California Desert Flora

3-5 March 2006

Jim Cornett, Instructor


Jim Cornett is a desert biologist living in Palm Springs” and “independent ecologist”

Writes for the Desert Sun


NOTE: unless otherwise indicated, page numbers are to Dole and Rose’s An Amateur Botanist’s ID Manual (1996).


        I.  What is a Desert?

            A. Precipitation (less than ten inches per year; semi-arid is 10-20 inches)

            B. Temperature (>38 degrees C/90 degrees F)

                        1.  Difference of one degree can increase range by 100 miles north

            C. Wind, lack of cover (day versus night, solar radiation released)


II.    Types of Deserts

A.    High (Mojave)

B.     Low Sonoran (Colorado)


III. Kinds of Desert Plant Communities

A.    Not a rigid schema; all of associated plants, animals, and abiotic components (make up an ecosystem)

B.     Pinyon-Juniper Woodland

1.      4,000-8,000 foot level

C.     Joshua Tree Woodland

2.      6500 – 3,000 range, but 4000-2500 foot level generally

3.      Creosote Bush Scrub (CBS)

a.      Below 3500 feet in both deserts

b.      On alluvial fans and flatlands

c.       Spaced out, artificially appears to be

d.     Smell; ancient 10K BCE; growth marks on branch; growth in concentric circles

e.      dominant plant in this ecosystem (creosote bush) and others

f.        Flowers: Sahara mustard (non-native pushing out many other species), cheesebush (p. 100, yellow flower pedals), chuparosa (p. 31,38, 46, and 92), popcorn flower (Plagiobothrys nothofulvus, 1 of 16 plants found everywhere; desert tortoise food—sample), burrobush (food for burros), **** (problem with LB: Mirabilis Fremontii), Trixis California (p. 99), desert lavender (mint family), calico or strawberry hedgehog cactus (Echinocereus Engelmannii), indigo bush, wild heliotrope (purple), teddy bear cholla, golden/silver cholla (birds like to nest in it), Fremont’s pincushion, little gold poppy, barrel cactus (worth up to $1000 for mature specimens), beaver tail cactus (short/no spines)

4.      Alkali Sink

a.      Dry lake beds; below sea level in the Mojave

IV.             Plants Facts, Strategies, and Adaptations

A.    Four parts to a flower (PPPS--see figure 1 on page 4):

1.      Pedicel—stalk and receptacle at the base

2.      Perianth (composed of both a and b)

a.      sepal (all of them taken together are known as calyx)

b.      petals (all of them taken together are known as corolla)

i. ray petals versus disc flower

3.      Pistil (female)

a.      ovary, ovules

b.      style and stigma

4.      Stamen (male)

a.      filament and anther

B.     Dioecious (male and female--“two houses”) versus monoecious (having reproductive parts on different flowers—“perfect”)

C.     Drought deciduous means to drop its leaves, becoming dormant in times of extreme drought

D.    Color

1.      Yellow is easiest to see at a distance

2.      Red appeals to hummingbirds

E.     Armament

1.      Due to slow growth; can’t give up leaves

2.      Chemical (e.g., milk vetch)

3.      Physical (e.g., cactus)

F.      Drought avoiders (most ephemerals)

G.    Drought endurers (e.g., creosote and brittlebush)

H.    Drought escapers (e.g., mesquite, smoke tree, Palo verde)

V.                Keying out plants

A.     Botanizing, based on dichotomous keys (natural or artificial)

1. Larrea tridentata; common name: creosote bush (dominant plant; growth marks on branches; 10,000CBE)

a)      Dole and Rose:

3.      Encelia farinosa; common name: brittlebush (pioneer plant)

a)      Dole and Rose:

4.      Justicia californica; common name: chuparosa; from the Spanish meaning “to suck,” found in low-elevation washes

a)      Dole and Rose: 1B, 2B, 3A, Key C p. 23: 1A, 2B, 3B, 4A, and Key C-4.2: 1A, go to p. 92

5.      Ferocactus cylindraceus; common name: California barrel cactus

a)      Dole and Rose: 1A, Key A: 1B, 4B, go to p. 139

6.      Viguiera parishii; common name: desert sunflower

a)      Dole and Rose: 1B, 2B, 3A, Key C, p. 23: 1A, 2B, 3B, 4A, Key C-2: Flowers in Heads, p. 24: 1B, 2B, Key C-2.2: Ray and Disc Flowers, p. 26: 1B, 5B, 6B, and 8A, go to p. 100

VI.             Plants Not Keyed Out

A.    Flowers: desert agave, oleander (fatal to bighorn sheep), honey mesquite (pea family; always has fruit; roots always in ground water within 60 feet of surface; shelter for rabbits and rats; in the Colorado desert, they are on fault line), cat’s paw acacia, devil’s claw or unicorn plant (requires summer rain), Thurber’s sandpaper, Palo verde (pea family), ocotillo (nesting site for wood rats), desert lily (only in rainy years), prickly pear poppy (pioneer plant), Coachella Valley milkvetch (“loco weed”—chemical armament, selenium), chinch weed (summer rain plant), giant four o’clock (shrub), paperbag bush (Salazaria Mexicana), lotus (deer weed), climbing milk weed (small vine), crucifixion thorn (I-8 preserve in Imperial County),  Arizona lupine, ghost flower, Mojave owl’s clover, Sahara mustard, cheesebush (aka burrobrush; Hymenoclea salsola), chuparosa, popcorn flower (Plagiobothrys nothofulvus; tortoise food—sample), burrobush (Ambrosia dumosa, food), mirabilis fremontii, California Trixis (Trixis californica), desert lavender (mint), calico cactus (englemanni), indigo bush, wild heliotrope (purple), teddybear cholla cactus, golden/silver cholla (birds like to nest), fremont’s pincushion, little gold poppy (ephemeral) , Spanish needle (no ray pedals; disc flowers; in the dunes can be 7’ tall—gigantia), brown-eyed primrose, California croton, hairy sand verbena (Abronia pogonantha), desert sunflower (Gereae Canscens; most typical under Edom Hill—see GPS reading), tumbleweed (aka Russian thistle; came with Asian grain shipments), cattle spinach (allscale), mesquite (220’ long tap root), California buckwheat, jumping cholla (Opuntia bigelovii), fiddleneck, Mammallaria (CAM metabolism)

B.     Cactus: only in new world (North and South America) found in desert and tropical rain forest (up in tree forks). Examples: foxtail cactus,

C.     Trees: Saltcedar, Smoke Tree, Tamarisk tree (Tamarix chinensis; Native to Asia and eastern Europe, but naturalized in much of the Western U. S. and northern Mexico.”  Planted as a windbreak along the railroad (SP, which irrigates them) and then CAL DOT

VII.          Related Animals in the Ecosystem

A.    California desert kangaroo rat lives in hemispherical holes

B.     Ground squirrel lives in round holes

C.     California desert tortoise, Gopherus (Xerobates) agassizii

D.    Sun Spider (Solpugids)

VIII.       Recommended Textbooks

A.    Key Approaches (based on dichotomous decisions)

A.    Dole and Rose, An Amateur Botanist’s ID Manual for the Shrubs and Trees of the Southern California Deserts (1996)

1.      good for basic vocabulary so you can talk about cacti, shrubs, and plants; illogical arrangement (i.e., non-alphabetical), so you can’t use it directly without going through the key or index

B.     Botany in a Day ( for $17.50)

1.      Strong on family ID by general characteristics

2.      See spreadsheet to help learn them

C.     Edmund C. Jaeger, Desert Wild Flowers (Stanford University Press, 1941)—intermediate level text; strong on the biographical or social history of who is behind the genus and species

D.    The Jepson Desert Manual (2002)—advanced; mostly line drawings, only 128 color plates


B.     Picture Books (match the flower to the picture)

A.    Pam MacKay, Mojave Desert Wildflowers (2003)

1.      Falcon series has superior pictures


IX.              Websites Discovered

A.    Michael Charters HomePage at

B.     USDA National Resources Conservation Service’s “Plant Database” at


Revised: 7 March 2006; 3 April 2006; 10 April 2006