Paratrophis pendulina
(formerly Streblus pendulina)
Moraceae or Mulberry family
Synonyms: Morus brunoniana, Morus pendulina, Pseudomorus brunoniana, Pseudomorus brunoniana var. sandwicensis, Pseudomorus pendulina, Pseudomorus pendulina var. sandwicensis, Pseudomorus sandwicensis, Streblus brunonianus, Streblus sandwicensis
Aʻiaʻi
Hawaii roughbush, Hawaiian false-mulberry, Isaac wood, Sia's backbone, Siah's backbone, Whalebone tree
Natural Range & Environment
Paratrophis pendulina is indigenous in Hawai‘i and uncommon to relatively common on all the main islands except Niʻihau and Kahoʻolawe from about 300 m (984 ft) to over 1,680 m (5,512 ft). It is mainly seen in mesic forests but can also be found in the upper portions of dry forests or the drier parts of wet forests. Outside of Hawai‘i, Paratrophis pendulina can be found from New Guinea to Micronesia, south to Norfolk Island, eastern Australia, New Hebrides, Fiji, and Rapa (Rapa Iti) [Wagner et al. 1990].
Ripe and unripe fruits (Photograph courtesy of Forest & Kim Starr CC BY 3.0 US; cropped in header). A small aʻiaʻi growing in Amy Greenwell Garden at about 1,000 ft. elevation on Hawaiʻi Island. Close-up of female flowers (Photograph courtesy of G.K. Linney via G.D. Carr ©). Close-up of mostly ripe fruits. Habit and ripe fruits are growing at only about 300 ft above sea level (Oʻahu), with male and female flowers producing viable seed. An old wild aʻiaʻi at Auwahi, Maui (Photograph courtesy of Forest & Kim Starr CC BY 3.0 US).
Description
Aʻiaʻi has pale gray bark and a milky sap. Leaves are lance-like, serrated, and have a shiny dark green upper surface and a paler green lower surface with hairs. Flowers are unisexual, with many yellowish-white male flowers gathered along a long spike, while several green ovoid female flowers are clustered on a short spike. Plants are often unisexual (having only male or only female flowers), but can also be bisexual (i.e., have both male and female flowers). Manual of the Flowering Plants of Hawaiʻi notes "Plants are nearly always dioecious in Hawaiʻi; only rarely, and then in perhaps in stress response to stress, are they monoecious" [Wagner et al. 1990]. We have observed the blooming period at low elevations to be mostly spring, summer and fall months, and less so in the "cooler" Hawaiian winter months. After pollination, female flowers enlarge and mature into ripe dark red or purple fruits about the size of your pointer finger nail and containing a single seed.
Growth Requirements
General
Aʻiaʻi appears to be very adaptable to its growing conditions. Despite being naturally found at nearly a thousand feet and higher, aʻiaʻi does fairly well at lower altitudes but can be fussy and can die back for yet unknown reasons or perish altogether! Our experience is that it flowers and fruits on trees less than 2 ft tall at near sea level in very warm locations. The leaves also tend to be smaller than those seen in upper-elevation trees. (See the photos above for comparison) Time will tell how this species does or even thrives at lower elevations.
When potting in containers, use a generous amount of organic matter in a very well-drained potting media and incorporate at least a third or more black cinder in the mix. If cinder is not available, large-grade perlite can be substituted. In our experience, aʻiaʻi appear to require full sun to grow to their potential.
Pests and Diseases
Aʻiaʻi is sometimes plagued by whiteflies. Refer to the Pests & Diseases page for treatments.
Uses
Ancient Hawaiian
No early Hawaiian use is known [Medeiros et al. 1998].
Modern
Uses Outside of Hawaiʻi:
Joseph Rock noted in 1913, “The wood of the Aiai is light brown, close-grained, hard, and tough." He continues that the Aboriginals living in "New South Wales employed the wood for their boomerangs. When properly dressed and polished it has a remarkable resemblance to Oak” [Rock 1974].
Special Features and Information
General
Aʻiaʻi (Paratrophis pendulina) is an indigenous member of the Mulberry family (Moraceae) comprising over 1,100 species and is in the Moraceae Section Paratrophis, for which the genus has been renamed from Streblus to Paratrophis. The Mulberry family includes familiar alien and Polynesian-introduced plants common in Hawai‘i, such as figs and banyans (Ficus), ʻulu or breadfruit (Artocarpus altilis), wauke or paper mulberry (Broussonetia papyrifera), and kilika or white mulberry (Morus alba). However, aʻiaʻi is the only species in the family native to the Hawaiian Islands.
Hawaiian Name
Etymology
The generic name Paratrophis, para, means "near-, beside-, wrong, irregular" and trophis, means "food eaten by cattle" [Gledhill 2008]. The plants previously referred to as Steblus pendulinus in the Mariana Islands, Micronesia, Papua New Guinea, Australia, New Caledonia, south-western and southern Pacific, and Hawaiʻi are now referred to as Paratrophis pendulina, with Steblus pendulinus being endemic to Norfolk Island [Flora of Australia, Conn 2015]. The specific epithet pendulina means "drooping or hanging down" [Gledhill 2008].
DWE