Native Plants of Hawai‘i - Schoenoplectus tabernaemontani

Schoenoplectus tabernaemontani

Cyperaceae or Sedge family

Synonyms: Schoenoplectus lacustris, Schoenoplectus lacustris subsp. creber, Schoenoplectus lacustris subsp. glaucus, Schoenoplectus lacustris subsp. tabernaemontani, Schoenoplectus lacustris subsp. validus, Schoenoplectus validus, Schoenoplectus validus var. creber, Schoenoplectus validus subsp. luxurians, Scirpus glaucus, Scirpus lacustris, Scirpus lacustris subsp. glaucus, Scirpus lacustris f. luxurians, Scirpus lacustris var. luxurians, Scirpus lacustris subsp. tabernaemontani, Scirpus lacustris var. tabernaemontani, Scirpus lacustris subsp. validus, Scirpus lacustris var. validus, Scirpus tabernaemontani, Scirpus tabernaemontani f. luxurians, Scirpus validus, Scirpus validus subsp. creber, Scirpus validus var. creber, Scirpus wahuensis

ʻAkaʻakai

ʻAkaʻakai naku, Kaluhā, Naku, Nānaku, Neki

Common club-rush, Giant bulrush, Great bulrush, Greater bulrush, Grey club-rush, Lakeshore bulrush, Soft-stemmed bulrush, Tule

Natural Range & Environment

Schoenoplectus tabernaemontani has a (presumably native) worldwide distribution, being found in nearly all of North America, Europe, Asia, Australia, and the Pacific (including Hawai‘i). Only in South America and Africa is its presence somewhat limited (but not absent) [Kew: Plants of the World Online].

In Hawai‘i, Schoenoplectus tabernaemontani is indigenous to all the main Islands except Lāna‘i and Kaho‘olawe. It occurs in fresh and salt water marshes from sea level to 1,220 m (4,003 ft) [Erickson & Puttock 2006].

ʻAkaʻakai produces tassels of small spikelets (each containing many tiny flowers) atop their stems. Flowers mature into ovoid brown achenes when pollinated (achenes photograph courtesy of Robert L. Carr ©). ʻAkaʻakai spreads via robust rhizomes with new stems emerging every couple of inches (photograph courtesy of Stefan.lefnaer CC BY-SA 4.0). The stems have many internal air cavities, which make them compress easily when squeezed, hence one common name for S. tabernaemontani is soft-stemmed bulrush (photograph courtesy of User:Bb143143 CC BY-SA 3.0). ʻAkaʻakai has a wide geographic range. Here a cultivated plant grows in wet soil on Hawai‘i Island (photograph courtesy of J.B. Friday ©) as easily as this wild plant grows in the shallows of a lake in upstate New York, USA (photograph courtesy of Erik Danielsen CC BY-NC 4.0).

Description

Perhaps the best way to describe ʻakaʻakai is that it looks like a giant green onion with a brown tassel on top, and instead of a bulb below, it has creeping rhizomes. ʻAkaʻakai typically lives longer than five years, but portions can die back, particularly under poor environmental conditions (e.g., drying).

ʻAkaʻakai has round bluish-green culms (stems) that can be nearly 10 feet (3 m) tall, emerging every couple of inches along its thick rhizomes. Inside the culms is a specialized spongy tissue called aerenchyma containing many tiny interconnected gas-filled cavities that facilitate the exchange of gases (e.g., oxygen, carbon dioxide, ethylene) between the aerial parts of the plant and its submerged or waterlogged roots [WikipediA;Aerenchyma]. The aerenchyma also makes the stems easy to compress when squeezed, hence one of the common names for Schoenoplectus tabernaemontani is soft-stemmed bulrush.

ʻAkaʻakai produces drooping inflorescences with reddish brown spikelets, each containing many tiny perfect (bisexual) flowers. Cultivated plants in Hawai‘i seem to bloom sporadically or near continuously. The pollinated flowers develop into small ovoid achenes (see photograph above.)

Growth Requirements

General

ʻAkaʻakai looks great along a stream's edge, in wet ground, or in a container, pond, or other water feature. 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 rhizomes and roots of multiple ʻakaʻakai planted along a stream or pond edge can control soil erosion; space the plants about three feet (1 m) apart. In restoration projects, ʻakaʻakai can be a source of food and shelter for native waterfowl [USDA Forest Service]. Lastly, because its stalks are very tall, you can use ʻakaʻakai as a screen or freeform hedge in a landscape.

ʻAkaʻakai does best in a site that receives full sunlight for all or most of the day. However, it can tolerate some shading provided it has at least a few hours of direct sunlight each day. It is essential that its roots always have easy access to water. Otherwise, this native rush will quickly dry out and begin to die. Of course, the easiest way to avoid having your plant dry out is to keep it in a pond or other water feature.

ʻAkaʻakai grows at a slow to moderate pace. If planted in wet soil, fertilizer doesn't seem to be necessary or speed its growth. If kept in a pond or water feature or planted along a stream, any type of fertilization is normally not needed and generally should be avoided since the fertilizer can pollute the water and cause excessive algal growth. Only when kept in a container, does ʻakaʻakai appear to possibly benefit from added fertilizer. However, even here, be cautious and avoid fertilizers with a high nitrogen percentage; single-digit types are safest.

ʻAkaʻakai is obviously tolerant of waterlogged soil. It is also tolerant of extreme heat (provided its roots remain wet) and salt spray. ʻAkaʻakai doesn't seem to be picky about soil or media type and will grow in sandy, silty, clay- or organic-dominant soils or media. It will even grow directly in water, provided you can somehow anchor its rhizomes to prevent it from falling over.

Avoid keeping your ʻakaʻakai in a site with strong or gusty winds since they might overwhelm the strength of its stalks and cause them to kink. Unfortunately, when this happens, the damage is usually permanent even if the stalk is later righted and supported. Consider removing these damaged stalks (near their base) in order to keep your plant looking tidy. Obviously, stalks that die and brown naturally can also be pruned.

Pests and Diseases

Above ground, ʻakaʻakai is infrequently attacked by aphids or mealybugs, typically near its tips. These pests are often farmed and protected by ants. Below the ground or the media in a pot, plants are sometimes attacked by root mealybugs. Look for these by carefully removing the pot from the plant's root mass; infestations appear as hairy/powdery white masses on the roots or in the media. Refer to the Pests & Diseases page for ways to battle the above-mentioned pests.

If your ʻakaʻakai 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 animals. Wait at least a week before returning your treated plant to the pond or water feature.

Uses

Ancient Hawaiian

The stems of ʻakaʻakai were used for thatching hale (houses) [Neal 1965], and while not as durable as other fiber plants, were plaited into mats and placed in one or two layers directly on the pebble floors of hale as part of a hikieʻe (couch or bed) to protect the more precious top layer(s) of lau hala (Pandanus tectorius) mats from wearing out prematurely [Neal 1965; Abbott 1992; Krauss 1993].

Ka‘aiakamanu & Akina [1922] claim that AKAAKAI NAKU or NEKI roots (likely meaning the rhizomes), along with kukui, noni, and kō kea, were used medicinally "for gripping pain of the stomach or intestines and for internal hemorrhage." They also mention the dried reeds being woven into hats and mats.

Modern

According to Neal [1965], today (likely referring to the mid-1900s), truck farmers in Hawai‘i use bulrushes as string to tie vegetables into bundles.

I (Koebele) have been unable to find a comprehensive list of all the uses of Schoenoplectus tabernaemontani outside Hawai‘i, perhaps because of its numerous synonyms and extensive native range. However, here are some of the uses I have found:

In North America, young shoots, pollen, seeds, and rhizomes (referred to as "roots") are all considered edible, with most requiring some type of preparation or cooking. A sweet syrup can be made from boiled rhizomes [Eiias & Dykeman 1982].
In Asia, Schoenoplectus lacustris (a synonym of S. tabernaemontani) stems are used for baskets, chair seats, thatching, and paper. In the Philippines and India, the stems are used to make mats. In India, the rhizomes are also eaten raw or ground into flour to make bread. The stems reportedly have astringent and diuretic properties and are used medicinally. Worldwide, the species is used as fodder, an ornamental, and planted to filter and clean polluted or eutrophic water. In Europe, it is sometimes planted for land reclamation along seashores [PROSEA].
In New Zealand, the culms are occasionally used by Māori along with the korari of the flax (Phormium tenax) to make rafts, and as a flooring in waka [New Zealand Plant Conservation Network].

Special Features and Information

General

The large Sedge family (Cyperaceae) has about 5,000 described species in 70 to 115 genera. Members can be found on every continent except Antarctica and grow in a wide diversity of habitats. However, sunny, moist to wet areas are probably the most common place to see sedges. Few sedges are food plants. Rather, their fibrous stems and leaves have been most useful to humans for making mats, baskets, and even boats. Papyrus (Cyperus papyrus) was used in Ancient Egypt to make paper [Britannica].

There are over 50 recognized species of Cyperaceae native to Hawai‘i within multiple genera; current (2026) genera are: Bolboschoenus, Carex, Cyperus, Eleocharis, Fimbristylis, Gahnia, Machaerina, Morelotia, Oreobolus, Rhynchospora, Schoenoplectiella, Schoenoplectus, and Scieria. The majority of these species are considered "Apparently secure." However, there are also a few endangered or presumed extinct taxa in the genera Carex and Cyperus. Currently (2026), there are only two native species of Schoenoplectus in Hawai‘i, the indigenous S. californicus and S. tabernaemontani [Flora of the Hawaiian Islands].

Schoenoplectus tabernaemontani is an important species in wetlands, providing food (e.g., seeds) and cover for native and migratory waterfowl, and reducing pollutant loads carried by storm water runoff [USDA Forest Service].

A non-Hawaiian cultivar, Schoenoplectus tabernaemontani 'Zebrinus', with bright horizonal white or yellow stripes, is a popular plant sold for water gardens and landscapes [NatureSpot].

Hawaiian Name

Schoenoplectus tabernaemontani has multiple Hawaiian names, with ʻAkaʻakai and Nānaku appearing to be most specific to this species, although ʻAkaʻakai is also the Hawaiian name for S. californicus on Ni‘ihau, and for the common onion, presumably because their tops look like those of S. tabernaemontani [Ulukau]. Meanwhile, ʻAkaʻakai naku is defined simply as "bulrush" in Hawaiian dictionaries [Ulukau]. Naku has multiple other meanings, including: "To root, wallow, as a hog; to tread, trample, push, as through mud or grass; to struggle; to roil, as water; to delve, search", as well as being the name for a type of red-skinned onion [Ulukau]. Neki also has multiple other meanings, including: "full, crowded, packed" or "awkward, unskillful, ignorant", as well as "nursemaid, nurse", and the name for a mat made of the young shoots of the great bulrush [Ulukau]. Lastly, Kaluhā is a more generic Hawaiian name for several native and introduced species in the Sedge family (Cyperaceae) [Wagner et al. 1990].

Etymology

Schoenoplectus comes from the Ancient Greek words, skhoînos, meaning "reed," and plektós, meaning "twisted" [Wiktionary], likely referring to how the stems are/were traditionally woven into mats, etc., by many indigenous peoples, including Hawaiians.

The species name, tabernaemontani, honors Jacobus Theodorus, known as Tabernaemontanus (born 1520–1525; died in 1590), a German physician, botanist, and herbalist. His Latinized name is a compressed form of Tabernae Montanae ("tavern in the mountains"), the Medieval name of his hometown, Bergzabern [WikipediA].

BPK