Native Plants of Hawai‘i - Wikstroemia sandwicensis

Wikstroemia sandwicensis

Thymelaeaceae or ‘Ākia family [Wagner et al. 1990]; also sometimes referred to as the Daphne family or Stringbarks

Synonyms: Diplomorpha sandwicensis, Wikstroemia fauriei, Wikstroemia multispicata, Wikstroemia perdita

ʻĀkia

Kauhi (See Hawaiian Names below)

Variableleaf false ʻōhelo ***Check

Natural Range & Environment

endemic to Hawai‘i Island

The tubular flowers of ʻākia are one of its more consistent features

Description

The variation seen in morphology (primarily growth form and leaf characteristics) and habitat seen in Wikstroemia oahuensis has made taxonomic classification challenging, as evident by the numerous synonyms listed above. Currently, the majority opinion is that W. oahuensis is a single species with two varieties, var. oahuensis and var. palustris, with the variety oahuensis being widespread and extremely variable. However, other respected botanists disagree, and, based on their field observations, believe that the species was/were more accurately classified by Skottsberg [1972] as several closely-related species (such as W. macrosiphon and W. recurva, now considered synonyms of W. oahuensis var. oahuensis) with overlapping natural ranges (particularly on O‘ahu) resulting in a confusing geography of species and natural hybrids [Joel Lau, per. comm.].

Unfortunately, an analysis of macro- and micro-morphological characteristics of Hawaiian Wikstroemia by Mayer [1991A] failed to find any consistent characters that could provide taxonomic help at the species level. Additionally, in another study by Mayer [1991B], artificial crosses within and between 19 Hawaiian Wikstroemia populations from six islands resulted in almost all combinations producing viable seeds that grew into vigorous and fertile plants, supporting the hypothesis that the populations are genetically similar and not reproductively isolated. In conclusion, it seems likely, perhaps with molecular genetic studies [Cousins Westerberg], we will likely see future taxonomic revisions of this, and perhaps other, Wikstroemia species.

Wikstroemia oahuensis var. oahuensis (hereafter referred to as ʻākia) can be anywhere from a prostrate shrub to a tree up to nearly 20 ft (6 m) tall with a lifespan well in excess of five years. Its fibrous bark is often gray with whitish lenticels near the leaf scars (giving the stems a banded appearance) but can also be reddish brown to yellow. Because of the fibrous bark, stems, when bent severely, usually do not break away but rather split with the bark peeling away from the wood.

ʻĀkia leaves are narrow to broadly elliptic to egg-shaped but can vary significantly in size (less than 1 to more than 6 inches [2.5 to 15 cm] long). Leaves can be pale to dark green, occasionally with a reddish tinge. A network of veins is frequently visible, particularly on the leaf's lower surface; however, the veins on the leaf's lower surface are sometimes obscured by a whitish waxy covering on some forms of ‘ākia.

ʻĀkia produces clusters of usually yellow (sometimes green or orange) tubular flowers that can be perfect (bisexual) or appear perfect but are actually unisexual. The flowers produce a pleasant fragrance, especially at night. Flowering, particularly of cultivated plants, seems to be sporadic throughout the year, with peaks typically in the winter and spring. Pollinated flowers develop into small oblong to oval berries that vary from yellowish orange to red when ripe. Curiously, some ‘ākia display nearly-ripe white fruits for a short time before turning orange. Within each berry is one elliptical seed.

Growth Requirements

General

Because of the wide range of wild habitats Wikstroemia oahuensis is found in, it's important, if possible, to find out where your cultivated ʻākia originated. Therefore, don't be shy about asking the grower where he or she obtained their seeds, since this will help you decide how to best place and care for your plant. The recommendations given below are all based on my (Koebele) experiences growing the shrubby mid-elevation mesic forest form of W. oahuensis var. oahuensis seen in the Ko‘olau Mountains of O‘ahu (see photograph above).

Wikstroemia oahuensis var. oahuensis (hereafter referred to as ʻākia) is perhaps best displayed as an accent in the landscape because of its moderate to slow growth. Alternatively, planted a few feet apart, it can be used as an informal (i.e., lightly pruned) hedge or screen. ʻĀkia can also be kept as a container plant. There's still a lot we don't know about the toxicity of this and other ʻākia species (see Uses below). Therefore, until we know more, we recommend not planting ʻākia in any areas frequented by small children (e.g., daycares, play areas).

I have planted ʻākia in sites that received direct sunlight for most of the day and sites that received no direct sunlight (i.e., shaded but brightly lite). Under both levels of lighting, my plants grew just fine, provided the soil was always moist; while this ʻākia can withstand (lowland) heat and drying winds, it cannot withstand drought. My plantings have been limited to rocky clay- and organic-dominant soil types. However, John Culliney [Culliney & Koebele 1999] has successfully grown a sister species, Wikstroemia sandwicensis, in calcareous sandy soil. All my in-pot ʻākia were maintained in a cinder-rich media (i.e., 30%-plus black cinder with sphagnum peat moss). As with most native Hawaiian plants, ʻākia seem to do best in soil or media that easily drains water.

ʻĀkia grows at a moderate to slow pace. However, don't be surprised to see even small plants, one to two years old, begin to flower. I've never fertilized my in-the-ground ʻākia with anything more than a yearly topdressing of compost. For containerized ʻākia, I apply either a balanced controlled-release fertilizer every six months to a year, or sprayed the plants with a foliar fertilizer, diluted to one-half the recommended strength, every few months. Because of its slow growth, avoid pruning your ʻākia except to remove dead branches.

All the Wikstroemia oahuensis var. oahuensis I have grown presumably had perfect flowers since they all produced fruit with viable seeds. However, this may not be true of all W. oahuensis var. oahuensis, and we know that some Wikstroemia species such as W. uva-ursi and W. sandwicensis are usually dioecious (i.e., separate male and female plants). Therefore, if your goal is to display a plant with colorful berries or collect seeds for propagation, it would be wise to plant several ʻākia in your landscape to ensure you have at least one plant producing male flowers and one plant producing female flowers.

Pests and Diseases

Few pests seem to bother ʻākia. However, you may infrequently encounter an infestation of scale insects, usually farmed and protected by ants. Refer to Pests & Diseases for ways to deal with scale insects and ants. A more common occurrence is leaf-cutter bees removing semicircular sections from an ʻākia's leaves. Lilleeng-Rosenberger [2005] has noted that chickens will eat ʻākia fruits and scratch at and expose the plant's roots.

Uses

Ancient Hawaiian

All the formally recognized native species of Wikstroemia in Hawai‘i (currently 12 species) have the common Hawaiian name ‘ākia. And, while according to Pukui & Elbert [1986], some "varieties" were given qualifying adjectives such as lau nui (large leaf), mānalo (sweet, safe from harm), and pehu (swollen), it's currently impossible to attribute ancient species-specific uses to any Hawaiian Wikstroemia species. Therefore, the following is a collection of all the ancient Hawaiian uses of "‘ākia" we were able to find in the literature.

Perhaps the most interesting ancient use of ‘ākia was to catch fish, a process called hola. Hawaiian fishermen, using a nearby rock, would pound the bark and leaves of ‘ākia and then place double handfuls of the mash inside a sheath of coconut leaf or twisted grass. This was then placed under the water, most often in a tidepool but sometimes in deeper water or a stream. Within about ten minutes, the narcotic poison would cause the fish to swim about aimlessly or float to the surface where they were easily collected. Although the ‘ākia poison often killed the fish, it did not taint their flesh, which could be eaten without concern [Degener 1973].

While fish poisoned and caught using ‘ākia were safe to eat, apparently the ‘ākia poison itself was not. Degener [1973] and others state that the poison, while harmless to the touch, was extremely poisonous if eaten. He further describes that a deadly drink, prepared with the root and bark of ‘ākia along with several other plant parts, was used for suicide and the execution of criminals. Supposedly, the person giving the doomed person the poison in a cup called apukoheoheo would sarcastically say, "He wahi mea ola ia" ("This is to keep you alive.").

The strong fibrous bark of many species of Thymelaeaceae have been used worldwide for cordage [Britannica] and ‘ākia in Hawai‘i was no exception. Peterson in Wagner et al. [1990] has an excellent review of Hawaiian Wikstroemia fiber use and strength, where he states: "Species of Wikstroemia have furnished one of the strongest Hawaiian fibers, used in making ropes and braids. It is also said to have been used in making kapa." He goes on to say that measurements made at the Swedish Institute for Textile Research have shown that the fibers from W. oahuensis var. oahuensis branches desiccated for six months were about the same density as that of New Zealand flax (Phormium tenax) and ramie (Boehmeria nivea). And, in another study by Beatrice Krauss using traditional Hawaiian methods, cord made from W. oahunesis bark had half the tensile strength of Tossa jute (Corchorus olotorius).

Additional ancient uses of ‘ākia include:

Lamb [1981] claims ‘ākia wood was used as ‘auamo (carrying pole) or beating sticks.
Kamakau [1964], page 126, describes ‘ākia being used in an ‘ana‘ana magic ceremony: "In preparing for the prayer ritual of a kuni ceremony, the kapuahi kuni, the ritual fireplace, was set blazing with ho‘awa and ‘akia with stalks and leaves still green."
ʻĀkia berries were used in lei-making [Abbott 1992; Krauss 1993].
According to Ka‘aiakamanu & Akina [1922], ‘ākia, mixed with several other plant parts, was used as a laxative or to treat asthma.

For the reader interested in the many ancient Hawaiian uses of ‘ākia, Medeiros et al. [1998] provides an extensive review along with a more comprehensive list of ethnobotanical and historical sources than I present here.

Modern

ʻĀkia berries are sometimes used in lei-making [McDonald & Weissich 2003].

Is ʻĀkia Poisonous?

The short answer, given the recorded uses described above, is "Yes, you should always consider ‘ākia poisonous," and always treat it appropriately, particularly when making planting decisions (e.g., not a smart choice for landscaping a daycare or childrens' playground). However, what do we really know about the toxicity of ‘ākia? Well, unfortunately, I (Koebele) was unable to find any comprehensive scientific study on the toxicity of Hawaiian Wikstroemia and nearly all the recorded "data" on this subject is anecdotal. Most scientific investigations of Wikstroemia chemistry have been conducted on the non-Hawaiian species W. indica and have focused on its potential pharmacological uses.

Handy & Handy [1972], page 214, describe two types of ‘ākia: an “‘Akia ‘awa (bitter ‘akia). A shrub that bears orange-red fruits. Decoctions of bark and roots are deadly poisonous, and were used for killing and suicide” and “‘Akia manalo (mild ‘akia). Not poisonous; the bark and leaves were used as a narcotic.” Unfortunately, while their description of ‘Akia ‘awa (i.e., orange-red fruits) corresponds with Hawaiian Wikstroemia species, Handy & Handy do not provide a description of ‘Akia manalo.

Neal [1965], page 616, states without citation that "No part of the plant has been found to be poisonous to mammals" in her description of Wikstroemia. Similarly, Arnold [1944], pages 58 & 59, describes personally eating ‘ākia fruits and leaves and feeding an alcohol extract of bark to two guinea pigs without any ill effects to himself or the animals. Arnold concluded that "the plant is not as poisonous as it is commonly reputed to be, and it is easily possible—indeed, the writer considers it likely—that it is not poisonous at all."

More recently, Medeiros et al. [1998] notes that "the fruit is slightly bitter but eaten by birds"; however, the "foliage may be poisonous or at least unpalatable to cattle as it is almost never browsed." Rick Barbosa, co-owner of Hui Ku Maoli Ola, states, "I’ve also seen birds eat the fruits daily with no ill effects and the fruit taste so bad that any human who put it in their mouth would immediately spit it out, you can trust me on that, its terrible" [Hui Ku Maoli Ola]. Lastly, Nagata [1992] refers to the work of Dr. Frank Tabrah on the toxicity of Wikstroemia pulcherrima (to date, I've been unable to find this study). According to Nagata, Tabrah found that W. plucherrima caused mice to go to sleep, and that the toxicity of W. plucherrima varied from high to zero even in the same plant at different times.

Special Features and Information

General

Thymelaeaceae is a family of about 890 species of trees, perennial herbs, and lianas in 46 to 50 genera that are found worldwide (but rarely in cold regions), and are particularly common in Africa and Australia. Members of the family have a fibrous bark, with many having an unpleasant odor [Britannica].

Wikstroemia is the only native genus of Thymelaeaceae found in Hawai‘i, where currently, there are 12 formally recognized species, all endemic, with most species restricted to a single main island. W. oahuensis is the most widespread species, being found on five of the main Hawaiian Islands [Flora of the Hawaiian Islands].

The common name "false ʻōhelo" is believed to have originated because the orange to red fruits of ʻākia closely resemble the berries of the native and frequently collected ʻōhelo (Vaccinium spp.). ʻĀkia is sometimes referred to as the "fish poison plant" (see Uses above).

Hawaiian Name

On page 385, under W. foetida var. Oahuensis (a synonym of Wikstroemia oahuensis var. oahuensis), Hillebrand & Hillebrand [1888] make the somewhat obscure statement: "Nat. name: "Akia" or "Akea", the root of which recurs in the Vitian name "Mati". In Tahitian it is called "Ovao"." Some have interpreted this to mean that the Hawaiian name, ʻākia, originated from an ancient name for the related species, Ixora foetida (syn. Wikstroemia foetida), found in Fiji and Tahiti but not in Hawai‘i except under cultivation [Plants of Hawai‘i].

‘Ākia is also the Ni‘ihau name for the endangered endemic Solanum nelsonii, a small native shrub in the Solanaceae or Nightshade family, better known as pōpolo [Wagner et al. 1990].

ʻĀkia can also mean "to ferment; very sour, as poi. ʻAi ʻākia, sour poi;" however, it's unclear if this meaning has any relationship to the plant.

Pukui & Elbert [1986] define aoaoa as a "small seaside shrub (Wikstroemia sp.)." Given its normal habitat, this name seems unlikely to apply to W. oahuensis, and more probably was used for another more coastal species such as W. uva-ursi.

Etymology

Wikstroemia is named in honor of Johan Emanuel Wikström (1789–1856), a Swedish botanist and author of several papers on Thymelaeaceae [Wagner et al. 1990].

The species name, sandwicensis, refers to the "Sandwich Islands," as the Hawaiian Islands were once called and named by James Cook on one of his voyages in the 1770s. James Cook named the islands to honor John Montagu (The fourth Earl of Sandwich) for supporting Cook's voyages [Gledhill 2008].

BPK