Mates for a Rare Manzanita Offer Hope for Its Future

The blossoms of the Raven's manzanita must be pollinated by another plant in order to produce berries and seeds. NPS / Michael Chasse

January 2018 - Two of the rarest plants in the world grow in San Francisco. The Franciscan manzanita (Arctostaphylos franciscana) and Raven's manzanita (Arctostaphylos montana subsp. ravenii) are unique to the city, known only from the stretch of hills between Mount Davidson and the Presidio. Once locally abundant, each species is now reduced to one genetic individual in the wild. They have been called the "loneliest" plants, the last of their kind in the wild. Both are protected as endangered species.

The Franciscan manzanita was actually considered extinct in the wild for seven decades until a single plant was discovered in the Presidio in 2009. The plant was saved and is now protected but, like the Raven's manzanita, it cannot reproduce without "mates" (i.e., other individuals of its species with which it can cross-pollinate and produce seeds). To ensure a viable future for these rare manzanitas, the National Park Service and Golden Gate National Parks Conservancy have partnered with local botanical gardens to embark on a conservation "matchmaking" project.

Last year, the Presidio Nursery worked with the UC Berkeley, East Bay Regional Parks, and San Francisco botanical gardens to grow plants from their collection of original Franciscan manzanitas, saved from other areas of San Francisco prior to urban development. These plants represent the "perfect mates" for our lonely manzanitas in the Presidio: the same species, but different genetic individuals. Over the past week, these plants were planted by park staff into areas designated as critical habitat for the species. In a few years, the plants will be mature enough to produce flowers and, after pollinator visits, berries that resemble little apples (hence the name manzanita). Inside those berries will be the seeds that represent future generations of this rare species. To learn more contact Michael Chasse.

Where this belongs

• Golden Gate National Recreation Area
• Presidio of San Francisco

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