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The Flowering Plants of Hawaii (beta)

Part 62 Poaceae

Heteropogon contortum
Heteropogon contortum. Photo by Forest Starr

Poaceae, or Gramineae (Mabberley lists Gramineae, pp 370-373), are a very large cosmopolitan family consisting of some 10,500 species in 715 genera. A few of the more common member of the grass family known to most readers would be corn (maize), sorghum, barley, oats, rice, rye, ryegrass, wheat, wild rice, the many varieties cultivated for lawns, and the largest of them all, the bamboos. The Hawaiian Islands have their fair share of grasses as well, 147 species in 67 genera. There are no endemic genera but 39 endemic species occur widely distributed throughout the islands. The problem, at least for me (and a few others who have confessed as much to me) is the overwhelming presence of alien grasses that makes finding endemic species especially difficult, coupled with my very limited experience with grasses in general. What the reader will encounter below is a very specialized group of species including two endemic species from the Starr collection of images. We can start with them.

One of the most important grasses to the early Hawaiians was Heteropogon contortus (see image), known as pili or pili grass (Krauss points out that grass is redundant in this name), lule, (flexible, and a variety of pili) and, in English, tanglehead or twisted beardgrass. Bundles of pili were tied to the frame of a house being built using lengths of fiber obtained from the lily `uki`uki (Dianella sandwicensis). Trisetum glomeratum (see image), pili uka or mountain pili, grows at higher elevations often in dry cinder fields and a variety of habitats in the subalpine.

Trisetum glomeratum
Trisetum glomeratum. A Starr photo.
Deschampsia nubigena
Deschampsia nubigena. Photo by Gerry Carr.

Deschampsia is a genus of about 30 species about half of which occur in North America and Europe in temperate and arctic regions, and at higher elevations in warmer regions, e.g. Hawaiian Islands. One of its species, D. antarctica from Refuge Island, at 68°21' S, is the most southerly flowering plant known Mabberley (p. 264). Deschampsia nubigena (see image), a Hawaiian endemic species and the only member of the genus on the islands is a plant of usually higher elevation sites, often occurring in bogs alpine hillsides.

Melinis minutiflora
Melinis minutiflora

The next grass was introduced from Africa as a fodder plant but it has become a problem owing to its capacity to form dense colonies that force native species out. The plant in question is Melinis minutiflora (see image) known as molasses grass owing to the odor associated with the sugary exudate on its leaves and stems. The aroma is very characteristic making this one of the few plants that can be identified from afar by smell alone. Walking through a patch of molasses grass leaves a sticky residue on trousers and socks. A very serious characteristic of this species, in contrast to native species, is that its seeds are fire tolerant allowing it to regenerate readily following brush fires. Apparently, it is not favored by range cattle if other grasses, of which there are many as noted above, are available.

By far the most prominent grass on the islands, at least in acreage planted, was sugar cane. At one time sugar was the most important agricultural crop on the islands. Cultivation of sugar has significantly declined in recent years, however, as cheaper products have become available from sources having lower costs (land value and cost of labor). Sugar cane is Saccharum officinarum (images), in Hawaiian. Commercial varieties are hybrids of S. officinarum, S. spontaneum, and S. robustum. Technically, commercial sugar would be classified as a cultigen.

Saccharum officinarum
Saccharum officinarum
Saccharum officinarum
Saccharum officinarum Detail of stem.

Sugar cane has been known to Polynesians for a very long time during which a number of varieties have been selected. The common kö kea, white sugar, although an element of diet, was mostly consumed as a sweet treat between meals. During hard times, however, sugar and banana, both of which were routinely grown in the vicinity of houses, could serve to ward off starvation. Segments of cane would be chewed during long journeys to ward off hunger, and young children were given a piece of cane as a soother. Early Hawaiians believed that chewing the tough fibers of cane helped to strengthen children's teeth. (That this practice almost invariably leads to serious dental trouble is not usually discussed.) Sugar cane leaves were used for house thatching when pili grass was not available (Handy et al. 1991).

Schizostachyum glaucifolium
Schizostachyum glaucifolium. Detail of fruiting structure.
Schizostachyum glaucifolium
Schizostachyum glaucifolium Detail of stem.

The largest of the grasses, the bamboos, are as familiar to most readers as they were to early Polynesians who reputedly brought at least two species (Handy et al. 1991) describes two species (they called them varieties) of bamboo that colonists brought to the islands. One of these was the giant bamboo, `ohe kahiki, which belongs to the genus Schizostachyum, a genus of some two dozen species widely distributed in central and southeastern Asia, New Guinea, Tahiti, the Philippines, and Madagascar. The Manual lists a single species, S. glaucifolium with a distribution that includes all the main islands except Läna`i, Ni`ihau, and Kaho`olawe. This very large plant reaching as much as 15 m (50') in height with diameters reaching 6cm (4'), is illustrated in the photos.

Schizostachyum glaucifolium
Schizostachyum glaucifolium
Phyllostachys nigra
Phyllostachys nigra. A Starr photo.

The smaller black bamboo, Phyllostachys nigra (see image) is a naturalized species from China. This species is planted widely as a decorative plant. It does not attain the height of `ohe kahiki but can reach 8 m (ca. 25').

Literature cited…

Handy, E. S. C. Handy, E. G. Handy and M. K. Pukui.1991. Native Planters in Old Hawaii. Their Life, Lore, and Environment. Revised edition. Bishop Museum Press, Honolulu, HI.

Krauss, B. H. 1993. Plants in Hawaiian Culture. University of Hawaii Press. Honolulu, HI.

March 4, 2013

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