If you look up Gouania vitifolia in the first edition of Wagner et al. (1990), they state:
Joel Lau, a friend of mine, loves these challenges. So, in January 2001, he asked his friends, Amy Tsuneyoshi and Jeff Preble, to go with him on a hike into Kea‘au Valley in search of Degener’s “verge of extinction” Gouania vitifolia. While the valley still harbors a significant population of wiliwili, ‘a‘ali‘i and other native plants, many areas are dominated by alien guinea grass, koa haole and kiawe. After several hours of searching and stumbling over the rocky landscape hidden by alien grasses, the group was just about to turn around and call it quits when Amy noticed an odd-looking vine entwined around a straggly koa haole. It wasn’t one of the alien Passiflora common in these alien-dominated dry shrublands, so, she asked Joel to take a look. As soon as he saw the plant he knew, Amy had rediscovered a Gouania vitifolia. Later hikes by Joel and others revealed other G. vitifolia still alive in the valley.
Today, the State’s PEP (Protect Endangered Plants) team and the US Army O‘ahu Natural Resources Program have begun stewardship of this small population of about 50 plants. It’s a tough job because the plants face numerous threats. In addition to the ever-present threat of a brushfire destroying the population, there are also the feral pigs, goats and cattle that roam the valley. Fencing by the Army will help, as will the collection and storage of seed from each of the plants. And, more good news, Gouania vitifolia was also recently rediscovered in the forests of South Kona, Hawai‘i.
Habitat & Appearance: Gouania vitifolia lives in dry grassland, shrubland and forest but has also been found in mesic forest. Technically a climbing shrub not a vine, G. vitifolia has strong pliable branches and tendrils that wined around and firmly attach it to any nearby tree or shrub. As the name implies, the leaves are similar in appearance to those of grapes. These are shed during dry periods, leaving the bare branches difficult to identify in the field. The white flowers are tiny but numerous, clustered on inflorescences. The dry fruits are larger (10 mm) with 2-3 wings, yellow-green when immature and brown or black when ripe.
Gouania vitifolia in Hawaiian Culture: I could find no mention of this plant in Hawaiian literature; not surprising since we do not know its Hawaiian name. Given the strength and pliability of its branches, it would not surprise me if someone discovered it was used for cordage in ancient times.
Collecting Seeds: The flowering and fruiting of Gouania vitifolia appears to depend on both moisture and sunlight. With sufficient moisture, plants growing in full sun retain their leaves and flower and fruit repeatedly throughout the year. During dry periods the plants drop their leaves and do not flower. Oddly, I have never seen flowering of a plant growing in constant shade. Collect the fruits only when they are completely dry and brown or black. Inside the fruit are 2-3 black seeds, each in its own chamber. Removing the seeds from their chambers is a challenge requiring some patience and a nailclipper or small scissors; be careful not to damage the seed with your cutting tool. Often the embryo within the seed is undeveloped and nonviable, a condition likely caused by non-pollination or inbreeding. (I have collected dozens of fruits from some plants, none of which, held viable seed.) Check for good seed by placing the seed in water; a viable seed will sink, a nonviable seed will float.
Growing from Seed: Soak the seeds 1-2 days in a shallow pan of tapwater, then, scar each with a nailclipper or sandpaper. The seeds are small so be careful not to damage the embryo inside. Using Method One, the seeds will begin sprouting in a week and continue for a couple more. Transfer the seedlings to individual pots when they have 1-2 true leaves. The seedlings grow quickly and will benefit from either slow-release or foliar fertilizer. In a couple of months, the plants should be 6-12 inches tall/long and ready for planting in your garden.
Growing from Cuttings: Gouania vitafolia can also be propagated via cuttings. Follow the directions for cuttings using Method Two (mist chamber).
Growth in the Garden: Gouania vitifolia grow quickly if planted in full sun and watered just enough to avoid leaf loss; given their natural habitat, avoid overwatering. Within a few months, you should have one or more branches 3-4 feet in length. When planted in shade the plant grows more slowly. I have never fertilized my G. vitifolia. As mentioned above, if you plant your G. vitifolia in sun, you should expect flowering and fruiting within the year. Of course, whether any of the resulting seed will be viable is the big question. G. vitifolia likes to climb. So, plant it near a tree, fence or trellis. (Once they get growing, they really do look like grape vines.) Unlike the alien banana poke or the native kūpala (Sicyos pachycarpus), G. vitifolia appears to be a relatively benign climber. I have had plants grow into and over kauila, koai‘a and hao without harm; undoubtedly, they decrease the sunlight coming to the trees and, likely, slow their growth but all the host trees have remained healthy and growing.
Diseases & Pests: When still small, I have had to treat the plants for scale insects and mealbugs. The only pest I’ve seen on larger plants is a single case of whitefly infestation. I treated this several times with horticultural oil and a systemic pesticide and the flies eventually disappeared.
Ā ā Ē ē Ī ī Ō ō Ū ū