Puu Mahoe literally means "the hill of twins," but it is so much more. Puu Mahoe is a cinder cone on the eastern flank of Haleakala. You have to go through three locked ranch gates to get there. It’s worth the trip.

D.T. Fleming Arboretum at Puu Mahoe is the largest and oldest arboretum in Hawaii dedicated to native Hawaiian trees and plants. Its 2,600-foot elevation is a plus for nurturing rare Hawaiian plants.

The garden won Scenic Hawaii Inc.’s 2011 Legacy Award and the Community Gardens Award at the all-volunteer group’s ninth annual Betty Crocker Landscape Awards last month.

Tutu kane (grandfather) David Thomas "D.T." Fleming was an agronomist. He solved a major weed problem for Ulupalakua Ranch using bio-control. In gratitude the ranch offered him his choice of land. He looked, searched and chose Puu Mahoe.

Stunning views from the sweeping site are of the Auwahi dry-land forest preserve, eastern Maui, Molokini, Kahoolawe and Lanai. Puu Mahoe crater is a unique kipuka of botanical diversity. Rare and unusual plants grow well, flower and set seed here. They have seven of Maui’s "exceptional trees" — the only native species on the list: alaa, ohe, alani and loulu.

The botanic garden began in 1952, planted largely with native trees back when few thought they were of any value. Records were meticulously kept, as that’s what scientists like Fleming do. His legacy continues to grow.

The Friends of the Fleming Arboretum has really helped the garden flourish. As Martha Vockrodt Moran, Fleming’s granddaughter, says, "It’s not me, Heidi. In 2000, I, an artist with no money, was looking at a property with old infrastructure and a museum of trees that were going extinct. The arboretum soared once it became a nonprofit." Huge support comes from plant scientists, schools, artists and people who cherish and malama native Hawaiian plants.

James Fleming, grandson of D.T. Fleming, and wife Joanie accepted the award on behalf of the arboretum.

I first visited Fleming Arboretum with a group from Kaulunani (an urban forest support group) in 2007. We had given the garden a grant for botanical signage, and we planted a memorial mamane tree for our friend, forester Patrick Costales.

The arboretum has long been the "secret botanical garden" of Maui people who cherish and perpetuate native Hawaiian and historical Maui introduced plants. They keep good botanical and historical records and are extremely generous and hospitable to garden visitors. It is a place to learn how to grow and perpetuate native plants.

Regular monthly tours and volunteer workdays engage residents and visitors in the preservation of our cultural and natural resources. The Fleming Arboretum is a major conservation and education resource for Hawaii, also serving as a seed bank for Maui dry-land forest species and supporting reforestation efforts that nurture Maui’s watershed and native habitat.

For more information, visit www.flemingarboretum.org.

Heidi Leianuenue Bornhorst is a sustainable landscape consultant specializing in native, xeric and edible gardens. Email her at heidib@hawaii.rr.com.