The Harold L. Lyon Arboretum is located in a zone of tropical rainforest with an annual rainfall average of 13 feet (4 meters). The site lies in the ili (land division) of Haukulu and `Aihualama, in Mānoa valley, on the island of O`ahu. Several man-made features, including stone platforms, lo`i and the occurrence of many Polynesian-introduced plants attest to the importance of the site. Alteration of the forest by early Hawaiian farmers was followed by post-contact agriculture, and free-ranging cattle that grazed their way up the valley. By the early 1900’s native forest had been heavily impacted in Mānoa and in other watersheds throughout the Hawaiian Islands. Without healthy forest cover, rainwater flowed to the ocean rather than recharging the ground water table, Hawaii’s primary source of potable water. This loss was of special concern to the Hawaiian Sugar Planters’ Association (HSPA) because sugar required great quantities of water. Dr. Harold Lyon, a plant pathologist hired by HSPA, concluded that healthy forests should be preserved, that heavily damaged native forests could not recover on their own, and that damaged watersheds could be restored with introduced plants.
In 1919, HSPA purchased 124 acres in upper Mānoa to serve as a test site to evaluate trees that could be used for reforestation throughout the islands, and to test sugarcane seedlings. The test site became the basis of the Manoa Arboretum. Planting began in 1920, and was essentially completed by 1945. In the late 1940’s HSPA had achieved their reforestation research objectives and no longer needed the site. Dr. Lyon strongly believed that Hawai‘i needed a botanical garden and saw this as an opportunity for the state of Hawai`i. In 1953 the Board of Regents of the University of Hawai‘i accepted the land from HSPA for fee of $1.00. The deed stipulated that the University “…use, maintain and preserve the granted premises as an arboretum and botanical garden only.” Lyon used his own money to fund Arboretum operations. When Dr. Lyon died in 1957, he left part of his estate in trust, to help fund the Arboretum in perpetuity. Seven days later, the University of Hawai`i Board of Regents renamed the Manoa Arboretum the Harold L. Lyon Arboretum. A plaque located along the main trail commemorates the many contributions of Dr. Lyon.
In the 1960’s collections were assembled, trees inventoried, and the main greenhouse was built. Until 1972 the Arboretum served as a research station, and was closed to the public. In 1972 the idea for a community support/fundraising group arose, resulting in the formation of the Lyon Arboretum Association (aka Friends of Lyon Arboretum). Lyon Arboretum staff and volunteers established education and outreach programs, which were later expanded to include adult education, children’s education, internships and a guides program. These programs have been a major factor in bringing the public to the Arboretum. Plant sales added to revenues, and events brought more people to enjoy the Arboretum. Groups of volunteers helped maintain the grounds, made crafts, lei, jams and jellies, and helped in the book and gift shop. Various theme gardens were established: including the Beatrice Krauss Hawaiian Ethnobotany Garden, the Herb Garden, Economic Section, Palm Section, and the Hawaiian Garden.
Researchers from around the world have taken advantage of the large living collections, particularly palms, heliconias, gingers, ethnobotanical and native Hawaiian plants. Other researchers have studied stream life, birds, insects, climate, soils and hydrology. Horticulturists at Lyon have developed new varieties of rhododendron, gingers, calathea, hibiscus, and alocasia. The Arboretum has evaluated and released over 180 plant introductions to nurseries and the public.
In the early 1990’s the horticulture aspect was expanded to include micropropagation of rare & endangered Hawaiian plants, and native forest restoration began. This tremendously important Hawai`i Rare Plant Program has greatly expanded and is leader in the field of plant conservation. Several University of Hawai‘i departments utilize the garden for research or instruction. High school and college groups, Community service groups, corporate groups, and others have participated in large service projects that help maintain the Arboretum while providing opportunities for learning and community service. In recent years an annual average of 1,500 adults attend the Arboretum’s adult classes; and over 10,000 schoolchildren and teachers visit on field trips using STEM curriculum developed specifically for the Arboretum. Lyon Arboretum’s trained docents guide an annual average of 1,500 visitors on garden tours. Recently several ancient Hawaiian lo`i (taro growing field) were reopened, and a new Hale Halawai (traditional Hawaiian meeting house) was built. Wood harvested from the grounds have been used to create traditional canoes, tools and other educational and cultural resources and many classes that perpetuate cultural knowledge are offered.
Throughout its history Lyon Arboretum has worked to bring beauty, knowledge and an appreciation of and respect for nature to its many audiences. The Arboretum is a gem, an important resource for both the University of Hawai‘i and the community at large. Harold Lyon’s 1956 words from his “Honolulu Can Have a Botanical Garden” article still ring true: “Here then is a golden opportunity to build in upper Mānoa Valley, a vast botanical garden of native and introduced plants and at the same time carry through a project in water conservation that would prove of immense value to Honolulu.”