Carex wahuensis subsp. wahuensis
Genus
Carex
Species
wahuensis
Subspecies
- wahuensis
Common Names
- Oʻahu sedge
Synonyms
- Carex nuptialis
Names with Unknown Sources
- Oʻahu carex
Distribution Status
Endemic
Endangered Species Status
No Status
Plant Form / Growth Habit
- Non-Woody, Clumping
Mature Size, Height (in feet)
- Grass-like, Medium, 1 to 2.5
- Grass-like, Tall, Greater than or equal to 2.5
Mature Size, Width
Oʻahu sedge has a spread of 2 feet or more.
Life Span
Long lived (Greater than 5 years)
Landscape Uses
- Accent
- Container
- Erosion Control
- Ground Cover
Additional Landscape Use Information
Carex of several species have been used as ornamental additions in landscapes on the mainland for the interesting, sometimes colorful, foliage and seedheads. A few species are now in cultivation in Hawaiʻi.
Oʻahu sedge is an excellent and tough accent plant. They can be use sparingly or en masse. A good non-invasive alternative for non-natives such as Umbrella sedge (Cyperus alternifolius).
They can be grown in containers in part to full sun with regular waterings. [1]
Source of Fragrance
- No Fragrance
Plant Produces Flowers
Yes
Flower Type
Not Showy
Flower Colors
- Brownish
- Green
- Red
- Yellow
Additional Flower Color Information
Oʻahu sedge has either green to yellowish green or reddish brown to dark red diminutive flowers.
Blooming Period
- Year Round
Additional Blooming Period and Fruiting Information
This sedge is a perennial. While the flowers are not attractive, the stalks of yellow seeds somewhat resemble small corn cobs and are a nice feature in the landscape.
Plant texture
- Coarse
Additional Plant Texture Information
The leaves are no smaller than 6 to 15 inches and as large as 40 inches long.
Leaf Colors
- Dark Green
Additional Leaf Color Information
Leaves have sharp teeth along the edges.
Additional Pest & Disease Information
Oʻahu sedge can attract ants, scale, thrips, mealy bugs and aphids.
Fertilizer
Light applications of a balanced slow release fertilize with minor elements every six months is suggested. Foliar feeding in early morning with a water-soluble or an organic fertilizer (e.g. kelp or fish emulsion) at one-third to one-fourth the recommended strength monthly has proven beneficial. [David Eickhoff, Native Plants Hawaiʻi]
Pruning Information
None required except to trim off dead leaf and stem material. Trim off flower spikes (achenes) if you want the plant to last years longer. However, the flowering spikes are one of the nicer features to this sedge.
Water Requirements
- Dry
Additional Water Information
Once plant is established, water only during prolonged drought. Plants can tolerate moist conditions, but does best in drier conditions.
Soil must be well drained
Yes
Light Conditions
- Full sun
- Partial sun
- Shade
Additional Lighting Information
Overall appearance of this sedge is nicest when grown in partial shade.
Spacing Information
For thick a groundcover, Oʻahu sedge can be planted every 1 to 2 feet apart or randomly spaced for a more natural appearance.
Tolerances
- Drought
- Wind
Soils
- Clay
- Cinder
- Organic
Limitations
Most sedge leaves have sharp teeth along edge. As the saying goes "sedges have edges."
They are only somewhat salt spray tolerant.
Natural Range
- Kauaʻi
- Oʻahu
- Molokaʻi
- Lānaʻi
- Maui
- Hawaiʻi
Natural Zones (Elevation in feet, Rainfall in inches)
- Less than 150, 0 to 50 (Dry)
- 150 to 1000, 0 to 50 (Dry)
- 1000 to 1999, 0 to 50 (Dry)
Habitat
- Terrestrial
Additional Habitat Information
Oʻahu sedge are known to grow in dry to mesic forest, mesic to subalpine shrubland and sometimes coastal forests usually on ridges, slopes and gulches or rocky substrate.
Special Features and Information
General Information
There are about 2,000 species of Carex worldwide, more than any other genus in the Sedge family or Cyperaceae. Half of the eight species of Carex native to the Hawaiian islands are endemic or naturally found nowhere else.
Carex wahuensis has three recognized subspecies:
- subsp. wahuensis is commonly seen from 1475 to 3280 feet in elevation on all of the main islands except Niʻihau and Kahoʻolawe.
- subsp. herbstii is rare and known from a single collection from Moanalua Valley, Oʻahu at around 1180 to 1210 feet.
- subsp. rubiginosa is found at 1675 to over 8200 feet primarily on Maui and Hawaiʻi Island, but also at a few scattered sites on Kauaʻi, Oʻahu, Molokaʻi, and Lānaʻi from about 785 to 1970 feet.
Etymology
The generic name Carex is the classical Latin name for sedge, pehaps from carere, to be absent, as the upper spikes are staminate (male) and do not produce seeds.
The specific epithet wahuensis is an old spelling variation referring to the island of Oʻahu.
The subspecies name herbstii named after Derral R. Herbst, botanist.
The subspecies name rubiginosa, rusty.
Early Hawaiian Use
None of the eight native species appear to have any known Hawaiian names. Certainly the people knew these of interesting sedges and perhaps had uses for them.
Modern Use
Seed spikes are rather unique and can be added to cut flower arrangements. [David Eickhoff, Native Plants Hawaiʻi]
Additional References
[1] "Container Gardening in Hawaii" by Janice Crowl, page 52.
PHOTOS FOR THIS SPECIES CAN BE SEEN AT THE LINK (Copy & Paste to your browser):
https://www.flickr.com/search/?user_id=50823119%40N08&sort=date-taken-desc&view_all=1&text=Carex%20wahuensis%20subsp.%20wahuensis
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