The right tree for the right place: this is horticulturalist Richard Criley’s focus. Both the location—away from utility lines, not too close to a sidewalk or drainage lines, positioned to provide shade where needed or to enhance a landscape with its beauty—and the tree choice itself—size, canopy density, flowering, fruiting, amenability to pruning—can influence the decision to plant a tree, and which tree to plant. Some of the most appropriate, and loveliest, of the available trees are rarely planted, however. Hawai‘i’s landscape architects tend to select from the same relatively small group, explains Dr. Criley, emeritus professor in the department of Tropical Plant and Soil Sciences, because these have worked for them in the past. Adventuring into new trees is often frowned upon by landscape firms, in case they may not work out and the firms are blamed.
There are many reasons to choose alternate trees, however. One is the growing interest in utilizing native plants, which not only may have cultural significance but tend to be better suited to the climate and other conditions than imports, requiring less water, fertilizers, and pest-control measures. Another important reason to diversify has been the impact of invasive insects on popular trees. For instance, the Islands have been affected by the monkeypod defoliator, lobate lac scale, Erythrina gall wasp, and a similar pest affecting Chinese banyans. When a common type of tree has to be removed due to insect damage, it’s noticeable in a landscape without a wide variety. Most recently, the rhinoceros beetle that attacks coconut palms has become a concern. Hawai‘i is fortunate that coconut yellowing, which has decimated coconut palms across the southern part of Texas and Florida, has not yet been found in the state, as it would hugely impact the landscape and would also affect the native loulu palms.
For these reasons, Dr. Criley initiated a project to identify tree species that could be used to diversify local landscapes. He and his collaborators have developed more than twenty information resources, available through CTAHR’s free publications, to help landscape architects and homeowners choose alternatives to some of the most commonly planted trees. These include the gorgeously flowering Colvillea racemosa, the fragrantly scented lechoso, and look-alike alternatives to popular choices, such as the native alahe‘e rather than the imported mock orange. With such a range to choose from, consider planting a new tree today!
