This database represents over 30 years of research and monitoring of locally rare and statewide rare plants by both the Rare and the Unusual Plant Committees and their volunteers. It currently includes 1,022 plants with almost 19,000 observation records from a myriad of sources including CNPS volunteers, local botanists, herbaria records, plant lists, etc.
Because the East Bay is such a melting pot of California vegetation, there are a great many plants that have very limited distribution in our two-county area, including many that reach their range limit here.
In 1989 the Rare Plant Committee started studying the local flora in terms of local rarity, and by 1992 we had identified 658 taxa that had five or fewer known locations in the East Bay. A database was set up to track these “Unusual and Significant” (locally rare) plants, and research and monitoring have continued ever since. An on-line version of the database was launched in 2016 for public use.
Access the Rare, Unusual and Significant Plant Database
By 1992 we had formed the Unusual Plants Committee and compiled a report addressing these unusual, or locally rare, plants. The report was very well received and became an invaluable tool for land managers, planners, agencies, conservationists, and others. We went on to produce eight more updated editions through 2010.
As time went on, however, we received more and more requests for a digital version, so in 2010 we began a project to make the database available on-line so that individuals could access the data themselves, and tailor their searches to more specifically meet their own needs. It was a long effort and involved many tasks, people, and problems, but we were finally able to launch the database in 2016 and it has since become very popular, with more and more users signing up every year.
Changes for 2021
In 2020, we took on another major endeavor and began to re-examine how we assessed local rarity and, as a result, improved some of the ways rarity ranks are determined. To make this possible, however, a three-year project preceded it, starting in 2017, that reviewed the A-ranked unusual plants and identified individual populations for each species, thus making them easier to track over the years.
Originally, the Unusual Plants Project had been based on a Locations system because so many records were fairly general, with many of them coming from plant lists, herbarium records, and the vague memories of numerous botanists. But as we conducted more and more field surveys over the years and were able to record more detailed locations for many of the populations, we were able to develop a Regions system that was less general and provided a clearer depiction of actual distribution. But eventually this system was also found to have flaws, and in 2017 we realized that with the amount of detailed population location data we had now developed, it was possible to develop a Populations system that would provide even better accuracy as well as easier tracking.
Once individual populations had been identified for most of the A-ranked species, we began a review of every species in the database, first determining how many current and historical populations each had, and then applying our eleven other criteria assessing vulnerability to determine if a species deserved a higher or lower rank than if only its number of current populations was considered.
As of January 15, 2021, there are 247 A1-ranked unusual plants in the East Bay, with 93 having only one known current population in the entire two-county area, 91 with only two, and 64 between three and five. An additional 169 species are ranked A-2, having four to six populations in the East Bay, or up to nine if other criteria are met. In addition, a two-tiered watch list consists of 142 B- and 135 C-ranked plants. But these numbers can change as research continues and more data is gathered.
It should be noted that these numbers only include the unusual (locally rare) plants, and that statewide rare plants occurring in our two counties are usually considered separately, although both are tracked in the database. 80 of the statewide rare plants that occur here are ranked A-1 locally using the East Bay Chapter’s ranking system, with 25 of them having only one population here, 15 having two, and 12 with three to five but meeting other criteria that make them more vulnerable. 31 are ranked A-2.
In addition, 30 statewide rare plants and 120 unusual plants are only known historically from our two counties.
All A-ranked species, both locally rare and statewide rare, are required for consideration under CEQA guidelines, and the database provides detailed information on all of them.
How You Can Help
The continued monitoring, tracking and preservation of our local native flora is dependent on the efforts of our many CNPS volunteers and others who provide data on the Rare and Unusual plants they find and monitor while working and hiking in the East Bay.
Every year a list is compiled of the Priority Unusual Plants most in need of monitoring. Volunteers are asked to choose plants from the list and monitor as many of them as possible. This year an additional list has been compiled of just native grass populations to be monitored.
No formal training is required to become a volunteer, but the more experience and knowledge of our local flora the better. There are generally no group surveys (especially during Covid-19) and volunteers are asked to work on their own as much as possible and observe Covid-19 safety precautions. The following forms can help get you started: Data Collection Form, Monitoring Hints, and Recording and Entering Data.
Plant identifications do need to be verified, which can be done in a few different ways. Some plants are easily keyed using the Jepson Manual or other flora, some can be identified from photographs on CalFlora, CalPhoto, or other sources, but many have subtle differences and will need to be looked at by an expert. The Jepson/UC Herbaria staff at UC Berkeley are an excellent resource. If they cannot identify something themselves they will usually be able to direct you to someone who can.
Volunteering is often a good way to learn more about our local flora and increase your taxonomic skills. Some of our volunteers who have adopted a particular plant or group of plants have even become experts on those plants, learning to recognize the subtle differences distinguishing similar-looking plants that many of us miss.
Please review the Priority Plant Surveys list and the Priority Grasses list and contact me at diannelake@yahoo.com if you can help us monitor some of these plants. Lists are also available for parks and other places in the East Bay with plants that need to be monitored at those places. Let me know if there is a particular park or area that you are interested in, or a particular plant or group of plants.
— Dianne Lake, Chair, Unusual Plants Committee
Unusual And Significant Plants Of Alameda And Contra Costa Counties
Definition of Unusual Plants
The East Bay has a wealth of native plant species. Alameda and Contra Costa Counties act as a botanical melting pot where many native species reach their range limit in one of the two counties, and many others occur in habitats that are very limited, isolated, or threatened here. Still others are in severe decline due to habitat loss, weed and insect invasions, changes in land use, altered water courses, or other detrimental factors.
Many of the native plant species in our two counties have been found to be rare statewide and are thus given some level of protection. But there are many more species that occur in only a few places in Alameda and Contra Costa counties, even though they may be more common in other parts of California. Some of these species are even rarer in our area than the statewide rare plants that occur here.
The East Bay Chapter of CNPS has designated these species that are rare or threatened locally, but possibly more common elsewhere in the state, as “Unusual Plants.” These species are given some protection under CEQA in sections 15380 and 15125a (see the “Legal Implications and Protection for Unusual Plants” section below).
The term “Unusual” was chosen because when the Unusual plants program was first started back in the late 1980’s, it was a brand new concept, and the term “locally rare” at that time was usually interpreted to mean the statewide rare plants that occurred locally. Although the distinction between “locally rare” and “statewide rare” is clearer now, and many Chapters have since started their own “locally rare” programs, the name “Unusual” has persevered for our Chapter.
Determining and Tracking Our Unusual Plants
Many years of surveying, monitoring and research by many dedicated CNPS volunteers went into determining which plants of our local native flora qualify as Unusual plants.
When rare plant surveys were conducted every week, year round, back in the 1980’s and 90’s, the participants started noticing that some native plants were seen quite often, and others very rarely even though they were not designated as rare by state CNPS. Several years of combing through plant lists, herbarium vouchers, and other plant records, plus interviewing numerous local botanists and others, resulted in a list of “Unusual” plants for Alameda and Contra Costa counties.
A database was set up in the late 1980’s to track these plants, and surveying, monitoring, and other research activities have continued over the years so that we can constantly reassess and update the status of these plants in our two-county area.
Over the years, criteria were developed and location and ranking systems were devised to denote the degree of rarity and endangerment of these unusual plants in our two counties.
In 1991 a report was published, Unusual and Significant Plants of Alameda and Contra Costa Counties, with the results of this constant monitoring and research. Providing rank, locations and habitat for each species, the report quickly became an important tool for botanists, land managers, planners, researchers, consultants, conservationists, etc. in their work around the East Bay.
Although the report originally addressed only the locally rare plants, it now includes the statewide rare plants that occur here as well, and has been renamed Rare, Unusual and Significant Plants of Alameda and Contra Costa Counties.
The report has been updated periodically, and the last (8th ) edition was released March 2010.
Since the last edition of the report was released, efforts have turned more towards making the database behind the report available online so that more people can use it, search in multiple categories, and find data that meets their particular needs. As one might guess, this proved to be a much more daunting task than first envisioned. Although we have made great strides, we have found that there are still several things that need to be ironed out to assure accuracy and easy usability.
Work still continues in both the surveying and monitoring of our Unusual plants, and also in making the database publicly accessible. There have been many great volunteers over the years contributing to these efforts, but we can always use more help. See the “How You Can Help” section below to learn how you can contribute to the monitoring and preservation of the East Bay’s Unusual plants.
Importance of Unusual Plants
In many instances our Unusual plant species are even rarer and more threatened locally than several of the statewide rare plants that occur in the East Bay. The preservation of these locally rare populations is important for a multitude of reasons.
Isolated and range limit, or peripheral, populations have often been found to possess plants with greater genetic variation and better survival rates than those in populations occurring where the species is more common. In rapid and catastrophic extinctions of large populations, the plants on the periphery of a range or in isolated disjunct populations have often survived. Common species with large populations can often disappear rapidly in the face of a catastrophic event or a pathogen moving from plant to plant, but isolated populations can often escape this fate simply due to their distance from the main populations. Conditions at the range edges of a species, or in isolated populations, are often more hostile and plants there tend to develop stronger survival mechanisms. These isolated and peripheral populations can sometimes be the only hope for survival that a species has in the event of an environmental disaster, and thus it is essential to identify where these populations exist and to take the necessary steps to ensure their survival.
Several of our Unusual plants occur in habitats that are limited or threatened statewide as well as in the East Bay, such as vernal pools, alkali sinks, serpentine environments, and miscellaneous wetlands and riparian areas. Because these habitats are so limited, many of the species that occur in them are also rare or threatened. Many of the Unusual plants in the East Bay occur only in these limited or threatened habitats, although some can also be found in other types of habitats and are thus less vulnerable. By identifying the Rare and Unusual plants found in these local places, these declining or limited habitats can be identified and protected.
Clusters or suites of Rare and Unusual plants are sometimes found, and these “botanical hotspots” usually indicate special environmental conditions such as unique soils, water patterns, limited pollinators, or other factors that contribute to our local biological heritage and diversity and that need to be preserved. Studying the plants and conditions in these areas can also help us better understand what various rare plants need to survive and to define patterns and trends that may cause local rarity. Some of the “botanical hotspots” of the East Bay are Mt. Diablo State Park, Antioch Dunes National Wildlife Refuge, Flicker Ridge in Canyon, Black Diamond Mines Regional Preserve, Lime Ridge, Byron Hot Springs, Corral Hollow, Springtown Wetlands Preserve, Sunol and Ohlone Regional Wildernesses, Don Edwards National Wildlife Refuge (Warm Springs section), Redwood Regional Park, and the Mines Rd. area south of Livermore.
It is important to recognize that plants and their habitats are interdependent and when species are found to be in rapid decline in an area it is an indication that the natural resources and biodiversity of that area are in trouble. Studying and becoming aware of our local Unusual plants is not just about preserving individual species but is also a way to determine local botanical areas of native plant diversity, define places with threatened habitats or suites of endangered plants, define patterns and trends that cause local rarity, and identify areas in need of study or conservation that may have other special environmental factors.
Legal Implications and Protection for Unusual Plants
When several Unusual species occur on a property, even if there are no statewide rare plants there, it should be considered a significant impact under guidelines in the California Environmental Quality Act (CEQA) that refer to locally rare populations in sections 15380 and 15125a which address species of local concern and place special emphasis on environmental resources that are rare or unique to a region.
CNPS and other organizations and individuals have been instrumental in alerting local land planners and managers about the existence and importance of these Unusual plants during public review periods for EIRs and other land planning documents.
CNPS has also notified the cities and agencies of Alameda and Contra Costa Counties about the Rare and Unusual plants known to occur in each of their areas. A list of CEQA-protected species for their area has been provided to every city and agency along with a letter explaining the importance of these species, their legal protection, and the need to consider these species in any land use activities or changes in their area.
Location System for Unusual Plants: Regions and Specific Sites
A location system was developed using regions and specific sites rather than individual occurrences partially because of the difficulty of comparing many historical records for an area to current sites. Records from the late nineteenth and early twentieth centuries often merely describe a site as “Berkeley Hills” or “Oakland”, for example, and provide no further detail. Thus, when sites or multiple sites for a plant species are now found in these areas, it is usually impossible to determine if any of those sites correspond to the historical site, or if there were more, or possibly even less, populations of that particular species there in the past.
For this reason, specific location details are now always requested when populations are reported (although this specific location data is usually not made available to the general public because of past incidents of vandalism, over-collecting, etc).
The region system was developed by analyzing the two counties according to vegetation, geology, habitats, soil types, and other factors. The area was then divided into 40 botanical regions.
Each of these regions contains several specific sites (or sub-regions) within them, that cover a certain area such as Tilden Park, Antioch Dunes, Mt. Diablo, etc. Detailed locations are then described within these specific sites.
