Harold Lyon, botanist for the Hawaiian Sugar Planters' Association, established this 200-acre tropical garden at the head of Manoa Valley in 1918, and the arboretum entrance in front of you opens onto one of Honolulu's great natural treasures. The arboretum was established in 1918 by Harold Lyon, the botanist for the Hawaiian Sugar Planters' Association, on land that had been used for sugarcane cultivation. Lyon's original purpose was watershed conservation: he planted trees on the denuded upper slopes of Manoa Valley to restore the forest cover that captures rainfall and replenishes the aquifers that supply Honolulu's water.
The work he began continues today: the arboretum now protects more than five thousand tropical plant species from around the Pacific, and it houses one of the most important collections of native Hawaiian plants in existence. The ethnobotany collection — plants that Native Hawaiians used for food, medicine, fiber, and ceremony — is of particular significance, as it preserves knowledge and genetic material that might otherwise be lost forever. Walking the arboretum's trails, you move through ecosystems from across the tropical Pacific, all contained in a valley that receives over 150 inches of rainfall per year and seems to grow everything with effortless abundance.