Nephrolepis exaltata subsp. hawaiiensis
Hawaiian Names with Diacritics
- Common sword fern
- Sword fern
- True ʻōkupukupu
Names with Unknown Sources
- Hawaiian Boston fern
Endangered Species Status
Plant Form / Growth Habit
- Non-Woody, Clumping
- Non-Woody, Spreading
Mature Size, Height (in feet)
- Fern/Fern-like, Tall, Greater than 3
Mature Size, Width
ʻŌkupukupu or niʻaniʻau can have a spread of 6 feet or more and grow to about 4 feet tall.
Long lived (Greater than 5 years)
- Ground Cover
- Hanging Basket
- Specimen Plant
Additional Landscape Use Information
A beautiful full spreading fern with fronds over three feet long makes ʻōkupukupu an ideal fern for deep pots, pots on pedestals, or hanging baskets in part shade to shady areas. Once established in the pots and hanging baskets they will send out rhizomes. When the small ferns begin to show a few fronds, they can easily be removed with some of the surrounding soil to make new plants without upsetting the entire pot. Be sure to fill in the pukas with more soil. It is, though, a good practice to repot these ferns every year or two because they will become root bound and plantlets will begin to appear from the drainage holes. [David Eickhoff, Native Plants Hawaiʻi]
They do very well in the landscape as a groundcover in a rich organic mix in moist, but not soggy, soil.  With some sun protection, such as under tall shrubs or trees, the plants will remain vibrant dark green. Sometimes they will even climb trees. [David Eickhoff, Native Plants Hawaiʻi]
Does very nicely on north and east facing locations, but plants grown on the west and south sides will get scorched if not protected, especially during the intense summer months. [David Eickhoff, Native Plants Hawaiʻi]
ʻŌkupkupu, like the Boston fern, makes a wonderful indoor plant and is listed as safe or nontoxic for children, cats and dogs. [5,6]
Plant Produces Flowers
No data available.
- Dark Green
- Medium Green
Additional Pest & Disease Information
Mealybugs can be a nuisance and should be treated right away. Occasionally, caterpillars can damage the fronds. Look for curled fronds with webbing for the pest.
13-13-13 slow release fertilizer every six months for plants in pots or planted in the ground. For larger potted ferns showing poor color or not producing crosiers (fiddleheads or emerging fronds) use a complete fertilizer at half the recommended strength. Do not till solid fertilizers into soil since ferns have a shallow root system. 
ʻŌkupukupu love foliar feeding with fish emulsion and also benefit from occasional feedings with Miracle-Gro fertilizer for acid loving plants at half the recommended strength. [David Eickhoff, Native Plants Hawaiʻi]
Dead fronds should be pruned off for a clean appearance.
Additional Water Information
ʻŌkupukupu does well in moist, but not soggy, conditions.
Soil must be well drained
- Partial sun
Additional Lighting Information
While these ferns can occasionally be seen growing in fun sun conditions in their natural habitat, they seem to perform best under partial sun or shady conditions which will produce dark bright green foliage that these lovely fens are famous for. [David Eickhoff, Native Plants Hawaiʻi]
ʻŌkupukupu can be spaced at 3 to 4 feet apart for a dense groundcover; further apart 5 or 6 feet to show case their beutiful sweeping fronds. [David Eickhoff, Native Plants Hawaiʻi]
The Boston fern (Nephrolepis exaltata) is considered somewhat drought tolerant.  But our native subspecies tend to do best with at least some reliable source of moisture.
Natural Zones (Elevation in feet, Rainfall in inches)
- Less than 150, 50 to 100 (Mesic)
- Less than 150, Greater than 100 (Wet)
- 150 to 1000, 50 to 100 (Mesic)
- 150 to 1000, Greater than 100 (Wet)
- 1000 to 1999, 50 to 100 (Mesic)
- 1000 to 1999, Greater than 100 (Wet)
- 2000 to 2999, 50 to 100 (Mesic)
- 2000 to 2999, Greater than 100 (Wet)
- 3000 to 3999, 50 to 100 (Mesic)
- 3000 to 3999, Greater than 100 (Wet)
- 4000 to 4999, 50 to 100 (Mesic)
- 4000 to 4999, Greater than 100 (Wet)
Additional Habitat Information
ʻŌkupukupu is a common fern found on all the Main Islands except Kahoʻolawe from about 80 to nearly 4600 feet in mesic, wet and upper elevation dryland forests.
They usually can be found growing on the ground as a terrestrial, but also over or in cracks of mossy boulders and as an epiphyte climbing up trees or in crotches of trees with debris. [David Eickhoff, Native Plants Hawaiʻi]
ʻŌkupkupu or niʻaniʻau (Nephrolepis exaltata subsp. hawaiiensis) belong to Lomariopsidaceae.  There are several common naturalized swordferns and will hybridize with the native species. This species and kupukupu (Nephrolepis cordifolia) are the only two native Nephrolepis in the Hawaiian Islands. However, some question whether N. cordifolia is an indigneous species, but rather a possible an early introduction.
There are also three naturalized Nephrolepis species and two localized hybrids in the islands.
The true ʻŌkupkupu has been given the name to distinguish it from the False Okupukupu (Nephrolepis multiflora). 
There is some discussion as to whether this species actually warrants an endemic subspecies status. However, for now, it remains recognized as an endemic fern pending further data.
The generic name Nephrolepis is derived from the Greek nephros, kidney, and lepis, scale, in reference to the kidney-shaped indusia (sori covering).
The Latin specific name exaltata, raised, high, lofty, alludes to the upright fronds of this fern.
The subspecies hawaiiensis is referring to the place of origin, Hawaiʻi.
Kupukupu is a general name for ferns on a single stem. 
Palapalai is a Niʻihau name.
There is a hybrid with the native Nephrolepis exaltata subsp. hawaiiensis and the introduced Nephrolepis multiflora known as Nephrolepis x medlerae. 
Early Hawaiian Use
The fronds were fashioned as into lei for the wrists and ankles called kūpeʻe or as haku for the head. 
The fern was used medicinally to treat a number of skin disordes by means of bathing in the processed juice. 
The Hawaiian name kupu means "to sprout." The early Hawaiians would place kupukupu on hula altars so that knowledge would sprout.
There are nearly one hundred cultivars that exist for this species. A few of the more popular cultivars (cv.) seen in Hawaiʻi are the Boston fern cv. 'Bostoniensis', cv. 'Fluffy Ruffles', cv. 'Rooseveltii', and cv. 'Smithii.' 
 Kay Lynch, Lāʻau Hawaiʻi
 http://www2.bishopmuseum.org/HBS/botany/cultivatedplants/ [Accessed on 10/1/08]
 "Hawaiʻi the Fires of Life--Rebirth in Volcano Land" by Garrett A. Smathers and Dieter Mueller-Dombois, page 127.
 http://www.floridata.com/ref/N/neph_exa.cfm [Accessed on 12/21/09]
 http://www.earthcouncil.net/freshair.htm [Accessed 12/22/09]
 http://www.ladybug.uconn.edu/hotissues/SafeandPoisonousHouseplants.html [Accessed 12/22/09]
 "The World of Ferns: Checklist of World Ferns" http://homepages.caverock.net.nz/~bj/fern/nephrolepis.htm [12/27/09]
 Taxon 55 August 2006: Fern Classification, by Alan R. Smith et al., page 14.
 "Nā Lei Makamae--The Treasured Lei" by Marie A. McDonald & Paul R. Weissich, pages 59-60.
 "Native Hawaiian Medicine--Volume III" by The Rev. Kaluna M. Kaʻaiakamanu, page 66.
 Hawaiian Dictionaries online http://wehewehe.org [Accessed 11/29/11]
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