Checklist of Ventura County Rare Plants[1]

By David L. Magney

California Native Plant Society, Channel Islands Chapter

Updated 21 May 2008

Ventura County is located in southern California, USA, along the east edge of the Pacific Ocean. The coastal portion occurs along the south and southwestern quarter of the County. Ventura County is bounded by Santa Barbara County on the west, Kern County on the north, Los Angeles County on the east, and the Pacific Ocean generally on the south (Figure 1, General Location Map of Ventura County).

Ventura County extends north to 34.9014ºN latitude at the northwest corner of the County. The County extends westward at Rincon Creek to 119.47991ºW longitude, and eastward to 118.63233ºW longitude at the west end of the San Fernando Valley just north of Chatsworth Reservoir. The mainland portion of the County reaches southward to 34.04567ºN latitude between Solromar and Sequit Point west of Malibu. When including Anacapa and San Nicolas Islands, the southernmost extent of the County occurs at 33.21ºN latitude and the westernmost extent at 119.58ºW longitude, on the south side and west sides of San Nicolas Island, respectively.

Ventura County occupies 480,996 hectares [ha] (1,188,562 acres [ac]) or 4,810 square kilometers [sq. km] (1,857 sq. miles [mi]), which includes Anacapa and San Nicolas Islands. The mainland portion of the county is 474,852 ha (1,173,380 ac), or 4,748 sq. km (1,833 sq. mi.) in area and ranges in elevation from sea level on the southwest to 2,692 meters [m] (8,831 feet [ft.]) above sea level at its northern border on Mount Piños (Figure 2, Shade Relief Map of Mainland Ventura County). There appears to be some discrepancy in the actual area covered by Ventura County, depending on the source. For example, according to the California County Fact Book, 1983 edition (California Supervisors Association of California 1983), Ventura County occupies an area of 482,668 ha (1,192,680 ac) or 2,999 sq. km (1,863.6 sq. mi), with 3,254 ha (8,040 ac) or 20.3 sq. km (12.6 sq. mi) of that as water. The discrepancy appears to be a little over 2,469 ha (6,100 ac), which does not correspond to the area occupied by the two islands within the County. However, thhe difference does appears to match the area occupied by a rectangular portion of the county in the northeast corner, where the Ventura County Board of Supervisors voted to give away approximately 6,100 acres to Kern County to accommodate a proposed development that Ventura County felt it could not provide adequate County services to.

Mainland Ventura County is located between 34º00' and 35º00'N latitude and 118º38' and 119º28'W longitude, excluding Anacapa and San Nicolas Islands, and is generally longer than wide. Anacapa Islands are the smallest and easternmost of the northern Channel Islands while San Nicolas Island is an outer southern Channel Island.

Figure 1. General Location Map of Ventura County

Figure 2. Shade Relief Map of Mainland Ventura County

The flora of Ventura County is comprised of approximately 2,321 native and naturalized vascular plant taxa, including those expected to occur but for which no vouchers are known (214 taxa). A total of 2,111 taxa (91.0%) are known to occur in the county that are supported by voucher specimens, or have been observed by the author. Approximately 1,833 taxa (78.9%) of the flora are native, and another 488 (21.0%) taxa are not native (based on a flora of 2,321 taxa). A small percentage (8.0%) of the flora taxa (186 taxa) are quite common (dominant or common), on a scale ranging from dominant to rare (dominant, common, occasional, scattered, uncommon, and rare). Many more of the plant taxa in Ventura County are uncommon to quite rare.

All the species (including varieties and subspecies, which are lower taxonomic units than full species) of native and naturalized plants are important components of the biodiversity of life in Ventura County. While most species do not recognize political boundaries, such as county boundaries, our government agencies set policies and manage land use and resources based on such jurisdictional boundaries.

This list represents a compilation of known records and observations (many by the author) of all native vascular plant species:

· With ten (10) or fewer populations within Ventura County;

· Listed by CNPS on a statewide basis (CNPS 2001);

· Listed by the US Fish and Wildlife Service as Threatened or Endangered under the federal Endangered Species Act;

· Listed by the California Fish and Game Commission as Rare, Threatened, or Endangered;

· Are at the limits of their distribution range (southernmost, northernmost, westernmost extent); or

· The Type Locality occurs within the County (then only the Type Locality is considered sensitive).

Some taxa are considered rare or uncommon throughout California, as established by the California Native Plant Society (CNPS) in it’s Inventory of Rare and Endangered Plants of California, sixth edition[2], even though more than ten populations are known from Ventura County, including Anacapa Islands and San Nicolas Island. Currently there are 1,203 taxa (51.8% of the county flora) included on this list of locally rare plants (including taxa rare statewide), which include taxa on the mainland and two islands (Anacapa and San Nicolas). Another 164 (7.1%) were appended that are likely to occur in the County but for which no voucher specimens or reliable locality data are available. These are included at the end of this list. Many of these potential additions are known to occur in adjacent counties and expected to occur in Ventura County. A total of 62 plants (2.7%) considered rare in Ventura County occur only on the Channel Islands (Anacapa and San Nicolas Islands) portion of the county. A number of taxa were deleted from this list when over ten occurrences were known to occur in Ventura County.

This list was compiled as the results of extensive research of the flora of Ventura County. It is based on extensive field searches; examination of specimens collected by others housed at public herbaria; and published reports. The author began research on the Ventura County flora in the late 1970s.

Soon to be published separately, Ventura County Rare Plants will provide much more information about those plants included in this checklist, including: a brief description of the plant, habitat preferences, associated plant communities, elevation range, and blooming period. That publication will include additional information for each taxon, including complete scientific name, known synonyms, common name(s), habit and size, rarity status, months it is in bloom or identifiable, and general and specific locality data, with supporting voucher collection information. Each specimen cited for a specific location includes the name of the collector, the collection number (or collection date if no number was assigned), and the herbarium in which it is stored (some duplicate specimens have been deposited in more than one herbarium). Location information is provided at two levels: a general geographic area, and then specific locations.

This list should be considered the best available information at the time of publication, as our knowledge of the Ventura County flora is dynamic, and growing with each botanical survey or foray. This checklist will be updated periodically and revised according to all new verifiable information provided. Occurrences of vascular plants found in Ventura County that add to or could change the status of any plant listed here should be submitted to the author via CNPS (attention: David Magney) or via email to david(at)magney(dot)org. Any lists submitted must be supported by voucher specimens that are deposited in a public herbarium, according to CNPS and California Botanical Society policies based on Ferren et al. (1995[3]).

Plants not included in CNPS’s Inventory, or listed by federal and state agencies, that have more than ten populations in Ventura County will be dropped from this list, except for those plants:

· representing range limits, such as the westernmost limit of the taxons range; or

· the “Type Locality” sites (“Type Locality” sites are the sites from which the plant was originally collected and formally described from, and is represented by a “Type Specimen”, for which a note occurs after the herbarium at which it is deposited as “Holotype” or “Isotype”).

For those plants that are otherwise relatively common in Ventura County, only the populations that represent the limit of a plants range should be considered of concern (as sensitive), with the remaining population(s) noted to provide perspective, but not considered sensitive/rare for the purposes of this checklist. Artemisia tridentata var. tridentata is an example of this, where it should be considered of local concern when it occurs in the western portion of the Santa Clara River Valley (the limit of its range) while the populations in the Upper Sespe Creek watershed and the northern part of the county are not of concern from a rarity perspective.

Special-status species are plants that are either listed as endangered or threatened under the Federal or California Endangered Special Acts; or considered to be rare under the California Native Plant Protection Act; or considered to be rare (but not formally listed) by resource agencies, professional organizations (e.g. California Native Plant Society), and the scientific community. For the purposes of this checklist, special-status species are further defined in Table 1, Definitions of Special-Status Plant Species.

Listed species are those taxa that are formally listed as endangered or threatened by the federal government (e.g. U.S. Fish and Wildlife Service [USFWS]) pursuant to the national Endangered Species Act or as endangered, threatened, or rare (for plants only) by the State of California (i.e. California Fish and Game Commission) pursuant to the California Endangered Species Act or the California Native Plant Protection Act.

The CNDDB Element Ranking system provides a numeric global and state ranking system for all special-status plant and wildlife species and rare habitats tracked by the CNDDB. The global rank (G-rank) is a reflection of the overall condition of an element (species or natural community) throughout its global range. The state ranking (S-rank) is assigned much the same way as the global rank, except state ranks in California often also contain a threat designation attached to the S-rank. This Element Ranking system is defined below in Table 2, Natural Diversity Data Base Element Ranking System. Not all special-status species considered in this checklist are tracked by the CNDDB, nor have global or state rarity ranking been given to them; therefore, the author has applied the rules described above to “rank” those special-status species lacking such ranking. Taxa for which Global and State rarity ranking have been devised here are followed by a “?” in parentheses, denoting tentative assignment.

Table 1. Definitions of Special-Status Plant Species

1. Plants legally protected under the California and Federal Endangered Species Acts or under other regulations.

2. Plants considered sufficiently rare by the scientific community to qualify for such listing; or

3. Plants considered to be sensitive because they are unique, declining regionally or locally, or are at the extent of their natural range.

Special-Status Plant Species

¨ Plants listed or proposed for listing as threatened or endangered under the Federal Endangered Species Act (50 CFR 17.12 for listed plants and various notices in the Federal Register for proposed species).

¨ Plants that are Category 1 or 2 (species of special concern) candidates for possible future listing as threatened or endangered under the Federal Endangered Species Act (55 CFR 6184, February 21, 1990).

¨ Plants that meet the definitions of rare or endangered species under the CEQA (State CEQA Guidelines, Section 15380).

¨ Plants considered by the CNPS to be "rare, threatened, or endangered" in California (Lists 1A, 1B, and 2 in CNPS [2001][4]).

¨ Plants listed by CNPS as plants about which we need more information and plants of limited distribution (Lists 3 and 4 in CNPS [2001]).

¨ Plants listed or proposed for listing by the State of California as threatened or endangered under the California Endangered Species Act (14 CCR 670.5).

¨ Plants listed under the California Native Plant Protection Act (California Fish and Game Code 1900 et seq.).

¨ Plants considered sensitive by other federal agencies (i.e. U.S. Forest Service, Bureau of Land Management) or state and local agencies or jurisdictions.

¨ Plants considered sensitive or unique by the scientific community or occurring at the limits of its natural range (State CEQA Guidelines, Appendix G).

CNPS’s Inventory of Rare and Endangered Plants of California[5] categorizes rare California plants into one of five lists (1A, 1B, 2, 3, & 4) representing the five levels of species status, one of which is assigned to a sensitive species to indicate its status of rarity or endangerment and distribution. A CNPS List is a more general designation than the three separate sets of information provided in a CNPS R-E-D Code (see the CNPS Inventory for definitions). However, the CNPS List is a significant designation in terms of a species’ overall status throughout all of California, and it works well in conjunction to the specifications of the R-E-D Code. The CNPS R-E-D Code is a three-numbered numeric ranking, which is assigned to a special-status species, consisting of one number (1, 2, or 3) for each of the three categories (Rarity-Endangerment-Distribution). Each number accurately describes the species’ population levels and distribution patterns within each category.

As described for the NDDB ranking, not all special-status species (most) considered in this checklist are tracked by CNPS, nor have R-E-D codes been given to them; however, the author has applied the rules described above to “rank” those special-status species lacking such ranking to either “rare” or “uncommon”; however, these rankings are not included in the checklist. Rather the occurrence rankings for each are provided in the Ventura County Rare Plants and in the Flora of Ventura County to be published in 2006 by the author.

The large number of taxa on this list is the result of several factors:

1. Development in Ventura County has eliminated a majority of the natural vegetation in the southern half of the County, eliminating many occurrences of native plant species;

2. A number of taxa found nowhere else are present in Ventura County, local endemics, and several of these are listed as threatened or endangered by either the California Department of Fish and Game or the U.S. Fish and Wildlife Service;

3. Ventura County is geographically situated such that floral influences from the north, south, and east enter the County at its edges (limits of some species’ ranges);

4. Anacapa and San Nicolas Islands support many species found only on the California Channel Islands, including island endemics;

5. Ventura County is topographically and climatically diverse, providing numerous habitats for uncommon and rare species; and

6. Botanical surveys have not been conducted systematically everywhere in the County. In other words, the flora of Ventura County is not fully understood or documented, and additional populations of a number of the plants listed below likely occur in the County, we just aren’t aware of them yet. Regardless, significant collecting has occurred in the County over the last 150 years, and the author has a reasonably good understanding of the flora.

This list was compiled according to definitions under the California Environmental Quality Act (CEQA) under Initial Study Checklist Section 6, Subsections A and E. Projects reviewed under CEQA should consider impacts to one or more of the species included in this checklist as potentially significant. Generally, if a project would impact a population of one or more of the plants listed herein, that/those impact(s) should be considered significant unless substantial evidence is provided that may support an alternate conclusion.

What significance does a list of locally rare species have under CEQA?

The following answer is provided by John Buse, Esq., of the Environmental Defense Center of Ventura, California[6]. The CEQA Guidelines provide that a lead agency shall find that a project may have a significant effect on the environment if the project “… has the potential to … reduce the number or restrict the range of an endangered, rare or threatened species …”. Guidelines §15065(a). In addition, the CEQA Guidelines Appendix G Environmental Checklist Form considers whether a project would “have a substantial adverse effect, either directly or through habitat modifications, on any species identified as a candidate, sensitive, or special status species in local or regional plans, policies, or regulations …”.

According to the CEQA Guidelines, a species is considered “rare” when either:

(A) Although not presently threatened with extinction, the species is existing in such small numbers throughout all or a significant portion of its range that it may become endangered if its environment worsens; or

(B) The species is likely to become endangered within the foreseeable future throughout all or a significant portion of its range and may be considered “threatened” as that term is used in the Federal Endangered Species Act. Guidelines §15380(b)(2).

Table 2. Natural Diversity Database Element Ranking System

Global Ranking (G)
G1	Less than 6 viable element occurrences (populations for species) OR less than 1,000 individuals OR less than 809.4 hectares (ha) (2,000 acres [ac]).
G2	6 to 20 element occurrences OR 809.4 to 4,047 ha (2,000 to 10,000 ac).
G3	21 to 100 element occurrences OR 3,000 to 10,000 individuals OR 4,047 to 20,235 ha (10,000 to 50,000 ac).
G4	Apparently secure; this rank is clearly lower than G3 but factors exist to cause some concern (i.e. there is some threat, or somewhat narrow habitat).
G5	Population or stand demonstrably secure to ineradicable due to being commonly found in the world.
GH	All sites are historic; the element has not been seen for at least 20 years, but suitable habitat still exists.
GX	All sites are extirpated; this element is extinct in the wild.
GXC	Extinct in the wild; exists in cultivation.
G1Q	The element is very rare, but there is a taxonomic question associated with it.
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, whereas the T-rank refers only to the global condition of var. hartwegii.
State Ranking (S)
S1	Less than 6 element occurrences OR less than 1,000 individuals OR less than 809.4 ha (2,000 ac). S1.1 = very threatened S1.2 = threatened S1.3 = no current threats known
S2	6 to 20 element occurrences OR 3,000 individuals OR 809.4 to 4,047 ha (2,000 to 10,000 ac). S2.1 = very threatened S2.2 = threatened S2.3 = no current threats known..
S3	21 to 100 element occurrences OR 3,000 to 10,000 individuals OR 4,047 to 20,235 ha (10,000 to 50,000 ac). S3.1 = very threatened S3.2 = threatened S3.3 = no current threats known
S4	Apparently secure within California; this rank is clearly lower than S3 but factors exist to cause some concern (i.e. there is some threat, or somewhat narrow habitat). NO THREAT RANK.
S5	Demonstrably secure to ineradicable in California. NO THREAT RANK.
SH	All California sites are historic; the element has not been seen for at least 20 years, but suitable habitat still exists.
SX	All California sites are extirpated; this element is extinct in the wild.

Notes: 1. Other considerations used when ranking a species or natural community include the pattern of distribution of the element on the landscape, fragmentation of the population/stands, and historical extent as compared to its modern range. It is important to take a bird’s eye or aerial view when ranking sensitive elements rather than simply counting element occurrences.

2. Uncertainty about the rank of an element is expressed in two major ways: by expressing the rank as a range of values (e.g., S2S3 means the rank is somewhere between S2 and S3), and by adding a ? to the rank (e.g. S2?). This represents more certainty than S2S3, but less than S2. (CNDDB 2002.)

Species already listed under the California or federal ESA shall be presumed to be endangered, rare, or threatened. Guidelines §15380(c). A species not currently listed shall nevertheless be considered to be endangered, threatened, or rare if it meets the criteria in the CEQA definitions of “endangered” or “rare”. The term “sensitive” species, which appears in the Appendix G checklist, is not defined in CEQA.

If a species is considered locally rare due to its limited occurrence within a political boundary, such as the County of Ventura, and if the species’ local population constitutes a significant portion of its range, the species must be considered a rare species under CEQA. The mere placement of a species on a list of locally rare species is probably not enough to meet the CEQA criteria for endangered, threatened, or rare species. However, if the list contains some additional explanation indicating why the species meets the CEQA criteria, such as the fact that the local population constitutes a significant portion of the species’ range, the list should provide substantial evidence of rarity.

If the CEQA criteria are satisfied, it is irrelevant that a species is relatively common in other locations. For example, the Pacific Coast populations of the Snowy Plover are listed as threatened under the federal ESA, despite the fact that inland populations are relatively common and are not protected. The existence of the non-listed populations does not diminish the Snowy Plover’s status as a endangered, threatened, or rare species under CEQA. By extension, if the Pacific Coast populations of the Snowy Plover were not listed as threatened, these populations would still be considered endangered, threatened, or rare under CEQA. Accordingly, the special status for Snowy Plover in Ventura County under CEQA would still apply even if Snowy Plover was relatively common in, for example, Mono County. Assertions implying that a species necessarily does not warrant inclusion on a list of locally rare species if it is common elsewhere in California simply because it occurs rarely in Ventura County within a political boundary are incorrect. As the Snowy Plover example indicates, there will be instances when a locally rare species must be considered rare under CEQA despite the species’ common occurrence elsewhere in California.

Snowy Plover on the Pacific Coast is protected under the federal ESA based on the concept of a “distinct population segment” (DPS). Something similar to the DPS concept could be used to determine whether a locally rare species is, in fact, endangered, threatened, or rare under CEQA. The federal ESA allows a DPS, defined according to geographic or reproductive isolation, to be treated as a “species”. Therefore, as in the Snowy Plover example, a DPS can be listed even though the populations of the taxonomic species are common elsewhere. CEQA does not preclude use of the DPS concept to assist in understanding whether a species is endangered, threatened, or rare based on its local rarity; on the contrary, the CEQA Guidelines definition of “rare” appears to invite the consideration of similar circumstances that would inform the determination of a DPS under the federal ESA.

Under CEQA, lead agencies have considerable discretion in determining whether a species should be considered rare or sensitive. See, for example, the State CEQA Guidelines Appendix G checklist cited above, which indicates that lead agencies may designate candidate, sensitive, or special-status species in local or regional plans, policies, or regulations. A list of locally rare or sensitive species, if it is developed based on evidence that the local rarity meets the CEQA criteria for rarity, will effectively establish a rebuttable presumption of significance for species that may be adversely affected by a project. In this respect, a list of locally rare species as presented below will function in a manner similar to the threshold of significance that a lead agency may establish. CEQA requires, however, that thresholds of significance for general use in a lead agency’s environmental review process “must be adopted by ordinance, resolution, rule, or regulation, and developed through a public review process and be supported by substantial evidence.” Guidelines §15064.7. For a list of locally rare or sensitive species to function as a set of thresholds of significance, therefore, the list should be adopted through a public review process. Even if the list is not adopted through a public review process, it will establish substantial evidence of rarity if it is accompanied by additional information showing, for example, that the local occurrences of a listed species constitute a substantial portion of the species’ range.

CNPS believes that this list of locally rare plants meets the definitions of rarity, at least locally, to satisfy consideration under CEQA. This checklist is supported by substantial evidence in the files of the author and data obtained from public herbaria and knowledgable local botanists. Many of the taxa listed in this checklist are also listed by CNPS as rare or sensitive statewide, as well as those taxa formally listed under the California and/or federal ESA.

This checklist is updated regularly based on new information on the Ventura County flora. Species are added or deleted from this list as the new data warrant; therefore, be sure to obtain the most up-to-date version of this checklist. For example, for this update, compared to the 3 August 2007 version, 9 taxa were added, 20 were dropped (listed at end of this list), 13 had their rarity status changed (usually lowered from Rare to Uncommon), and 2 taxa were added to the “expected to occur” list while 9 taxa where removed. Changes in nomenclature were also made, where appropriate. Future changes to this list will not likely be as dramatic as the status of the flora of Ventura County is now better understood after extensive searches of California public herbaria were conducted through the Jepson Herbarium on-line Consortium database.

The most up-to-date version can be downloaded (as a PDF) from the Channel Islands Chapter CNPS website at www.cnpsci.org, or by contacting the author directly. Please send your notes on corrections, errors, and plant populations/occurrences you are aware of that may not be on this checklist to the author: David Magney, P.O. Box 1346, Ojai, CA 93024-1346 or via email at david(at)magney(dot)org. Also contact the author if you need any specific locality data on any particular taxon included in this checklist.

Checklist of Rare Plants

Scientific Name[7] Common Name[8]

Abies lowiana (Gordon & Glendinning) E. Murray California White Fir (U) LPNF

Abronia maritima Nutt. ex S. Watson X A. umbellata Lam. Hybrid Sand-verbena (R)

Abronia maritima Nutt. ex S. Watson Red or Sticky Sand-verbena (U) CNPS 4