1. Educational Bulletin #11-1
A publication of the Desert Protective Council protectdeserts.org
Ten California Desert Plants That Should Be Protected
Under The Federal Endangered Species Act
by James Andre and Chris Clarke
The Inyo star tulip (Calochortus excavatus), a California desert plant whose survival
depends on the survival of its alkali marsh habitat, lately threatened by water
diversions for agriculture. Miguel Viera photo
Though the endangered species that capture public attention mer – this means that we are far from completing even the basic
are generally animals, extinction looms for plants as well. Out of inventory of species in the California desert. The deserts are not
all the species of seed plants, 25-40 percent may be in danger of quite a blank spot on the botanical map, but they are about as
extinction worldwide. In 2010 Kew Gardens botanists estimated unexplored, in the botanical sense, as any tropical rainforest. As
that 400,000 plant species now live on the planet, which would put many as a tenth of the plants you see in a specific desert landscape
the total of endangered seed plant species at between 100,000 and may be undescribed, or described so recently that they are not yet
160,000. By comparison, about 4,300 species of mammals, birds, included in the canonical Jepson Desert Manual.
amphibians and reptiles are considered endangered. Losing any plant species to extinction is a tragedy, as plants,
With its varied microclimates and soil types, as well as its rug- the primary producers of biomass from sunlight, are the center
ged topography that provides abundant barriers to the flow of of the web of life. Losing a plant species means losing that spe-
plant genes, the California desert is an engine of evolution. More cies’ ecology – the relationships that species had with the animals,
than 2,400 vascular plant species and subspecies have been docu- fungi and other plants it lived with. A plant’s extinction often has-
mented in the California desert, representing more than a third of tens the extinction of the other organisms that depend on it. If the
the state’s known plant biodiversity, and yet the desert is still es- California desert’s flora is largely unknown, its botanical ecology
sentially a floristic frontier, with many species and subspecies yet is even more so.
to be discovered. We can only guess at the number of California As an example: no one knows what animal pollinates the
desert plants facing extinction, primarily because comparatively Mojave monkeyflower, Mimulus mohavensis, which is known only
little is known about what plants grow there in the first place. The from a few sites in the Mojave River drainage. The monkeyflower’s
remote and forbidding character of the desert has impeded bo- habitat is under extreme pressure from residential and industrial
tanical exploration, as has a long-term decline in plant taxonomy development, and much of it would be designated a federally rec-
as a career choice for new biologists. Most records of desert plant ognized off-road vehicle park by the California Desert Protection
species now kept in herbaria were collected along paved roads, Act. Whatever unknown creature pollinates the Mojave monkey-
many of them more than 50 years ago. As the deserts are home to flower is likely to be dependent on the species for survival. Losing
many plant species with severely restricted ranges, or which ap- the flower could mean losing that unknown creature, and perhaps
pear only during certain unusual climate patterns – such as fall setting in motion a cascade of damage to one ecological relation-
annuals that grow and bloom only after a wetter than usual sum- ship after another.

2. Today California’s deserts are under threat as never before, with Mimulus mohavensis
potential energy development over millions of acres added to the (Mojave monkeyflower)
usual threats from urbanization, invasive species, grazing, min-
ing and off-road vehicle use. Despite this, the US Fish and Wildlife
Service has not enacted Endangered Species Act protection for a
California desert plant species since 1998, when it listed the Lane
Mountain milkvetch (Astragalus jaegerianus) as endangered. In
fact, the political momentum has been running toward weaken-
ing protections: Fish and Wildlife proposed down-listing the Lane
Mountain milkvetch to “Threatened” in 2010, despite there being
only four known populations of the plant.
Following is a list of ten California desert plant species we feel
are deserving of protection under the federal Endangered Species
Act. The plants listed here are prominent candidates for listing,
but they are by no means the only such plants, and perhaps not
even the most critically endangered plants in the California des- Lara Hartley
ert. Each species account includes the “threat” ranking applied
to the species by the California Native Plant Society (CNPS) and
the “Global Rank” assigned by the International Union for the
Conservation of Nature (IUCN), along with an explanation of the Present Status: CNPS List 1B.2: Fairly endangered in California
rank. We’ve also included a short summary of the threats to each Global Rank: G2 Imperiled – At high risk of extinction or elimi-
species, and photos where possible. nation due to very restricted range, very few populations, steep
declines, or other factors
Penstemon albomarginatus Plant Communities: sandy or gravelly washes, Joshua tree wood-
(white-margined beardtongue) land, Mojavean desert scrub
Though it is a member of a genus that is widespread and abundant
in California, this species is restricted to a few scattered occur-
rences in the hills south and east of Barstow, California.
Why should this plant be listed under ESA? Once more common
in the upper half of the Mojave River watershed, the majority of
historic populations of this tiny annual have been harmed by hu-
man activity, with many such populations extirpated. Threatened
by development (especially in the highly developed Barstow-Vic-
torville corridor), mining, invasive plants, solar and wind energy
projects, and ORV activity.
Mentzelia tridentata
(creamy blazing star)
Present Status: CNPS List 1B.3, Not very endangered in California
Global Rank: G2 Imperiled – At high risk of extinction or elimi-
Jim Andre nation due to very restricted range, very few populations, steep
declines, or other factors
Plant Communities: Mojavean desert scrub
Present Status: CNPS List 1B.1; Seriously endangered in California This showy blazing star is a California endemic restricted to the
Global Rank: G2 Imperiled – At high risk of extinction or elimi- Rodman and Ord Mountains southeast of Barstow, and the Black
nation due to very restricted range, very few populations, steep Mountain area near Calico northeast of Barstow. Occurrences of
declines, or other factors this species in the southern Owens Valley have been reported, but
Plant Communities: dunes, Mojavean desert scrub these reports have not been verified.
A showy tap-rooted perennial that is known from just four widely Why should this plant be listed under ESA? The species is highly
separated populations; one in California, two in Nevada, and one restricted in its distribution. Threats to Mentzelia tridentata in-
in Arizona. clude damage by recreational vehicles, mining, military activities,
Why should this plant be listed under ESA? All occurrences grazing, and renewable energy development.
are threatened by solar energy development, military activities,
or impacts associated with encroaching urbanization. The lone Photo credits: Calochortus excavatus: Miguel Viera. Penstemon
California occurrence near Pisgah Lava Flow is imperiled by the albomarginatus, Plagiobothrys parishii: Jim Andre. Mimulus
proposed Calico solar energy project. mohavensis, Cymopterus deserticola: Lara Hartley. Linanthus
maculatus: Mark Skinner. Penstemon bicolor: Stan Shebs.
Puccinellia parishii: Robert Soreng.

3. Linanthus maculatus Cymopterus deserticola
(Little San Bernardino Mtns. linanthus) (desert cymopterus)
Lara Hartley
Mark Skinner
Present Status: CNPS List 1B.2: Fairly endangered in California Present Status: CNPS List 1B.2: Fairly endangered in California.
Global Rank: G2 Imperiled – At high risk of extinction or elimi- Global Rank: G3 Vulnerable – At moderate risk of extinction or
nation due to very restricted range, very few populations, steep elimination due to a restricted range, relatively few populations,
declines, or other factors recent and widespread declines, or other factors.
Plant Communities: dunes, Joshua tree woodland, Mojavean and Plant Communities: dunes, Joshua tree woodland, Mojavean
Sonoran desert scrub desert scrub
This minute annual in the phlox family is known only from the A celery-family plant with a very small native range restricted to
northern section of Joshua Tree National Park and along the BLM and Defense Department lands near Boron, California.
northern boundary of JTNP in adjacent Morongo Valley between Why should this plant be listed under ESA? The desert cymop-
29 Palms and Yucca Valley. terus has very limited and patchy distribution. Most known oc-
Why should this plant be listed under ESA? The range of this currences of the plant are within the boundaries of Edwards Air
species is highly restricted and fragmented. Individual plants are Force Base with low numbers of individuals. Threats include mil-
reproductively self-incompatible, which means long-term viabil- itary activities, sheep grazing, recreational vehicles, utility con-
ity of the species requires sizable, non-fragmented populations to struction, solar and wind energy development, and urbanization.
ensure reproductive success. The species is threatened by all the
issues one might expect near Joshua Tree National Park, including Penstemon bicolor
urbanization, recreational foot traffic, vehicles, and dumping. (two-toned beardtongue)
Eriogonum bifurcatum
(forked buckwheat)
Present Status: CNPS List 1B.2: Fairly endangered in California
Global Rank: G2 Imperiled – At high risk of extinction or elimi-
nation due to very restricted range, very few populations, steep
declines, or other factors
Plant communities: shadscale scrub
This small annual buckwheat grows in barren clay saline valleys.
Known in California from one occurrence in western Pahrump
Valley. The species is also very rare in Nevada; its distribution is
limited to Pahrump and Mesquite Valleys.
Why should this plant be listed under ESA? Fewer than 1,500 Stan Shebs
individual plants of this species exist, by most estimates. All oc-
currences seriously impacted include commercial or residential
development, agricultural conversion, offroad vehicle activities,
dumping, and proposed renewable energy development. Present Status: CNPS List 1B.1: Seriously endangered in California.
Global Rank: G3T3Q Vulnerable – At moderate risk of extinction
or elimination due to a restricted range, relatively few popula-
tions, recent and widespread declines, or other factors. Both named
subspecies are vulnerable, though there is some disagreement over
whether those subspecies are valid.
Plant Communities: Joshua tree woodland, Mojavean desert scrub

4. This showy perennial includes recognized subspecies bicolor (yel- nants of former populations.
low flowers) and roseus (magenta flowers). Both subspecies are Why should this plant be listed under ESA? Alkali meadow
limited in distribution in Clark County Nevada, with ssp. roseus habitat is disappearing rapidly; occurrences of the Inyo star tulip
known from only one locality in California in the Castle Moun- are threatened by groundwater pumping, development, livestock
tains. Conservationists are attempting to add the site, which has grazing and trampling, invasive plants, road maintenance, and
several nearby pending renewable energy applications, to the Mo- proposed energy developments.
jave National Preserve.
Why should this plant be listed under ESA? Distribution has been Puccinellia parishii
seriously fragmented by development with many historic occur- (Parish’s alkali grass)
rences extirpated. The majority of existing occurrences are threat-
ened by mining, burgeoning renewable energy development, ex-
panding urbanization (e.g., Las Vegas), and hybridization with the
more widespread Penstemon palmeri, a popular garden plant. Robert Soreng
Plagiobothrys parishii
(Parish’s popcorn-flower)
Jim Andre
Present Status: CNPS List 1B.1: Seriously endangered in California,
Global Rank: G1 Critically Imperiled – At very high risk of extinc- Present Status: CNPS List 1B.1: Seriously endangered in California.
tion due to extreme rarity, very steep declines, or other factors. Global Rank: G2G3 – At between moderate and high risk of
Plant communities: alkali meadows extinction or elimination due to a restricted range, relatively few
This California endemic grows in alkali meadows and seeps and populations, recent and widespread declines, or other factors.
is extremely limited in its distribution – it is known in California
from just four or five occurrences at Rabbit Springs in San Ber- Plant communities: alkali meadows
nardino County and in the Owens Valley region of Inyo County. Known in California only from Rabbit Springs, where it was con-
There is some taxonomic ambiguity within the species; some bot- firmed in 1992. An occasionally cited occurrence on Edwards Air
anists speculate that the Owens Valley plants represent a distinct Force Base is misidentified Puccinellia simplex. Also very rare in
taxon separate from the Rabbit Springs occurrence. AZ and NM (where is it state listed).
Why should this plant be listed under ESA? Highly restricted Why should this plant be listed under ESA? Highly restricted and
distribution. All the known occurrences are threatened by water- disjunct distribution. The known occurrences are threatened by
course diversions and groundwater pumping, livestock grazing, hydrological alternation (flood control, diversions and groundwa-
and competition with exotic species. ter pumping), livestock grazing and trampling, and competition
with exotic species. Fish and Wildlife briefly considered listing the
Calochortus excavatus grass during the 1980s.
(Inyo star tulip)
Botanist James M. Andre is Director of the University of Cali-
Present Status: CNPS List 1B.1 : Seriously endangered in California fornia’s Granite Mountains Desert Research Center in California’s
Global Rank: G3 Vulnerable – At moderate risk of extinction or Mojave Desert. Chris Clarke is a natural history writer in Palm
elimination due to a restricted range, relatively few populations, Springs.
recent and widespread declines, or other factors.
Plant communities: alkali meadows
This showy California endemic is known only from alkali mead-
ows of the Owens Valley region. Most occurrences are small rem-