Hawaiian Names with Diacritics
- Koolau eugenia
- Eugenia molokaiana
Did You Know ?
Nīoi is very closely related to the delicious introduced Surinam cherry (Eugenia uniflora) with its bright red pumpkin shaped fruits. The round red to orange fruits of nīoi are palatable ranging from bland to mildly sweet.
Endangered Species Status
Plant Form / Growth Habit
Mature Size, Height (in feet)
- Shrub, Small, 2 to 6
- Shrub, Medium, 6 to 10
- Shrub, Tall, Greater than 10
- Tree, Dwarf, Less than 15
- Tree, Small, 15 to 30
Mature Size, Width
Nīoi is from about 6 to over 20 ft. tall, with a spread of ten feet or more.
Long lived (Greater than 5 years)
- Specimen Plant
Additional Landscape Use Information
This species is an attractive native shrub, and should be used as a shrub or small tree in the urban Hawaiian landscape. Plant in full sun for best performance where it will flourish and flower and fruit seasonally. [David Eickhoff, Native Plants Hawaiʻi]
Plant Produces Flowers
Additional Flower Color Information
The small white flowers are similar guava and straberrry guava.
- Year Round
Additional Blooming Period and Fruiting Information
In cultivation, nīoi may begin flowering in late October and continously throughout the year with perhaps a very slight break in September or early October. However, nīoi may be a year round bloomer and fruiter. [David Eickhoff, Native Plants Hawaiʻi]
There are from one to three, rarely four, mature seeds per fruit. [David Eickhoff, Native Plants Hawaiʻi]
Introduced birds to Hawaii, such as Red-vented and Red-whiskered bulbuls (Pycnontus spp.) relish nīoi fruit and keep a close eye on the fruits as they ripen. If you plan to collect nīoi seed, protect the fruits from these birds. Bird netting works good. But it has been observed that bulbuls eating the fruit on site dropping the seeds below. So, look for clean tannish-white pea-sized or split pea-shaped seeds in the debris beneath the nīoi. You may be pleasantly surprised! [David Eickhoff, Native Plants Hawaiʻi]
- Dark Green
- Medium Green
Additional Leaf Color Information
The terminal, or new, leaves are reddish-green, fuzzy and cupped.
Additional Pest & Disease Information
Black twig borer. Trim off pieces infested by black twig borer, wrap in a plastic bag, and dispose of or destroy right away.
Nīoi is highly susceptible to attacks by the bright yellow ʻōhiʻa, or guava, rust (Puccinia psidii) especially in wet environments or during the rainy season. It is usually a seasonal pest. But this aggressive rust can be a serious problem during the wetter periods if action is not taken right away. At the first sign of ʻōhiʻa rust, infected material can be carefully trimmed off, bagged securely, and disposed of. An untested suggestion is to put cut pieces in a bottle with a small amount of alcohol before disposing. Then, the plant and any others, including relatives (Metrosideros spp., Syzygium spp.), in the area should be treated with an appropriate fungicide immediately. 
Never add trimmings damaged by ʻōhiʻa rust or black twig borer to a compost pile. [David Eickhoff, Native Plants Hawaiʻi]
Foliar feedings monthly or every other month appears to greatly benefit this plant. [David Eickhoff, Native Plants Hawaiʻi]
Additional Water Information
Does best with some moisture and is drought tolerant. However, too much water can be the cause of ōhiʻa rust (Puccinia psidii).
Soil must be well drained
- Full sun
Additional Lighting Information
Nīoi is best grown in full sun but seems to tolerant some shade.
Natural Zones (Elevation in feet, Rainfall in inches)
- 150 to 1000, 0 to 50 (Dry)
Additional Habitat Information
Formerly in dry gulches and slopes from 325 to about 985 feet in the north and south areas of the Koʻolau Mts., Oʻahu, and Mauna Loa, Molokaʻi. Now presumed extinct on Molokaʻi.
Currently extremely rare and now found in the northern Koʻolau Mountains on the north fork of the Kamananui Stream, Waimea Valley and from Pūpūkea-Paumalū, Oʻahu. A small population exist at Palikea and Kaimuhole in the Waiʻanae Mountains, Oʻahu.
Nīoi (Eugenia koolauensis) belongs to the Myrtle family or Myrtaceae with a current figure at over 5,650 species worldwide.
Other native Myrtaceae members include ʻŌhiʻa hā (Syzygium sandwicensis) and five endemic species of Metrosideros: Lehua ʻāhihi or ʻāhihi (M. tremuloides), lehua papa (M. rugosa), and three known by the name ʻōhiʻa (M. polymorpha, M. macropus and M. waialealae).
The non-native relatives, some of which have become naturalized and even highly invasive in Hawaiʻi, are numerous and host notables such as Surinam cherry (Eugenia uniflora), myrtle, clove, apple or common guava, strawberry guava or waiwī, allspice, eucalyptus, melaleuca or paper bark, bottlebrush (Callistemon), mountain apple or ʻōhia ʻai, rose apple, and Java plum--to name a few.
Eugenia is named for Prince Eugene (1663-1736) of Savoy, France.
The specific epithet koolauensis is referring to the Koʻolau Mountains on Oʻahu. This addition of -ensis, indicates origin or place.
The "Hawaiian" or bird chile pepper (Capsicum frutescens) also goes by the name nīoi or nīoi pepa.
The small fruits of both species of nīoi (Eugenia koolauensis, E. reinwardtiana) are edible, but the indigenous E. reinwardtiana seems to be more palatable and sweeter than E. koolauensis. [David Eickhoff, Native Plants Hawaiʻi]
Early Hawaiian Use
Early Hawaiians used the wood for kapa beaters. 
Nīoi wood was said to be poisonous and was carved into images called kālaipāhoa, literally poison gods or goddesses. The tree is said to grow only at Maunaloa, Molokaʻi where this species once grew, but now extinct there. These images were always in possesions of the ruling chiefs. Shavings from the back of the images were placed in an enemies food to cause death. Two other trees also used were aʻe and ʻohe. 
It was only when sorcery was employed were they said to be poisonous. 
Today, we know these trees to be harmless.
Nīoi have semi-sweet to bland fruit. Perhaps with selective cultivars nīoi may produce sweeter fruits and thus adding another true native fruit crop such as ʻōhelo, ʻākala, and pōpolo (Solanum americanum). [David Eickhoff, Native Plants Hawaiʻi]
 "Plants in Hawaiian Culture" by Beatrice H. Krauss, page 63.
 "Hawaii Forest Disease and Pests" http://www.ctahr.hawaii.edu/forestry/disease/index.html [Accessed 2/4/11]
 "Resource Units in Hawaiian Culture" by Donald D. Kilolani Mitchell, page 78.
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