Saharan mustard (Brassica tournefortii) is a member of the
mustard family (Brassicaceae) and is native to the arid regions and
deserts of North Africa, the Middle East, and Southern Europe
surrounding the Mediterranean Sea. Botanists believe that it was
introduced several times into Southern California and Arizona in the
early part of the twentieth century, and locally seeds likely
hitched a ride in the seeds and plant stock of date palms that were
planted in the Coachella Valley in the early 1920s.
It is an extremely invasive
annual species that has become an increasing threat to annual desert
wildflowers and other native species in several western states.
Unfortunately there is not now an effective way to treat large areas
of infestation, but locally we can reduce the threat in selected
areas within the park. Anecdotal reports indicate that Saharan
mustard may be substantially decreased where it is not common if
there is follow-up treatment in subsequent years.
Saharan mustard is an annual plant that has a
basal rosette of turnip-like lobed leaves that are covered with
bristly hairs and produces mostly leafless branching flowering
stalks that extends above the basal leaves. Larger plants may also
have lateral flowering shoots arising from the base of the plant.
The flowers are pale yellow and have four petals later producing
long, narrow seed pods. Plants may vary in size from a few inches
tall in drier areas to very robust plants that are often 2 – 3 feet
across in wetter areas, especially in sand, washes, and along
roadsides. The mustard uses up water and nutrients and crowds out
the native plants.
Saharan mustard seeds commonly
germinate after the early winter rains, but occasionally they will
germinate after late summer and fall storms, generally after August.
There may be a series of germination events after each storm,
creating a mosaic of plants of different sizes and stages of
development. It may be necessary to revisit the site after each
storm. Also, plants may appear in areas where you may have not seen
It is important to know that
there are similar looking native plants that often co-occur with
Saharan Mustard and an effort should be made to learn the
differences with someone trained in plant identification during a
scheduled training session.
1) Tansy mustard (Descurainia
pinnata) is an annual plant that has very finely divided
gray-green leaves and small yellow four-petaled flowers
producing short club-shaped seed pods.
2) California Mustard (Guillenia
lasiophylla) has tiny white to cream-colored four-petaled
flowers. The leaves (although variable) are usually scalloped or
comb-like and are smooth to the touch. This delicate plant is
somewhat lax and often grows at the base of small shrubs.
3) False mustard (Camissonia
californica) a native plant in the evening-primrose plant
family that may be mistaken for Saharan Mustard because it has
relatively larger yellow four-petaled flowers. It has scalloped
to toothed leaves that are often red-dotted and are smooth to
the touch. The long seed pods are reflexed down along the axis
of the stem.
You may find photos of the
plants listed above online at Calphotos – plants
homepage browse using the first letter of the scientific name, the
genus name, for example, "C" for Camissonia, then in the next
window, scroll down until you find the two word scientific name Camissonia californica
on the list and click on that.
Incidentally, the common name False Mustard does not occur on the
common name list. There may be several common names for a plant,
therefore it’s better to browse using the scientific name.
Early treatment is essential. The mustard seeds may germinate
before many of the native wildflowers, but not always. You will soon
develop a ‘search image’ for the plant in the various stages of
development and be able to distinguish it from the wildflower
At the Henderson Canyon Road
site, we have found that carefully weeding with a hand-held weeding
tool is more effective than using a hoe where the mustard is growing
close to the native plants. You may use a stirrup hoe (a
long-handled tool with an oval cutting edge). It is better than a
garden hoe because it doesn’t drag as much soil with it but cuts the
plant at ground level.
Small pulled plants can be
left in the field as long as they don’t cover native plants. In the past, we have started treatment late in the season when the
plants were in flower and/or fruit, but that required a lot of extra
work to pull, bag and dispose of them. Later in the season before
the larger plants produce mature seed pods, they will need to be
bagged and removed from the site.
sturdy boots, gloves, plenty of drinking
water, snacks, sunscreen, wide-brim hat, and a hoe, and hand shears
to cut off the taproot and the flowering stalks of larger plants
later in the season.
placard for 2010-11: Park
volunteers must attend one of the scheduled training sessions. You
will be required to fill out a volunteer service agreement and will
receive a placard (permit) to work within the park. Please display
this placard in the window of your vehicle when you enter Borrego
Palm Canyon Campground, or are working elsewhere within the park.
Anza-Borrego Desert State Park volunteers who have had previous
training may pick up a placard from the volunteer coordinator at the
Visitor Center or contact Larry Hendrickson (phone number and email
The following suggestions will
help us reduce any negative impacts to native plant species and
ensure that the park visitor experience is not affected by this
Select an area and survey
it first. Smaller plants often occur in the drier gravelly soil
and are almost invisible. These plants will often mature faster
(bolt) than plants in wetter areas, that is, they may have
already produced flowers and seed pods. These smaller mature
plants should be bagged for removed. Also, smaller less
developed plants are often hidden in the shade at the base of
shrubs and cacti. You may be able to use your weeding tool to
Be careful not to disturb
native vegetation. If working with others, spread out so that
you minimize trampling of native annual plants.
For aesthetic as well as
safety reasons, do not dispose of plants on or at the edge of
Be vigilant for
rattlesnakes at any time of year.
Do not place pulled plants
on top of other plants or toss them onto shrubs. You may place
plants in a bare area nearby or on top of boulders. You make
stack them if space is limited, but piled plants may not dry
sufficiently, and surprisingly, the larger plants have enough
energy to continue to grow even after they have been pulled out
of the ground!
There are many rodent
burrows at the Henderson Canyon site, usually several holes
surround a mound of sand. Do not walk on them because you may
sink into the burrow. Use a hoe to remove the mustard around
must keep a record of hours and where they worked and convey
that information to Larry Hendrickson. ABDSP volunteers should
record their hours at the visitor center and report hours
to Larry Hendrickson.
take the opportunity to educate interested park visitors about
the program. If asked, explain that they will not be able
to pull mustard in the park without attending a training session
and have written permission to do so.
Thank you very much for your
Larry Hendrickson, Senior Park Aide,
California State Parks, Colorado Desert District, 200 Palm Canyon
Drive, Borrego Springs, CA 92004