Euphorbia degeneri
(formerly Chamaesyce degeneri)
Euphorbiaceae or Spurge family
Synonyms: Anisophyllum cordatum, Chamaesyce cordatum, Chamaesyce degeneri, Chamaesyce degeneri f. minuscula, Chamaesyce degeneri var. molokaiensis, Euphorbia cordata, Euphorbia degeneri f. minuscula, Euphorbia degeneri var. molokaiensis
ʻAkoko
ʻEkoko, Koko, Kōkōmālei
Beach sandmat, Spurge
Natural Range & Environment
Euphorbia degeneri is endemic to all the main Hawaiian Islands except Kaho‘olawe [Flora of the Hawaiian Islands]. It is found scattered in coastal areas (but see next paragraph) from sea level to 50 m (164 ft) [Wagner et al. 1990].
Joel Lau, an expert botanist known for his rare finds and analysis, has discovered an ‘akoko on the basaltic cliffs of windward O‘ahu (Ko‘olau Mountains) that matches the description of Euphorbia degeneri. You can view his photographs of these plants at this Flickr link.
ʻAkoko have separate reduced (i.e., no petals or sepals) male and female flowers on the same plant. Here are two close-up photographs showing the male flower in the center of each photograph with its single long stamen surrounded by mostly pollinated female flowers in various stages of fruit development; the fruit hangs to the side as it develops and only become erect just before it bursts open to disperse it tiny seeds (Photograph with black gloves courtesy of Forest & Kim Starr CC BY 3.0 US; second flower photograph courtesy of Susan Fawcett CC BY-NC 4.0.). ʻAkoko leaves can vary in color from green to blood-red (Green ʻakoko photograph courtesy of Forest & Kim Starr CC BY 3.0 US; red and green ʻakoko photograph courtesy of Mike Wood CC BY-NC 4.0.). A cultivated ʻakoko quite "happy" in its non-coastal habitat.
Description
Euphorbia degeneri is a small (often less than 12 inches (30 cm) across) prostrate subshrub with a lifespan exceeding five years. It has numerously-jointed stems with thin gray to brown bark/skin and a milky sap that may irritate those with sensitive skin. The round to elliptical leaves are green to blood-red, hairless (or nearly so), and arranged in pairs opposite each other along the stem. During periods of severe drought, plants will drop many of their leaves. Damaged green leaves turn red, orange, or yellow.
ʻAkoko have greenish-white to yellow male and female flowers on the same plant that have neither petals nor sepals but instead a large cup-like structure called a cyathium at their base. The male flower has a single long stamen at its center, while female flowers have a pistil with multiple stigmas (see photographs above). (Female flowers also seem to have a ring of stamens surrounding the pistil; however, I (Koebele) was unable to determine if these were functional.) Cultivated plants (and presumably wild plants) are self-fertile. Wild plants seem to produce their tiny flowers most of the year except during periods of extreme drought. Cultivated plants flower sporadically or continuously.
The pollinated female flower develops into a green capsule that hangs to the side as it grows larger. When ripe, typically in the morning hours, the capsule will straighten from its downward-curved position and become upright shortly before it explodes to disperse the few tiny white seeds inside.
Growth Requirements
General
While it's possible to grow this little ʻakoko inland as an accent in a native Hawaiian coastal or rock garden, it will face fewer threats if you keep it as a container plant. Euphorbia degeneri grows too sparsely to be used as an effective weed-controlling groundcover.
Fill your container with crushed coral (mostly at the bottom) and sand. Alternatively, you can fill the container with black cinders. Place the container with your ʻakoko in a site that receives full sunlight for all or most of the day.
Water your ʻakoko minimally; around once or twice a week is more than enough for this xeric plant. Do not overwater.
Euphorbia degeneri grows at a moderate pace, and you should have a plant 6 to 12 inches (15 to 30 cm) wide in about a year. Fortunately, this little ʻakoko begins flowering early, perhaps as soon as three months in its container. If your plant seems to stop growing or never flowers, you can try using a foliar organic or inorganic fertilizer at ⅓ or ¼ the recommended strength. And, if you are interested in collecting the tiny seeds to grow more plants, look for and harvest any ripe capsules in the morning. Ripe capsules will straighten from their downward-curved position and become upright shortly before they explode to disperse the tiny seeds inside.
If your ʻakoko begins to overflow the container, it's okay to hand-prune some of its branches. However, do this slowly, a few branches every couple of weeks, and take care not to get covered with the milky sap exuding from the cuts; Euphorbia sap can cause skin irritation. You can also try growing new plants from the cuttings; however, this is more difficult than growing them from seeds.
I (Koebele) haven't yet figured out why some ʻakoko have all green leaves while others have a mixture of red and green. It's true that if you damage a leaf (try squeezing one really hard), it will turn from green to red. However, I have often seen wild and cultivated ʻakoko with red leaves and no signs of leaf damage. Perhaps it's just genetics, like in the case of color variations in some other plants (e.g., ʻākulikuli (Sesuvium portulacastrum)), or it's a mix of genetics and environmental conditions; an interesting project for a graduate student wanting to work on native Hawaiian plants. If you're interested in learning more, here's an online article by Nathan Taylor to get you started: Euphorbia leaf colors and patterns.
Pests and Diseases
ʻAkoko is occasionally attacked by mealybugs, scale insects, spider mites, and whiteflies. However, this is rare, and, in the case of mature plants, the pests often disappear over time, probably due to natural predators such as ladybird beetles or leaf shedding. ʻAkoko's milky sap may also deter many pests. Refer to the Pests & Diseases page for ways to deal with each of these pests. Persistent infestations are more likely if you have placed your ‘akoko in an unnatural environment, such as a heavily-shaded or windless site; consider moving your plant to a sunnier and windier location rather than resorting to continued chemical treatments.
Another ʻakoko pest is the giant African snail (Lissachatina fulica), which will come out of its hiding place at night and girdle the stems or eat the leaves of ‘akoko; girdled stems eventually die. If this happens, first try to solve the problem by moving your ʻakoko to a safer location. Also, closely inspect your container to make sure the snail(s) are not living inside. Refer to the Pests & Diseases page for other ways to deal with snails.
Uses
Ancient Hawaiian
There are about 17 endemic species of ‘akoko found in Hawai‘i, depending on which taxonomist you talk to. All possess a milky sap. According to Krauss [1993], the sap was used in the paint for canoe hulls.
Pukui & Elbert [1986] state that Euphorbia (Chamaesyce) multiformis leaves and buds were chewed to treat debility. This claim likely originates from Ka‘aiakamanu & Akina [1922], who recommended this practice for mothers and babies.
Note: The milky sap of all Euphorbia species can cause skin irritation, warts, and, despite the claims above, should not be ingested without medical supervision due to potential toxicity.
Modern
Special Features and Information
General
Euphorbiaceae is a large family with about 7,500 species within 300 genera, found on all the continents except Antarctica, with the greatest diversity in the tropics. Some well-known non-native relatives of ʻakoko are the Castor oil plant (Ricinus communis), kukui (Aleurites moluccana), poinsettia (Euphorbia pulcherrima), cassava (Manihot esculenta), and the Pará rubber tree (Hevea brasiliensis) from which we get latex [WikipediA;Euphorbiaceae].
There are currently (2025) 17 native species of ʻakoko (Euphorbia spp.) — all endemic to the Hawaiian Islands. Several ʻakoko are either vulnerable, rare, or endangered, and two varieties are considered to be extinct [Flora of the Hawaiian Islands]. They range in stature from very prostrate shrubs like Euphorbia degeneri to tall trees like Euphorbia olowaluana, which can grow to nearly 30 feet — perhaps the tallest in the entire genus of about 2,000 species worldwide!
In addition to the many endemic Euphorbia species, the only other member of Euphorbiaceae native to Hawai‘i is the endemic poʻolā (Claoxylon sandwicense) [Flora of the Hawaiian Islands].
Hawaiian Name
ʻAkoko comes from the Hawaiian word for blood, koko. This is likely a reference to the red, or blood-colored, seed capsules that look like drops of blood on the plant [Krauss 1993, Neal 1965]. Alternatively, some believe the name comes from the observation that ‘akoko leaves, when damaged, often turn red, giving the appearance that the plant bleeds when it is injured.
Etymology
Euphorbia is named after Euphorbos, a Greek physician of King Juba II of Numidia and Mauretania (52–50 BC – 23 AD), who married the daughter of Anthony and Cleopatra [WikipediA; Euphorbia].
The former genus name, Chamaesyce, is derived from the ancient Greek words, χαμαί (khamaí), meaning “near the ground,” and συκῆ (sukê), meaning "fig-tree," perhaps referring to the low habit of most species and the fig-like appearance of the fruit capsules [Wiktionary;Chamaesyce].
The species name, degeneri, honors noted botanist(s) Otto Degener (1899–1988) and Isa Degener (–Hansen) (1924–2018), husband & wife, both botanists and conservationists who specialized in identifying the plants of Hawai‘i. Among the many books and papers they co-authored, the most influential was Flora Hawaiiensis, which appeared in seven volumes between 1932 and 1957 [WikipediA;Otto Degener].
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