Chapter 9. Polynesian-Introduced Plants.

Botanical Descriptions and Traditional Uses

[Illustration: Lo‘i kalo (taro patch)]

‘Ono kāhi ‘ao lū‘au me ke aloha pū.

A little taro green is delicious when love is present.

Even the plainest fare is delicious when there is love.

(Pukui: 2523-276)

Polynesian-Introduced Plants—An Introduction

The ancient Polynesian settlers of the Hawaiian Islands brought many plant species with them on their voyaging canoes, and these plants were important for many uses in early Hawaiian culture. The precise number of plants brought to the Hawaiian Islands by the early Polynesian settlers remains uncertain.

The 25 species discussed at length in this chapter include 24 species shown quite conclusively by research to be Polynesian introductions, along with ‘ohe (Schizostachyum glaucifolium, bamboo), which is probably a Polynesian introduction, though its status is still questionable.

Several other plant species were likely brought to the Hawaiian Islands by the Polynesians, and were already native (indigenous) to the Hawaiian Islands. These species include: hala (Pandanus tectorius, screwpine), hau (Talipariti tiliaceum), and kou (Cordia subcordata).

The Polynesian settlers of the Hawaiian Islands also brought numerous plant species to the Islands unintentionally (as well as various non-plant species; see Overview of Native and Polynesian-Introduced Species of the Hawaiian Islands, Chapter 5).

Plant species presumed to be unintentionally Polynesian-introduced include: ‘ihi ‘ai (Oxalis corniculata, yellow wood sorrel); kāmole (Ludwigia octivalvis, primrose willow); and Solanum viride. Koali kua hulu (Merremia aegyptia, Hairy merremia), kūkaepua‘a (Digitaria setigera), neke (Thelypteris interrupta, maiden fern) and Paspalum scrobiculatum (ricegrass), also may be unintentional Polynesian introductions.

Species that are generally considered indigenous in the Hawaiian Islands, but which may be Polynesian-introduced, include: pā‘ihi (Rorippa sarmentosa), pili (Heteropogon contortus, twisted beardgrass), and ‘uhaloa (Waltheria indica). (See below for more details.)

Though niu (Cocos nucifera, coconut palm) is considered a Polynesian introduction, there is a chance that it also may be native to the Hawaiian Islands, as the seeds are very durable in ocean water for many months.

Some plants that are currently considered Polynesian introductions may later, upon further scientific evidence, turn out to be native to the Hawaiian Islands.

One recent example of this is kou (Cordia subcordata), long thought to be a Polynesian introduction (and not native to the Hawaiian Islands) but recently determined to be native (see Kou).

This was also the case with hala (Pandanus tectorius, screwpine), long thought to have been a Polynesian-introduced species (and not native to the Hawaiian Islands), until hala fossils dated to more than one million years ago were discovered along Kaua‘i’s north shore. This find proved quite conclusively that hala is indeed a native Hawaiian plant.

[Photographs: Kou; hala (with note about native status)]

In summary, because of the various uncertainties regarding plant origins (noted above and explained in more detail below), the exact number of plant species brought to the Hawaiian Islands (intentionally or unintentionally) by the Polynesian settlers of the Hawaiian Islands remains speculative.

The number of Polynesian-introduced plant species is at least 24, and probably includes more than 26 species. In this text, the numerous uncertain cases are explained along with each species’ current status.

Almost all of the species brought to the Hawaiian Islands by the Polynesian settlers eventually became naturalized in the Hawaiian Islands, growing without the aid of human cultivation.

Two important Polynesian-introduced species that did not become naturalized in the Hawaiian Islands are ‘uala (Artocarpus altilis, breadfruit) and ipu (Lagenaria siceraria, bottle gourd).

For an overview of native and Polynesian-introduced plant species taxonomy, traditional plant uses, and sources regarding plants and ferns described in this text, see the Introduction to Chapter 8—Native Plants and Ferns of the Hawaiian Islands.

A Brief Review of Questions Relating to Polynesian-Introduced Species

The following is a brief review (synopsis) of species whose Polynesian-introduced status is uncertain, or whose status has recently changed. For the purposes of this brief review, the 1999 Manual of the Flowering Plants of Hawai‘i: Revised Edition[i] will be referred to as the Manual, and the 2002 Electronic Supplement to the Manual of the Flowering Plants of Hawai‘i[ii] will be referred to as the Supplement.

· Hala (Pandanus tectorius, screwpine). Hala was long thought to have been a Polynesian-introduced species, not native to the Hawaiian Islands. Then hala fossils dated to more than one million years ago were discovered along Kaua‘i’s north shore, proving that hala is indeed a native Hawaiian plant.

However, given the many uses of hala in early Polynesian culture, it is likely that the early settlers also brought the plant with them to the Hawaiian Islands on their voyaging canoes.

· Hau (Talipariti tiliaceum). The Manual lists hau as “ind?” (questionably indigenous), noting that “...it is not possible to ascertain whether this species is indigenous or a Polynesian introduction.”

It is also noted that the plant’s seeds remain viable in the ocean for several months, and dispersal reaching the Hawaiian Islands (though not proven) is not unlikely. Note: Hau (formerly Hibiscus tiliaceus) was reclassified by the Supplement as Talipariti tiliaceum.

· ‘Ihi ‘Ai (Oxalis corniculata, yellow wood sorrel). The Manual lists Oxalis corniculata as “pol?” (questionably Polynesian-introduced), noting that the plant “...may represent a Polynesian introduction or an indigenous species.” St. John[iii] mentions Oxalis corniculata as a weed that may have been unintentionally introduced by the early Polynesian settlers of the Hawaiian Islands.

· Kāmole (Ludwigia octivalvis, primrose willow). Ludwigia octivalvis was first collected in 1779 by botanist David Nelson on Captain Cook’s third expedition.

The plant is noted by St. John[iv] and Kirch[v] as potentially an inadvertent Polynesian introduction, since it is common as a weed in fields of kalo (Colocasia esculenta, taro) on some islands, and the seeds may have arrived in the Hawaiian Islands in the mud that was packed around the corms of the taro while it was being transported to the Hawaiian Islands on voyaging canoes.

The Manual lists Ludwigia octivalvis as “pol?” (questionably Polynesian-introduced), noting that “...the seeds of this species originally could have been brought to the Hawaiian Islands unintentionally by Polynesians on taro plants; however, they could just as easily have been brought by migratory water birds such as ducks.”

· Koali Kua Hulu (Merremia aegyptia, hairy merremia). Koali kua hulu is noted by St. John[vi] as a weed that may have been unintentionally introduced to the Hawaiian Islands by the early Polynesian settlers.

The Manual lists Merremia aegyptia as “nat?” (questionably naturalized) and “...perhaps indigenous,” noting that the plant was first collected in 1779 by David Nelson, a botanist on Captain Cook’s third expedition.

· Kou (Cordia subcordata). Kou has long been considered a Polynesian introduction (as documented in the Manual), but recent subfossil seed discoveries[vii] resulted in the reclassification of Cordia subcordata as indigenous. This new indigenous status is documented in the Supplement.

· Kūkaepua‘a (Digitaria setigera). The Manual lists Digitaria setigera as “ind?” (questionably indigenous), noting that the plant is “...indigenous or a very early introduction.”

Kirch[viii] and St. John[ix] note the possibility that the plant was an unintentional introduction to the Hawaiian Islands due to its association with pigs (Sus scrofa) brought by the early Polynesian settlers. The Hawaiian name of the plant, kūkaepua‘a, means “pig dung.”

· ‘Ohe (Schizostachyum glaucifolium, bamboo). ‘Ohe is considered by many to be a native Hawaiian species, and it is classified as a native species in Pukui and Elbert’s Hawaiian Dictionary (1986).[x]

The Manual (2002), however, lists Schizostachyum glaucifolium as “pol?” (questionably Polynesian-introduced), noting that ‘ohe is “...possibly a Polynesian introduction or perhaps indigenous,” and “...believed to be a Polynesian introduction.”

· Pā‘ihi (Rorippa sarmentosa). Pā‘ihi was used to dye kapa (tapa) as well as for medicinal purposes, and is listed by the Manual as “pol?” (questionably Polynesian-introduced), noting that the plant is “...an accidental or intentional Polynesian introduction, or perhaps indigenous.”

Rorippa sarmentosa was formerly listed as Nasturtium sarmentosum, but was reclassified in the Supplement as Rorippa sarmentosa).

· Paspalum scrobiculatum (ricegrass, no known Hawaiian name). The Manual lists Paspalum scrobiculatum as “ind?” (questionably indigenous), noting that the plant is “...presumably indigenous or an early introduction.”

· Pili (Heteropogon contortus, twisted beardgrass). The Manual lists pili as “ind?” (questionably indigenous), noting that it “...may be a Polynesian introduction.”

· Solanum viride (no known Hawaiian name). Native to the Central Pacific, this shrub grows to about 6½ feet (2 m) and is known in the Hawaiian Islands from just three early (post-contact) collections.

The Manual lists Solanum viride as “pol?” (questionably Polynesian-introduced), noting that “...if it was used as a sub-cultigen, its transport to the Hawaiian Islands by Pacific islanders is likely, but its persistence may not be long at the margins of its geographical distribution.”

· Neke (Cyclosorus interrupta, formerly Thelypteris interrupta; maiden fern). This fern was collected in 1779 by botanist David Nelson on Captain Cook’s third expedition.

St. John[xi] and Kirch[xii] note that the fern is potentially an inadvertent Polynesian introduction, since it is common in fields of kalo (Colocasia esculenta, taro) on some islands, and the spores may have arrived in the Hawaiian Islands in the mud that was packed around the corms of the taro while it was being transported to the Hawaiian Islands on voyaging canoes.

Neke (Cyclosorus) is listed as indigenous by the University of Hawai‘i Botany Department’s Hawaiian Native Plant Genera.[xiii]

· ‘Uhaloa (Waltheria indica). The Manual lists Waltheria indica as “ind?” (questionably indigenous), noting that the first collection was made in 1779 by David Nelson, a botanist on Captain Cook’s third expedition, and is “...apparently indigenous.”

St. John[xiv] mentions Waltheria indica as potentially introduced (unintentionally) by the early Polynesian settlers of the Hawaiian Islands. However, the plant has many traditional (including medicinal) uses in ancient Hawai‘i (see ‘Uhaloa in Native Plants and Ferns of the Hawaiian Islands, Chapter 8).