Native Plants of Hawai‘i - Cyperus javanicus

Cyperus javanicus

Cyperaceae or Sedge family

Synonyms: Cyperus caricifolius, Cyperus owahuensis, Mariscus javanicus

ʻAhuʻawa

ʻEhuʻawa

Java sedge, Javanese flatsedge, Marsh cyperus

Natural Range & Environment

Cyperus javanicus is found in Madagascar, India, Sri Lanka, Bangladesh, Myanmar, southern China, southeastern Asia to New Guinea, northern Australia, and islands in the Pacific. It is very similar to and possibly not specifically distinct from C. ligularis, which is widely distributed in West Africa and tropical America [Useful Tropical Plants]. In Hawai‘i, Cyperus javanicus is indigenous to Midway Atoll (Pihemanu), Lehua Island (Rock), and all the main Hawaiian Islands except Kaho‘olawe [Flora of the Hawaiian Islands].

In Hawai‘i, ‘ahu‘awa is common in fresh to seawater sites such as marshes, lo‘i kalo (taro paddies), streams, ditches, disturbed areas, coastal areas, and wet cliffs, from sea level to 180 m (591 ft) [Erickson & Puttock 2006].

ʻAhuʻawa inflorescence with unripe fruits (achenes). Cultivated plant with ripe fruits. Wild plant in wetland with underlying ʻaeʻae (Bacopa monnieri) (Photograph courtesy of Hubert Szczygieł CC BY-NC 4.0).

Description

Cyperus javanicus is a perennial grass-like sedge about two feet (61 cm) tall with a lifespan difficult to determine because it often spreads out over time; confined to a container, it typically lives less than five years. Its long slightly-folded strap-like leaves have a sandpaper-like surface. And, while ʻahuʻawa leaf margins are only slightly serrated and not as sharp as some other sedges, one should still be careful when handling this plant. Leaves are green to bluish or grayish green, often with a powdery white cast.

Cyperus javanicus has many tiny perfect (bisexual) flowers on a flattened branched inflorescence that develops at the end of a long spike, which frequently extends above the plant's leaves. Pollinated flowers develop into golden brown to brown achenes when ripe. ʻAhuʻawa flowers and fruits repeatedly year-round.

Growth Requirements

General

Cyperus javanicus looks great in the ground, a container, a pond, or other water features. Consider creating a miniature native Hawaiian wetland using a large container or an in-the-ground flexible pond-liner (see Marsilea villosa; Growth Requirements for how-to details) that is home to all your native wetland plants (e.g., Bacopa monnieri, Bolboschoenus maritimus, Cyperus javanicus, C. laevigatus, C. trachysanthos, Eleocharis erythropoda, E. obtusa, Marsilea villosa, Schoenoplectus tabernaemontani). On a more practical note, the fibrous roots of ʻahuʻawa planted en masse (2 to 4 ft [61 to 122 cm] apart) along a water bank can control soil erosion. And, in restoration projects, ʻahuʻawa is a source of food, nesting material, and shelter for native waterfowl. Lastly, it is a great alternative to the popular alien umbrella sedge (Cyperus involucratus).

Place your ʻahuʻawa in a site that receives full sunlight for all or most of the day. A plant grown in a heavily shaded site will become leggy. ʻAhuʻawa has sharp leaf margins, so avoid planting it immediately adjacent to a walkway or near places where children play.

ʻAhuʻawa has numerous tolerances. While it does great in freshwater wetland conditions, it can also be grown in drier soils (or media) or in brackish wetland sites. It is even somewhat drought-tolerant. However, it will only naturally seed and regenerate if the surface soil is wet all or most of the time. ʻAhuʻawa can withstand extreme heat, strong winds, and salt spray, and it will grow in sand, coralline, clay, lava/cinder, or organic-dominant soil (or media).

ʻAhuʻawa grows quickly but doesn't live very long. Expect your plant to be nearly full size (i.e., about 2 ft [61 cm]) and produce seeds in a year or less. Also, plan to replace your plant every three to five years. If grown in a site with constantly wet soil, you can expect seedlings to appear near your plant, which makes replacement easy or even unnecessary. However, if grown in a drier site, you should collect your plant's achenes early and store them in your refrigerator so you can sprout them later; ʻahuʻawa is easy to grow from sown achenes.

If your ʻahuʻawa grows slowly or begins to yellow, consider applying a small amount of balanced single-digit fertilizer or spraying your plant with an organic or inorganic water-soluble fertilizer diluted to ⅓ to ½ recommended strength. Then, wait to see how your plant responds before repeating the treatment. Only apply fertilizer if your plant is in the ground or a container; if it is in a pond or water feature, the fertilizer can pollute the water and cause excessive algal growth. Do not over-fertilize.

When the golden seed heads of ʻahuʻawa eventually turn brown, they can be pruned away to keep the plant looking tidy. If you intend to grow ʻahuʻawa only for its leaves, remove the inflorescences early before they flower; there are some reports that this may prolong the life of the plant.

Pests and Diseases

ʻAhuʻawa is occasionally attacked by aphids, mealybugs, or scale insects. These, in turn, are often farmed and protected by ants. Refer to the Pests & Diseases page for ways to battle these pests. However, if your ‘ahu‘awa is growing in a pond or water feature with fish or other aquatic fauna, you should remove your plant (hopefully, you kept it in a pot) before treating it with any chemicals such as soaps, oils, etc., that could poison the water and kill your fish, etc.

Uses

Ancient Hawaiian

Abbott [1992] describes the preparation and uses of ʻahuʻawa as follows:

First, Hawaiians encouraged ‘ahu‘awa to grow around lo‘i kalo (taro paddies) where it would have been convenient to harvest. Stalks were pounded on a flat stone or squeezed between two round sticks to separate the fibers from the rest of the stalk. The fibers were then left for a day or two in the sun to dry. After, the fibers were ready to stir niu (coconut) cream or strain ‘awa (Piper methysticum). Otherwise, the fibers were twisted into two- or three-ply cordage. (Hawaiians made cord from the fibers of numerous other plants such as coconut, hau (Hibiscus tilaceus), wauke (Broussonetia papyrifera) and others; however, the strongest and most durable cord was made from the endemic olonā (Touchardia latifolia)). ‘Ahu‘awa cord could last at least four days in water, and remain strong out of water for two or more years. The cord was primarily used for lashing when building a hale (house). However, it was also used to apply a "cord-rubbing" design to kapa, and for net bags (kōkō) designed to carry ʻumeke (food or water containers). Lastly, Krauss [1993] states that ‘ahu‘awa was used to make large-mesh turtle nets.

ʻAhuʻawa leaves and achenes (fruits) were used in lei [McDonald & Weissich 2003].

The medicinal uses of ʻahuʻawa are questionable since they all seem to come from one source, Ka‘aiakamanu & Akina [1922] = Chun [1994], and are not confirmed by any other ethnobotanical sources we could find. Furthermore, Ka‘aiakamanu's and Akina's description of "AHUAWA" uses the species name Cyperus laevigata, which we guess is a misspelling of C. laevigatus, the scientific name for makaloa, another indigenous sedge in Hawai‘i. While their first paragraph seems to be a description of C. javanicus rather than C. laevigatus, the whole account is confusing. Given these uncertainties, we will leave any further interpretation up to the reader since [Ka‘aiakamanu & Akina 1922], page 9, is available online at the link provided on our References page.

Modern

Special Features and Information

General

The large Sedge family (Cyperaceae) has about 5,500 described species in approximately 90 genera [WikipediA;Cyperaceae]. There are currently (2025) fourteen Cyperus species native to Hawai‘i, nine being endemic while the rest are indigenous. There are also about 25 non-native and naturalized Cyperus species in Hawai‘i [Flora of the Hawaiian Islands]. Some of the better-known non-native Cyperus species in Hawai‘i are: papyrus (Cyperus papyrus), the source of ancient Egyptian paper and the origin of the English word "paper"; umbrella sedge (Cyperus involucratus), a popular ornamental; and purple nutsedge or "nutgrass" (Cyperus rotundus), a noxious lawn weed that keep homeowners busy and commercial gardeners employed.

Hawaiian Name

The ‘awa in ‘ahu‘awa is almost certainly a reference to its use for straining crushed ‘awa mixed with water before drinking the mixture. The name ʻehuʻawa for this species should not be confused with ehuʻawa for Cyperus laevigatus, which lacks the first ʻokina.

Etymology

The genus name Cyperus comes from kyperos, the Greek word for sedge [Wagner et al. 1990]. The species name, javanicus, is Latin for "from Java" [Gledhill 2008]. This species is indigenous to Java, Indonesia, and other parts of the world.

BPK