Introductory
SPECIES: Chilopsis linearis | Desert Willow 



ABBREVIATION : 
CHILIN

SYNONYMS : 
NO-ENTRY


SCS PLANT CODE : 
   CHLI2


COMMON NAMES : 
   desert willow
   desertwillow
   flowering willow
   flowering-willow
   willowleaf catalpa
   desert catalpa
   catalpa willow
   false-willow
   bow willow
   mimbre
   Flor de Mimbre
   jano


TAXONOMY : 
The currently accepted scientific name of desert willow is Chilopsis
linearis (Cav.) Sweet [17,27,49].  

Chilopsis is a monotypic genus native to the southwestern United States
and northern Mexico.  It is a member of the Bignoniaceae family, and is
most closely related to the genus Catalpha Scop.  Presented below is a
recent taxonomic revision of Chilopsis, which divides the species into 3
subordinate taxa based primarily on leaf morphology and growth form
[13]:

Chilopsis linearis (Cav.) Sweet

  ssp. linearis

    var. linearis - Chihuahuan Desert

    var. tomenticaulis Henrickson - eastern Mexico

  ssp. arcuata (Fosberg) Henrickson - Sonoran and Mojave Deserts


LIFE FORM : 
Tree, Shrub

FEDERAL LEGAL STATUS : 
No special status

OTHER STATUS : 
NO-ENTRY


COMPILED BY AND DATE : 
Ronald Uchytil, September 1990


LAST REVISED BY AND DATE : 
NO-ENTRY


AUTHORSHIP AND CITATION : 
Uchytil, Ronald J. 1990. Chilopsis linearis. In: Remainder of Citation

DISTRIBUTION AND OCCURRENCE
SPECIES: Chilopsis linearis | Desert Willow 



GENERAL DISTRIBUTION : 
Desert willow is distributed from southwestern and Trans-Pecos Texas
west to extreme southwestern Utah, southern Nevada, and southern
California [21].  It is also found in northern Mexico.

Subspecies linearis var. linearis occurs primarily east of the Rio
Grande River in eastern New Mexico and western Texas, while subspecies
arcuata occurs primarily west of the Rio Grande River [13].  


ECOSYSTEMS : 
   FRES30  Desert shrub
   FRES32  Texas savanna
   FRES33  Southwestern shrubsteppe
   FRES40  Desert grasslands


STATES : 
     AZ  CA  NV  NM  TX  UT  MEXICO


ADMINISTRATIVE UNITS : 
     AMIS  BIBE  CACA  CHIR  CORO  FOBO
     GRCA  GUMO  JOTR  LAME  MOCA  ORPI
     SAGU  WHSA


BLM PHYSIOGRAPHIC REGIONS : 
    7  Lower Basin and Range
   12  Colorado Plateau
   13  Rocky Mountain Piedmont


KUCHLER PLANT ASSOCIATIONS : 
   K027  Mesquite bosque
   K041  Creosotebush
   K042  Creosotebush - bursage
   K043  Paloverde - cactus shrub
   K044  Creosotebush - tarbush
   K054  Grama - tobosa prairie
   K058  Grama - tobosa shrubsteppe
   K059  Trans-Pecos shrub savanna
   K061  Mesquite - acacia savanna


SAF COVER TYPES : 
   242  Mesquite


SRM (RANGELAND) COVER TYPES : 
NO-ENTRY


HABITAT TYPES AND PLANT COMMUNITIES : 
Desert willow sometimes codominates desert washes and water courses with
other phreatophytes [see SITE CHARACTERISTICS for a list of codominant
plants].  Published classification schemes listing desert willow as an
indicator species or dominant part of the vegetation in community types
(cts) or plant associations (pas) are listed below:

  Area               Classification                 Authority

s CA                general veg. pas           Paysen & others 1980

s CA                general veg. cts           Burk 1977

VALUE AND USE
SPECIES: Chilopsis linearis | Desert Willow 



WOOD PRODUCTS VALUE : 
Desert willow is occasionally used for fence posts and fuel [14,46].


IMPORTANCE TO LIVESTOCK AND WILDLIFE : 
Livestock:  Livestock generally do not browse desert willow.  It is
consumed only when other forage is scarce [18,46].

Wildlife:  Various species of birds eat desert willow seeds [12,46].
Hummingbirds are attracted to the showy flowers and feed on the nectar
[3,12].  Mule deer eat small quantities of the leaves and fruit [34].


PALATABILITY : 
Desert willow is considered to be unpalatable to livestock and low in
palatability to wildlife [5].  The presence of cyanogenic glycosides may
account for its low palatability [50].  Following fire, however, tender
sprouts may be highly palatable.  Two months after a July wildfire in
southern California, 55 percent of available desert willow sprouts were
browsed by mule deer, bighorn sheep, and cottontail rabbits, but this
use declined to about 1 percent within 1 year [41].


NUTRITIONAL VALUE : 
The sucrose in desert willow nectar is a good energy source for bees and
hummingbirds [3].


COVER VALUE : 
Desert willow provides nesting sites for desert songbirds and cover for
other wildlife species [20].


VALUE FOR REHABILITATION OF DISTURBED SITES : 
Desert willow is used in soil stabilization plantings.  It is often used
along highways and in well-drained barrow ditches [36].  Numerous
cultivars are available, including 'Barranco', released by the Soil
Conservation Service [40], and 'White Storm', 'Dark Storm', 'Marfa
Lace', 'Alpine', and 'Tejas', released in 1988 from the Texas A&M
Research and Extension Center [36,39].  It is usually transplanted from
nursery stock.  Removing competing vegetion around transplants and
irrigating during the first season after transplanting is recommended
[48].  Methods for growing seedlings in a nursery have been discussed
[15,48].  Plants may be successfully propogated by both softwood and
hardwood cuttings [7,48].


OTHER USES AND VALUES : 
Desert willow is cultivated as an ornamental because of its attractive
flowers [38].  It has been used for roadside beautification, border
rows, screenings, and mass plantings [48].  In the 1930's the Civilian
Conservation Corps planted desert willow in shelterbelts [35].  Indians
used the wood to make bows and baskets [35,46].


MANAGEMENT CONSIDERATIONS : 
Use of desert willow by livestock generally indicates overbrowsing or
overstocking of the range [45,48].  

BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Chilopsis linearis | Desert Willow 



GENERAL BOTANICAL CHARACTERISTICS : 
Desert willow is a large deciduous shrub or small tree that may grow 10
to 30 feet (3-9 m) tall, and often has a leaning trunk and an open,
spreading crown [18,25,46].  Basal diameter of the trunk rarely exceeds
5 inches (12.5 cm) [14].  The dark brown bark is very thin, up to about
0.25 inch (6.3 mm) thick [14].  Pale green willowlike leaves are about 5
inches (12.5 cm) long and less than 0.5 inch (1.25 cm) wide with smooth
margins [27,46].  The pink to light violet flowers are 1.25 inches (3.2
cm) long and wide, and occur in clusters up to 4 inches (10 cm) long at
the end of the twigs [25].  The fruit is a narrow, elongated two-celled
podlike capsule 4 to 10 inches (10-30 cm) long [48].  First year twigs
are green but later turn gray to reddish-brown [46].

Henrickson [13] provides a key for separating subspecies and varieties.


RAUNKIAER LIFE FORM : 
   Undisturbed State:  Phanerophyte (microphanerophyte)
   Burned or Clipped State:  Hemicryptophyte


REGENERATION PROCESSES : 
Desert willow reproduces sexually by producing abundant seed.  Flowers
are primarily pollinated by numerous species of bees and hummingbirds
[3].  Large numbers of flowers are produced continuously over several
weeks [31].  Desert willow flowers are self incompatible.  Fruit set may
be limited by insufficient amounts of outcrossed pollen and by
inadequate movement of pollinators between trees [31].  Fruit production
does not appear to be limited by inadequate moisture, probably because
plants are primarily found along washes.  

Several 0.33 inch (8 mm) long, light brown, oval seeds are encased
within a two-celled capsule [26].  Seeds have a fringe of soft white
hairs at each end which aid in wind dispersal [26,30].  Seeds do not
display dormancy, and probably only remain viable until the spring
following dispersal [26].  There are between 50,000 and 100,000 seeds
per pound (110,200-220,400/kg) [26,45].  Germination has been reported
between 40 and 60 percent [45].  Commercial seed has shown 92 percent
purity and 87 percent soundness [26].

Sprouting:  Following damage to the aboveground portion of the plant,
such as by fire, most plants regenerate by sprouting from the root crown
[41].


SITE CHARACTERISTICS : 
Desert willow primarily occupies dry washes, intermittent streams and
other water courses, and moist canyons in deserts and mountain foothills
[4,16,18,27,35,49].  These sites generally have underground water
available year-round.  Plants can withstand seasonal flooding quite
well, and often occupy the middle of drainage channels, sometimes
covering broad expanses in wash areas [10,16].

Soils:  Sites are mostly well drained, neutral to basic and mildly
saline [48].  Soils are mostly sandy to gravelly alluvium [29,35,48].

Associated species:  Common associates of desert washes include blue
paloverde (Cerdidium floridum), desert ironwood (Olneya tesota), catclaw
acacia (Acacia greggii), smoketree (Dalea spinosa), mesquites (Prosopis
spp.), desertbroom (Baccharis sarothroides), netleaf hackberry (Celtis
reticulata), littleleaf sumac (Rhus microphylla), Arizona walnut
(Juglans major), velvet ash (Fraxinus velutina), spitleaf brickellia
(Brickellia laciniata), cottontop (Digitaria californica) and
southwestern condalia (Condalia lycoides) [4,10,16,29,31,48].

Elevational range by location:

        Range                              State              Reference

below 4,000 feet (1,219 m)                  AZ                  [18]
below 5,000 feet (1,524 m)                  CA                  [27]
from 2,000 to 5,000 feet (610-1,524 m)      TX                  [32]
below 4,920 feet (1,500 m)                  UT                  [49]


SUCCESSIONAL STATUS : 
Desert willow sometimes invades freshly deposited channel sediments
following seasonal water runoff.  As plants develop they may trap
sediments, leading to the formation of islands within the channel [10].

Desert willow plants are long-lived and help stabilize the banks of
water courses.  Desert willow is a component of desert wash communities
that are somewhat stable.


SEASONAL DEVELOPMENT : 
Since desert willow is primarily restricted to washes or water courses
with available underground water, it is able to maintain a full
compliment of leaves during the summer months even though it is not well
adapted to high temperatures [4].  Plants are winter deciduous and drop
leaves in late fall following the first hard frost [6].  Leaf drop may
be photoperiodically controlled, as plants in temperature controlled
greenhouses lose their leaves during the winter [6].

Flowering occurs mostly in May and June but may occur later in the
summer after rain [46].  Most fruits ripen from late summer to fall, and
the capsules persist overwinter [46,48].  Under extremely dry
conditions, plants may fail to form fruits [31].  In a wash near Tucson,
Arizona, flowering occurred mostly in May and June, and most fruits were
mature by September 2 [31].

Flowering time by location is as follows:  

     Time of flowering        Location         Reference

      May - September          s CA              [27]
      April - August           AZ                [18]
      April - September        w TX              [32]

FIRE ECOLOGY
SPECIES: Chilopsis linearis | Desert Willow 



FIRE ECOLOGY OR ADAPTATIONS : 
Desert willow primarily occurs in washes wich rarely burn [48].  It is
able to sprout from the root crown following top-kill by fire [41,42].


POSTFIRE REGENERATION STRATEGY : 
   survivor species; on-site surviving root crown or caudex

FIRE EFFECTS
SPECIES: Chilopsis linearis | Desert Willow 



IMMEDIATE FIRE EFFECT ON PLANT : 
Most fires probably top-kill desert willow.  In southern California, a
July wildfire in a chaparral-desert ecotone resulted in nearly all
desert willow plants being charred and defoliated, but less than 10
percent of the plants were killed [41].


DISCUSSION AND QUALIFICATION OF FIRE EFFECT : 
NO-ENTRY


PLANT RESPONSE TO FIRE : 
Following top-kill by fire, desert willow survives by producing numerous
root crown sprouts.  Following a July wildfire in southern California,
more than 90 percent of desert willow plants survived [41].  These
residual plants started sprouting within 2 months after the fire.
Plants developed a multistemmed growth form and averaged 171 sprouts per
plant 10 months after this fire.  Sprout growth is summarized below
[41]:

                   Average #     Average length of   Ave. productivity
                 sprouts/plant   unbrowsed sprouts   per plant in grams
                                  (inches)   (cm)    (oven dry weight)

2 months after      
fire (Sept)           16             2.2      5.5            2

4 months after 
fire (Nov)            21            10.7     27.1           40

7 months after
fire (Feb)            48            18.7     47.6          132

10 months after
fire (June)          171            19.4     49.3          892
                 


DISCUSSION AND QUALIFICATION OF PLANT RESPONSE : 
NO-ENTRY


FIRE MANAGEMENT CONSIDERATIONS : 
NO-ENTRY

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Related categories for Species: Chilopsis linearis | Desert Willow