Native Hawaiian Garden (7722)

Aʻiaʻi (Paratrophis pendulina; formerly Streblus pendulinus) – So much we still don't know.

Sometimes it is difficult for me to decide whether or not I know enough about a species to justify creating a new webpage about it for this site. Such is the case with aʻiaʻi. While I have propagated and grown aʻiaʻi for several years, I have yet to plant one in a garden (or restoration site) and have it survive for more than a year — and, I have tried many times! On the other hand, I have kept aʻiaʻi alive in pots for many years, starting from either a seed or cutting and having them grow large enough to flower and produce viable seeds. Along the way, I have discovered some new propagation methods and species characteristics I have not seen reported by anyone else. It is for this reason, to share my discoveries, that I decided this webpage was merited.

My incomplete horticultural knowledge of aʻiaʻi does not appear to be unique. After looking around, it seems no one knows a lot about growing and caring for aʻiaʻi, or, if they do, they have yet to share much of their understanding in a published (print or digital) format. This absence again highlights how much we still do not know about Hawai‘i's native plants. And, how a person like you can often discover something previously unknown, sometimes with surprisingly little effort. However, for your discoveries, horticultural or otherwise, to be important, it is essential you share them — widely — with others. Otherwise, we will be forever 'rediscovering the wheel' when it comes to the cultivation of our native flora.

Habitat & Appearance: A large shrub to small tree native to eastern Australia, New Guinea, the Caroline Islands, Mariana Islands, Norfolk Island, New Caledonia, Vanuatu, Fiji, Tubuai Islands, and Hawaiian Islands (found on Kauaʻi, Oʻahu, Molokaʻi, Lānaʻi, Maui, and Hawaiʻi) [WikipediA 2024]. In Hawai‘i, aʻiaʻi grows primarily in mesic forests, but can also be found in the wetter portions of dry forests and the drier portions of wet forests.

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). After pollination, female flowers enlarge and mature into ripe dark red or purple fruits about 1 cm in diameter each containing a single seed.

Male & female flowers on the same plant (Photograph courtesy of Timothy Kroessig ©). Ripe and unripe fruits (Photograph courtesy of Forest & Kim Starr CC BY 2.0). Seedling. Small fruiting plant growing under LED lights. Wild tree in Auwahi, Maui. (Photograph courtesy of Forest & Kim Starr CC BY 2.0). (Header photograph of flowers courtesy of G.K. Liney via G.D. Carr ©).

Aʻiaʻi in Hawaiian Culture: I was unable to find any record or mention of aʻiaʻi in Hawaiian culture.

Collecting Seeds: Aʻiaʻi drupes turn from green to dark red or purple as they ripen. I have most often seen ripe fruits in the spring or summer. Remove the exocarp (fruit skin) and fleshy mesocarp by hand and wash the small endocarp (pit) within. Immediately sow the endocarp-seeds, or air dry and store them in a refrigerator. The seeds remain viable for at least a year in storage.

Growing from Seed: Using Method One, seeds begin sprouting in 1-2 months. Interestingly, the seedling's cotyledons undergo little development, but instead, the first true leaves quickly appear and grow. Transfer the seedlings to individual pots after they produce their second pair of true leaves. Seedling growth is moderate, and you should have a 10-12 inch tall plant in 6-9 months. Seedlings are susceptible to infestations of sap-sucking insects such as aphids, mealybugs, and scale insects. Refer to Enemies in the Garden for treatments.

Growing from Cuttings: My propagation of aʻiaʻi by cuttings was a bit of an accident followed by some experimenting. One of my plants at home was getting too tall beneath the LED lights inside my air-conditioned condo, so I pruned it. Rather than throwing away the cuttings, I decided to try and root them.

After dipping the cuttings in DipN'Grow ®( 5x dilution), I placed them in moist vermiculite inside a large clear jar (i.e., a 2-inch layer of 100% vermiculite in the bottom of an empty peanut butter jar). I then sealed the jar with its top. Each day, I would look through the glass on the bottom and sides of the jar for developing roots. On average, it took 3-4 months for roots to become visible and spread over the bottom of the jar. I then removed the rooted cuttings and potted them up in a mix of 1:1:1, peat moss:vermiculite:perlite, and kept them in a larger semi-sealed clear box for about a week until I was convinced the roots had recovered from the transfer. After that, I removed them from the box and treated them like any other plant.

I have tried three or four media mixes other than 100% vermiculite (e.g., 1:1; vermiculite:perlite), and other methods (e.g., pots inside a large clear box), but nothing worked better than the 100% vermiculite inside a clear glass jar. I have yet to try rooting the cuttings using a misting chamber, so that might also work; I just don't know. Rooting was successful even with quite small cuttings (3-4 inches). Additionally, I have noticed that all the aʻiaʻi I have grown from cuttings have never grown as upright as plants I have propagated from seed.

Growth in the Garden: As stated in the Introduction, I have yet to keep an aʻiaʻi alive in the ground for more than a year despite numerous attempts. My failures were not the result of inadequate watering or any visible disease or pest. Rather, I think all the plants died because of some type of lethal pathogen in the soil at all my planting sites. My best evidence for this hypothesis is that I have been able to repeatedly keep potted aʻiaʻi alive for many years, both inside my home and outside (on raised benches inside a shadehouse). These in-ground deaths were a bit surprising given aʻiaʻi is indigenous to Hawai‘i; in my experience, indigenous species are more resilient than endemics. Please do not let my failures discourage you. Rather, I encourage you to try planting an aʻiaʻi in your garden at least once or twice. Hopefully, your garden's soil proves to be more friendly than mine.

In pots, aʻiaʻi grows at a slow to moderate pace of about one foot per year. (Obviously, you will need to repeatedly transfer your aʻiaʻi to larger and larger pots to maintain this growth.) Plants grown from cuttings will begin producing flowers and fruits within 1-2 years. Plants grown from seed take longer, normally three years or more. If you are lucky enough to have a plant with both male and female flowers, you will discover they are self-fertile (in my experience) and produce viable seeds. However, if you are unlucky, you will need to keep at least two plants to harvest viable seeds. Aʻiaʻi is an attractive houseplant when given sufficient light. Mine have done well under a mix of filtered sunlight (through curtains) and LED lighting.

Diseases & Pests: Both seedlings and mature plants are occasionally attacked by sap-sucking insects such as aphids, mealybugs, and scale insects. Refer to Enemies in the Garden for ways to eliminate these pests. Aʻiaʻi will sometimes drop all its leaves when newly-transplanted or water-stricken (i.e., the pot goes dry because you forgot to water). Do not panic, and just wait. Most often, the plant will recover and a new flush of leaves will appear within a couple of weeks. As noted above, I suspect an unknown soil pathogen is responsible for killing all the aʻiaʻi I have ever planted in the ground. If this happens to you, consider keeping your next aʻiaʻi in an elevated container.

Ā ā Ē ē Ī ī Ō ō Ū ū