California Native Plant Society

Rare Plant Treasure Hunt

Map of rare plant occurrences documented throughout California in the first 5 years of the project. Click to view larger.

Project Background and Results

CNPS and the California Department of Fish and Wildlife (CDFW) track California's rare plants in the California Natural Diversity Database (CNDDB), which has now provided us with a map of nearly 38,000 rare plant occurrences across the State. Right now, nearly half of those occurrences are historical, meaning that they have had no documentation in at least 20 years. Getting up-to-date information on our rare plants is critical to understanding which populations are still present and which species need our closest attention to ensure their long-term conservation.

The project has already seen some incredible results in the first 5 years since its inception: we've documented over 2500 separate rare plant occurrences, and of those, nearly 1000 occurrences are new to science! Focus areas for RPTH vary from year to year, and are dependent on project funding. The California deserts were a major focus area of the project during its first four years, as many solar energy projects threaten this biodiversity hotspot. In other years we have focused on the Los Padres National Forest, other National Forests, and the Central Coast. In 2015 we will focus on Northern California and the Bay Area, but are always working to expand the Program throughout California. We encourage botanical enthusiasts from all parts of the State to get involved!

RPTH occurrence data
The data presented here highlight the importance of the data being collected by RPTH volunteers. Over a third of the rare plant occurrences are reported on, and about a fifth of them completely lack data from the past 20 years (historical occurrences). The data on Rank 3 and Rank 4 occurrences is also very important, as these plants are sometimes ignored in rare plant surveys. An incredible group of over 700 volunteers have contributed over 12,000 hours to the RPTH!


Highlights from the Central Coast 2014 field season:

A small group of volunteers and staff made the 30 mile round-trip trek to Ventana Double Cone, to check on the status of Carlquistia muirii. This mountain-dwelling plant is completely endemic to the Sierra Nevada Mountains, with the exception of the population we visited in Monterey County. Unfortunately, the population declined significantly since it was last seen nearly 30 years ago. Carlquistia muirii
Carlquistia muirii click to view larger
We re-located one of the few known locations of Erythranthe hardhamiae, a recently-described rare plant from the Central Coast. The population we found hadn't been seen in 1960, and it consisted of only four individuals. Hopefully this annual plant will bounce back at this location in better rain years. Erythranthe hardhamiae
Erythranthe hardhamiae
click to view larger


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