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The Flowering Plants of Hawaii
by Bruce A. Bohm

Part 52 Araceae

A typical flower of Anthurium.
A flora stand at the Hilo Saturday market.

Araceae are a medium sized family, 3,250 species in 105 genera, mostly tropical and subtropical in distribution with a few species from temperate areas. Most readers will recognize some members of the family owing either to their use as decorative plants, either indoors or in the garden, or unique morphologies (or aromas). A few familiar genera within Araceae are: Amorphophallus (A. titanum; one of the largest arums, from Sumatra); Anthurium (popular in Hawaiian Islands); Arisaema (Jack-in-the-pulpit); Caladium (colored foliage); Dieffenbachia (so-called dumb cane because it can cause numbness of the tongue); Lysichiton and Symplocarpus (skunk cabbages); Monstera and Philodendron (large epiphytic lianas); and Zantesdeshia, the ‘Calla’ of horticulture.

Some of the most conspicuous members of the family on the islands are the anthuriums. They are so common, in fact, that some visitors might be excused in thinking that they are the state flower. Anthurium is a large tropical American genus with at least 1,000 species (Mabberley, p. 52), or more than 1,500 (A. M. Alvarez et al., 2006). It is not listed in the Manual of the Hawaiian flora insofar as naturalization has not been documented. Anthuriums provide long lasting and colorful floral displays and are very common as decorative plants or as a source of cut flowers (see images). The four major producers of anthuriums in the world are the Hawaiian Islands, the Netherlands, Mauritius, and Jamaica, but with many other tropical countries, both in the New World and in Asia, growing for the commercial market as well. The level of production in the Hawaiian Islands peaked in 1980 with the shipments of up to 232,000 dozen flowers per month. The yield of 2.5 million dozen flowers that year did not meet demand (A. M. Alvarez et al., 2006).

Anthuriums are subject to several pathogenic organisms the worst of which, bacterial blight, is known to be caused by the bacterium Xanthomonas axonopodis pv. dieffenbachiae. Blight first appeared in the islands in 1972, but did not manifest itself as a major problem until about 10 years later. The epidemic peaked in the years 1985-1989 causing the failure of a large number of small farms. [Most commercial production at the present is done by a few large farms.] Several approaches to controlling the disease have been attempted including breeding the principal species of commerce, Anthurium andraeanum, with A. antioquiense, which resulted in offspring with increased resistance to infection, but with some changes in floral features. The possibility of developing a biological control of blight came from the work of microbiologists who discovered a suite of bacteria in susceptible strains of Anthurium that did not develop blight symptoms even at high inoculation levels in tests. Gene transfer techniques have been successful in developing lines of Anthurium that carry proteolytic enzymes active against the pathogen. There has also been a good deal of effort into means by which the pathogen, which is easily transmitted by contaminated tools, work areas, and certain irrigation methods, with steps to improve these culture methods. Although all of these attempts have been successful to some extent, total control has not been achieved, and work is continuing on all of these fronts.

More detailed information, and a thorough list of research sources, can be found in the article by Anne M. Alvarez and colleagues (2006) who are associated with the Department of Plant and Environmental Protection Sciences at the University of Hawai'i (Mänoa).

elephant ear taro
Alocasia macrorrhiza, the elephant taro.
Colocasia esculenta, taro.
A private taro patch on Moloka'i.

Two genera of particular interest to Hawaiians within Araceae are Alocasia, a tropical genus of perhaps 65 species, and Colocasia, which consists of seven species, also of tropical Asian origin. Polynesians brought one species of each, Alocasia macrorrhizos (see image), known as 'ape in Hawaiian, and as the very descriptive elephant’s ear in English; and Colocasia esculenta, known to all as taro or kalo. Unlike taro, about which more will be said below, 'ape was of only marginal use as a food plant—mostly during times of famine—owing to the presence of high concentrations of calcium oxalate (technically, raphides) in the corms of this plant (corms are elongated, underground stems, as opposed to bulbs, which are modified leaves and leaf bases; both are food storage organs). Since calcium oxalate is only sparingly soluble in water, boiling the plant parts with several changes of water was necessary. Leaves of 'ape were used, however, in a preparation for dying gourds, and as a wrap for helping to induce sweating in some ritual healing practices (Krauss).

The key player in this drama, however, is Colocasia esculenta, (see image), which has been cultivated throughout the history of the Hawaiian Islands, and indeed, in Asia well before the Polynesians set out on their trans-Pacific migrations. Taro has been a major staple in the diets of Pacific peoples for a very long time. And, as we shall soon see, it is much more than just a source of carbohydrate. Before we delve into the social history of the plant it might be nice to see some of these plants where they are best appreciated, in the field. A small, private plantation in southern Moloka'i (see image) shows mature plants and patches being prepared for the next crop. Visitors to Kaua'i can see an ancient taro plantation when they visit Limahuli Botanical Garden (see image). One of the most accessible taro fields—and certainly one of the most often photographed—lies in the Hanalei Valley in Northern Kaua'i (see image). In addition to the overall view from the scenic point, it is possible to see the taro patches up-close by turning left onto the access road (just beyond the single-lane bridge). Walking along the road provides an opportunity to see taro plants in different stages of growth. But, the no trespassing restriction is for real! In addition to keeping visitors from wandering about on the levees, the area lies within the Hanalei National Wildlife Refuge amongst whose residents are the protected nënë. It is thought that Polynesian colonists brought about a dozen varieties of taro with them, and that by the time of contact with Europeans (early 19th century) well over 300 varieties had been selected. Although cross pollination was known, most selection of new varieties was done by nurturing spontaneous mutations, or 'sports' in common terms. Varieties differed in leaf color and shape; stem color; and various characteristics of the corms, whether they were more or less fibrous; and the quality of the poi that was produced. Some varieties fared better than others under more limited irrigation regimes, a feature of importance during times of draught. The production of such a wealth of taro varieties attests to the skill of these early farmers.

When harvested the corms were steamed in an underground oven (imu), peeled, broken into pieces, and pounded using special mallets or flat, hard boards. A little water was added to make the mass tractable. At this stage the thick paste could be wrapped in ki leaves and stored for several months if necessary, or carried on a journey. A softer poi was used as soon as the desired amount of fermentation had occurred. It is also interesting to learn that planting, tending, harvesting, and preparation of poi were men’s work. Women knew how to do all of these tasks, of course, but only performed them when men were not available, perhaps when they were otherwise occupied as with the business of war. Other parts of the taro plant were eaten as well, for example: young leaves were eaten as greens; peeled stems were steamed; some flower parts were eaten as a delicacy; and grated raw taro mixed with shredded coconut, coconut water, and sugar was wrapped in a ti leaf, steamed and eaten as a desert (Krauss).

But, taro isn’t just a source of excellent dietary carbohydrate; the plant itself embodies the very spirit and being of the Hawaiian people. Why should this be so? All cultures have an account of creation upon which the very nature of their view of humankind is based. The Polynesian account of creation, varying in details, fundamentally involves a coupling of Father Sky with Mother Earth. The first offspring was a prematurely born, deformed boy (another version says the first birth was a root) who was buried and from the grave there sprung a taro plant. A second coupling produced a healthy boy, who was named Haloa (meaning long stalk); it is from Haloa that humankind has sprung. The significance of birth order in Polynesian life cannot be overemphasized, a point described best by E. S. C. Handy et al. (p. 74) which is quoted here in full:

The historical taro patch at the Limahuli Garden on Kaua'i.
The large, commercial taro farm in the Hanalei River Valley, Kaua'i.

"In Polynesian genealogical principle, precedence in birth, determines for all time status and deference. When, therefore, the learned men in early times, all of them taro planters, compounded the myth as a part of their heritage of ancient lore, which describes the birth of nature and man as the consequence of impregnation of Mother Earth by Father Sky, they sealed into their people’s unwritten literature this idea, that the taro plant, being the first-born, was genealogically superior to and more kapu (sacred) than man himself, for man was the descendent of the second-born son of Sky and Earth. The taro belonged, then, in the native parlance of family status, to the kai kua'ana (elder or senior) branch of cosmic lineage, man himself to the kai kaina or junior. To the kai kua'ana, however many generations or degrees removed in actual kinship, the kai kaina owes deference and fealty.'

With the establishment of taro as the most important food crop of the Polynesians—and hence, present day Hawaiians—as well as a revered ancestor, the scene was set for confrontation when efforts to 'improve' the plant were undertaken. What was there to improve? Some background is necessary. There has been a downward trend in taro production over the past 50 years, not just because of reduced acreage under cultivation, but also because yield per acre has decreased. Several factors have played roles throughout the history of taro culture including loss of land to other commercial developments, increased competition for adequate water supplies, and a variety of pests and pathogenic organisms. Land and water are local issues; the arrival of potentially devastating organisms is a global problem. The Hawaiian Islands may be the most isolated archipelago on the globe, but they are only a matter of hours distant from continental land masses by air, and a matter of days by sea. The contamination of the Hawaiian Islands by all manner of organisms—ranging from the mosquito that brought avian malaria, to the green cancer (Miconia) that is ravaging forests on several islands, to the little coqui frog that enlivens the nights on the Big Island, to the ungulates that have devoured forests of mamane (among other native plants)—is an all too common phenomenon. In the case of taro, growers encounter Phytophthora leaf blight, Pythium corm rot, pocket rot (several pathogens), apple snails (Pomacea canaliculata), and a number of other uninvited guests. Likely none of these is a native either.

The potential devastation that these taro diseases can wreak on an agricultural system can be appreciated by considering some examples. Phytophthora, which appeared on Samoa in the early 1990s, led, in a matter of a few years to the loss of almost all of the varieties under cultivation and drastic reduction in taro yield. Taro cultivation in the Caribbean, where the plant was introduced to provide a familiar food source for displaced Africans, came under attack from Phytophthora in the early years of the 21st century. The crop was reduced by 80% in the Dominican Republic and totally decimated in Puerto Rico. An even more frightening prospect is effect that the Alomae-Bobone viral complex would have on the Hawaiian Island taro industry should this pathogenic threat make it to the islands. In 15 years this complex completely wiped out taro production on Makira in the Solomon Islands. Acutely aware of the potential disaster awaiting the islands should this complex gain access to Hawaiian taro, scientists from the University traveled to the Solomon Islands where they subjected several Hawaiian strains of taro to the local viral complex; none of the strains survived. The insect vectors of this viral system, taro leaf hoppers, are already present in the Hawaiian Islands.

The classical approach to meeting the problem of disease susceptibility in plants is based upon finding varieties that are resistant to a particular pathogen and breeding that resistance into the productive line. Although this approach has worked well with many systems in the past—and continues to be a reliable method—there are some drawbacks. One of these is that crossing two organisms results in a set of offspring out of which the ones with the desirable trait must be isolated. Another problem lies in the simple fact that the newly acquired resistance is not necessarily permanent. Pathogenic organisms are also capable of mutations some of which have the effect of increasing virulence and thus countering the new resistance trait. Plant breeders and pathologists alike are aware of the ongoing 'battle' between the virulence genes of the pathogens and the resistance genes of the host: the war rages on.

With the readily available tools of molecular genetics, developed over the past two decades or so, new approaches to confronting plant disease became available. Rather than searching for specific natural resistance features, the genetic engineering approach targets identifiable features of pathogenic organisms in general. For example, all fungal pathogens contain chitin in their cell walls. By inserting the gene for chitinase (from rice), an enzyme that specifically targets fungal cells, into a plant genome the recipient acquires a built-in defense against any fungal attacker. Similarly, insertion of the gene for resveratrol, an antifungal substance from grapes, provides another form of protection. In 2001 the College of Tropical Agriculture and Human Resources (CTAHR) of the University of Hawai'i, in association with Cornell University, undertook the genetic transformation of Chinese taro (var. Bun long) to include the two genes just mentioned as well as a gene for oxalate oxidase (produces hydrogen peroxide which inhibits pathogen growth). Results were mixed. The oxalate oxidase-transformed taro resisted Phytophthora colocasiae in contrast to non-transformed controls which died within 12 days of inoculation. The chitinase-transformed plant material, however, was not as effective against the pathogen Sclerotium rolfsii whose growth was slowed but the plant ultimately perished.

Reaction from the Hawaiian community toward the genetic manipulation of taro was swift and to the point. Don’t mess with our ancestors! With cries of "We are Haloa! Haloa is us,' (Recall that Haloa was the name of the second son in the Hawaiian creation story, the son from whom humanity arose), it is clear that the issue hit a very sensitive spot. Emotions ran high—and still do!—a situation capitalized upon by a segment of society that is adamantly opposed to any genetic manipulation of food stuffs. Activists who oppose GMO (genetically modified organisms) foods in general were quick to seize this opportunity to further their cause, thus appealing to a broader audience. Discussions eventually resulted in a ten year moratorium on manipulation of the Hawaiian varieties of taro (the Chinese variety is exempt).

The frustration of the people, at least the activist component who claim to speak for the people, is well articulated in the following statement made by Walter Ritte Jr., one of the most outspoken of the critics of the GMO movement: "It is no small matter when an indigenous people share the importance of their traditional knowledge and genealogy, and the dominant culture refuses to listen. This is the time when we are making it perfectly clear that there is a kapu placed on all genetic modifications and patenting our genealogical brother the taro. There should be limits to academic research when it conflicts with indigenous culture. No one can own our traditional knowledge, intellectual property rights or our biodiversity.'

The activists demanded that all genetic manipulation on the Hawaiian taro cultivars be terminated, that the patents be withdrawn, and that the university stop all genetic manipulation work. The spokespeople claimed that traditional methods of taro improvement are sufficient to meet any challenges presented by pathogens. Activity at the political level, as opposed to the usual media, has also been noteworthy and vigorous. County by county there have been referenda calling for cessation of all genetic engineering activity—not just on taro—and that such activity become a criminal act. Response from the University has been to terminate genetic manipulation of the Hawaiian varieties for a period of ten years and withdraw patents; work on the Chinese variety is not involved in the moratorium.

Funding for the project ran out in 2007, and with the bad press that came out of the confrontation, other donors would understandably be reluctant to leap into the picture. Proponents of the genetic engineering approach point out a serious problem that arises from situations of this sort in that the entire enterprise of unrestricted research and academic freedom are put in harm’s way. In a word, to stifle research that offers such potential, especially in view of the very nasty consequences should another pathogen, e.g., the Alomae-Bobone viral complex, make it to the island, is seen as terribly short-sighted and potentially disastrous.

In order to provide a broader view of the long-term historical setting in which the taro confrontation occurred, I will cite, in full, a paragraph from the introduction to the March 2009 background paper, entitled CTAHR and Taro: "The recent opposition to, or dissatisfaction with, CTAHR work on taro cultivar development arises from several sources. One source of opposition, and perhaps the most locally relevant, is members of the Hawaiian community that regard taro as a revered ancestor. They perceive manipulation of the taro genome as a desecration of their legendary heritage. This objection may, with some justification, be related to a broader resentment about usurpation of Hawaiian hegemony over the islands by Euro-American foreigners, and it also may be related to the current, diverse movement toward Native Hawaiian sovereignty. CTAHR, as a state and federal institution, may in some sense be a proxy for entities responsible for the historical intervention that ended the Hawaiian monarchy, resulted in the annexation of Hawai'i by the United States, and led to Hawai'i becoming a state.' The full report can be found at For readers not familiar with the sovereignty-related political unrest referred to above, I recommend reading Tom Coffman’s 1998 the Nation Within. The Story of America’s Annexation of the Nation of Hawai'i.

It is impossible to predict how the GMO situation will be resolved in such a way that the strongly held views on sacred ancestry are not abused, and the islands’ taro-cultural future is secured. What worries me, if I am allowed a personal view in all this, is what will the response be some day when a disaster does occur, and someone comes out with the all too familiar question: "Why didn’t somebody do something about this?'

The Flowering Plants of Hawaii Menu

Literature cited…

Alvarez, A. M., P. J. Toves and T. S. Vowell. 2006. Bacterial blight of anthuriums: Hawaii’s experience with a global disease. APSnet Feature Story, February.

Coffman, T. 1998. Nation Within. The Story of America’s Annexation of the Nation of Hawai'i. Epicenter, Käne'ohe, HI.

Handy, E. S. C. Handy, E. G. Handy and M. K. Pukui.1991. Native Planters in Old Hawaii. Their Life, Lore, and Environment. Revised edition. Bishop Museum Press, Honolulu, HI.

Krauss, B. H. 1993. Plants in Hawaiian Culture. University of Hawaii Press. Honolulu, HI.

November 10, 2012

© LC
Tallahassee, Florida USA