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The Flowering Plants of Hawaii (beta)

Part 2 Amaranthaceae - Anacardiaceae


Achyranthes splendens
Photo 1 - Achyranthes splendens

Amaranthaceae would be known to readers who are familiar with decorative plants such as Celosia with its yellow or red cockscomb floral display. Amaranthus itself has among its 60 or so species several grain crops, e.g., grain amaranth and globe amaranth, as well as the decorative species. Amaranthus is represented on the Hawaiian Islands by six species, five of which are naturalized in disturbed areas on most of the islands. A peculiar situation exists with regard to the only endemic amaranth: Amaranthus brownii is known from two populations on Nihoa (the first island in the northwestern chain beyond Kaua`i) with only about three dozen plants. Nothing is known about relationships of this species, how it got to Nihoa, or how it will fare in light of encroachment of alien species. Another risk faced by species with limited numbers of individuals is the increased likelihood of emergence of deleterious traits owing to limited size of the breeding population. This is a common problem that we will meet with several other rare island species.

Charpentiera elliptica
Photo 2 - Charpentiera elliptica

Achyranthes, a genus of perhaps 10 tropical to subtropical Old World species, is represented in the Hawaiian Islands by four species, one of which, A. atollensis, a native of sand islands of the Northwestern Hawaiian Islands, may be extinct. Achyranthes is an Old World genus of perhaps ten species with representatives in Arabia, Java, Gambier Island (southern Pacific), Norfolk Island, and the Hawaiian Islands. The Manual suggests that the Hawaiian species are the result of a single colonization and are most closely related to other Pacific species. I am unaware of any studies designed to test this hypothesis. Achyranthes splendens var. splendens occurs on Läna`i and Maui; the endangered var. rotundata occurs on Läna`i, Moloka`i, and O`ahu. Variety rotundata (Photo 1) was photographed at the National Tropical Botanical Garden in Lawa`i, Kaua`i (hereafter referred to as the NTBG).

Charpentiera is a genus of six species, five of which are endemic to the Hawaiian Islands; the other species occurs on the Austral and Cook Islands. The Hawaiian species are moderately abundant in mesic to wet forests. Two species occur only on Kaua`i, Charpentiera elliptica, illustrated in Photo 2, and C. densiflora; the others occur on more than one island, e.g. C. obovata (Photo 3).

Justicia betonica
Photo 3 - Charpentiera obovata

The high flammability of the dried wood of Charpentiera was used by Hawaiians in the past for a pyrotechnic display. On certain auspicious occasions, young men would climb to a high point above the ocean, light pieces of the dry wood and throw them off the cliff top. Trade winds, flowing upward along the steep hill side, would carry the flaming pieces out over the bay where people would be waiting in canoes. Mt. Makana (1,280', ca. 390 m), which stands above Ke`e Beach on the northwestern shore of Kaua`i, is an especially revered spot (apparently there was only one other) where this show was performed.

The Hawaiian dictionary (Pukui & Elbert, p. 227) defines makana as a gift, present, or reward; according to some sources it can be taken to mean “gift from heaven”, but whether this is a true interpretation or merely a fanciful take on the entire enterprise would be best debated elsewhere.

Nototrichium sandwicense
Photo 4 - Nototrichium sandwicense Photo courtesy of Forest Starr

The Hawaiian Islands are home to the endemic genus Nototrichium, which consists of three species, one of which, rare and restricted to the Nä Pali area of Kaua`i (northwestern cliffs), was only discovered in 1996. This area is a difficult place for collection work owing to the precipitous terrain and loose substrate, the combination of which along with the intrinsic scarcity of the species helps to explain its recent discovery. Nototrichium sandwicense (Photo 4), which occurs in open forests and lava fields at low to medium elevations on all of the main islands, is much more common. The floral spikes of N. sandwicense are stout and rarely over 5 cm. long, whereas those of the related N. humile are narrower and can attain lengths of up to 14 cm. Nototrichium humile is listed as endangered.


Rhus sandwicensis
Photo 5 - Rhus sandwicensis Note color of young leaves.

Anyone who has ever encountered poison ivy or poison oak will have met Anacardiaceae, specifically certain species of Rhus, or Toxicodendron to use the exquisitely descriptive name preferred by some authorities. Initial contact with these plants may not necessarily cause a reaction, but subsequent exposures can bring about skin rashes that can be extremely severe in some individuals. An insidious feature of this reaction is that contact with one species can sensitive a person to other members of the family. Some other anacards (the term used as a general descriptor of family members) that readers will certainly know include cashew (Anacardium occidentale), mango (Mangifera indica), and pistachio (Pistacia vera). Several species of Rhus are used to produce lacquers, much appreciated for their deep colors and attractive surfaces. It is well known that individuals who have been sensitized by contact with one of the species containing the toxic substances can experience dermatitis by drinking from lacquered vessels.

The Hawaiian Islands are home to three genera of anacards, including one species of Rhus. Fortunately, the Hawaiian Rhus, the endemic R. sandwicensis (Photo 5), does not produce the phenolic compounds typical of its toxic cousins. This species is known as neleau, or neneleau, in Hawaiian.

Schinus terebinthifolius fruit
Photo 6 - Schinus terebinthifolius fruits

People to whom I have spoken have never experienced skin problems when handling the plant, and I did not have any reaction when I handled it (I have been sensitized to poison oak, but do not react to mangoes or lacquer ware). Neleau can readily be found growing on road cuts north of Hilo, Hawai`i, where the photograph was taken, and scattered in disturbed areas on most islands. The brightly colored young leaves provide a convenient identification feature.

The evolutionary relationships of Rhus were investigated by T. Yi and colleagues (2004) using DNA sequence data. In addition to addressing the diversification of Rhus in North America, the data revealed that the Hawaiian species is most closely related to species in North America; no specific ancestor was identified, however.

Photo 7 - Mangifera indica Mango fruit on the tree. Not ripe
Photo - 8 Mangifera indica Mangoes for sale at a Maui market.

Schinus terebinthifolius (Photo 6), a native of South America, is a widespread invasive weed in the islands. One of the Hawaiian names for this plant is wilelaiki, which requires explanation. There was a Hawaiian politician named Willy Rice who wore a hat lei made of the berries of the Christmas berry. His first name was reduced to wile, while laiki is the Hawaiian word for rice. The shiny green foliage and bright red berries are popular seasonal decorations, which explains the English common name Christmas berry.

The third representative of Anacardiaceae in the Hawaiian Islands yields one of the tastiest of all tropical fruits, the mango. Mangifera indica is a native of southeastern Asia but has been spread very widely throughout the tropics and subtropics. Mangifera consists of as many as 60 species (Mabberley, p. 520), with the number of cultivated varieties (cultivars) numbering as high as a 1000.

One of the most popular and commercially important varieties is the Haden mango shown here in Photo 8 in a market on Maui. The mango, introduced to Africa before 1000 AD, eventually found its way, with human assistance, to the New World, and to the Hawaiian Islands early in the 19th century via Mexico. Mango trees have been cultivated widely in the islands and are often planted around homes for their shade and general attractive appearance, as well as for their fruit. Ripening fruit are seen in Plate 7, an individual flower in Photo 9. Not likely to appeal to every one is the quest for road mangoes. The trick is to get to the freshly fallen fruit–usually perfectly ripe–before the rats, mongooses, birds, and local kids do. Cars can be a problem as well.

September 19, 2011

Literature cited…

Mabberley, D. J. 2008. Mabberley's Plant-Book, 3rd Edn. Cambridge University Press, Cambridge.

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Dicot Families:

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