Gouania hillebrandii
Rhamnaceae or Buckthorn family
Synonyms: Gouania cucullata, Gouania fauriei, Gouania lydgatei, Gouania mannii, Gouania pilata, Gouania remyi, Gouania sandwichiana, Gouania thinophila, Isodendrion fauriei, Pleuranthodes hillebrandii
No known ancient Hawaiian name
(see Hawaiian Name below)
Hairy-fruit chewstick, Hairyfruit chewstick
Natural Range & Environment
Gouania hillebrandii is endangered and currently endemic to west Maui, with historical populations reported on Molokaʻi, Lāna‘i, and Kaho‘olawe; the Molokaʻi, Lāna‘i, and Kaho‘olawe populations are now believed to be extinct. Formerly seen in dry forests, today (2023), it is only found in dry pastureland (see photograph below).
In 2011, a 5-year review by USFWS reported about 1,000 plants in west Maui and about the same number on Molokaʻi. A newer report in 2023 stated that: (1) there were about 200 plants seen in west Maui in 2018 (with some natural recruitment) and (2) no plants have been observed on Molokaʻi since 2010. Unfortunately, very few seeds from wild plants have been collected and stored, and there have been few restoration efforts (i.e., plantings) made to date. Additionally, the remaining populations grow in areas threatened by wildfires, which in the past have damaged or destroyed other wild populations (e.g., above Lahaina, Maui). [USFWS;ECOS].
A close look at the leaves, flowers, and immature fruits of Gouania hillebrandii. Cultivated plant on O‘ahu. Wild plant in pastureland on Maui (Photograph courtesy of Forest & Kim Starr CC BY 2.0).
Description
Gouania hillebrandii is an endangered short-lived (less than five years) small sprawling to erect shrub with slender branches covered with a rust- or ash-colored fuzz. Leaves are oval or oblong, 2-3 inches (5 to 8 cm) long, broadly pointed with entire margins, and somewhat papery. The upper leaf surface is normally dark green and glabrous (without hairs) while the lower surface is pale and fuzzy, becoming less so with age. Flowers, both perfect (bisexual) and staminate (male), are small, nearly white (sometimes with pink tinges), and fragrant. Tiny brown seeds are held within small 3-winged capsules that are covered with a soft white fuzz [Wagner et al. 1990]. Flowering, fruiting, and vegetative growth occur mostly during the wet months of winter and spring.
Growth Requirements
General
Gouania hillebrandii is an attractive small native shrub with great landscape potential when (or if) it becomes readily available to the public; currently (2025), it is not commercially available. It does best in a site with full to partial sunlight for all or most of the day. G. hillebrandii requires minimal watering (i.e., keep the surface soil dry) and is wind- and drought-tolerant. In-ground planting sites or containers should have good drainage. This species does not appear to require much, if any fertilizer, but does respond well to foliar feedings of fish or kelp emulsion at half strength monthly. Prune only if necessary and very sparingly. Because this plant is short-lived, be sure to collect and store seeds (in your refrigerator) as soon and as often as possible in order to propagate replacement plants.
Pests and Diseases
The black twig borer can be a major threat to Gouania hillebrandii. Treat plants as soon as this beetle is detected because they can quickly kill them. Red spider mites and thrips can also infest Gouania hillebrandii and will quickly spread if not controlled. Refer to the Pests & Diseases page for ways to deal with each of these pests.
Uses
Ancient Hawaiian
We could not find any record of Hawaiians using this plant. However, please refer to the General section below describing how a related species, Gouania lupuloides, is used in Jamaica.
Modern
Special Features and Information
General
Rhamnaceae is a family of mostly trees and shrubs (with some vines) containing about 950 species within 55 genera. The family has a worldwide distribution but is most common in tropical and subtropical regions [WikipediA;Rhamnaceae].
There are between 50-70 Gouania species in tropical to sub-tropical regions throughout the world [WikipediA;Gouania]. In Hawai‘i, there are three endemic species (all endangered): the hairy-fruit chewstick (G. hillebrandii); the smooth-fruit chewstick (G. meyenii); and the O‘ahu chewstick (G. vitifolia).
In addition to the three endemic Hawaiian Gouania species, other native Hawaiian species in the Buckthorn family include: the indigenous shrub ʻānapanapa (Colubrina asiatica); and two endemic trees, both called kauila or kawila, Alphitonia ponderosa and Colubrina oppositifolia.
Gouania lupuloides, known as chewstick or whiteroot, is a neotropical plant native to Mexico, South America, and the West Indies. In Jamaica, chewstick is used to clean one's teeth by peeling back the bark and chewing the stem tip, which becomes fibrous and frothy; the taste is slightly bitter but not unpleasant [WikipediA;Gouania lupuloides].
Hawaiian Name
There is no known Hawaiian name for this species. Therefore, we refer to it within this website using its scientific name or its non-Hawaiian common name, hairy-fruit chewstick.
Etymology
The genus Gouania is named after Antoine Gouan (1733-1821), a French professor and naturalist [Wagner et al. 1990]. The species name honors William Hillebrand (1821–1886), a Prussian physician and plant collector who lived in Hawai‘i. Hillebrand planted many of the plants he collected at Queen's Hospital and on his own property in Nuʻuanu, O‘ahu. After moving back to Germany, the property was sold to his neighbors, Thomas & Mary Foster. Today, the site is known as Foster Botanical Gardens [Meier 2005].
BPK