Wednesday was Mary Foster Day, proclaimed by Mayor Mufi Hannemann, and a new hibiscus has been named in her honor (Hibiscus kokio subsp. saintjohnianus Mary Foster). On Sunday, the Friends of Honolulu Botanical Gardens will hold the Mary Foster Birthday Festival.

Who was Mary Foster, and why should we celebrate her birthday now?

Mary Mikihala Robinson Foster's Honolulu garden — what is now Foster Garden — is the ultimate friendship garden. What a gift this garden is to the people of Hawai'i and gardeners around the world. So many Hawai'i people have never visited Foster garden, or haven't been since small-kid time. Lots of people don't even know where this tree-filled urban garden is (it's on the corner of Vineyard and Nu'uanu). You see the big trees as you drive along the freeway, town-bound, before the Pali exit.

Some people think I knew Foster personally, but, eh, I'm not that old! — she was born in 1844, and died in 1930. I wish I could have talked to her about her wonderful trees and plants and her vision of this garden for all of us. But in a way I do know her — through her garden. A garden says a lot about the person who creates it.

I know she liked big trees. One mo'olelo is that she wanted Foster Garden maintained as a botanic garden in perpetuity because she saw her late husband Capt. Thomas Foster galloping his horse through the grounds. I always picture the horse as a big rangy bay, with wild eyes, slowing down to a calm walk beneath the big trees. There is a certain old kine lamppost that we were told had to stay there in the garden. Maybe that's where they would meet ...

Giant lumbering Galápagos tortoises used to make their way amid the tropical terraced trails, with a niece or nephew of Mrs. Foster on their wide, smooth backs. The tortoises were a gift, like many of the plants, from visiting sea adventurers. When Mary Foster passed away the Galápagos tortoises went to the zoo.

The quintessential Mary Foster tree is her Bodhi tree. Interested in Buddhism, Foster donated money to the Ceylonese Maha Bodhi Society, helping to fund the construction of the Foster-Robinson Hospital in Colombo, Sri Lanka. In 1913, Buddhist devotee and Sri Lankan hero Anagarika Dharmapala gave her a bo tree, propagated from an ancient tree at Sri Lanka's temple at Anuradhapura, which in turn was planted from a piece of the very tree in India under which Buddha sat.

Propagules of this Ficus religiosa tree have been shared with other gardens around Hawai'i. The bo tree greets you right as you climb the stairs to Foster garden.

During Foster's time, being a Buddhist in Hawai'i was scandalous. According to one story, Mary Foster had an "anger management problem" (that's what they'd call it today). Now why would a hapa-Hawaiian lady, a woman of color, be mad about anything in Hawai'i before the 1930s?

She was a friend and confidant of our deposed Queen Lili'uokalani. Liliu also was a lover of gardens. She gave us the adjoining mauka section of the garden, which is now bisected by the freeway. Called Lili'uokalani Botanic Garden, it is home to Waikahalulu falls, a favorite picnic site of the queen's.

We invite people to celebrate Mary Foster's birthday. Her hau'oli la hanau pa'ina starts at 9 a.m. on Sunday in Foster Garden.

Mahalo nui loa, Mary Foster, we love and pay tribute to you and your green gift.

Heidi Bornhorst is a sustainable landscape consultant.