Rare Plants 3

Saturday, October 22 at 1:00-2:40 pm, Donner Room

*note alternate instances of this session – Friday at 3pm and Saturday at 10am

Session Description: Rare plants make up one-third of California’s native flora. They encompass nearly every habitat type and elevation range, are beautiful, and are important contributors to pollinators, ecosystem functions, and the rich biodiversity of the state. While great progress has been made at broader levels—families and genera—the California flora is still far from being understood at the species-level and it’s expected that hundreds of taxa have gone unnoticed by taxonomists; most of these will have narrow ranges and thus be more vulnerable to human impacts. Powerful tools are now available to describe and understand plant diversity in California, including a host of reduced representation sequencing methods, to understand fine-scale diversity and evolution.

Session Chairs: Aaron E. Sims (California Native Plant Society, Sacramento, CA, USA) and Israel Borokini (University and Jepson Herbaria, University of California, Berkeley, Berkeley, CA, USA)

*Session generously sponsored by Nomad Ecology, LLC

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41.1    California Native Plant Society unveils the most powerful rebuild of its flagship product: the Rare Plant Inventory

John Donoghue (John Donoghue Consulting, Redlands, CA, USA), Aaron E. Sims (California Native Plant Society, Sacramento, CA, USA)

For nearly 50 years the California Native Plant Society’s Rare Plant Inventory (RPI) has provided current, accurate information on the distribution, ecology, and conservation status of California’s rare and endangered plants. Today, CNPS continues its legacy of setting the standard for guiding rare plant conservation, protection, education, planning, and land management by developing a new and advanced RPI platform. The new platform merges back-end data maintenance and front-end data search and exploration into a single web-based interface. It’s built on leading technologies and includes a completely redesigned database that stores both tabular and spatial data. The platform also provides a foundation for future RPI enhancements as well as potential integrations with other CNPS datasets. Updates and changes are made live for immediate use in searches to help inform conservation priorities. For the first time, dedicated volunteers can add photos and perform data updates via user accounts with varying access permissions to make the RPI as up to date as possible. To advance rare plant conservation, the site now includes an “Other Status” section with additional conservation status information and details on seeds banked as part of the California Plant Rescue initiative. Additional features include newly integrated web pages where CNPS Status Review and potential Species of Conservation Concern publications can be downloaded, selected references as downloadable content within plant detail pages, links to the Jepson eFlora, and a Core Report where select users can identify and advance conservation priorities. Future versions of the RPI will include geographic-based searches, microhabitat, and threat searches, and summaries of documented threats for the rarest plant taxa. The new RPI was developed with support from the state of California, Center for Plant Conservation, the California Plant Rescue initiative, corporate sponsors, CNPS memberships, and continued donations.

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41.2    Stronger together: A collaborative effort to conserve and recover 14 listed plants on the Channel Islands

Heather E. Schneider (Santa Barbara Botanic Garden, Santa Barbara, CA, USA), John Knapp (The Nature Conservancy, Ventura, CA, USA), Kathryn McEachern (US Geological Survey, Ventura, CA, USA), Morgan Ball (Wildlands Conservation Science, Lompoc, CA, USA), Sean Carson (Santa Barbara Botanic Garden, Santa Barbara, CA, USA), Katy Carter (California Institute for Environmental Studies, Ventura, CA, USA), C. Matt Guilliams (Santa Barbara Botanic Garden, Santa Barbara, CA, USA), William Hoyer (Naval Base Ventura County, Point Mugu, CA, USA), Seth Kauppinen (Santa Barbara Botanic Garden, Santa Barbara, CA, USA), Denise Knapp (Santa Barbara Botanic Garden, Santa Barbara, CA, USA), Kristen Lehman (Santa Barbara Botanic Garden, Santa Barbara, CA, USA), Annie Little (Channel Islands National Park, Ventura, CA, USA), David Mazurkiewicz (Channel Islands National Park, Ventura, CA, USA), Ken Niessen (U.S. Fish and Wildlife Service, Ventura, CA, USA), Katrina Olthoff (Wildlands Conservation Science, Lompoc, CA, USA), Mike Parker (California Institute for Environmental Studies, Davis, CA, USA), Hans Sin (California Department of Fish and Wildlife, San Diego, CA, USA) 

California’s Channel Islands are a haven for unique biodiversity – supporting the highest levels of endemism of any region in California. More than 10% of the islands’ flora is endemic, representing approximately 100 taxa. But this unique diversity is also vulnerable and the islands suffered from nearly two centuries of anthropogenic impacts, including the introduction of mainland vertebrates such as cattle, sheep and pigs, and the proliferation of invasive plants. Fortunately, all but one of the Channel Islands is now free of introduced herbivores and, as a result, the Channel Islands as a whole are on a trajectory toward recovery. However, recovery is not moving at the same pace for all species. In 2019, a group of island partners initiated an ambitious project to address the conservation and recovery of 14 state and federally-listed plants across the Channel Islands. The goals of the project were to update the status of our focal taxa using surveys and mapping; to bring them into ex situ conservation collections as appropriate; to conduct research about demography, reproductive biology, and genetics; and to conduct on-the-ground recovery actions such as restoration outplanting and seeding. This work represents a robust and diverse partnership between non-profit, state, federal, and private partners to conduct collaborative plant conservation and recovery actions across seven of the eight Channel Islands over several years. As the first phase of the project nears its conclusion, we reflect back on what has been accomplished, lessons learned, and share our plans for the work that lies ahead.

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41.3    Status of the federally endangered Coachella Valley Milkvetch, Astragalus lentiginosus var. coachellae (Fabaceae), within the Coachella Valley, California

Melanie J. Davis (Center for Conservation Biology, University of California, Riverside, Palm Desert, CA, USA), Lynn C. Sweet (Center for Conservation Biology, University of California, Riverside, Palm Desert, CA, USA), Scott A. Heacox (Center for Conservation Biology, University of California, Riverside, Palm Desert, CA, USA).

Coachella Valley Milkvetch, Astragalus lentiginosus var. coachellae Barneby (Fabaceae), is an annual or perennial herb endemic to the Coachella Valley in Riverside County, California. Astragalus lentiginosus var. coachellae is restricted to sandy aeolian habitats that require regular replenishment of windblown sand. This species was listed in 1998 under the U.S. Endangered Species Act as federally endangered, is assigned a California Rare Plant Rank 1B.2, and is covered under the Coachella Valley Multiple Species Habitat Conservation Plan (CVMSHCP). Little has been published on how this species is responding to the effects of urban development. However, A. lentiginosus var. coachellae habitat appears to be disappearing in the Coachella Valley due to expanding urbanization, reduced sand flow, and dune stabilization resulting from the establishment of invasive species, notably Sahara mustard (Brassica tournefortii). We designed this study to provide a status update of A. lentiginosus var. coachellae populations throughout its range, and especially along the wildland urban interface of communities throughout the Coachella Valley. We examined historical herbarium specimen localities, data from regional vegetation surveys, and community-sourced observations to determine locations for study plots. During the spring of 2022, we documented occurrences, population size, and population density at our study plots, and found that this species was extirpated from several locations, likely due to a combination of the aforementioned anthropogenic stressors. We discuss the impacts of the problematic invasive plant, B. tournefortii, as well as provide an update of current A. lentiginosus var. coachellae localities within the Coachella Valley. This information is necessary to inform ongoing conservation efforts for A. lentiginosus var. coachellae, as well as other dune-obligate species.

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41.4    Status updates and recovery actions for the three federally listed plant species endemic to the Amargosa River in the Mojave Desert, Inyo County, California

Naomi S. Fraga (California Botanic Garden, Claremont, CA, USA), Maria Jesus (California Botanic Garden, Claremont, CA, USA), Alejandra Soto (California Botanic Garden, Claremont, CA, USA), and Billy Sale (California Botanic Garden, Claremont, CA, USA)

The Amargosa River Basin in Inyo County, California supports numerous special status plant species and rare wetland vegetation types. This study focuses on three federally listed plant species endemic to the Amargosa River: Grindelia fraxinipratensis (Ash Meadows gumplant), Nitrophila mohavensis (Amargosa niterowort), and Zeltnera namophila (spring loving centaury). Groundwater pumping and subsequent hydrological alteration within the Amargosa groundwater basin has been identified as the most significant threat to the long-term persistence of these species. The groundwater supplies of the Amargosa River in California originate in Nevada and are essential to their long-term persistence. Therefore, management of the groundwater basin across political boundaries will be essential to protecting the unique biodiversity that occurs here. The objectives of this study were to conduct surveys and census all known occurrences of the listed plant species endemic to the Amargosa River in California, make conservation seed collections, study their life history attributes, conduct germination trials, and develop propagation protocols. This work collectively will support the creation of species specific conservation strategies to further recovery actions.

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41.5    Survey, study, and propagation of rare and sensitive plants from the Otay Mountain Wilderness

Joe DeWolf (San Diego Botanic Garden, California Plant Rescue, Encinitas, CA, USA)

Nestled against the U.S. border with Mexico in southeastern San Diego, the Otay Mountain area is home to more than 50 rare taxa of native plants, many of which are endemic to this region and poorly represented in ex situ conservation collections. Building upon early successes in the San Diego Botanic Garden’s (SDBG) fledgling science and conservation program, such as propagating the first acorns from Quercus cedrosensis collected in the U.S., SDBG worked to develop an ambitious project emphasizing study of endangered species through a range of conservation horticulture techniques and strategies, including genomic analysis, as a way to guide and benefit future restoration efforts for the target species and other rare native plants. Throughout 2022, SDBG staff have been intensively surveying for, mapping, collecting from, and propagating ten endangered species in the Otay Mountain Wilderness area as part of a conservation partnership with the Bureau of Land Management. Arctostaphylos otayensis, Baccharis vanessae, Brodiaea orcuttii, Calochortus dunnii, Clarkia delicata, Ceanothus otayensis, Comarostaphylis diversifolia subsp. diversifolia, Hosackia crassifolia var. otayensis, Lepechinia ganderi, and Monardella hypoleuca subsp. lanata are all listed as 1B species by the California Native Plant Society. Several of these only grow in the immediate vicinity of Otay Mountain in the U.S., while others represent the northernmost or southernmost extent of a taxon’s natural range. SDBG staff are scouring every aspect of this mountainous wilderness while collecting GIS data about population distribution, environmental factors, and threats related to each of these species. Herbarium vouchers and seedbank accessions and other propagules are also being gathered to supplement existing collections and bolster scientific understanding in coordination with other gardens and institutions such as the San Diego Natural History Museum and Salk Institute for Biological Studies.