Dr. Harold Lloyd Lyon was born and raised in Minnesota. He attended the University of Minnesota and received his Doctoral degree in 1902. In 1907, he moved to Hawai'i to work for Hawaiian Sugar Planters' Association (HSPA). In 1919, a pie-shaped region consisting of 124 acres was purchased by the HSPA from Fred Harrison. The property, called Haukulu, had once belonged to Charles Kana'ina, father of King William Lunalilo. Harrison had built a large house and stables, which he used as his country home. Its location was where the rain shelter is situated at the present-day Arboretum, halfway into the "tour area." A cobbled lane led to Harrison's home. Up beyond the old Harrison house was a seismograph station. The Yazawa family lived for a time at the Harrison house before it was torn down in the early 1930s.
He was the plant pathologist for the HSPA, had been placed in charge of a newly created Department of Botany and Forestation for the Territory of Hawai'i. After the purchase of the upper valley Manoa lands, he went to the two neighboring landowners, Bishop Estate and the Territory, to arouse interest in the HSPA water conservation project. The governor at that time was George R. Carter, who had a summer house in the area and was very supportive of the project. For a nominal fee, both parties leased to HSPA more than 325 adjoining acres. Consequently, once the reforestation project commenced, rows of trees were planted above Manoa as far as Pauoa Flats. This large area was to be used not only as a plant introduction site for reforestation, but also for trial plots of sugar cane. Thousands of species of exotic trees, shrubs and vines were introduced.
In 1922, he became the head of the hundred twenty-four acre tree experimental station in Manoa. Dr. Lyon noticed that native plants could not grow in the soil that was trampled on by cattle. For approximately thirty years, he experimented with many different introduced plants to find ones that were suitable for reforestation. The goal of HSPA, of finding trees suitable to build a watershed, was achieved.
By the 1940s, sugar cane cultivation was being phased out of Manoa. This upland area had been used experimentally to simulate the growing conditions of the Hamakua Coast on the island of Hawai'i. For the next experiment, ti was planted, replacing sugar cane. The new plant was rich in fructose, and it was hoped that it could be grown for the commercial purposes. However, because of this plant's slow growth rate, the venture was abandoned. When HSPA had achieved their goals, they no longer needed the land in Manoa.
The Arboretum, with 193 acres, was obtained by the University as a gift from the HSPA on July 1, 1953 under the condition that U.H., "maintain and preserve the granted premises as an arboretum and botanical garden only". This means that the arboretum is to be used for research, education, and public service.
When he died in 1957, the arboretum was renamed in his honor. The directors have been: Dr. Harold L. Lyon, Dr. Harold St. John, Dr. Horace Clay, Dr. George W. Gillett, Dr. Yoneo Sagawa, Dr. Charles Lamoureux, Dr. Alan Teramura, Dr. Charles Hayes, Dr. Gerald Carr, Dr. Clifford Morden, and at present, Dr. Christopher Dunn.