January 2021

by Tony Gurnoe, Director of Conservation Horticulture

San Diego Botanic Garden has a distinctive position in not only working to conserve endangered plants where they grow naturally, but also bringing those rare species into a managed setting which enables a deeper level of study, better community engagement without compromising preservation, and for us to highlight the unique beauty such rare plants bring to a garden.

Our recent endeavor to conserve the endangered Encinitas BaccharisBaccharis vanessae, exemplifies each of these botanical contributions. Two years ago, Encinitas was down to 26 remaining plants of this rare species and they were progressing toward extirpation. Today SDBG has a back-up population of more than 60 individuals (planted here at the Garden), with many of these plants featured prominently along the trail in our natural area. We have also distributed plants to botanical gardens around the state as additional safeguards.

In 2019, SDBG staff set out to survey and monitor Baccharis vanessae at the small Oak Crest Park population. We were alarmed to find only 26 left, with less than a dozen female plants remaining. After close mapping and monitoring of these rare plants, we collected seed separated along maternal lines to capture the best genetic representation possible before more plants disappeared.

Collecting these seeds was done as part of broader conservation strategies for endangered native plant species. The collecting protocols the Garden follows were established by the Center for Plant Conservation, and seed collection was done on behalf of the California Plant Rescue program as part of the California Biodiversity Initiative. Thanks to both the California Department of Fish & Wildlife and the City of Encinitas, this work was permitted. All this intensive coordination and partnering among these organizations is critical not only to make the most of extremely limited funds available for this work, but also to ensure that any collecting done is ecologically sensitive and appropriate.

Most of the seeds collected were put into duplicate seed banks in different parts of the country for long-term conservation storage. However, the Garden did grow a nice batch to plant as living backup. Throughout 2020 we anxiously watched as dozens of young Baccharis vanessae emerged first as seedlings then ultimately flourished into flowering adults in our nursery. Suddenly the prospect of this species disappearing completely from Encinitas was a notion drifting farther away as each flower bud emerged.

In November of 2020, Rachel Sadowski, SDBG’s Conservation Horticulturist, and I planted more than 60 Encinitas Baccharis within the Garden. While we would have been happy to plant even more, several of our partnering institutions in this work interjected with requests to add plants to their own botanical collections.

Within just two years, a little known species in our own backyard went from being on the verge of disappearing to now having safeguards and backups around the country, and an elevated position within the botanical collection and public exhibits at San Diego Botanic Garden!

This is certainly not the end of this plant conservation story. Not only do we need to continue to closely monitor existing populations, but we also need to continue to survey for new occurrences and to reinforce those that remain with outplanting projects. Fortunately, that work is much less dire and urgent thanks to our recent successes.

If you consider that California has more than 6,500 plant taxa, with more than 2,000 of them being rare, you’ll start to get a sense of the scale of the work before us and why we’re so grateful to each of our members and partners here at SDBG. Botanical gardens clearly have an important and direct role in preventing plant extinctions, but we couldn’t do any of this without your ongoing support.