Native Plants of Hawai‘i - Hibiscus waimeae

Hibiscus waimeae subsp. hannerae & subsp. waimeae

Malvaceae or Mallow family

Synonyms: Hibiscus waimeae var. hannerae & Hibiscus waimeae, Hibiscus waimeae var. helleri

Kokiʻo keʻokeʻo

Aloalo, Kokiʻo kea

Both subspecies: Kauaʻi white hibiscus, White Kauaʻi rosemallow

Subspecies hannerae: Minature Hawaiian white hibiscus, Small Kauaʻi white hibiscus

Natural Range & Environment

Hibiscus waimeae is endemic to Kauaʻi. Subspecies waimeae is found in the Waimea Canyon area and various western and southwestern ocean-facing valleys in mixed mesic forests from 250 to 1,200 m (820 to 3,937 ft) [NTBG]. The endangered subspecies hannerae is found along streams in wet forests at 61 to 564 m (200 to 1,850 ft) in Hanakāpīʻai and Limahuli Valley, and historically in Kalihi Wai Valley, in the northwestern part of the island. According to the last USFWS 5-Year Review, there are fewer than 80 wild individuals of H. waimeae subsp. hannerae on Kaua‘i. Fortunately, there are active recovery efforts (e.g., plantings and seed storage) to prevent the total extinction of this subspecies [USFWS:ECOS].

Flower and elongated seed capsules of subspecies hannerae (Capsules photograph courtesy of Forest & Kim Starr CC BY 2.0). Flower and leaves of subspecies waimeae. Two cultivated Hibiscus waimeae: a young blooming shrub and, left unpruned, a much older tree taking a brief blooming pause. Header photograph courtesy of Forest & Kim Starr CC BY 2.0.

Description

Hibiscus waimeae is a large shrub to small tree with a lifespan well beyond five years. In cultivation, subspecies waimeae can grow to be 20 feet (6 m) or taller, while subspecies hannerae is generally shorter; however, see comments below in Growth Requirements regarding pruning. Subspecies hannerae is very rare and federally listed as endangered.

Kokiʻo keʻokeʻo bark is gray, and its wood is white and brittle. Its egg-shaped leaves can vary from two to about six inches (5 to 15 cm) long, and have a fine sandpaper-like feel with their pubescent (hairy) lower surface being paler than their upper surface; subspecies hannerae typically have larger leaves than subspecies waimeae. (Hibiscus arnottianus, the other native species called kokiʻo keʻokeʻo, has glabrous smooth leaves.)

Hibiscus waimeae has large white five-petal perfect (bisexual) flowers with a red central reproductive column that last about two days [Huppman 2013]. The flowers of subspecies hannerae are significantly smaller than those of subspecies waimeae; subspecies waimeae match Hibiscus arnottianus in size, while subspecies hannerae are a closer match in size to koki‘o ‘ula (native red hibiscus). Kokiʻo keʻokeʻo flowers are slightly to very fragrant and, along with H. arnottianus, are supposedly the only known natural species of Hibiscus with fragrant flowers. The fragrant flowers have led biologists to speculate that native moths may be (were) the primary pollinators of koki‘o ke‘oke‘o [Huppman 2013]. Cultivated kokiʻo keʻokeʻo bloom nearly year-round but may stop for a short period, usually during the winter or early spring months. Pollinated flowers develop into dry tan five-chambered capsules with each chamber holding a few fuzzy brown angular seeds.

Growth Requirements

General

Like other hibiscus, Hibiscus waimeae is a versatile plant for landscaping and can be used as an accent, to create a hedge or screen, or to provide shade. It can also be kept as a container plant. While we like to describe kokiʻo keʻokeʻo as "a shrub that wants to become a tree," this doesn't mean you have to let it become one. Kokiʻo keʻokeʻo tolerates gradual pruning, a few branches at a time, quite well, allowing you to shape the plant into the form you want. If you desire a bushy shrub, concentrate your pruning on removing or shortening the central, most vertical branches. If, instead, you want your kokiʻo keʻokeʻo to become a tree as quickly as possible, prune away the lower side branches, and over time, work your way up. Kokiʻo keʻokeʻo grows fast, but not super fast. Therefore, if you decide to make/let your kokiʻo keʻokeʻo become a tree, understand that you're engaging in a decade(s) long project.

Hibiscus waimeae does best in a site with lots of sunshine. However, in hot dry locations, subspecies hannerae seems to prefer some shading, more so than subspecies waimeae. Koki‘o ke‘oke‘o will grow in lava/cinder, clay, or organic-dominant soils, provided the soil drains well; we have not grown it in sand or coralline soil.

How much you need to water your koki‘o ke‘oke‘o will depend primarily on where you plant it. In a hot dry lowland site, weekly watering is likely required, while in a cooler upland landscape, you may only need to water once a month or less. (Obviously, a container plant will require more frequent regular watering.) Fortunately, koki‘o ke‘oke‘o are drought-tolerant. This will give you enough time for your plant to "tell" you, with wilted or dropped leaves, that it needs more water.

With lots of sun and adequate water, koki‘o ke‘oke‘o grows quickly, reaching three or more feet (1 m) tall in a year. Most commercially available koki‘o ke‘oke‘o are propagated from cuttings, so flowers often appear soon after planting, even when the plant is small. If you have grown your koki‘o ke‘oke‘o from seed, you’ll have to wait 2 to 3 years for the first flowers. If you see leaf yellowing, or your koki‘o ke‘oke‘o doesn't seem to grow despite adequate sun and water, consider applying a single-digit major nutrients fertilizer with minor elements.

Most available Hibiscus waimeae are propagated from cuttings to ensure genetic identity (i.e., it is a clone of the parent plant). These plants never develop an anchoring taproot, typical of a koki‘o ke‘oke‘o grown from seed, and this can be a problem during a wind and/or rainstorm because the secondary roots cannot prevent the shrub from toppling over. To prevent this from happening, select a planting site that's protected from strong winds and regularly hand-prune your koki‘o ke‘oke‘o to prevent it from becoming top-heavy. If your shrub still falls over, assess the damage, remove any damaged branches, and decide on whether to let the plant recover as is or reposition and support it with stakes and ties. Generally, if many of the roots have been uprooted and exposed, it's best to reposition, reroot, and support the shrub; if not, leave the plant as is unless you find it too unsightly.

Hibiscus waimeae easily and frequently cross-pollinates with other hibiscus near it, producing hybrid seeds. Therefore, it's safest to only create new plants by rooting stem cuttings. If you still decide to collect seeds from your koki‘o ke‘oke‘o to grow new plants, you should hand-pollinate bagged flowers. Do this by enclosing the flower in a paper bag before it blooms. When the flower blooms, open the bag and hand-pollinate it with some pollen, preferably from a different flower on a different plant of the same subspecies. Re-close the bag around the flower, wait a week, and then remove the bag.

Pests and Diseases

Chinese rose beetles and grasshoppers sometimes get a taste for koki‘o ke‘oke‘o leaves. Additionally, plants are occasionally attacked, usually at or near the stem-tips, by all the usual sap-sucking insects: aphids, mealybugs, scale insects, and whiteflies. However, koki‘o ke‘oke‘o is a resilient plant, and attacks by these pests are almost never fatal. We normally wait for natural predators like ladybird beetles, lacewings, and mealybug destroyers to find and eliminate these pests. However, if the infestation doesn’t disappear on its own, or you just don’t want to wait, refer to the Pests & Diseases page for ways to deal with each of the above-mentioned pests.

The hibiscus erineum mite or hibiscus leaf-crumpling mite (Aceria hibisci) seems to prefer the Chinese hibiscus over native species (Thank goodness!). If you find this type of damage (i.e., leaves with pimples or other twisted distortions; see Hibiscus clayi for photographs of damage) on your koki‘o ke‘oke‘o, remove and discard the affected leaves or branches. If the problem persists, you can first try several sprayings of horticultural oil (about a week apart) before resorting to commercially available miticides. Miticides are tricky. Some are only available to licensed pest exterminators. Check out your local garden shop, and ask them what’s available to you for combating the erineum mite. Be sure to read and follow the label directions since miticides are often only effective if the application protocol is followed exactly.

Uses

Ancient Hawaiian

Both the native red and white Hibiscus were cultivated near homes for their flowers, which were used for both ornamental and medicinal purposes [Kepler 1995]. However, often these written references only use the more generic name for native Hibiscus, kokiʻo or aloalo, and, therefore, it is currently impossible to describe species-specific uses.

Kokiʻo was traditionally prepared by pounding it with other plants, straining the juice, and consuming it for purification purposes. The leaves were chewed and ingested as a natural laxative, while mothers would chew the buds and give them to infants and children for the same purpose [McDonald & Weissich 2003]. Additionally, mothers would chew the buds and give them to children, or children would consume the seeds to help strengthen a weak child. The beautiful flowers were skillfully crafted into stunning lei, but unfortunately, these only lasted a day [Handy & Handy 1972]. The bark of aloalo was likely used to make cordage (inferior to hau), but supportive written accounts are scarce. For example, Krauss [1993] mentions that "hibiscus" was used in her chapter on fiber craft.

Modern

Like the introduced Chinese hibiscus, native Hibiscus flowers are often used for decoration, such as placing a flower behind one's ear.

Special Features and Information

General

The large Mallow family, Malvaceae, contains about 4,200 species, with notables such as okra, cacao, durian, baobab, kenaf, and cotton [WikipediA;Malvaceae]. There are currently seven native species of Hibiscus recognized in the Hawaiian Islands, with all but two considered endemic [Flora of the Hawaiian Islands].

Koki‘o ke‘oke‘o, Hibiscus arnottianus and H. waimeae, are highly prized by plant breeders because they are supposedly the only natural Hibiscus species with a fragrant flower.

Huppman [2013], based on her DNA research, has suggested that Hibiscus waimeae subsp. hannerae be given full species status as Hibiscus hannerae.

Hawaiian Name

Kokiʻo kea and Kokiʻo keʻokeʻo translate to " the white kokiʻo" and " the very white kokiʻo," respectively [Pukui & Elbert 1986]. Kokiʻo is a more generic name for some native Hibiscus species, as well as plants in the related native genus of Kokia. Aloalo is a generalized name Hawaiians gave to native Hibiscus species.

Etymology

Hibiscus is the Latinized form of the Greek word ibiskoj or hibiskos from Virgil, hibiscum, for the marshmallow plant, Althaea officinalis [Gledhill 2008]. The species and subspecies name, waimeae, refers to the Waimea Canyon, Kauaʻi, where this species is found. The subspecies name, hannerae, was assigned by Otto and Isa Degener, famed botanists in Hawai‘i, to honor Mrs. Ruth Knudsen Hanner, a supporter of their work on Kauaʻi [Federal Register 1996].

BPK