For those of us who live on Maui’s dry leeward coastline, a good way to avoid the late Spring and early Summer heat is to take a morning drive up the long road to the summit of Haleakala volcano. For me the main attraction of the trip isn’t so much getting to the top as finding good places to pull off the road for the great views of the island and to hike out into the brush-covered meadows and slopes. Once you climb above the 3,000-foot elevation, you’re into the sub-alpine scrubland vegetation that blankets the volcano’s lower flanks. There are very few tall plants at this altitude: most species survive by growing close to the ground, developing strong and aggressive root systems, and producing foliage that is very good at trapping moisture from the cloud banks that perpetually sweep low across the mountain’s flanks. One of my favorite species of this plant community is ‘Ohelo (Vaccinium reticulatum), a modest little shrub known for its delicious red berries.
Fruit and foliage of 'Ohelo (Vaccinium reticulatum), Hosmer Grove, Maui.
Distribution and Habitat
‘Ohelo is native to the Hawaiian Islands where it grows in subalpine and alpine shrublands at elevations from 2,000 to 12,000 feet (610 – 3,600 m). It is most numerous on the main islands of Maui and Hawai’i, and to a lesser extent on Kaua’i, O’ahu, and Moloka’i. It is well adapted to growing on fresh lava flows, beds of volcanic ash, and cinders; it is among the first plants to colonize these inhospitable substrates. It has a high tolerance for volcanic activity and is known to survive ash falls deeper than 25 cm.
Description
Vaccinium reticulatum is a small (10-130 cm tall, rarely as tall as 2 m) flowering shrub in the Cranberry family (Ericaceae). It closely resembles several species of North American blueberries. Its Hawaiian name, ‘Ohelo, is also in common use throughout the scientific community. This species displays a lot of variation in its physical characteristics (such as leaf shape, and color and shape of flowers and fruit) to such an extent that local populations and even individual plants have been accidentally categorized as different species. The stiff, upright branches grow from underground stems (rhizomes) that develop when the plant reaches full maturity (at about 3 years).
Flowers and foliage of Vaccinium reticulatum, Haleakala National Park, Maui.
Leaves – The oval-shaped evergreen leaves are about 1.5 to 3 cm long. They are spirally arranged on the twig. When newly emerged they are red, then turn bluish-green or pale green with reddish patches as they mature. The shiny, leathery upper surfaces of the leaves may be smooth or somewhat hairy (pubescent). The leaf margins may be smooth or toothed; occasionally the edges are curled under. This wide variation is partly due to the fact that ‘Ohelo has both juvenile and adult foliage growing on the plant at the same time. It is not unusual for the uppermost leaves of the main stem to have adult foliage while the rest of the plant displays juvenile foliage.
Flowers – The numerous and attractive flowers are bell-shaped, 8-12 mm long, vary in color from red to yellow or pink, and have 5 petals and 10 stamens. The single flowers grow out of the bases of the leaves. Flowering occurs throughout the year. It takes about five years for plants grown from seeds to set flowers. Unlike most of the other species of the genus Vaccinium, the flowers of V. reticulatum are self fertile. However, self pollination results in the production of fewer seeds per berry than are produced by flowers that are cross pollinated. The nectar produced by the flower is an important food source of endangered Hawaiian native bird species such as the Scarlet Hawaiian Honey Creeper (Vestiaria coccinea) or ‘i’iwi.
Mature 'Ohelo berries, Hosmer Grove, Maui.
Fruit – The edible blueberry-like fruit is 8-12 mm in diameter and is generally bright red in color but may also be yellowish-green, purple, orange, pink, or even dark bluish-black. The color does not necessarily indicate the ripeness of the berry. The peak of berry production is June to September, when the fruit is harvested on Maui and Hawai’i for jams, jellies, and other preserves. ‘Ohelo was one of the few plants native to Hawaii with palatable fruit, and so early Hawaiians emphasized this distinction by referring to this species as ‘ohelo ‘ai (“edible ohelo”).
Seeds — Each berry contains approximately 70 to 200 tiny brown seeds, of which at least half are not viable. The seeds are round, triangular, or elliptical in shape. They take 50 to 60 days to ripen. The berries are the preferred food of the indigenous Hawaiian goose, the Nene. The birds consume large quantities of berries, broadcasting the seeds over large areas in their droppings.
Traditional Uses and Practices
The early Hawaiians believed that the `ohelo was sacred to Pele, the goddess of fire, lightning, dance, volcanoes, and violence. Ritual offerings to Pele included ‘ohelo branches with the berries still attached; these were thrown into the fire pit called Halema’uma’u, the crater at the summit caldera of Kilauea, Hawaii’s most active volcano. When eating the berries, it was customary to offer Pele the first one by throwing it in the general direction of Kilauea, thus appeasing her. The myth of the deification of one of Pele’s many sisters tells how the ‘ohelo became sacred to the goddess. Ka’ōhelo was a mortal sister of Pele. Just before her death, she instructed her son Kiha to bury her “on the navel of your grandmother at Kilauea” on Hawai’i. When she died, her bones and flesh were scattered to the other main islands where they became ‘ohelo bushes. The best known association of Pele with ‘ohelo berries is Proverb 2044 of Mary Pukui’s “Olelo No ‘Eau”: “Mai hahaki ‘oe I ka ‘ohelo o punia i ka ua noe.” (“Do not pluck the ‘ohelo berries lest we be surrounded by rain and fog.” Early Hawaiians treated abdominal pains with ‘ohelo leaf buds, leaves and fruit, combined with coconut meat, sugar cane, and the various parts of other medicinal plants. The ingredients were then pounded into a mash, strained through the leaves of ‘ahu’awa (Cyperus javanicus, a native sedge), and drunk in the morning and evening. The flowers and fruit were (and are to this day) used in lei making.
Closeup of leaves of V. reticulatum showing how flower grows out of the base of the leaf stem.
Commercial/Agricultural Uses
Currently, V. reticulatum is being researched for the feasibility of production of the species as an ornamental potted plant in Hawaii and Oregon, and as a specialty berry crop in Hawaii. As I mentioned earlier in this post, the ripe berries of the ‘Ohelo are extensively harvested by local residents to make preserves and pie filling. They scour the countryside in large numbers during picking season, disrupting fragile subalpine and alpine ecosystems and habitats. This impact on the environment could be minimized if the berries could be commercially grown and market to meet the demand for the fruit.
Red Leaf Disease
Red Leaf Disease, which is caused by the infective presence of the fungus Exobasidium vaccinii, affects all of the native species of Vaccinium sp. in Hawaii. While this disease is conspicuous and widespread in the Hawaiian Islands, its disfiguring symptoms are easily mistaken for normal foliage growth in otherwise healthy-looking plants. When I first photographed the plants included in this blog post, I was attracted to them by the bright-red clumps of foliage on more mature plants, thinking this was their normal coloration.
Foliage of V. reticulatum showing "Witch's Broom" symptom of Red Leaf Disease.
Viewable symptoms include the presence of clusters of conspicuous blood-red clusters of leaves high on the plant, the formation of contorted and scraggly-looking “witches’ brooms” on the tips of infected branches, and swollen branches that eventually become defoliated and die. While juvenile foliage of the ‘Ohelo often has a reddish coloration when it first appears, the leaves of branches infected with the fungal spores are noticeably curled at the margins by comparison with healthy leaves. In an ongoing attempt to learn how to control the spread of Red Leaf Disease in natural populations, U.S. National Park Service scientists have been experimenting with courses of various antibiotic drugs administered to infected ‘Ohelo plants in the Volcanoes and Haleakala National Parks on Hawai’i and Maui, respectively.
Tags: Ericaceae, Exobasidium vaccinii, Hosmer Grove, Mary Pukui, Ohelo, Olelo No Eau, Pele, Red Leaf Disease, Vaccinium, Vaccinium reticulatum
