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Mo`omomi Dunes, Moloka`i
title graphic

by Bruce A. Bohm

Page 2

naupaka
Photo 15 -The patches of lighter green are naupaka, Scaevola sericea. The dunes are visible in the upper right hand corner of the photograph.
naupaka
Photo 16 - Close-up of naupaka with an old flower and some fruits, which the Hawaiians think look like hailstones.
Lipochaeta integrifolia
Photo 17 - Forming dense mats on the fore-dunes Lipochaeta integrifolia is a common plant of the area.
akoko
Photo 18 - This sprawling mat plant is Chamaesyce skottsbergii ('akoko), a member of Euphorbiaceae.

The sand banks along these bays are home to several plant species characteristic of strand communities, a prominent member of which throughout the Pacific is Scaevola (taccada) sericea (Goodeniaceae) (Photo 15). In Hawaiian this plant is known as naupaka kahakai;  (literally, beach naupaka, since there are other Scaevola species that are not beach plants), or as huahekili. Huahekili is the Hawaiian word for hailstones in reference to the plant’s round, white fruits (Photo 16). Also abundant among the sand banks is the Hawaiian endemic Lipochaeta integrifolia (Asteraceae) (Photo 17). This island endemic genus, referred to in general as nehe in Hawaiian, is represented in the islands by some 20 species, although the precise composition of the group requires additional study since it may be an artificial assortment of species (that is, they may have been grouped together solely on the basis of superficial similarities).

Other plants to be found here include the Hawaiian endemic Chamaesyce degeneri (Photos 18 & 19), which the Hawaiians call `akoko or just koko. This species belongs to the Euphorbiaceae. One of the most attractive members of this community is Heliotropium anomalum var. argenteum, a Hawaiian endemic member of the Boraginaceae (Photo 20). This plant is known to the Hawaiians as hinahina in reference to the grayish-white surface of the leaves (hence the argenteum , or silver-like part of its Latin name). It was—and continues to be—a favorite of Hawaiian ladies who make hat leis out of the little rosettes of leaves. Often found growing with hinahina is the diminutive flowered Nama sandwicensis (Hydrophyllaceae) (Photo 21) known from all of the main islands, except Kaho`olawe, as well as some of the islands of the northwestern extension of the Hawaiian archipelago.

close-up of akoko
Photo 19 - Close-up of the tiny flowers of Chamaesyce skottsbergii.
hinahina
Photo 20 - Heliotropium anomalum var. argenteum, hinahina. The species is widespread on beaches of the Pacific but this variety is unique to the Hawaiian Islands.
dune plants
Photo 21 - Heliotropium growing with Nama sandwicensis, endemic to the Hawaiian Islands and the only member of the Hydrophyllaceae that grows on the archipelago. Its flowers are tiny and dark lavender in color.
ena ena
Photo 22 - Pseudognaphalium (Gnaphalium) sandwicensium, 'ena'ena, growing in the sand.

A plant of special interest because of its occurrence solely on this part of Moloka`i is Pseudognaphalium (a.k.a. Gnaphalium) sandwicensium var. molokaiense, `ena`ena. in Hawaiian (Photo 22). Other varieties are known in the islands, but this form is restricted to strand and consolidated sandstone of western Moloka`i. Photo 23 shows the dramatic location of a population of `ena`ena growing within the spray zone of late winter surf.

The potential instability of populations of this species is illustrated in Photo 24 which shows a small population growing on the edge of a dune. The nearly constant strong winds with the consequent mobility of the dunes lend a significant degree of vulnerability to such populations. The plants produce a large seed crop, however, and re-establishment does not seem to be a problem. 

The next member of the strand community is a plant that likely had a wider range of distribution at a time before beach habitats became prime real estate for developers. Since this area on Moloka`i is within the boundaries of the Nature Conservancy it is safe from such activities. The plant of interest, Solanum nelsonii (Solanaceae), or pöpolo in Hawaiian, is endemic on the islands with the only significant population at the Mo`omomi site.

It is rare on the other main islands—quite possibly owing to the destruction of its habitat as noted—but does occur on several of the Northwestern Hawaiian Islands. The population pictured in Photo 25 occurs on the protected side of a large dune. Photo 26 shows a close-up of the very attractive small flower.


Pseudognaphalium by the sea
Photo 23 - Pseudognaphalium and the Pacific Ocean...great partnership!
hinahina
Photo 24 - Pseudognaphalium growing on a dune edge, with naupaka. The big dunes form the background.
Solanum nelsonii
Photo 25 - Solanum nelsonii, possibly one of the largest populations known. It is growing with the the ever present naupaka on the protected side of a dune.
Solanum nelsonii
Photo 26 -Close-up of Solanum nelsonii flower turned upward for a better view.
Tetramolopium rockii
Photo 27 - Tetramolopium rockii, found at last!

Most of endemic species of plants that occur in the Mo`omomi Dunes area occur, or have related varieties, elsewhere in the islands. In the case of the next example, however, we encounter a plant that grows naturally nowhere else.

Among the rarest plants in the endemic Hawaiian flora is Tetramolopium rockii, a member of the Asteraceae. This small daisy (Photos 27 & 28) grows only on Moloka`i and is further limited to the sandstone substrate behind the first row of dunes. The rough, weathered sandstone habitat is illustrated in Photo 29. The genus is represented on the Hawaiian Islands by 11 endemic species several of which are considered rare and endangered; two are thought to be extinct. One species is known from Mitiaro in the Cook Islands and an additional two dozen or so occur in their native habitat, the New Guinea highlands.

Visitors who wish to see another species in this genus may do so with very little effort; T. humile (Photo 30), occurs on open cinder fields and in cracks in lava at the main parking area on Haleakala. This species is endemic to the high mountains of the Big Island and Maui.

The first time I visited Moloka`i, with T. rockii as my main goal, I really didn’t know what I was looking for. I found all of the other plants mentioned above, but not the one I wanted most to see. On my second visit, with my wife and a botanical colleague, we made an effort to go farther into the dune complex figuring that I hadn’t seen the plant the first time because I hadn’t got to its specific habitat. In that effort we encountered a dense thicket of kiawe (Prosopis pallida, also called algaroba or mesquite) that seemed to block the trail.

Bush whacking through this shrubby leguminous tangle, with its snarled limbs and sharp spines, lead us to ask whether a photograph of T. rockii was really worth the effort; we turned back.

T. rockii
Photo 28 - Close-up of T. rockii flower heads with author's fingers for scale.
Solanum nelsonii
Photo 29 - Author's wife posing in the T. rockii population. This area is undergoing lithification and is very rough.
Tetramolopium humile
Photo 30 - Tetramolopium humile photographed at ca. 10,000 ft on Haleakala (Maui) to contrast with T. rockii of the dunes area. The green, leafy thing to the right is a common introduced weed.
kiawe tunnel
Photo 31 - The author's wife and daughter emerging from the kiawe tunnel on the way to the T. rockii site. The sand is from a blow-through, where a gap has appeared in the vegetation and the dunes are taking back some territory.
sandstone tunnel
Photo 32 - This is fairly recently (in the geological scheme of things) formed sandstone on the trail to the dunes.
Casts
Photo 33 - Casts formed by the compaction of the dune sand around plant roots. The plant material has rotted away leaving their shapes set in sandstone.

On our most recent visit (March 2007), however, a bit more effort revealed that some sainted individuals had literally hacked a tunnel through the kiawe allowing hikers to continue on toward the dunes. Photo 31 shows my wife and our older daughter emerging from the ‘tunnel’ unscathed. Not far from the tunnel exit we found the plant!

While on the subject of kiawe, it may be of interest to the reader to learn a little more about the plant. Authors of the Manual of Flowering Plants of Hawai`i (ref. below) inform us that it is a native of Peru, Colombia, and Ecuador, and that it is now widely naturalized in the Hawaiian Islands, Australia, and Puerto Rico, where it occupies low lying, disturbed areas often forming dense thickets behind the first line of dunes, as well as other disturbed areas. It is drought and salt tolerant and produces large seed crops. Its presence in the Hawaiian Islands has been traced to a single individual!

Grown from seed planted on the Catholic Mission grounds on Fort Street in Honolulu by Father Bachelot in 1828 (he got the seed from the Royal Garden in Paris). For a time, the pods of kiawe were collected for making seed meal for animal feed thus providing a very efficient means of distributing the seeds since they moved unchanged through the animals’ guts. From a plant’s point of view, this is a very impressive success story; from a more realistic perspective, it provides a stunning example of the harm that can be done by the simple act of planting an alien seed.

The area is geologically interesting in that one can see the result of consolidation (lithification) of the sand dunes. The dunes have resulted from coral sand being blown onshore by the strong NE trade winds; consolidation ultimately occurs through the combined effects of salt spray, the accumulation of organic material, and gravity.

A view of some of the sandstone cliffs, clearly showing strata, appears in Photo 32. An intriguing phenomenon in this area is the formation of plant casts where the consolidating sand sets around plant parts, which eventually rot out leaving a cast of the original part. Photo 33 shows a set of root casts.


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Reference:
Manual of the Flowering Plants of Hawai`i, Vols. 1 & 2. (1999) W. L. Wagner, D. R. Herbst, and S. H. Sohmer. University of Hawai`i Press and Bishop Museum Press, Honolulu.



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