Chenopodium oahuense
subsp. oahuense & subsp. ilioense
Amaranthaceae or Amaranth family
Synonyms: Atriplex oahuensis, Chenopodium oahuense, Chenopodium oahuense var. discosperma, Chenopodium oahuense f. macrospermum, Chenopodium oahuense f. microspermum, Chenopodium pekeloi, Chenopodium sandwicheum, Chenopodium sandwicheum f. macrospermum
ʻĀweoweo
ʻAhea, ʻĀheahea, ʻĀhewahewa, Alaweo, Alaweo huna (Niʻihau), Kāhaʻihaʻi
Hawaiian goosefoot
Natural Range & Environment
Chenopodium oahuense subsp. oahuense is endemic to all the main Hawaiian Islands except Kaho‘olawe (where it likely grew in the past), as well as Lisianski (Papaʻāpoho), Laysan (Kauō), French Frigate Shoals (Kānemiloha‘i), Necker (Mokumanamana), and Nīhoa. It makes up much of the native vegetation on the latter two islands [Evenhuis & Eldredge 2004]. It grows from sea level to 2,520 m (8,268 ft) on a variety of substrates, including sand, coral, clay, and lava/cinder in dry coastal areas, as well as dry lowland to montane forests and shrublands. Additionally, on Maui and Hawai‘i Island, it grows in subalpine shrublands [Wagner et al. 1990]. Chenopodium oahuense subspecies ilioense is only found growing wild on tall sea cliffs of northwestern Moloka‘i [Flora of the Hawaiian Islands]. Within the last 20 years, ‘āweoweo has been planted out extensively in flora and fauna restoration efforts on islands such as Midway and Kaho‘olawe.
Prostrate ‘āweoweo (subspecies ilioense with ‘ilima and pā‘ū-o-Hi‘iaka). Shrub form ‘āweoweo. (Prostrate and shrub photographs courtesy of Forest & Kim Starr CC BY 2.0.) Treelike ‘āweoweo on Hawai‘i Island. Just three of āweoweo's many leaf forms (Leaf photographs courtesy of Forest & Kim Starr CC BY 2.0).
Description
Chenopodium oahuense is a long-lived (greater than five years) polymorphic species (see photographs above) that varies in stature, scent, and stem color, as well as leaf size, margin, color, and pubescence. Coastal forms are often short (less than 3 ft [1 m]) or even prostrate (such as the subspecies ilioense), while montane forms are generally taller or even treelike (up to 20 ft [6 m]). ‘Āweoweo leaves, flowers, and fruits can be anywhere from scentless to having a strong fishy fragrance. Stems normally have a pattern of red streaks, but this pattern can be vivid or barely visible. All ‘āweoweo leaves tend to have the generalized goosefoot shape indicative of Chenopodiaceae. However, they can vary considerably in size from less than ½ inch to 2 inches (1.3 to 5 cm) long. This size variation is both genetic as well as environmental (e.g., plants produce larger leaves during the rainy season and smaller leaves during the dry season). ‘Āweoweo leaves are often fleshy and olive green with many tiny hairs that give them a grayish or bluish-silver appearance. However, plants with darker green paper-thin leaves with very few hairs are not uncommon, particularly in wetter habitats. The tiny greenish-white perfect (bisexual) flowers of ‘āweoweo are clustered on panicles and bloom sporadically throughout the year in both wild and cultivated plants. These mature into dry tan to brown multi-fruited spikes.
Growth Requirements
General
Prostrate āweoweo (such as the subspecies ilioense pictured above) are excellent groundcover for sunny sites, while more upright shrubs (subspecies oahuense) are best displayed as a single accent or clustered to form a barrier or hedge; space the plants 2–5 feet apart. Older plants that form woody stems or trunks can be shaped as topiary. ‘Āweoweo can also be maintained in a container but will require greater care (i.e., watering and fertilizer) than grounded plants.
ʻĀweoweo does best in a site with full sunlight for all or most of the day, but can tolerate a more shaded site. They are tolerant of high temperatures, drought, strong winds, and salt spray, and can grow in a variety of soil types, including coralline, organic-dominant, clay, and lava/cinder. If grown in a container, be sure to use media that permits good drainage (e.g., lots of cinder or perlite).
If planted in the ground, ʻāweoweo requires little or no watering or fertilizer after a couple of months; water new plantings 1–3 times a week during this establishment period, but once established, do not overwater. Monthly foliar feeding at ½ to ⅓ the recommended strength can improve the plant's overall vigor and health. Container plants should be regularly watered and fertilized.
Grounded ʻāweoweo normally grow quickly and begin producing flowers and fruits in a year or less. Container plants can be slower growing, depending on the container size and the care they receive.
Many people do not prune their ʻāweoweo in order to keep a more natural appearance. However, removing flower and fruit spikes can encourage more foliage production and maintain a neater appearance.
ʻĀweoweo produces lots and lots of seeds that often sprout beneath and around the parent plant. These seedlings are easy to remove and discard (if you wish to maintain a tidier landscape), transplant to other sites in your landscape, or pot-up for gifts.
In our experience, the lifespan of an ʻāweoweo can be quite long or quite short, depending on both understood and unknown factors. For example, fast-growing plants seem to "burn out" and die sooner than slower-growing plants. Also, it's obvious that a treelike ʻāweoweo doesn't grow to 20 feet overnight. Given this uncertainty, we advise always keeping a few seedlings potted-up just in case your parent plant(s) dies unexpectedly.
Pests and Diseases
Occasionally, a small gray weevil (Myllocerus sp.) will eat ʻāweoweo leaves, or aphids or mealybugs will infest stem-tips; ants often protect and spread these two sap-sucking pests. Refer to the Pests & Diseases page for treatments. In the field, Forest and Kim Starr have seen leaf damage by the Hawaiian beet webworm (Spolodea recurvalis).
Uses
Ancient Hawaiian
Hawaiians fashioned ‘āweoweo wood into shark hooks (makau mano) fitted with bone points, and, to add greens and fiber to their diet, the leaves and shoots were wrapped in kī (Cordyline terminalis) leaves, cooked in an ʻimu, and eaten, particularly when other foods were scarce [Krauss 1993].
Ka‘aiakamanu & Akina [1922] describe multiple medicinal uses for āweoweo. However, they are alone in making these claims.
Modern
Special Features and Information
General
The Amaranth family (Amaranthaceae) is a large family with about 2,040 species in 165 genera, most being herbs or shrubs with a few trees and vines. They are found in tropical to cool temperate regions, with a few like spinach (Spinacia oleracea) and beet (Beta vulgaris) being economically important vegetables [WikipediA;Amaranthaceae].
Other native Hawaiian species within Amaranthaceae include: two endemic and endangered and one extinct species of Achyranthes; the likely extinct Amaranthus brownii from Nīhoa and critically endangered Amaranthus pakai; five species of pāpala (Charpentiera spp.); and three endemic species of kuluʻī (Nototrichium spp.) [Flora of the Hawaiian Islands].
Of the 130 or so species of Chenopodium known worldwide, ʻāweoweo is the woodiest in the genus, developing a trunk up to a foot in diameter and the only species to attain status as a tree [Carlquist 1980]. Native Hawaiian seabirds and land birds such as the Nīhoa finch (Telespiza ultima) eat ʻāweoweo and use it for nesting material or nesting sites [Evenhuis & Eldredge 2004].
Recently, the subspecies ilioense, which is endangered and endemic to Molokaʻi, was formally recognized as distinct from the other non-endangered and widespread Chenopodium oahuense (now recognized as subsp. oahuense) [Cantley et al. 2020].
Hawaiian Name
The two predominant Hawaiian names for this plant, ‘āweoweo and ‘āheahea, are very descriptive. ‘Āheahea means "to wilt," a common response of this plant's leaves to the drought conditions it often experiences. In the Kumulipo, the Hawaiian creation chant, many animals and plants were created in pairs, such that when one organism was created in the ocean, there was a counterpart created on land. So, while ‘āweoweo is the name of a plant, it is also the name for Hawaiian bigeye (Priacanthus spp.), a genus of all-red reef fish. What makes this shared name particularly appropriate is that the leaves, flowers, and fruits of some ‘āweoweo, when crushed, smell overwhelmingly like a fish. The red streaking sometimes seen on ‘āweoweo stems is also considered by Hawaiians as further evidence of the plant–fish connection. Alaweo huna is the name for Chenopodium oahuense on Niʻihau.
Etymology
Chenopodium is from the Greek words chen, meaning "goose," and pous, meaning "foot," referring to the shape of the leaves [Wagner et al. 1990]. The species name, oahuense, refers to the island of Oʻahu. The suffix -ense was added to form a geographical epithet [Gledhill 2008].
BPK