The Many Uses of the CNPS Rare Plant Inventory

By Ellen Dean and Aaron Sims

What is the Rare Plant Inventory?

It sounds mysterious and magical, like an ancient tome you would check out of the library. Where does it come from? Well, for more than 50 years, the CNPS Rare Plant Program has taken the lead on evaluating and ranking the rarity of California’s native plants. Those evaluations and rankings are available to the public via the CNPS Inventory of Rare and Endangered Plants (RPI). Unlike an ancient tome, however, the RPI is up-to-date and online!

CNPS Rare Plant Inventory website
Rare Plant Inventory home page

How Do People Use the Rare Plant Inventory?

Environmental Documents: Ellen first really understood the importance of the CNPS Rare Plant Inventory when she was taught how to do environmental documents and rare plant surveys by Petra Unger at the consulting firm EDAW. “‘Start with your rare plant table,’ she would say. When I had questions, she would ask ‘What does your rare plant table tell you?’ The rare plant table was the centerpiece of our Botanical Resources documents and can be generated from the Inventory.” It provides information on rare plant flowering times, elevations, and habitats. This information can then be used to predict whether a rare plant will occur at a particular site and to search for rare plants in the correct locations at the right time for identification.

Rare plant table
Example of a rare plant table
Rare Plant Inventory search results
An example of Rare Plant Inventory search results

Floras, Nature Walks, Rare Plant Treasure Hunts, and General Education: “Later,” continues Ellen, “when I worked on floras for many different land parcels, parks, and reserves, I would start with my rare plant table, so that I could familiarize myself and my helpers (often volunteers or students) with what rare plants we might encounter. This was especially important if we were collecting herbarium specimens, because we wanted to both carefully document and minimize our impacts on rare plants. I would create a pictorial rare plant table with images of the rare plants that we might see and hand it out to volunteers. You can do this too!” Stay tuned for our next blog posts, because we’ll show you how to use the search capabilities of the Inventory.

Rare plant pictorial table
Pictorial rare plant table

Conservation: Of course, anyone interested in conservation of lands/plants/animals in California uses the Rare Plant Inventory (in combination with the California Department of Fish and Wildlife Natural Diversity Database – CNDDB) to investigate the locations of rare plants. Maps of the locations of rare plants can guide decisions about which areas are a high priority for protection. In addition, the Inventory is used by conservation organizations to guide the seed collection of rare plants for ex situ seed banking.

Vegetation Mapping – The Vegetation Mapping team at CNPS first uses the CNDDB to investigate the rare plants they may encounter in a mapping project. Then, they use the Inventory and the Jepson eFlora to look up the details of the likeliest plants that they will see or when identifying plants they encounter in the field.

Land Management/Restoration – In Lands Management, which often involves some restoration, managers use the Inventory or CNDDB to find out what rare plants are in their area. Targeted searches for these plants, as well as floristic surveys, can be done to determine what plant resources are present prior to initiating restoration plans.

Research – Researchers in ecology, conservation, systematics, and other plant science use the Inventory to find out more about the rare plants of a particular region or to get more details on specific rare plants under study. For example, oak researchers might want to know how many oaks are considered rare. The Inventory’s data are also used in large scale analyses of issues that may affect rare plants.

So, as you can see, a lot of different teams with a lot of different needs use the Rare Plant Inventory. Thanks to Kendra Sikes, Mark Bibbo, Caroline Martorano, and Isabella Langone for their input!

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