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Wikstroemia oahuensis

Wikstroemia oahuensis (A. Gray) Rock

Oahu False Ohelo

Thymelaeaceae (Mezereum family)

Synonym(s):

USDA Symbol: WIOA

USDA Native Status: HI (N)

This taxon is "usually a shrub 2 to 4 feet high, but on the upper slopes of Mt. Konahuanui it is a small tree 12 to 15 feet in height. On the low lands on the outskirts of the forest on open glades, as in Niu Valley, it is only 2 feet or so in height. The trunk and branches are clothed in a black, very tough, fibrous bark, which, owing to its strength, was employed by the natives for ropes and other purposes where strong fiber was needed. The plant is poisonous and was employed by the natives… for fishing." (bibref: 1809). "Low, sometimes twiggy, often sparsely branched shrubs or small trees up to 4(-6) m tall; main stem sometimes short, branches slender to robust, ± erect, glabrous or with scattered hairs, usually becoming glabrate, or pubescent, bark sometimes with whitish lenticels close to the prominent leaf scars." (bibref: 1798).

"In the Hawaiian Islands, endemic to Kauai, Oahu, Molokai, Lanai, Maui." (webref: 49).

 

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Plant Characteristics

Duration: Perennial
Habit: Shrub , Tree
Leaf Arrangement: Opposite
Leaf Complexity: Simple
Leaf Margin: Entire
Breeding System: Flowers Unisexual , Flowers Bisexual
Inflorescence: Axillary , Terminal
Fruit Type: Drupe
Leaf: "Leaves pale to dark green on upper surface, occasionally tinged lilac crimson, sometimes glaucous, lower surface brighter, sometimes somewhat transparent, thin to firm chartaceous or coriaceous, narrowly to broadly elliptic, ovate-elliptic, or rarely slightly obovate, (1-)2.5-8(-20) cm long, (0.5-)1.5-3(-6.5) cm wide, lower surface with often conspicuous lateral veins, glabrous or pilose, especially along the midrib, sometimes hirsute, apex and base acute or rounded, apex sometimes acuminate or slightly apiculate, base rarely subcordate, petioles (2-)4-9(-13) mm long, thin or stout, glabrous or pilose. " (bibref:1798). "Leaves ovate or ovate-lanceolate 2.5 to 5 cm long, 12 to 25 mm wide, on petioles of 2 to 4 mm, acute at the apex, rounded or slightly contracted at the base, glabrous, pale underneath, thin chartaceous." (bibref: 1809).
Flower: "Flowers perfect or unisexual and sometimes appearing perfect, green to yellow, glabrous or hirsute, peduncles 2-15(-25) mm long, glabrous or pilose, sometimes recurved, rachis subglobose, conical, or filiform, rarely forked, 0.4-5 mm long, sometimes up to 12 mm long and then pendulous, glabrous or puberulent, pedicels 0.5-7 mm long, glabrous or with scattered hairs; calyx tube of staminate and perfect flowers (4-)5-9(-13) mm long, outer lobes 1.3-6 mm long, 1-4 mm wide, inner lobes l.2-5 mm long, 1-3.6 mm wide; calyx tube of pistillate flowers 3-10 mm long, outer lobes 1-9 mm long, 1-3.8 mm wide, inner lobes 1-5 mm long, 1-3.8 mm wide." (bibref: 1798). "Flowers 6 to 12 on pedicels of 1 mm clustered at the head of a short terminal peduncle, the cluster at most elongating into a spikelet of 4 mm in length; perianth pale or greenish yellow, tubular, puberulous, about 7 mm long, including the spreading lobes, which are somewhat obtuse, and perhaps half, often less, the length of the tube; lower stamens at the middle of the tube or somewhat higher; hypogynous scales 4 to 5, linear, connate at the base, as long as the ovary, which is glabrous except the apex which is often, but not always, strigose-pubescent, style very short, with capitate stigma." (bibref: 1809).
Fruit: "Fruit orange to red, ellipsoid, 6-18 mm long, 4- 10 mm in diameter." (bibref: 1798). "Drupe ovoid, 6 to 8 mm, reddish yellow." (bibref: 1809).

Bloom Information

Bloom Color: Yellow , Green

Distribution

USA: HI
Native Distribution: Endemic to the Hawaiian islands of Kauai, Oahu, Molokai, Lanai and Maui.
Native Habitat: "Common in hala forest, mesic to wet forest, diverse mesic forest, bogs, and on ridges and rocky ledges, (5-)100-1,400 m, on Kauai, Oahu, Molokai, Lanai, and Maui." (bibref: 1798). This taxon grows " in hala forests, mesic to wet forest, diverse mesic forest, bogs, ridges, and rocky ledges (5–) 100–1400 m". (webref: 47).

Growing Conditions

Water Use: Low , Medium , High
Light Requirement: Sun , Part Shade , Shade
Soil Moisture: Dry , Moist , Wet

Benefit

Use Other: "The plant is poisonous and was employed by the natives… for fishing." (bibref: 1809).
Warning: This taxon and all others in the family Thymelaeaceae are "poisonous to mammals, containing tricyclic daphnane and tiglane diterpenes, esters of daphnetoxin, and coumarins. The bark and fruit can be extremely irritating to mucous membranes even after drying and cause contact dermatitis in sensitive individuals." (webref: 3).
Fragrant Flowers: yes
Attracts: Birds
Deer Resistant: No
Poisonous: yes

National Wetland Indicator Status

Region:AGCPAKAWCBEMPGPHIMWNCNEWMVE
Status: FAC
This information is derived from the U.S. Army Corps of Engineers National Wetland Plant List, Version 3.1 (Lichvar, R.W. 2013. The National Wetland Plant List: 2013 wetland ratings. Phytoneuron 2013-49: 1-241). Click here for map of regions.

Bibliography

Bibref 1809 - Indigenous Trees of the Hawaiian Islands (1913) Rock, Joseph F.
Bibref 1798 - Manual of the Flowering Plants of Hawaii, Revised Edition (1999) Wagner, W.L.; Herbst, D.R.; Sohmer, S.H.

Search More Titles in Bibliography

Web Reference

Webref 49 - Flora of the Hawaiian Islands (2020) Smithsonian National Museum of Natural History
Webref 47 - Hawaiian Ethnobotany Online Database (2020) Bishop Museum
Webref 31 - Native Plants Hawai’i (2018) University of Hawaii
Webref 28 - NatureServe Explorer: An online encyclopedia of life (2018) NatureServe

Additional resources

USDA: Find Wikstroemia oahuensis in USDA Plants
FNA: Find Wikstroemia oahuensis in the Flora of North America (if available)
Google: Search Google for Wikstroemia oahuensis

Metadata

Record Modified: 2020-11-02
Research By: JAM

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