By Karen Kucher
While the San Diego Zoo and Safari Park are best known for rare and endangered animals such as giant pandas, koalas and California condors, all that green and flowering stuff found around the parks’ combined 1,900 acres also has won accolades.
The most recent honor came last month, when San Diego Zoo Wildlife Alliance won a prestigious Garden Excellence Award from the American Public Gardens Association.
The two parks earlier were designated accredited botanic gardens by Botanic Gardens Conservation International, while last year they were named Level 4 arboretums in recognition of the organization’s tree conservation efforts.
Zoo officials say the excellence award recognizes the organization’s commitment to safeguarding biodiversity and rewards the vital work of those who take care of the parks’ plants.
“We’re just trying to get the message out there a little bit,” said Adam Graves, director of horticulture at the zoo. “We do plant conservation work all over the world, we do a lot of plant conservation work here in our backyard.”
The zoo not only maintains a diverse array of plants but has established a Native Plant Gene Bank, which includes collections of preserved seeds from the region. It also conducts research into plant micropropogation and cryopreservation.
Between the two parks, there are about 80 to 90 people dedicated to horticulture. The teams include irrigation technicians, arborists, area horticulturists who maintain landscapes, propagators who create new plants, and workers who specialize in growing “browse,” or plants used as food for zoo animals, like bamboo for the pandas.
On a recent morning, several members of the zoo’s horticulture team highlighted some of the rare and endangered plants at its 100-acre Balboa Park location. First up were cycads, small stumpy trees in the zoo’s Africa Rocks area. The collection includes a descendant of the only known wild Wood’s cycad, which was removed from southern Africa in 1916.
Horticulture staff explained that natural reproduction of the species is impossible because the only specimen found was male, which can make pollen. But no females have been located, so no seeds exist. As a result, it is sometimes called “the loneliest plant in the world.”
“That original plant was salvaged and taken to a botanic garden at that point, and then they were able to reproduce it through offset, and share it with other botanic gardens,” Graves explained. “Every individual specimen of this plant you see anywhere in the world is now a genetic clone of that one last plant that was alive.”
Graves said the plant serves as a kind of cautionary tale. “This is a last-ditch effort to prevent something from going extinct,” he said. “Botanic gardens all over the world have clones of these now, and there’s only so much we can do to actually put it back in the wild because there are no females left.”
In contrast, he said, is the more hopeful story of an Albany cycad, a critically endangered species estimated to be 400 to 500 years old. The plant came to the U.S. in the 1960s and has been in the Africa Rocks habitat since 2017.
“It didn’t really do anything for a couple of years, and we were starting to really panic and seeing if it would make it through the plantings and transition,” senior horticulturalist Michael Diaz said.
The plant eventually produced a pollen cone, which is used in reproduction. But horticulturalists remained a little worried.
“When it finally produced the cone, we thought this might be the death rattle,” Diaz said. “And then it finally produced new growth.”
Christian Barnard, a senior horticulturist, said he gave the plant “a deep soak” after seeing new green leaves emerge about a week ago. “The leaves last week were half the size,” he said.
Graves said there are about 60 of the Albany cycads left in the wild, which he said is thought to be enough to keep a viable population.
“One of the real big reasons why we have botanic gardens is so you can keep plants like this alive, we can do genetic studies, which is currently being done, to see where this falls in the overall populations of all the ones that we know about,” he said. “And from there, we are able to share pollen, share genetic material” to help manage the species.
Plant lovers have several options when it comes to learning more about the zoo’s horticulture.
Zoo visitors can get botanical tour pamphlets near the ticket booth or online, which are filled with colorful pictures and plant facts. Each can assist with self-guided explorations of Fern Canyon, Elephant Odyssey, Australian Outback and highlight where specific types of plants can be found.
On special “plant days” each month, guests are invited to visit the Orchid House, which is celebrating its 50th anniversary. The zoo has around 1,500 individual orchids in its collection, the majority in the Orchid House, said Christy Powell, horticulture manager.
The Orchid House is open the third Friday of every month and recently attracted a record 972 visitors. Plant sales and special botanical bus tours are also offered on those days.
Visitors interested in growing orchids might get advice from Heinfried Block, an orchid specialist and senior plant propagator, who has been growing orchids since he was 10 years old. He hand-pollinates the orchids, takes the seed pods once they mature and puts them in a Jello-like substance that gives the plant everything it needs to grow.
For his part, Block has twice traveled to Palau since 2022 with other zoo staffers, helping teach students and local residents on the western Pacific Ocean island how to grow and care for native and endemic orchids.
Safari Park and the zoo both serve as government-approved plant rescue facilities, meaning they can take in confiscated plants when people unknowingly transport ones that require permits or when specimens are illegally smuggled into the U.S.
The specimens that smugglers choose vary greatly. In 2022, Safari Park accepted 881 pounds of succulents that were seized at Los Angeles International Airport. Some now live at the zoo, in the dry area of its nursery. In June, the zoo took in some orchids native to Thailand that were seized in Hawaii.
Other plants wind up at the zoo for protection. That’s the case of some Hawaiian palms sent to San Diego because they are being decimated in the wild by an invasive bug. “We’re establishing a safe site here because we don’t have the coconut rhinoceros beetle (and) we can grow them because of our climate,” Graves said.