BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Cercidium floridum | Blue Paloverde 



GENERAL BOTANICAL CHARACTERISTICS : 
Blue paloverde is a native, spiny, small tree or subtree [30,35,39,78].
It has multiple stems [4].  Blue paloverde grows to 32.8 feet (10 m)
tall with a trunk diameter of 1.5 feet (0.5 m) and a crown spread of
163.4 square feet (15.2 sq m) [4,5,30,39].  Blue paloverde has
thin-barked, photosynthetic stems [3,66].  Age influences photosynthetic
rate of stems; younger stems have higher photosynthetic rates [41].  Its
pinnately compound leaves are about 1 inch (2.5 cm) long and
drought-deciduous [3,30,54,66,78].  Inflorescences of blue paloverde are
1.5 to 4.7 inches (4-12 cm) long with one or more flowers [55,62,70].
The fruits are flat legumes, 1.5 to 4 inches (4-10 cm) long [39,62,70].
Each legume holds one to eight flat seeds [36,39,70].


RAUNKIAER LIFE FORM : 
   Phanerophyte


REGENERATION PROCESSES : 
Blue paloverde reproduces sexually and probably asexually.  In a
greenhouse study, young blue paloverde sprouted after plants were
clipped to less than one-half of their total height [3].  A close
relative, yellow paloverde, sprouts following top-kill [32].

Photoperiod controls blue paloverde flower and fruit initiation and stem
growth; however, moisture and temperature determine actual organ
production [13,66].

Abiotic and biotic agents aid in seed dispersal.  The flat seeds of blue
paloverde prevent air loft and allow downward dispersal into washes.
Fruits and seeds do not float.  Occasionally, blue paloverde fruits
disperse unopened.  Some seed dispersal occurs via animals.  Blue
paloverde has been found occasionally in ant formicaries below the soil
surface.  Seeds will germinate in these caches.  Birds probably move
seed upstream [36].

Large seedbanks of blue paloverde may be present.  Scarification from
flash floods or other abrasive processes facilitates germination
[36,43,71,73].  Blue paloverde germinates well on sandy deposits [67].
Shade and litter beneath mature blue paloverde alters seed microsites
and makes germination more likely [54].

Blue paloverde establishment is limited by climate extremes, low
moisture availability, poor soil characteristics, and herbivory.  Rapid,
deep root development is important for blue paloverde establishment.  In
greenhouse trials, blue paloverde roots grew an average of 0.3 inch per
day (0.9 cm/day) [3].  Mature blue paloverde has deep root systems that
reach ground water and make blue paloverde less vulnerable to drought
[42].  A herbivory experiment was conducted on blue paloverde at
Travertine Point, California.  Seven months after blue paloverde
germinated, rabbits and other rodents grazed 86 percent of the
seedlings.  Ninety percent of these grazed blue paloverde seedlings
appeared unlikely to survive [3].


SITE CHARACTERISTICS : 
Blue paloverde occurs in arid and semiarid climates characterized by
high summer temperatures and highly variable rainfall.  Precipitation
predominantly falls bimodally, in winter and in summer [40,52,53,66].

Blue paloverde is found at elevations from sea level to 4,000 feet
(0-1,220 m) [4,15,26,34,74].  It occurs on almost level (less than 5%)
to steep slopes [4].

Blue paloverde predominantly grows in washes, but is also found in
upland habitats.  Blue paloverde occurs in moderate to large watersheds
from 1 to 50 square miles (2.6-130 sq km) [81].  It grows on terraces,
high flood plains, arroyos or dry washes, and intermittent streambeds
more than 4 to 5 feet (1.2-1.5 m) wide with deep soil [8,54,79,81].  In
the northern Sonoran Desert at moderately high elevations, blue
paloverde grows in upland positions [66].  Blue paloverde occupies
hills, mountain slopes, and middle to lower bajadas [4,54,65].

Blue paloverde grows in soils with low levels of nutrients, especially
nitrogen and phosphorus [3].  Soil textures it occurs on may be sandy to
gravelly, coarse loamy to fine sand overlain with fine gravel [4,54,65].


SUCCESSIONAL STATUS : 
Facultative Seral Species

Blue paloverde occurs from pioneer to climax communities, depending on
site characteristics.  In fact, classical succession may not occur in
the desert ecosystems where blue paloverde occurs.  In the xeroriparian
systems to which blue paloverde belongs, community development is
influenced by catastrophic floods and long recovery periods [26].  After
disturbance of the desert scrub communities, former dominants such as
blue paloverde are the first to appear and replace themselves [48].


SEASONAL DEVELOPMENT : 
Flower and leaf production of blue paloverde vary according to the
amounts of precipitation received [66].  Blue paloverde remains leafless
throughout most of the year [30].  Leaves are produced between mid-July
and late November, depending on the summer rains [66].  Leaves drop
during drought and are not replaced until the following spring [13].
Blue paloverde typically flowers sporadically after rains from late
March to May, but flowering may extend into July [5,15,30,66,70].
Populations of blue paloverde also may bloom August to October [30].
Fruits mature about 1 month after flowering, typically from May to July
[66,70].

Related categories for Species: Cercidium floridum | Blue Paloverde