The Flowering Plants of Hawaii
Part 3 Apiaceae - Apocynaceae
Members of Apiaceae (Umbelliferae) (commonly called umbels or umbellifers) are likely among the most familiar plants to most readers. Some of the more common food or flavoring plants are angelica (Angelica), carrot (Daucus), celery (Apium), coriander or Chinese parsley (Coriandrum), dill (Anethum), fennel (Foeniculum), parsley (Petroselinum), and parsnip (Pastinaca). Other familiar umbels include the giant hogweed (Heracleum mantegazzianum), the cow parsnip (H. lanatum), and Queen Anne’s lace (Anthriscus sylvestris). Conium maculatum, whose common name is hemlock or deadly hemlock, is an extremely toxic plant reputed to be the source of poison taken by Socrates.
The flora of the Hawaiian Islands contains 18 species representing 13 genera of umbels. As one might expect, several of the more common food and flavoring umbels have escaped and become naturalized, e.g., carrot, coriander, dill, fennel, and parsley. There are no endemic genera of umbels in the flora but there are six endemic species in three genera: Peucedanum, Sanicula, and Spermolepis.
Peucedanum sandwicense is a species of the windward cliffs of Kaua`i, Moloka`i, West Maui, and Keöpuka Islet off the East coast of Maui. Access to this species in the wild can be very hazardous requiring some skill on very steep slopes. I have seen this species in the wild, however, not by means of mountain climbing skills, but merely by good fortune while hiking part way down the mule trail on Moloka`i that leads to the Kalaupapa Peninsula. Visitors with keen eyesight may see this species in its native habitat along that trail. A much clearer view is provided by visiting Limahuli Gardens on Kaua`i.
The Hawaiian word for this species is makou, a general term that serves to identify endemic Hawaiian as well as introduced species of Ranunculus (buttercups), and a species of the fern genus Botrychium; as a verb it means to blush, or to become red, as in sunburn (Pukui & Elbert, p. 230). Authors of the Manual note that the affiliations of makou are obscure. Peucedanum is a heterogeneous genus of 100-120 species with a center of diversity in the Old World (Mabberley, p. 652).
Sanicula, a widespread genus of about 40 species, has several members in the flora of western North America that may be familiar to many readers. Four endemic species occur in the Hawaiian Islands, three of which are rare and/or endangered. The only species that seems in no apparent danger is S. sandwicensis, which occurs in the alpine of Haleakalä, East Maui, and on Mauna Kea, Mauna Loa, Hualalai, and on the Big Island. DNA sequence data supported a western North American origin of Hawaiian and South American species of Sanicula (Vargas et al., 1998, 1999).
The last consideration in this family involves Spermolepis, a small genus of five species known from North America, Argentina, and the Hawaiian Islands. Up to the late 1980s S. hawaiiensis was known from two populations, one on West Maui and one on O`ahu. In 1995 the plant was rediscovered on Kaua`i and Läna`i. I have seen neither population in nature. The plant featured in the illustration is being grown at the Maui Nui Botanical Garden.
The name of this family is based upon the genus Apocynum, whose literal translation from the Latin is “away dog.” Apparently the bitter components of the leaves and sap of the plant are distasteful to dogs. The plant is equally distasteful to other critters, an excellent example of chemical defense against herbivores! North American readers may be familiar with two common species of this genus, A. androsaemifolium and A. cannabinum, known variously as Indian hemp, because of their strong fibers utilized by Amerinds to make cordage, and rheumatism weed, in reference to the use of preparations of the plants to treat joint pain and inflammation.
I should note here that the words “dogbane” or “dogsbane” are not uniquely applied to members of Apocynum. Common names are what might be called the bane of naming plants. Thus, in Europe Aconitum lycoctonum, a member of the Ranunculaceae, is also called dogbane, wolfsbane, or badger’s bane. Plectranthus ornatus (earlier known incorrectly as Coleus canis), a native of eastern India, is also called dogbane, again based upon its capacity to repel dogs. It is hardly necessary to point out to Harry Potter enthusiasts that “Wolfsbane Potion” is useful in dealing with werewolf problems.
The Apocynaceae consist of 380 genera and about 4,700 species (Mabberley, p. 56). In addition to dogbane, there are several other genera that are likely familiar to most readers, at least by reputation or newsworthiness. Several important drug plants belong to the family including Aspidosperma, Rauvolfia, Strophanthus, Tabernaemontana, and Vinca. Rauvolfia serpentina, an Indomalaysian species, is the source of drugs the most familiar of which, reserpine, is used to reduce blood pressure and treat certain mental illnesses.Catharanthus and Vinca, considered by some authorities as synonymous, are the source of very important drugs that have found use in cancer chemotherapy, e.g., vincristine and vinleucoblastine. Catharanthus roseus (Vinca rosea) is the common decorative periwinkle. Also a member of this family is the genus Nerium with the single species N. oleander, commonly seen as a hedge plant and available from nurseries as simply oleander or rose bay. The leaves contain significant quantities of cardiac glycosides and are highly toxic to humans; one leaf can prove fatal (Mabberley, p. 582).
The Apocynaceae are represented on the Hawaiian Islands by six genera and only 10 species, but a few of these are noteworthy. One of the most treasured members of the Hawaiian flora is Alyxia oliviformis, the much prized maile. The disposition of leaves of this plant, in sets of three, is a useful feature for identification. It is used as a decorative plant and in making lei. All parts of the plant contain a compound that releases coumarin when dried imparting a pleasant aroma (the new-mown hay odor). Although only a single highly variable species is recognized by the authors of the Manual, earlier workers recognized several variants and gave formal names to them. It is interesting to note that the four forms (technically, forma) agree with variants named by Hawaiians. The Hawaiian names, brief descriptions, and botanical names are shown in Table 1.
Table 1. Concordance between Hawaiian and Botanical nomenclature in the Hawaiian endemic species Alyxia oliviformis.
One of the intriguing phenomena encountered by European explorers in the tropics (and elsewhere) was that the local peoples knew their surroundings in impressive detail, and had names for virtually everything that grew in their area. These ‘folk taxonomies’, as they are called, reflect a deep understanding of natural variation patterns. This intimate awareness of one’s surroundings is not, of course, limited to the Polynesian peoples, but is a general phenomenon of indigenous groups the world around. Understanding this knowledge, and in many instances attempting to benefit—alas, also profit—from it is the foundation of the study of “ethnobiology.”
The genus Ochrosia, with 30 species, has representatives ranging from Madagascar to Australia and Polynesia. Four species are listed in the Hawaiian flora, although the authors voice some concern that this may be a tentative solution, with a better understanding awaiting detailed study. They do suggest that the four are the result of a single colonization followed by subsequent differentiation into the present condition.
Three of the species are rare and/or endangered, including O. haleakalae, which is known from East Maui (Haleakalä) and two sites on the Big Island. Ochrosia kauaiensis is a rare species endemic to mesic forests on Kaua`i. The plant is maintained in cultivation at the Limahuli Garden on Kaua`i.
The endemic genus Pteralyxia, known as kaulu in Hawaiian, consists of two species, P. macrocarpa, which occurs only in the mountains on O`ahu and is described as scattered and uncommon; and P. kauaiensis, which occurs only on Kaua`i and is considered rare. The latter is being cultivated at the Limahuli Garden.
Hao occurs fairly widely in the islands, except Kaho`olawe, in a variety of habitats ranging from ridges and hillsides in mesic forests, dry forest and shrubland, and on lava flows on Maui and on the Big Island. A colleague of mine described plants of the sort exemplified by Rauvolfia as being “distressingly tropical” in appearance.
I must admit to some sympathy with that point of view, especially when the plants in question are not in flower. In the case of Rauvolfia, the leaves grow in whorls of three to five at each node. Identification is much simplified when the tubular white flowers or characteristic lobed fruits are present.
I learned recently (Barrie Moss, per. Comm., Feb, 2010) that a related species, Rauvolfia vomitoria, a native of tropical Africa, has escaped from cultivation on the Big Island and has become a pest. Apparently this plant had been (or perhaps continues to be) cultivated by individuals who were interested in its medicinal properties.
One of the features of Rauvolfia species that brought it so much attention was its common use by people in southeastern Asia as a medicinal plant effective in treating anxiety, insomnia, insanity, and snakebite, and later as the source of reserpine and related alkaloids which are responsible for the therapeutic effects, other than snakebite. An examination of roots of hao revealed that it too contained reserpine, but only ca. 0.01%, a very low concentration compared to the medicinal varieties found in Asia.
The genus Catharanthus consists of eight species, seven of which occur in Madagascar with the remaining one a native of India and Sri Lanka. The most commonly encountered species, at least to North Americans, is C. roseus, the Madagascar periwinkle. Its pink flowers make it an attractive decorative plant. It is frequently seen in home and hotel gardens in the islands. It has escaped cultivation, however, and can be found growing in a variety of disturbed places, such as beside the trail on the south coast of Maui where the photograph for Catharanthus was taken. This plant accumulates a rich variety of alkaloids some of which have found use as therapeutic agents, but the yields are often so low that very large amounts of plant material are needed for the isolation of small amounts of useful drug. More success has been had with the closely related plant Vinca. Interested readers might consider looking for information on Vinca and some of its products, the anti-leukemia drugs vinblastine and vincristine.
Although they have not become naturalized in the islands, and are thus not listed in the flora, species of Plumeria are so common that it seemed reasonable to include one of them here. Plumeria, known commonly as frangipani, pagoda tree, or temple tree, is a native of Mexico and Central America. The first plants were brought to the islands by the German physician and botanist Wilhelm Hillebrand in the mid 1800s, along with many other colorful and potentially useful plants that caught his fancy.
Flowers of Plumeria are extremely popular for making leis in the Hawaiian Islands. Perfumers use the powerful aroma components of this flower to make an array of products carrying such tantalizing names as Wicked Wahini TM, about which little further comment seems necessary. Plumerias can be found on most hotel grounds and in gardens of private homes throughout the islands. Where do they come from today?
A few miles west of Kaunakakai, Moloka`i’s main city, lies a ten acre farm devoted to the cultivation of plumerias (Plumeria spp.). Molokai Plumerias is owned and run by the Wheelers who have had extensive experience, not only in growing these lovely plants, but in the world of bee culture as well (their barn was the honey factory at one time). The main white variety grown—the one most favored for leis—is shown in the photo.
They also grow a limited number of the darker pigmented variety. An overall view of the field in full flower is seen in the photo with the mountains of eastern Moloka`i in the distance. Although Dick claims that he can only smell the plants first thing in the morning (sensory overload no doubt), we enjoyed the aroma of these flowers during our entire visit. If the wind is right, it is also possible to smell the flowers as one drives past the farm.