Around half-mile beyond mile marker 16 on the Hana Highway you'll see a sign on the mauka side of the road marking the entrance to Ke'anae Arboretum. The arboretum is large with a paved parking lot makai after the sign.
Because of the sloped curve in the road, be careful crossing the street from the parking area to the arboretum. The Ke'anae Arboretum lies alongside the Pi'ina'au Stream on leveled terraces built hundreds of years ago by Hawaiians for growing taro, a mainstay of their diet. A 0.6 mile paved walkway takes visitors through timber, fruit, and ornamental trees from tropical regions around the world, many of which are marked with name plates. Inside the arboretum you can find some 150 varieties of tropical plants (including taro). This is a great location to see some indigenous flowers and the painted bark eucalyptus trees.
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An upper section of the arboretum features plants cultivated by the Hawaiians for food and other uses. This arboretum appears to have undergone a major renovation as of our last visit. The renovation included an expansion on the previous path that now leads into beautiful small taro fields not previously located in the arboretum. There are no facilities or amenities at this stop. Expect to spend 30 minutes to an hour here.