QUESTION: What are those gorgeous silvery trees found on some streets and in parks? Some are at Sandy Beach, some giant ones are on Paalea Street in Palolo Valley, and some are at Ala Moana Beach Park. Please inform us about these. Mahalo. — Max Silva, Palolo
ANSWER: Silver buttonwood trees! Aka sea mulberry or button mangrove. Conocarpus erectus is the Latin name. They grow naturally in mangrove swamps and are in the Combretaceae plant family. They have a very interesting horticultural history that I am happy to share.
As you may know they are very wind-resistant, xeric (drought-tolerant) and salt-tolerant. The bark and gnarled trunks are very attractive, especially as the trees mature. You can make lovely lei with them. Keiki can make a fun lei using masking tape and the leaves — easy and gorgeous!
At Lei Day in Kapiolani Park this year we saw some fab lei, using various parts of silver buttonwood trees. Some used the fruit clusters, some used the leaves, some crafted the leaves into silver “rose” buds and so on.
(A HUGE mahalo to all the dedicated city Department of Parks and Recreation and Honolulu Botanical Gardens employees and volunteers, who organized and coordinated that major free, public event in the park.)
Our late mentor Paul Weissich had just become director of the Honolulu Botanical Gardens in 1957 when he was reviewing all of the interesting plants growing in the nursery and lath houses at Foster Botanical Garden.
Weissich found a flat of seedlings. Some were green and some were silvery. One keiki plant was super silvery.
He selected the most silver of the lot and had them potted into larger individual pots. The best, consistently silver one was selected and more were propagated from air layers. He watched over them and had the expert plant propagators nurture and grow them. This is a prime example of horticultural selection.
He planted a bunch of them at Ala Moana Beach Park, which was an adjunct botanical garden back in those days (and still has his legacy of tough, salt-tolerant, interesting and rare trees).
A mixed silver-and-green hedge of them is still growing today around the tennis courts at McCoy Pavilion.
One of the most silver trees was planted at Foster Botanical Garden. The gnarled, sprawling tree has a growth habit similar to an ancient gnarled olive tree. We have been talking about making this an Exceptional Tree, a state designation that would protect the tree from improper trimming and unnecessary removal.
Over the years more of the silvery trees were grown and planted in beach parks like Sandy and as shady street trees in Oahu neighborhoods. They make a tough specimen tree (especially nice when lighted up with solar lights for a moonlight garden), a good hedge or windbreak.
Buttonwoods are native to a broad area spanning from the Caribbean coastal tropics all the way to west Africa.
This is one of the many horticultural legacies of Weissich who passed away this year at age 93. He really grew our beautiful and amazing botanic gardens here on Oahu. His legacy includes our five Honolulu botanical gardens: Foster, Lili‘uokalani, Wahiawa, Koko Crater and Ho‘omaluhia, as well as people like me and my husband, Clark, whose careers and lives he nurtured, just like that flat of keiki silver buttonwood trees all those years ago.
Heidi Bornhorst is a sustainable landscape consultant specializing in native, xeric and edible gardens. Reach her at heidibornhorst@gmail.com.
