ⅓ to ¼ the recommended strength every couple of months.

    Because of its rapid growth, you may need to trim back your nanea to confine it to a specific area or prevent it from smothering a nearby tree or shrub. Do this by hand since power-trimmers can pull at the vine(s) and uproot them. Pruning will also promote branching and, therefore, better coverage of the ground if that is your aim.

Pests and Diseases

    Like commercial peas and beans, nanea is vulnerable to a host of pests and diseases. Its leaves are frequently attacked by spider mites (in dry, windless sites), leaf miners, and chewing pests like cockroaches, grasshoppers, and snails (see leaf damage in photograph above). The quick growth of nanea makes it a race between the plant and it pests, and also makes it difficult to treat the entire plant with contact insecticides. Therefore, we recommend using a systemic insecticide if your nanea is severely attacked by any arthropod pest.

    Nanea leaves sometime becomes spotted, yellow, and eventually die. We suspect this may be caused by an infection of a mosaic virus [Ariga et al. 2022] or a type of rust [Lucidcentral;Vigna rust]; however, we really don't have the expertise to confirm this.

    Refer to the Pests & Diseases page for ways to combat the above-mentioned pests and diseases.  

Special Features and Information

General

    Fabaceae contains numerous agriculturally important plants, and is the third-largest land plant family in number of species, behind only the Orchidaceae and Asteraceae, with about 765 genera and nearly 20,000 known species [WikipediA;Fabaceae].

    Vigna marina is one of two Vigna species native to Hawai‘i, the other being the endemic and endangered V. owahuensis [Flora of the Hawaiian Islands]. Another species, Leptospron adenanthum, with the synonym Vigna adenantha, was found by Hillebrand on Diamond Head, Oʻahu, and Hawaiʻi Island, but was last collected by Rémy in 1851–1855. It is still found on other islands in the Pacific [Wagner et al. 1990]. 

Hawaiian Name

    Nanea is also the Hawaiian name for a red seaweed (Hypnea nidifica) [Pukui & Elbert 1986]. Pukui & Elbert [1986] list mohihihi as the primary name for Vigna marina. However, today, nanea is the more commonly used Hawaiian name. The literal translation of ʻōkolemakili is "cracked buttocks" [Pukui & Elbert 1986], perhaps, referring to the leaves?

Etymology

    Vigna honors Domenico Vigna (?–1647), an Italian botanist, Professor of Botany, and Director of the Botanical Garden of Pisa, Italy [The Eponym Dictionary of Southern African Plant Names T-Z]. The species name, marina, is Latin for "marine, of the sea, or sea born," likely referring to the coastal habitat of this species [Latdict].