The Rare, Threatened, and Endangered Plants of California

Glossary of Terms and Field Descriptions
(Adopted and modified from the CNPS Inventory, 6th Edition, 2001)

The heart of the CNPS Inventory is our assessment of the current conservation status of each of our state's rare, threatened, and endangered plants. We present these assessments together with a summary of current information on the distribution and ecology of each taxon. We also include entries for plants that were considered but rejected for one or more reasons, as well as other scientific names that have been used in the standard literature or in previous editions of this Inventory.

Basis for Inclusion 

The vast majority of the taxa in this Inventory are vascular plants (ferns, fern allies, gymnosperms, and flowering plants). We also present our evaluation of rarity and endangerment of California's bryophytes (mosses, liverworts, and hornworts). Algae, fungi, and lichens are not treated here.

A plant must be native to California to be included. Ornamentals, plants escaped from cultivation, and naturalized plants are excluded. So are the sporadic hybrids that sometimes occur under natural conditions. The relatively trivial color variants and occasional departures from typical vegetative or floral conditions, referred to by botanists as "forma," are similarly excluded.

This Inventory focuses on plants that are rare in California. A very small number of plants that are still somewhat common in California are included because they are in decline and face further immediate threats. We recognize that extensive habitat alteration and pervasive human impacts pose serious threats to many other species that are still common. However, evaluation of threats to species that are neither rare nor imminently becoming so is outside the scope of this Inventory. By limiting our scope in this way, we in no way imply that these species are not of concern.

Scientific Names 

The plants in this Inventory are presented by their scientific names which have been properly published according to the International Code of Botanical Nomenclature. See Shevock (1993)[10] for a general discussion of nomenclature.

In its simplest form, a scientific name has three parts. The first is the genus name. It is always capitalized. The second part is the specific epithet, often incorrectly called "the species name." Together, these two components make up the species name. If a scientific name is presented in its most complete form, these two words will be followed by the names of one or more persons, often in an abbreviated form, who first published the specific epithet or subsequently published a taxonomic modification of the plant. These names are the authorities. If a portion of an authority occurs within parentheses, then the author in parentheses originally placed the epithet in a different genus or species, or once assigned it to a different taxonomic rank. The name cited outside the parentheses is that of the person who published the combination as it now appears.

Often the scientific name is more complex because botanists have recognized categories below the level of species. The two most useful are the subspecies (abbreviated ssp.) and the variety (abbreviated var.) These names are also displayed according the International Code and they have their own authorities.

Consider the example Penstemon newberryi Gray var. sonomensis (Greene) Jeps. Penstemon is the genus name; newberryi is the specific epithet; Gray, for Asa Gray, is the author of the specific epithet; var. is the abbreviation for variety; sonomensis is the subspecific epithet; (Greene), for Edward L. Greene, first described the var. sonomensis as a full species; and Jeps., for Willis Lynn Jepson, modified its taxonomic position and made it a variety of P. newberryi. Following the general practice for foreign words and phrases, Latin portions of the name (genus, species, and infraspecific epithet) are typically distinguished from surrounding text with underlining or italic typeface.

Nomenclatural Usage

We use what we consider to be the current, best nomenclature based on the recommendations of the Rare Plant Program Committee and consultation with taxonomic authorities. Many names in this Inventory have been in use for a long time, appearing in Munz (1959, 1968, 1974)[7][8][9] and Abrams (1923-1960)[1]. Others have been introduced or reintroduced to us in The Jepson Manual (1993)[4] and The Jepson Online Interchange, or described new to science in the last several years.

The usage in this Inventory does not follow any single published source, though if other considerations are equal, we use the names found in The Jepson Manual and/or on their Online Interchange. When the nomenclature we use varies from that of The Jepson Manual, we include information in the Notes section of each entry describing the situation. See Skinner and Ertter (1993)[11] for a discussion of taxonomic coordination between the Inventory and The Jepson Manual.

Where there is disagreement among experts on taxonomic distinctiveness, we lean towards recognizing doubtfully distinct taxa. Such taxa are typically assigned to List 3. By encouraging protection until taxonomic questions are resolved, we hope to reduce ex post facto regret over taxa that have been shown to be distinct only after their disappearance.

We do not include taxa that lack formally published scientific names.

Common Names 

Each of the plants has a common or vernacular name. Although the majority of the plants in the Inventory have no real common name, we include them because it is often easier for many of us to refer to a plant by a more familiar sounding name.  Most of the common names were coined by Leroy Abrams for his Illustrated Flora of the Pacific States. In other instances, we simply follow his lead by contriving names, usually by translating the Latin or Greek roots into English or by selecting an appropriate geographical reference or person's name. We attempt to follow Kartesz and Thieret (1991)[6] in matters of capitalization, spelling, and hyphenation of common names.

Family Names 

Each entry includes the technical name of the family to which the plant belongs. Note that all of these names end with the suffix "-aceae." A few plant families have older, alternative names that the International Code allows to be used because their widespread acceptance predates formal nomenclature. Gramineae is a perfectly acceptable alternative for Poaceae; Compositae for Asteraceae; Cruciferae for Brassicaceae; Umbelliferae for Apiaceae; Leguminosae for Fabaceae; and Labiatae for Lamiaceae. However, these old names are gradually losing favor, so we use the standardized, modern names for these families.

The CNPS Ranking System

California Rare Plant Ranks (formerly known as CNPS Lists)

In the spring of 2011, CNPS officially changed the name “CNPS List” to “California Rare Plant Rank.” The definitions of the ranks and the ranking system have not changed, and the ranks are still used to categorize the same degrees of concern, which are described as follows:

California Rare Plant Rank 1A (formerly List 1A): Plants Presumed Extinct in California

The plants with a California Rare Plant Rank of 1A are presumed extinct because they have not been seen or collected in the wild in California for many years. This rank includes plants that are both presumed extinct as well as those plants which are presumed extirpated in California. A plant is extinct if it no longer occurs anywhere. A plant that is extirpated from California has been eliminated from California, but may still occur elsewhere in its range.

Plants are ranked 1A in an effort to highlight their plight and encourage field work to relocate extant populations. Since the publication of the fifth edition (1994), thirteen plants thought to be extinct in California have been rediscovered. These are Franciscan manzanita (Arctostaphylos franciscana), Ventura marsh milk-vetch (Astragalus pycnostachyus var. lanosissimus), San Fernando Valley spineflower (Chorizanthe parryi var. fernandina), California dissanthelium (Dissanthelium californicum), Mt. Diablo buckwheat (Eriogonum truncatum), diamond-petaled California poppy (Eschscholzia rhombipetala), Mojave tarplant (Hemizonia mohavensis), water howellia (Howellia aquatilis), Howell's montia (Montia howellii), northern adder's-tongue (Ophioglossum pusillum), Shasta orthocarpus (Orthocarpus pachystachyus), bearded popcorn flower (Plagiobothrys hystriculus), and caper-fruited tropidocarpum (Tropidocarpum capparideum). The rediscovery of these California Rare Plant Rank 1A plants is encouraging and CNPS hopes that it will motivate professional and amateur botanists alike to search for and rediscover more California Rare Plant Rank 1A species.
All of the plants constituting California Rare Plant Rank 1A meet the definitions of Sec. 1901, Chapter 10 (Native Plant Protection Act) or Secs. 2062 and 2067 (California Endangered Species Act) of the California Department of Fish and Game Code, and are eligible for state listing. Should these taxa be rediscovered, it is mandatory that they be fully considered during preparation of environmental documents relating to the California Environmental Quality Act (CEQA).

California Rare Plant Rank 1B (formerly List 1B): Plants Rare, Threatened, or Endangered in California and Elsewhere

Plants with a California Rare Plant Rank of 1B are rare throughout their range with the majority of them endemic to California. Most of the plants that are ranked 1B have declined significantly over the last century. California Rare Plant Rank 1B plants constitute the majority of taxa in the CNPS Inventory, with more than 1,000 plants assigned to this category of rarity.

All of the plants constituting California Rare Plant Rank 1B meet the definitions of Sec. 1901, Chapter 10 (Native Plant Protection Act) or Secs. 2062 and 2067 (California Endangered Species Act) of the California Department of Fish and Game Code, and are eligible for state listing. It is mandatory that they be fully considered during preparation of environmental documents relating to CEQA.

California Rare Plant Rank 2 (formerly List 2): Plants Rare, Threatened, or Endangered in California, But More Common Elsewhere

Except for being common beyond the boundaries of California, plants with a California Rare Plant Rank of 2 would have been ranked 1B. From the federal perspective, plants common in other states or countries are not eligible for consideration under the provisions of the Endangered Species Act. Until 1979, a similar policy was followed in California. However, after the passage of the Native Plant Protection Act in 1979, plants were considered for protection without regard to their distribution outside the state.

With California Rare Plant Rank 2, we recognize the importance of protecting the geographic range of widespread species. In this way we protect the diversity of our own state's flora and help maintain evolutionary processes and genetic diversity within species. All of the plants constituting California Rare Plant Rank 2 meet the definitions of Sec. 1901, Chapter 10 (Native Plant Protection Act) or Secs. 2062 and 2067 (California Endangered Species Act) of the California Department of Fish and Game Code, and are eligible for state listing. It is mandatory that they be fully considered during preparation of environmental documents relating to CEQA.

California Rare Plant Rank 3 (formerly List 3): Plants About Which We Need More Information - A Review List

The plants that comprise California Rare Plant Rank 3 are united by one common theme - we lack the necessary information to assign them to one of the other ranks or to reject them. Nearly all of the plants constituting California Rare Plant Rank 3 are taxonomically problematic. For each California Rare Plant Rank 3 plant we have provided the known information and indicated in the “Notes” section of the CNPS Inventory record where assistance is needed. Data regarding distribution, endangerment, ecology, and taxonomic validity are welcomed and can be submitted by emailing the Rare Plant Botanist at or (916) 324-3816.

Some of the plants constituting California Rare Plant Rank 3 meet the definitions of Sec. 1901, Chapter 10 (Native Plant Protection Act) or Secs. 2062 and 2067 (California Endangered Species Act) of the California Department of Fish and Game Code, and are eligible for state listing. We strongly recommend that California Rare Plant Rank 3 plants be evaluated for consideration during preparation of environmental documents relating to CEQA.

California Rare Plant Rank 4 (formerly List 4): Plants of Limited Distribution - A Watch List

The plants in this category are of limited distribution or infrequent throughout a broader area in California. While we cannot call these plants "rare" from a statewide perspective, they are uncommon enough that their status should be monitored regularly. Should the degree of endangerment or rarity of a California Rare Plant Rank 4 plant change, we will transfer it to a more appropriate rank.

Very few of the plants constituting California Rare Plant Rank 4 meet the definitions of Sec. 1901, Chapter 10 (Native Plant Protection Act) or Secs. 2062 and 2067 (California Endangered Species Act) of the California Department of Fish and Game Code, and few, if any, are eligible for state listing. Nevertheless, many of them are significant locally, and we strongly recommend that California Rare Plant Rank 4 plants be evaluated for consideration during preparation of environmental documents relating to CEQA. This may be particularly appropriate for:


Threat Ranks

The CNPS Threat Rank is an extension added onto the California Rare Plant Rank and designates the level of endangerment by a 1 to 3 ranking with 1 being the most endangered and 3 being the least endangered. A Threat Rank is present for all California Rare Plant Rank 1B's, 2's, 4's, and the majority of California Rare Plant Rank 3's. California Rare Plant Rank 4 plants are seldom assigned a Threat Rank of 0.1, as they generally have large enough populations to not have significant threats to their continued existence in California; however, certain conditions exist to make the plant a species of concern and hence be assigned a California Rare Plant Rank. In addition, all California Rare Plant Rank 1A (presumed extinct in California), and some California Rare Plant Rank 3 (need more information) plants, which lack threat information, do not have a Threat Rank extension.

Threat Ranks

Note: The above Threat Rank guidelines only represent a starting point in the assessment of threat level. Other factors, such as habitat vulnerability and specificity, distribution, and condition of occurrences, are also considered in setting the Threat Rank.


State and Federal Status 

For each taxon with official status under the California Endangered Species Act (CESA), the Federal Endangered Species Act (FESA), and/or the Native Plant Protection Act (NPPA), the plant's status is presented. Our definitions conform to those found in California state law and federal regulations.



Global Ranking

The global rank (G-rank) is a reflection of the overall status of an element throughout its global range.  Both Global and State ranks represent a letter+number score that reflects a combination of Rarity, Threat and Trend factors, with weighting being heavier on Rarity than the other two.

Species or Natural Community Level

Subspecies Level

Subspecies receive a T-rank attached to the G-rank.  With the subspecies, the G-rank reflects the condition of the entire species, whereas the T-rank reflects the global situation of just the subspecies or variety.  For example:  Chorizanthe robusta var. hartwegii.  This plant is ranked G2T1.  The G-rank refers to the whole species range i.e., Chorizanthe robusta.  The T-rank refers only to the global condition of var. hartwegii.

State Ranking

The state rank (S-rank) is assigned much the same way as the global rank, but state ranks refer to the imperilment status only within California’s state boundaries.



Occurrence Data from DFG California Natural Diversity Database[2]

Element Occurrence (EO)

Definition of plant EOs in California: A population or group of populations found within 0.25 miles and not separated by significant habitat discontinuities.

Total # of Known Element Occurrences / Occurrence Count

The current number of occurrences for a particular element.

Element Occurrence Ranks

An element’s Occurrence Rank is a ranking of the quality of the habitat and the condition of the population at that location.  The possible values for Occurrence Rank are:

Population Status

Displays number of element occurrences that have been seen and/or not seen within the past 20 years. Element occurrences that have not been seen within the past 20 years are considered historic.


Presence refers to the condition of the occurrence at the site when it was last observed.  The possible values for Presence are:


Life Form

A brief description of plant duration and life form. The information is primarily developed from published and unpublished literature and from herbarium material. Our simplified classification system is as follows:


Growth Form:

As in most classifications, some of the above distinctions are somewhat arbitrary, particularly the divisions between growth forms. Furthermore, plant growth form can vary depending on geography and local environmental conditions. Perennials that are often referred to as either suffrutescent herbs or subshrubs present special difficulties. Generally, if these plants die back seasonally to the ground or to a small crown of woody tissue we classify them as herbs, and if they retain much or all of their woody above-ground tissue we call them shrubs.

Blooming Period 

The month(s) when each rare plant is typically in bloom. For ferns and other spore-bearing plants, we give the months when spores are released and spore-bearing structures such as sori are typically present on the plant. We do not included any comparable information for gymnosperms and nonvascular taxa.
Note: Months in parentheses are uncommon.


One or more habitats in which a rare, threatened, or endangered plant is typically found. This information is compiled from field survey forms, unpublished reports, original descriptions, floras, and herbarium material. Note that for habitats which typically occur within a broader matrix of another habitat, we usually list both. For example, a rare plant from Meadows and Seeps occurring in a matrix of Upper Montane Coniferous Forest would typically have its habitat presented as "Meadows and Seeps, Upper Montane Coniferous Forest."

Habitats follow brief characterizations outlined by Robert F. Holland and John O. Sawyer, Jr. and are presented in taxonomic rather than alphabetical order.  Please refer to Holland (1986)[5] for a more complete discussion of the types and their classification.


Habitat Modifiers

Descriptors that denote substrate type, hydrological information, etc., are often used to modify habitat types as follows:

Typical Modifiers


  burned areas
disturbed areas
vernally mesic
lake margins

freshwater (used for Marshes and Swamps)
coastal salt (used for Marshes and Swamps)
maritime (used for Chaparral)



The distribution of the taxon is described by county or island within California, together with other states and countries where we know the plant to exist. We record only natural occurrences of rare plants, or occurrences that have been reestablished within the species' historic range as part of an approved recovery plan. For example, although both Northern California black walnut (Juglans hindsii) and Monterey pine (Pinus radiata) are widely planted within the state, we track only the few natural occurrences of these taxa. When we indicate that a particular plant occurs in a particular county, we are making a positive statement that is based upon specimens, photographs, the literature, or field observations. In no way does this imply that a plant does not occur in other counties in California or in other states. Our understanding of plant distribution constantly improves, and new localities for rare plants are discovered often in unpredicted circumstances.

The following symbols are used as modifiers preceding counties, quads, and/or states to express extirpation and/or uncertainty:

Counties and Islands

Three letter codes have been attributed for each county and island within California to maintain and manage swift data control of the Inventory. In turn, these codes are used as abbreviations in the "Notes" section on the plant detail page for some taxa.    

County and Island Codes:

ALA    Alameda
ALP    Alpine
AMA   Amador
ANA    Anacapa Isl.
BUT    Butte
CAL    Calaveras
CCA   Contra Costa
COL    Colusa
DNT    Del Norte
ELD    El Dorado
FAR    Farallon Isl.
FRE    Fresno
GLE    Glenn
HUM   Humboldt
IMP     Imperial
INY      Inyo
KNG    Kings
KRN    Kern
LAK    Lake
LAS    Lassen
LAX    Los Angeles
MAD   Madera
MPA   Mariposa
MRN   Marin
  MEN   Mendocino
MER   Merced
MOD   Modoc
MNO   Mono
MNT    Monterey
NAP    Napa
NEV    Nevada
ORA    Orange
PLA    Placer
PLU    Plumas
RIV      Riverside
SAC    Sacramento
SBA    Santa Barbara
SBD    San Bernardino
SBR    Santa Barbara Isl.
SBT    San Benito
SCL    Santa Clara
SCM   San Clemente Isl.
SCT    Santa Catalina Isl.
SCR    Santa Cruz
SCZ    Santa Cruz Isl.
SDG   San Diego
SFO    San Francisco
SHA    Shasta

SIE      Sierra
SIS      Siskiyou
SJQ    San Joaquin
SLO    San Luis Obispo
SMI     San Miguel Isl.
SMT    San Mateo
SNI      San Nicolas Isl.
SOL    Solano
SON    Sonoma
SRO    Santa Rosa Isl.
STA    Stanislaus
SUT    Sutter
TEH    Tehama
TRI      Trinity
TUL     Tulare
TUO    Tuolumne
VEN    Ventura
YOL     Yolo
YUB    Yuba

BA       Baja California
GU      Isla Guadalupe, Baja
SA       South America
SO      Sonora, Mexico


To provide more detailed location information, we cite the U.S. Geological Survey (USGS) 7.5 minute quadrangle (quad) map for all plants on CNPS Lists 1, 2, and 3, as well as some plants on List 4 (please see warning about quad maps for List 4’s below). We employ a modified version of the quad numbering system previously used by the California Department of Water Resources. Please follow this link to translate this system's quad numbers into USGS topographic map names or vice versa. In those few cases where a quad is listed without a letter following the number, this indicates that our occurrence data are too vague to pinpoint its location on a 7.5 minute quadrangle. As with counties, this is positive siting information - when we indicate that a plant has been reported from an area on a topographic quad, it is based on hard data. In no way does this imply that a plant does not occur on a topographic quad we have not listed; rather, it may be there but botanists have yet to find it. As with distribution, quads are also often modified with the symbols "*" and "?", which respectively express extirpation and uncertainty (see above).

Quad data is not available for all List 3 and 4 plants. For those that do contain this data, it has not been quality controlled and is potentially incomplete, inaccurate, and/or out of date. Please use caution when referencing this information. We are currently working hard to maintain this data and hope to provide accurate and up to date information in the near future.

A complete list of California USGS quads is available here.  Alternatively, an abbreviated index of only quads occupied with taxa included in the Inventory is available here.


An elevational range is provided for each taxon in meters. The stated range is for the California portion of a plant's range only (if the taxon also occurs outside the state). These elevational range data are accumulated from literature, herbarium specimens, and field survey information.



Many entries include additional notes on distribution, endangerment, relationship to names in The Jepson Manual, or important literature citations. We again include information about legal status and endangerment in neighboring states in the notes; official state designations are specifically indicated as such and capitalized, as in "State-listed as Endangered in OR". We make a special effort to indicate missing information about distribution, endangerment, or taxonomy for each entry, in the hope that knowledgeable users will fill in the gaps.

Abbreviations that are commonly used in the notes include:

ACEC Area of Critical Environmental Concern   NF National Forest
AFB Air Force Base   NM National Monument
BA Botanical Area   NP National Park
BLM Bureau of Land Management   NS National Seashore
CalTrans California Department of Transportation   Pk. Peak
Cyn. Canyon   Pt. Point
DFG California Department of Fish and Game   RNA Research Natural Area
DOD United States Department of Defense   SP State Park
ER Ecological Reserve   SR State Reserve
Ft. Fort   TCF The Conservation Fund
FNA Flora of North America   TJM (1993) The Jepson Manual: Higher Plants of California
HCP Habitat Conservation Plan   TJM 2 The Jepson Manual: Vascular Plants of California, Second Ed.
Mt. Mount   TNC The Nature Conservancy
Mtn. Mountain   USFS United States Forest Service
Mtns. Mountains   USFWS United States Fish and Wildlife Service
NA North America   WA Wildlife Area


Threats: Includes information on significant threats to the plant over its range in California. Typical threats provided in the notes section include, but are not limited to the following:


horticultural collecting
illegal dumping

road construction
road maintenance
road widening

innappropriate grazing
feral herbivores
feral pigs
feral goats


recreational activities
foot traffic (i.e. from people)

energy development
pipeline construction

sand mining
gravel mining
carbonate mining
limestone mining

flood control projects
hydrological alterations
water diversions
waterway channelization
groundwater pumping
flood control

military activities
Border Patrol activities

alteration of fire regimes
fire suppression
frequent wildfires

non-native plants
introgression with…
hybridization with…

meadow succession
habitat loss
habitat alteration
habitat disturbance


Literature Cited

  1. ^ Abrams, L.R. 1923-1960. An Illustrated Flora of the Pacific States, Washington, Oregon and California. Vol. 4 by R. Ferris. Stanford University Press. Stanford, CA. 4 vols.
  2. ^ California Department of Fish and Game, Natural Diversity Database. 2010. Metadata Description of CNDDB fields. RareFind 4 internet application. Accessed November 5, 2010.
  3. ^ California Department of Fish and Game, Natural Diversity Database. 2010. Special vascular plants, bryophytes, and lichens list. Quarterly publication, October 2010. 85 pp. Available online at:
  4. ^ Hickman, J.C., ed. 1993. The Jepson Manual: Higher Plants of California. University of California Press. Berkeley, CA. 1400 pp.
  5. ^ Holland, R.F. 1986. Preliminary Descriptions of the Terrestrial Natural Communities of California. Nongame-Heritage Program, California Department of Fish and Game. Sacramento, CA. 156 pp.
  6. ^ Kartesz, J.T., and J.W. Thieret. 1991. Common names for vascular plants: Guidelines for use and application. Sida 14(3):421-434.
  7. ^ Munz, P.A. 1959. A California Flora. In collaboration with D.D. Keck. University of California Press. Berkeley, CA. 1681 pp.
  8. ^ Munz, P.A. 1968. Supplement to a California Flora. University of California Press. Berkeley, CA. 224 pp.
  9. ^ Munz, P.A. 1974. A Flora of Southern California. University of California Press. Berkeley, CA. 1086 pp.
  10. ^ Shevock, James R. 1993. How plants get their names and why names change. Fremontia 21(1):19-24.
  11. ^ Skinner, Mark W. and Barbara Ertter. 1993. Whither rare plants in The Jepson Manual? Fremontia 21(3):23-27.