Native Plants of Hawai‘i - Sapindus saponaria

Sapindus saponaria

Sapindaceae or Soapberry family

Synonyms: Sapindus saponaria f. inequalis, Sapindus saponaria var. jardiniana, Sapindus saponaria f. microcarpus, Sapindus saponaria var. thurstonii, Sapindus thurstonii

Mānele

Aʻe

Hawaiian soapberry, Soap seed, Soapberry, Western soapberry, Wingleaf soapberry

Natural Range & Environment

Sapindus saponaria is considered to be native to southern Florida (USA), Mexico, the Caribbean, Central America, South America, and the Galápagos Islands, as well as to some of the Pacific Islands, including Hawai‘i [Franck 2024]. (See Description below for more discussion of the current taxonomy and distribution of S. saponaria.)

In Hawai‘i, Sapindus saponaria is (currently) considered to be indigenous to Hawai‘i Island, where it grows in mesic forests from 900 to 1,370 m (2,953 to 4,495 ft) [Wagner et al. 1990]. However, it is also possible that the species was indigenous to O‘ahu and Maui as well [Plants of Hawai‘i]. Because S. saponaria from America was introduced early to places like Honolulu while the naturally growing trees on Hawai‘i Island were not observed and recorded by non-Hawaiian botanists until later [Rock 1974 reprint of 1913 book], its pre-contact (i.e., before 1778) natural range remains controversial.

Mānele produces large branched inflorescences with hundreds of small greenish white flowers (Closeup flowers photograph in header courtesy of João Medeiros CC BY 2.0.). Pollinated flowers develop into round marble-sized fruits that turn from green to orange and then nearly black when ripe. Sapindus saponaria has the common name "wingleaf soapberry" because of the unusual wings on the rachis of its pinnate compound leaves that can vary considerably in their prominence (Photograph courtesy of Sam Rickert CC BY-NC 4.0.). Eventually, mānele becomes a very large tree, particularly here in Hawai‘i, as this series of photographs illustrates: young cultivated tree (photograph courtesy of Forest & Kim Starr CC BY 3.0); older cultivated flowering tree; large wild tree on Hawai‘i Island (photograph courtesy of J.B. Friday ©); and very large wild trees; note the large flakes of bark being shed to reveal a smooth younger bark beneath (photograph courtesy of J.B. Friday ©). A comparison of the ripe fruits and seeds of the two native Sapindus species in Hawai‘i, both used by Hawaiians for seed lei.

Description

Currently (2026), Flora of the Hawaiian Islands recognizes Sapinidus saponaria without subspecies or variety divisions. However, Wagner et al. [1990] have recognized that S. saponaria is a variable species, and that a worldwide investigation of S. saponaria may warrant taxonomic revision of the species. In 2024, Franck [2024] examined over 1,000 herbarium specimens (along with four species in the field or in cultivation) of Sapindus sect. Sapindus, the sect. that includes S. saponaria, and proposed a new classification containing 12 species, three being newly described. Additionally, Franck reorganized S. saponaria into two regional subspecies, S. saponaria subsp. saponaria, found only in the Americas (including the Caribbean and the Galápagos), and S. saponaria subsp. jardinianus, which includes those plants found in the Pacific, including Hawai‘i. Since we currently don't know if Flora of the Hawaiian Islands will recognize the Franck [2024] revision and revise their classification, for the time being, we will follow their present-day undivided classification of S. saponaria.

Mānele is a medium-sized to large (up to 82 ft [25 m] tall) deciduous tree with a lifespan best measured in decades. Rock [1974 reprint of 1913 book] noted that the species grows considerably larger on Hawai‘i Island than recorded in other parts of the world. The bark of branches and young tree trunks is comparably smooth. However, the truck of large older trees frequently cracks with large portions (i.e., scales) falling away to reveal a smoother bark beneath (see photograph above). Mānele sapwood is whitish while the heartwood is yellow to light brown. The wood is heavy and hard but not durable when exposed [Little & Skolmen 1989].

Mānele has large (about 1 ft [30 cm] long) pinnately compound leaves with three to six pairs of leaflets. Their upper surface is a dull green and hairless, while the lower surface is paler and sometimes has soft hairs. The leaf's rachis often has wings (see photograph above), particularly common on younger leaves, which is the origin of the common name "wingleaf soapberry."

Mānele is one of a few native Hawaiian trees that is deciduous or partly deciduous, that is, they lose most or all of their leaves once a year. However, in contrast to other native Hawaiian deciduous trees like ‘ohe makai (Polyscias sandwicensis) and wiliwili (Erythrina sandwicensis) that drop their leaves during the hot, dry summer, mānele looses its leaves during the winter. However, Rock [1974 reprint of 1913 book] notes that mānele often develop new leaves even before all the old leaves have fallen, such that the tree is only bare for a brief period.

Mānele produces large branched inflorescences (panicles) with many small five-petaled greenish white male, female, and bisexual flowers; female and bisexual flowers can be distinguished by their central green pistil with a three-celled ovary (see header photograph). Trees typically flower during the fall with fruits ripening in the summer.

Pollinated mānele flowers develop into round marble-sized fleshy fruits that turn from green to orange and then nearly black when ripe. Often, only one of the three ovaries develops such that there are two small aborted "fruits" fused to one large fruit. The fruits contain a substantial amount of saponins which are mildly toxic (to humans) and used worldwide as a natural soap; it's unclear if pre-contact Hawaiians used mānele for washing (see Uses below). Within each large fruit is one round reddish brown to black seed. The seeds are reported to be toxic and used in tropical America as a fish poison [Little & Skolmen 1989].

Growth Requirements

General

While mānele is considered indigenous to Hawai‘i, we also know from Rock [1974 reprint of 1913 book] that Sapindus saponaria was introduced (from America) and cultivated in places like Honolulu, O‘ahu, early on in Hawai‘i's post-contact (i.e., after 1778) history. The reason for this importation were as obvious then as they are today — S. saponaria is a large and easy-to-grow tree that provided valuable shade in the hot, sunny lowlands of leeward O‘ahu and elsewhere. When planting your mānele, be sure the location is large enough to accommodate its potential mature size (see photographs and Description above). Also, avoid planting it too close to your house, other structures, or where you park your car. It's not the tree's roots you need to worry about. They seem to be rather benign, and we've never seen mānele roots crack a foundation, sidewalk, etc.; if you have witnessed the contrary, please let us (EickhoffandKoebele@gmail.com) so we can improve this webpage. Rather, the concern is that a large branch may break during a windstorm and come crashing down. We've never tried to keep mānele in a container for very long — however, it would be an interesting experiment. Lonomea (Sapindus oahuensis) can be kept in a container, although they ultimately become (non-fatally) root-bound and stunted, much like the ubiquitous Ficus trees commonly seen in hotel lobbies and outside store entrances.

As a shade tree, it's obvious you should plant your mānele in a site that receives full sunlight for all or most of the day. However, also note that mānele seedlings and saplings can survive in shaded areas (but will grow more slowly) if your goal is to increase a landscape's shading on existing plants (e.g., a struggling fern or lobelioid).

While wild mānele are only found in upland mesic locations, once established in the ground (after a few months of weekly watering), they are capable of surviving and growing in much lower, hotter, and drier areas. Ultimately, the natural rainfall at your planting site will determine if you need to water your tree regularly or not at all. Unfortunately, this can sometimes be a bit difficult to determine since mānele naturally drops most of its leaves once a year. However, this typically happens during the wetter winter months. Therefore, if your mānele starts dropping leaves during the drier summer and fall, it's likely trying to tell you that it needs your attention (i.e., watering).

Mānele grow rather quickly (but not as fast as lonomea [Sapindus oahuensis]) and you can expect to have a 3 to 6 ft [1 to 2 m] tall tree in about two years. Expect to see your first flowers after three to five years. While soil moisture seems to be the primary determinate in how fast mānele will grow, trees also benefit from either a balanced controlled-release fertilizer added to the surrounding soil every six months, or a foliar feeding of an organic or inorganic fertilizer at ⅓ to ¼ the recommended strength every couple of months.

Based on personal plantings and plantings by others (e.g., public parks), mānele appears capable of growing in just about any type of soil as long as it drains water reasonably well. Similarly, if you decide to keep your plant in a pot, use a media mix containing about 33% cinder or perlite to obtain good drainage.

Most mānele we've seen naturally grow into an attractive shape. However, dead branches and stems are not uncommon and should be pruned away before breaking unexpectedly. Examine all pruned dead stems and branches closely for the tiny holes of black twig borers to determine if you have a problem. Mānele naturally shed quite a lot of leaves, particularly during the winter months, as well as dropping their numerous round fruits. In wetter or irrigated landscapes, these deteriorate fairly quickly (except for the seeds which often sprout beneath their parent) and disappear in (and can improve) the soil. However, we recommend not planting mānele near a swimming pool or pond to avoid the hassle of continuous leaf and fruit removal. In very dry areas, the leaves can accumulate and require collection and removal if you wish to maintain a tidier look.

Pests and Diseases

Mānele seems to have few serious pests or diseases. Black twig borers, lace bugs, and spider mites are probably the most common pests, but for large saplings and trees, these are normally not life-threatening. Refer to the Pests & Diseases page for ways to combat each of these pests if they become a persistent or serious problem.

Uses

Ancient Hawaiian

Hawaiians strung the round dark seeds of mānele into lei [Krauss 1993]. Additionally, Malo [1898/1903], page 44, briefly mentions that "The a-e and the po-ola were trees the wood of which was used in spearmaking." While Sapindus saponaria fruits are used in other parts of the world as a traditional soap for washing hair and clothing, I was unable to find any record of pre-contact (i.e., before 1778) Hawaiians using mānele fruits for washing. This isn't too surprising given the plant's limited geographic range in Hawai‘i and the fact that Hawaiians had many other alternative and more common plants, such as the Polynesian-introduced ʻawapuhi or shampoo ginger (Zingiber zerumbet) to use for washing.

Modern

Today, mānele seeds are still strung into permanent lei as they were in ancient times [Neal 1965; McDonald & Weissich 2003]. Also, in modern times, the fruits are occasionally used for washing. The fruits contain saponins which are bitter and mildly toxic to humans, so avoid getting the soap in your mouth; saponins are the chemicals responsible for producing the soapy suds [Useful Tropical Plants]. Check out the great Instagram video by nattybynature808 on how to make soap from mānele fruits. Outside Hawai‘i, Sapindus saponaria has a multitude of traditional uses. For a good summary of most (but not all) of these uses, check out Useful Tropical Plants.

Both unripe green and ripening orange (to black) fruits can be used to produce a soap for washing hair or clothing. (Green fruits photograph courtesy of Alex Popovkin CC BY 2.0; orange fruits photograph courtesy of Jim Conrad Pubic Domain.)

Special Features and Information

General

The Soapberry family (Sapindaceae) has about 1,860 species in 138 genera. Well-known non-Hawaiian family members include maples, horse chestnut, ackee, and the locally popular lychee [WikipediA;Sapindaceae]. Native members include the endemic lonomea or āulu (Sapindus oahuensis), as well as the endangered endemic māhoe (Alectryon macrococcus), the common indigenous ʻaʻaʻliʻ (Dodonaea viscosa), and the indigenous (but possibly naturalized) pōnui (Cardiospermum halicacabum).

Soapberry fruits contain saponins, a type of natural detergent that foams when mixed with water. This makes them a natural and eco-friendly alternative to synthetic detergents. However, while saponins are useful for cleaning, they are also slightly toxic if ingested, and, therefore, should not be accidentally consumed when washing [Cornell].

The disjunct distribution of Sapindus saponaria between the continental Americas, Hawai‘i, and other Pacific Islands is puzzling. However, Degener [1973], page 202, offers a possible explanation. He observed that when mānele fruits dry, an airspace is formed between the fruit's outer wall and the seed so that the fruits float in water. Additionally, about one-fourth of the mānele seeds he tested floated in seawater. Therefore, long distance transport of fruits or seeds by ocean currents might explain the disjunct distribution of this species. However, lonomea (Sapindus oahuensis) also produces dry fruits that float in water, but it is endemic to only two nearby islands in Hawai‘i, Kaua‘i and O‘ahu. Furthermore, viable lonomea seeds sink in seawater while non-viable seeds will float. Therefore, were the floating mānele seeds Degener observed also non-viable?

Hawaiian Name

In addition to being one of the names for Sapindus saponaria in Hawai‘i, mānele can mean "Sedan chair, palanquin, litter, stretcher, bier; to carry on a stretcher," said to have been a common mode of conveyance by ali‘i (chief or noble person). It is also the name of a harbor and bay on Lāna‘i [Ulukau].

The names a‘e and mānele are shared with several other native Hawaiian trees, specifically species in the genus Zanthoxylum, while on Maui, Xylosma hawaiiense is called a‘e [Wagner et al. 1990]. A‘e also has multiple means, including: "northeast tradewind," "blight," as a directional to express nearness in space or time, and as a replacement for e in mele (Hawaiian songs) [Pukui & Elbert 1986].

Etymology

Sapindus is derived from the Latin words, sapo, meaning "soap," and indicus, meaning "Indian," [Gledhill 2008] probably referring to the use of soapberry trees in India for soap. The species name, saponaria, like the genus name, is derived from the Latin word for soap, sapo, [Gledhill 2008] likely referring to the soapy chemicals, saponins, within its fleshy fruits.

BPK