Native Plants of Hawai‘i - Sesuvium portulacastrum

Sesuvium portulacastrum

Aizoaceae or Fig-marigold family

Synonyms: Portulaca portulacastrum, Trianthema portulacastrum var. hillebrandii

ʻĀkulikuli

Sea purslane, Sea-purslane, Seaside purslane, Shoreline sea-purslane, Shoreline seapurslane

Natural Range & Environment

Sesuvium portulacastrum is native to Africa, Asia, Australia, Hawai‘i, and both North and South America. It has also become naturalized in many places where it is not native [WikipediA;Sesuvium portulacastrum]. In Hawai‘i, ʻākulikuli is found on all the main Islands as well as the Northwestern Islands of Midway Atoll (Pihemanu), Pearl & Hermes Atoll (Holoikauaua), Lisianski (Papaʻāpoho), Laysan (Kauō), Necker (Mokumanamana), and Lehua [Flora of the Hawaiian Islands]. It grows in nearly all sunny coastal areas such as sandy beaches, on coralline or basalt rock, and in sandy to muddy salt marshes and tidal flats.

Sesuvium portulacastrum fruit capsules with tiny round seeds. ʻĀkulikuli can vary a lot in the color of its flowers (white to pink to light purple), the color of its stems and leaves (completely green to almost entirely red), and the shape of its leaves (short and thick to long and thin). Here are some examples: fleshy green leaves with pink stems is the most commonly seen form; a green and yellow short-leaf form with rarely seen white flowers (Photograph courtesy of James Bailey [silversea_starsong] CC BY-NC 4.0); a form with extra long and thin leaves (Photograph courtesy of cachola9 CC BY-NC 4.0); a jellybean-like form with orange-green leaves (Photograph courtesy of Forest & Kim Starr CC BY 3.0 US); a nearly all-red form.

Description

Sesuvium portulacastrum is an extremely prostrate long-lived (greater than five years) succulent herb that is typically one to three feet (30 to 91 cm) wide, but sometimes roots at its stems' nodes to produce a mat several feet in diameter. Plants can vary in stem, leaf, and flower characteristics both within a population and between populations. The fleshy and hairless stems of ʻākulikuli can be yellowish-green to green to green and red to entirely red. Its leaves can be short (⅓ inch [0.8 cm]) to long (nearly 2 inches [5 cm]), fat (i.e., round in cross-section) to flat, and yellowish-green, orange, red, or a mix of these colors. Plants growing in dry environments tend to have fatter leaves than those growing in wet sites. ʻĀkulikuli has small five-pointed (rarely four-pointed) perfect (bisexual) flowers that range from deep purple to pink to (rarely) white. Blooming tends to be year-round and continuous for cultivated plants and sporadic for wild plants; wild plants cease flowering during extended periods of drought. Pollinated flowers mature into dry tan to gray capsules that eventually pop open to disperse the many tiny black snail-shell-like seeds within.

In the field, ʻākulikuli can be confused with its similar-looking alien sister species Sesuvium verrucosum (western sea-purslane), which is naturalized on O‘ahu, Moloka‘i, and Maui, and, to a lesser extent, with the alien and invasive pickleweed (Batis maritima) that is naturalized on all the main Hawaiian Islands. Here are some key differences between the two Sesuvium species: (1) The flowers of S. portulacastrum have a short stalk attaching it to the stem, while S. verrucosum flowers normally lack this stalk; (2) S. portulacastrum often has roots at its stem nodes holding it mat-like to the ground; S. verrucosum lacks these stem node roots; (3) S. portulacastrum typically has thicker, more succulent, and glossy leaves and stems than S. verrucosum, which appears duller. And, here a few key differences between ʻākulikuli and pickleweed: (1) ʻĀkulikuli has star-shaped flowers, pickleweed does not — it has very tiny flowers; (2) ʻĀkulikuli stems are always fleshy while pickleweed's stems become woody at their base; (3) ʻĀkulikuli always grows horizontally along the ground while pickleweed will put out horizontal branches which then develop vertical stems; (4) We have never seen a pickleweed with even a hint of red in its stems or leaves.

In the field, ʻākulikuli can be confused with two similar-looking alien plants, Batis maritima (pickleweed) and Sesuvium verrucosum (western sea-purslane), both typically more upright than ʻākulikuli. Above is a photograph of Batis maritima (alone), a small Sesuvium verrucosum (next to the concrete curb), and the three species growing together (All photographs courtesy of Forest & Kim Starr CC BY 2.0). In the three-species photograph, the ʻākulikuli is the light green plant in the center, while the S. verrucosum is the darker green plant to the right of the ʻākulikuli, and the B. maritima is/are the two light-colored strands coming from the left-side corners of the photograph. See Description above for some reliable ways to distinguish between these three species.

Growth Requirements

General

Regrettably, we cannot recommend planting ʻākulikuli in the ground — unless you happen to own some oceanfront property. This is because, inland, snails and slugs will eventually discover your plant and relentlessly each night eat both its leaves and stems until there is little left. (If you are fortunate enough to have an oceanside landscape, ʻākulikuli can be a beautiful and valuable (for erosion control) groundcover. Rather, we recommend growing ʻākulikuli in a container, where it is far easier to avoid or eliminate this threat by simply moving the container or making it inaccessible; see Pests & Diseases for how to deal with snails and slugs.

Sesuvium portulacastrum does best in full sunlight for all or most of the day. Therefore, place your container with plant in an appropriate site. Somewhat surprisingly, you can also grow ʻākulikuli inside, either right next to a (very) sunny window or under LED lights. An indoor ʻākulikuli will not grow as well or as fast as one grown outside in direct sunlight; however, it does have the advantage of being farther away from harmful pests.

ʻĀkulikuli tends to do best and is most succulent when given the near-minimum amount of water required to keep it growing. Surprisingly, it will also grow under very wet — even waterlogged — conditions (see description of experiment below); however, these plants tend to be leggy, develop thin leaves, and are more susceptible to stem or root rot.

Sesuvium portulacastrum grows anywhere from very slow to fast, depending largely on how much light and water it gets; more light and more water generally equals faster growth. However, even small plants begin flowering within a year or less. ‘Ākulikuli doesn't seem to require much fertilization. However, if your plant is growing too slowly for you or seems stunted, try transferring it to a larger container, giving it a little more light or water, or giving it just a bit of fertilizer (e.g., an organic or inorganic water-soluble fertilizer at ⅓ to ½ the recommended strength).

‘Ākulikuli can tolerate extreme heat, drought, strong winds, salt spray, and waterlogged (from fresh to seawater) soil; however, leaves and stems exposed to prolonged immersion will rot. Plants actually seem to benefit from an occasional (e.g., once a month) media drench or foliar spraying with seawater, perhaps because the seawater provides nutrients. While wild ‘ākulikuli can be seen growing in lava/cinder, clay, sand, coralline, or organic-dominant soils, we prefer to grow our plants in easily-drained media such as cinder, crushed coral, or sand.

Recently, I (Koebele) have been experimenting with ways to make ʻākulikuli less palatable to snails, slugs, and sap-sucking insects in a landscape setting, while still keeping it edible for humans. Here is one method I tried.

Obtain a large shallow (about six inches deep) plastic tray (like those used to mix concrete) and fill it about halfway with either black cinder or crushed coral. Place the tray in your landscape space — somewhere where it will not be filled with freshwater from a sprinkler, etc., — and fill it with brackish water (about 15 ppt) so the water level is just a little above the top of the cinder or coral. (A handheld refractometer is a quick, easy, and inexpensive instrument to measure salinity with just a couple of drops of water.) Plant a few ʻākulikuli in the cinder or coral, or try rooting some ʻākulikuli stem tips. Check the water level every day or so and test the water's salinity weekly. Add freshwater to the tray when needed to keep the water level and salinity stable; over a long time, you might also need to add a bit of seawater to keep the salinity up. If possible, try to protect the tray from overflowing during a rainstorm. Or, install a drain in the side of the tray to direct any overflow away from your landscape site (e.g., into a storm drain), and then re-establish the water level and salinity when the weather clears. Over time, your ʻākulikuli should grow and spread until they eventually overflow the borders of the tray.

Unfortunately, I had to end the above experiment after only a few months. However, the results were promising (i.e., good growth with no snail or slug damage), and we encourage you to try this method or some modification and let us know how it works for you. Contact us at: EickhoffandKoebele@gmail.com.

Lastly, if you choose to disregard our advice and plant your ‘ākulikuli directly in the ground, there are some things you can do to discourage the snails and slugs from devouring your plant. Go to our Pests & Diseases page for details.

Pests and Diseases

In a container, ‘ākulikuli remains mostly free of pests. However, sap-suckers like spider mites and mealybugs can sometimes become a problem. Refer to the Pests & Diseases page for ways to deal with these pests.

Uses

Ancient Hawaiian

Hawaiians ate ‘ākulikuli raw or cooked [Merlin 1999], we suspect, as a less tasty alternative to limu (Hawaiian marine algae).

Modern

ʻĀkulikuli leaves or shoots can be eaten raw or cooked. However, be certain you only collect from plants that have not been contaminated by pesticides or pollutants (e.g., heavy metals). Here's a receipt from Sayo Costantino, Education Specialist for Mālama Learning Center, for a very simple-to-make Cucumber Tsukemono, modified by replacing the cucumber slices with raw ‘ākulikuli leaves and eliminating the salt since ‘ākulikuli is already quite salty.

Harvest about 2 cups of ‘ākulikuli leaves, and soak them in a gallon of freshwater for 1 to 2 hours; this will leach out some of the salt within the leaves. Drain away the water, and place the leaves in a bowl. Mix together 1 cup sugar, ¾ cup white vinegar, and ¼ cup rice vinegar. Pour the sugar and vinegar mix over the leaves. Refrigerate or keep on ice for at least one hour. Enjoy!

Zhang et al. [2024] describe the nutritional value of Sesuvium portulacastrum, as well as the different ways it is eaten or used medicinally in Africa, Asia, and the United States (see some photo-examples below).

ʻĀkulikuli has also been used to clean polluted or contaminated waters and soils. Here on Oʻahu, floating platforms of ‘ākulikuli were used to clean the stagnant, murky waters in the Ala Wai Canal in Waikīkī. And, similarly, in China, it was used to remove nitrogen and phosphorus from a contaminated beach (see photograph below).

According to Rick Barboza, co-owner of Hui Ku Maoli Ola, ʻākulikuli flowers can be used to make a beautiful lei, but the lei requires a lot of work to collect and string together the hundreds of flowers needed.

A: Cooked ʻākulikuli shoots. B & C: ʻĀkulikuli shoots cooked with fish and squid, respectively. D: Pickled ʻākulikuli. ʻĀkulikuli was used to remove nitrogen and phosphorus from a contaminated beach in China. (All photographs courtesy of Zhang et al. CC BY 4.0.)

Special Features and Information

General

Aizoaceae is a large family with about 1,800 species within 135 genera, often referred to as ice plants or carpet weeds, with the overwhelming majority of species endemic to the arid to semiarid regions of Southern Africa. Sesuvium is a small genus of only about eight species [WikipediA], with two present in Hawai‘i, the indigenous native Sesuvium portulacastrum and the alien naturalized S. verrucosum [Flora of the Hawaiian Islands].

Sesuvium portulacastrum or "Seaside purslane" was one of the plants listed as an emergency food for World War II servicemen in a manual titled Emergency Food Plants and Poisonous Plants of the Islands of the Pacific, published by the War Department. The manual states its purpose “is to aid the individual who becomes separated from his unit…so that this individual can live off the land.” It then briefly identifies the plant and how to prepare it [Merrill 1943].

Hawaiian Name

ʻĀkulikuli is a general name for succulent plants [Hawaiian Dictionaries]. However, most native Hawaiian plant growers have this species in mind when referring to the name ʻākulikuli.

Etymology

Sesuvium refers to the land of Sesuvii, a Gallic (Gaul) tribe [Wagner et al. 1990]. The species name portulacastrum is derived from the genus name Portulaca, which, in turn, is from the Latin word porto, meaning "I carry," and lac, meaning "milk," combined to mean "milk-carrier," and from the word castrum, meaning "resembling" [Gledhill 2008]. Combined, the reference is to the similar appearance of S. portulacastrum to plants in the genus Portulaca.

BPK