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The Flowering Plants of Hawaii
by Bruce A. Bohm

Part 46 Solanaceae

Solanum sandwicense
Solanum sandwicense. Photo by Gerry Carr.
Solanum nelsonii
Solanum nelsonii population.
Solanum nelsonii
Solanum nelsonii showing flowering habit.
Solanum nelsonii
Solanum nelsonii flower detail.

Solanaceae are a moderately large family consisting of 90 or 91 genera and between 2,450 and 2,700 species, depending upon the source of information. The family is home to many plants familiar to most readers: Solanum (egg plant, potato, woody nightshade), Lycopersicon (tomato, now considered Solanum), Capsicum (peppers), Nicotiana (tobacco), and the decorative genera Schizanthus and Petunia. The Hawaiian Islands have their fair share of common genera, as well as one with an indigenous species. There is also an endemic genus, Nothocestrum, with four species.

The most common genus in the family is Solanum itself with at least 1,250 species worldwide; there are 16 in the islands, four of which are endemics. The first example of an endemic member of the genus is the very rare S. sandwicense (see image), known only from a few sites in mesic forest on Kaua`i and O`ahu. In Hawaiian, this species is known as pöpolo, as are other members of the genus, or more specifically, as pöpolo `aiakeakua, literally, pöpolo eaten (`ai) by the (a ke) gods (akua). Authors of the Manual note that plants from Kaua`i, which differ in the degree and color of leaf pubescence, were recognized by earlier botanists as a separate species, S. kavaiense.

I met the next species by accident. I was making my way carefully along a narrow dune-top trail on the northern coast of Moloka`i heeding the signs telling me that I was in, or very near, a seabird nesting area. A particularly strong gust of wind—the area is wide open to the trades—sent my hat sailing down the dunes. It came to rest next to a patch of vegetation that was different from the normal dune plants of the area. The leaves were small, densely pubescent, and exhibited an unusual—at least in my experience—gray-green color. The few flowers that were visible (see images) clearly indicated that I had fallen into, or very nearly so, a patch of Solanum of some sort. This was my introduction to S. nelsonii, once more widespread but now limited to a few coastal sites that have been spared the devastation of development.

This species occurs on several of the northwestern islands, where it is fairly common, but it is increasingly difficult to find, and may in fact be extinct, on several of the main islands from which there have been no recent collections (Kaua`i, Maui, O`ahu, the Big Island, and Laysan). The patch that I saw on Moloka`i may be among the largest extent populations on the main island group. The unusually pigmented anthers suggest that different pollinating insects may be involved relative to other species of Solanum on the island.

Solanum nelsonii
Solanum incompletum. Note lovely spines!
Solanum linnaeanum
Solanum linnaeanum
Solanum linnaeanum
Solanum linnaeanum fruit.

Be careful when examining this next species of Solanum! An incautious person will find Solanum incompletum (see image) unfriendly to the touch, equipped as it is with spines along the veins on the undersides of the leaves and on the stems. The spines are a striking orange. This has been recorded on all of the main islands except O`ahu, Ni`ihau and Kaho`olawe. Other than the general Hawaiian name for all Solanum species, it is also known as pöpolo kü mai. Kü! can be used as a warning, meaning Stop! Mai is a directional word in Hawaiian indicating action toward the speaker. Could this be a warning to approach this armored plant with care?

Representing naturalized species of Solanum on the islands is S. linnaeanum (see images), the apple of Sodom, pöpolo kïkänia, or yellow-fruited or thorny pöpolo. This native of Africa is a widespread weedy species that grows in pastures and dry shrubland. It occurs on all of the Hawaiian Islands except Ni`ihau and Kaua`i. Its existence on Kaho`olawe attests to its capacity to grow in very dry, almost hostile, habitats.

The presence of this species in a pasture in South Africa is taken as an indication of over-grazing; and in Australia, it is a marked plant, meaning that the owner of property on which it is found growing is under legal obligation to get rid of it. A further example of a marked plant in Australia is the castor bean, Ricinus communis. The simple rule is: if you find it, kill it!

The islands are home to the endemic genus Nothocestrum with its four species. Authors of the Manual state that this genus is " …gravely in need of conservation." Two of its species are described as endangered, one, N. peltatum, is known from only a few locations on Kaua`i. The plant illustrated is N. latifolium (image), a small tree species that occurs in dry to mesic forest on all of the main islands except the Big Island, Ni`ihau, and Kaho`olawe. This specimen is being maintained in the Rare Plant Nursery at Volcano.

Nothocestrum latifolium.
Nothocestrum latifolium
 Lycium sandwicense.
Lycium sandwicense

The genus Lycium consists of 60 species from warm temperate parts of the globe with significant concentrations in South Africa and in the Americas. It is represented in the Hawaiian Islands by a single indigenous species, Lycium sandwicense (see image), which occurs otherwise on Rapa, Tonga, and the Juan Fernandez Islands. This species is known by a variety of names in Hawaiian, most of which refer in some way to the ocean; these include `öhelo kai, `ae`ae, `akulikuli `ae`ae, `akulikuli kai, and `akulikuli `öhelo. `Ae`ae refers specifically to Lycium, although it can refer to other seaside species as well. `Akulikuli is a general term for succulent plants. `Öhelo is berry and kai is ocean referring to the small red fruits that characterize Lycium, which as we just learned, grows by the seaside.

The small genus Brugmansia, with its five South American species, was at one time considered part of Datura. Datura currently is seen as comprising 11 species from southern North America. The two differ in the floral display; flowers of Brugmansia are pendulant, those of Datura open upward; and in life style, where species of Brugmansia are woody perennials while species of Datura are annuals. (see Floridata's Profiles of Datura stramonium and Datura metel) They both accumulate significant levels of alkaloids (mostly tropane alkaloids) and are poisonous to a greater or lesser degree depending on dosage. The Hawaiian Islands are home to one naturalized species of Brugmansia, B. candida (see image), according to the Manual. Other sources, including the NTBG web site, tell us that B. candida, or B. x candida, is a natural hybrid between B. suaveolens and B. versicolor. (Some sources have it as B. arborea.) This plant is reported to have been brought to the islands on board H. M. S. Blonde in 1825. The species is native to Peru, and the port from which the ship departed for the Galapagos leg of its journey was Callao—a port city north of Lima—it seems reasonable to suggest that the naturalist on board, the Scottish botanist John Macrae, saw its attractive flowers and collected seeds, or possibly entire plants. Many of the early botanical explorers were either employed directly by botanical gardens or were under contract to collect interesting specimens; it would not be out of line to suggest that that might have been the case with regard to Brugmansia (Datura in Macrae’s century).

Brugmansia candida.
Brugmansia candida

The long, tubular flowers have led to the name angel’s trumpet in English. The Hawaiian name for this species is nänähonua which translates literally to 'looking at the ground', descriptive of a plant whose flowers open toward the earth. The specimen pictured here is obviously the white variety, but visitors to the islands may find plants with very pale apricot-colored flowers, or possibly even pink ones. Since there has been a good deal of interest in cultivating this attractive plant, several color varieties have been developed as well as a double form. Furthermore, different hybrid combinations yield offspring with different colored flowers. Interested readers could consult growers’ societies who specialize in Brugmansia.

Datura stramonium
Datura stramonium

Datura is represented on the Hawaiian Islands by two species, D. metel and D. stramonium. The only specimens that I have seen in this genus were individuals of D. metel in very poor condition in a seasonally dry streambed in western Moloka`i. Illustrated here in its stead is the closely related D. stramonium (see image). Datura metel is known as the horn-of-plenty, but I’m not at all certain what the plenty refers to. This species is, as are all in the genus, deadly poisonous, although carefully controlled consumption by some peoples is part of spiritual rituals. This is probably more commonly seen with D. stramonium, known commonly in North America, where it is native, as Jimson weed. The origin of the common name is open for discussion. Hawaiians, however, called it la`au hänö, which is translated into asthma plant. Leaves are dried and pulverized to yield a preparation called ‘stramonium.’ The alkaloids of this species, mainly atropine and scopolamine, are powerful autonomic nervous system blockers and in anything but carefully controlled dosages can prove deadly. Medicinally, they are most commonly used to dilate the pupil in eye examinations, and treat motion sickness. Hawaiians also call this plant kïkänia or kïkänia haole, names that are also applied to cockleburs (Xanthium species) whose fruits, like those of Datura, are spiny. The presence of spines accounts for another of its common names, thorn-apple.

The genus Lycopersicon in the older literature was described as a genus of 10 species native to the western coast of South American including the Galapagos. So few differences between Lycopersicon and Solanum differentiate the genera, however, that Lycopersicon is now considered as part of the larger genus Solanum. Following the earlier view, authors of the Manual list two species of Lycopersicon on the islands, L. esculentum, the common tomato, and L. pimpinellifolium, the current tomato, a native of Peru and Ecuador. I think I may have seen the current tomato once—through a fence surrounding a construction site on Kaua`i—but when I returned with my camera the area had been cleansed of all visible life forms, except for the bulldozer operator.

Nicotiana glauca
Nicotiana glauca. A Starr image.
Capsicum frutescens
Capsicum frutescens
Solandra maxima.
Solandra maxima

Nicotiana, the genus that is home to the common tobacco, N. tabacum, is represented on the islands by common tobacco and by N. glauca (see image), a species that likes open, arid, disturbed sites. This would be a plant familiar to visitors from California who would know it as rabbit tobacco common along roadsides and disturbed hillsides in the hot southern part of that state. Nicotiana tabacum, paka in Hawaiian, was first collected in the islands in 1825 by John Macrae whose contributions to island botany have been commented on above.

Capsicum, the pepper or chili pepper genus, has a single representative in the islands. Capsicum frutescens (see image) is called bird pepper in English, nïoi or nïoi pepa in Hawaiian. It can be found, other than in home gardens, in low elevation disturbed habitats. I have seen it on the southern coast of Maui, where the photograph was taken, and in the Pololü Valley on the northeastern coast of the Big Island. The former site is in the rain shadow of Haleakalä, whereas the Pololü Valley lies in the direct flight path of the trade winds with their loads of moisture.

The next genus is not recognized as naturalized in the islands, but it is commented upon in the Manual. Solandra maxima (see image) is seen from time to time as a decorative plant owing undoubtedly to its very attractive large flower. The large showy flower of this plant is recognized in some of its common names, golden chalice vine (the species are all vines), and cup of gold. One source even calls it Hawaiian lily, although that is misleading since it is neither a lily nor, as we have noted, Hawaiian. The photograph was taken of a plant growing in native vegetation along the road to Koke`e Park (Kaua`i). H. D. Pratt (1998) states in his A Pocket Guide to Hawai`i’s Trees and Shrubs that Solandra may have become naturalized in the forests above Honolulu. The cover of his book features a photograph of the flower. The genus, which consists of 10 species, is native to tropical America (Mabberley, p. 804). As is the case with most members of Solanaceae, species of Solandra accumulate alkaloids.

The genus Physalis consists of at least 75 species (Mabberley, p. 662) many of which are native to Mexico. Two species are likely familiar to most readers, P. alkekengi, the Chinese lantern or winter cherry plant, with its attractive orange calyces, and the so-called Cape gooseberry, P. peruviana (see images). The common name Cape gooseberry is doubly in error. Neither is the plant from the Cape, it is a native of Peru as the specific epithet records, nor is it a gooseberry, a name that refers to some members of the genus Ribes (currents). It is most frequently encountered as a decorative bit served with some desserts. The orange fruit is edible; the fruit of pohä is used to make jam in the islands.

Physalis peruviana
Physalis peruviana. Flower.
Physalis peruviana
Physalis peruviana. Fruit capsules.

The Flowering Plants of Hawaii Menu

Literature cited…

Pratt, H. D. 1998. A Pocket Guide to Hawai`i’s Trees and Shrubs. Mutual Publishing, Honolulu, HI.

September 28, 2012



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