BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Sapindus saponaria var. drummondii | Western Soapberry 



GENERAL BOTANICAL CHARACTERISTICS : 
Western soapberry is a small to medium-sized deciduous tree which
reaches 20 to 50 feet (6-15 m) in height [7,16].  Crown spread can reach
25 to 30 feet (7-9 m) [16], and trunk diameter can reach 1 to 2 feet
(0.3-0.6 m) [41].  Branches are commonly erect and form a rounded crown
[41].  Twigs are brittle, moderately stout, yellowish-gray to gray-brown
and pubescent to glabrous [27,33,41].  The thin bark is split by deep
fissures into long narrow plates [17,34].  Bark is grayish to
reddish-brown and scaly [15,17].  Western soapberry is described as
moderately slow growing [16].

The alternate leaves are pinnately compound [33].  The 4 to 10 pairs of
leaflets are oblong to elliptic-lanceolate and entire and 1.5 to 3.2
inches (4-9 cm) in length [10,17,33,34].  Leaflets are glossy-green and
glabrous above and soft pubescent or glabrous beneath [16,41].  Leaves
turn a yellow-gold in fall [34].

Western soapberry is dioecious [33].  Small, yellowish-white flowers are
borne in large terminal or axillary panicles on new growth [16,29,33].
Panicles are 5 to 10 inches (13-25 cm) in length [41].  Fruit is a
fleshy, translucent yellow-orange drupe [16,29,33].  The
leathery-skinned drupes are somewhat wrinkled and are borne in clusters
of 10 to 30 [17,33].  Fruit is persistent but shrivels and blackens by
spring [34].  Each drupe averages 0.5 inch (2.5 cm) in diameter [34] and
generally contains a single seed, although drupes may sometimes contain
as many as two or three seeds [16,41].  Obovoid seeds are dark brown or
black and semiglossy [16,33].  Seeds have a hard seed coat, and although
the surface appears smooth, it is minutely pitted [10,16].


RAUNKIAER LIFE FORM : 
   Undisturbed State:  Phanerophyte (microphanerophyte)
   Undisturbed State:  Phanerophyte (mesophanerophyte)
   Burned or Clipped State:  Cryptophyte (geophyte)


REGENERATION PROCESSES : 
Seed:  Western soapberry produces an abundance of seed annually [29].
Seed soundness averages approximately 77 percent [41].  Seedcoat
structure and seed response to pregermination treatments vary greatly
[29].

Germination:  Germination of western soapberry is often difficult
because of embryo dormancy and an impermeable seed coat [29].  In
laboratory tests at alternating day (86 degrees F [30 degrees C]) and
night (68 degrees F [20 degrees C]) temperatures, germination capacity
of western soapberry ranged from 7 to 68 percent [29].  Germination can
generally be improved by soaking seeds in sulfuric acid for 2 hours or
more, and then stratifying seeds in moist sand at 35 to 45 degrees F
(2-7 degrees C) for 90 days [29,47].  Vora [42] reported increased
germination after acid soaks of 45 minutes or more; greatest germination
(71 percent) occurred after acid soaks of 120 minutes.  However, Munson
[23] observed better germination after soaking seeds in acid for 60 to
90 minutes than after soaking for either 30 or 120 minutes.  In general,
stratification can increase germination by up to 25 percent [23].

In some instances, freshly collected seed may germinate well without
pretreatment [23,29].  Generally, if seeds absorb water after 5 to 7
days of soaking, they can be planted without further treatment [29].
However, if seeds remain small and hard, they should be scarified and
stratified prior to planting [29].  Dried fruit can be stratified at 70
to 85 decrees F (21-29 degrees C) for 6 to 10 weeks followed by low
temperature stratification for 90 days [29].  Germination of western
soapberry has been examined in detail [23,29,42].

Seedling establishment:  Initial top growth of seedlings is typically
slow [29].  Early height growth has been reported as follows [42]:

                            height (cm)
                      ----------------------  
                        5       10      25
    date planted      (days after emergence)

    June 1986           -       -       80

Vegetative response:  Western soapberry reportedly spreads by
underground rhizomes [32].  However, little is known about vegetative
regeneration of this species.


SITE CHARACTERISTICS : 
Western soapberry grows along rivers and canyon sides, and in desert
washes, arroyos, and dry watercourses [7,16,19,26].  It also grows
singly or in thickets in foothills and uplands, at the margins of woods,
and in pasture ravines on waste ground [10,19,33].  Western soapberry is
a common component of upper desert scrub, desert and semidesert
grasslands, tropical and subtropical scrublands, and oak-woodland
communities [4,5,16,24].  It is particularly well represented in many
riparian woodland communities.

Plant associates:  Common associates in Arizona gallery or canyon
forests near streamcourses include netleaf hackberry (Celtis
reticulata), Texas mulberry (Morus microphylla), Goodding willow (Salix
gooddingii), velvet ash (Fraxinus velutina), Arizona sycamore (Platanus
wrightii), burrowbrush (Hymenoclea spp.), seepwillow (Baccharis
glutinosa), walnut (Juglans spp.), skunkbush sumac (Rhus trilobata), and
poison ivy (R. toxicodendron) [11,48].  Netleaf hackberry, American elm
(Ulmus americana), boxelder (Acer negundo), indian-currant coralberry
(Symphoricarpos orbiculatus), post oak (Quercus stellata), and blackjack
oak (Q. marilandica) occur with western soapberry in bottomland forests
of south-central and southwestern Oklahoma [8,25].  On floodplain
bottoms and river terrace communities of Texas, pecan (Carya
illinoensis), live oak (Quercus virginiana), hackberry (Celtis spp.),
Mexican ash, cedar elm, Texas persimmon (Diospyros texana), and honey
mesquite (Prosopis glandulosa) are often well represented [43,46].

Soils:  Western soapberry commonly grows on highly calcareous or clayey
soils [23,29].  It occurs on heavy clay, silty clay, and other soil
types [43].  Western soapberry is highly tolerant of soils with limited
moisture [16,34] and grows well on dry, well drained sites [40].
However, it also thrives on many moist soils [37].  Plants grow well on
infertile soils [16,34].  Western soapberry occurs on soils derived from
a variety of parent materials including sandstone, but it is most often
associated with limestone soils [32].

Climate:  Western soapberry is tolerant of low to high humidity and
rainfall [32].  It grows naturally in subhumid to semiarid mesothermal
climates [39].  On the Edwards Plateau of southern Texas, annual
precipitation can range from 16 to 33 inches (38-84 cm) [39].

Elevation:  Generalized elevational range by geographic location is as
follows [3,14,26]:

      location                      elevation                           

      AZ                            2,500 to 6,000 feet (762-1,829 m)   
      Trans-Pecos, TX               1,100 to 6,500 feet (335-1,981 m)   


SUCCESSIONAL STATUS : 
Western soapberry is a prominent member of mature bottomland forests of
south-central Oklahoma [25].  These climax stands can persist for
hundreds of years and are characterized by an extensive colonization
period [25].  In floodplain bottomlands of south Texas, species such as
retama (Cercidium spp.), dry-land willow (Baccharis neglecta), huisache
(Acacia smallii), and Texas prickly pear (Opuntia lindheimeri) dominate
earliest successional stages [43].  Common overstory species in
subsequent successional stages include retama, sugarberry (Celtis
laevigata), and cedar elm, with Texas persimmon, spiny hackberry (Celtis
pallida), Wright acadia (Acacia wrightii), and anacua (Ehretia anacua)
occurring as understory dominants.  In later successional stands,
western soapberry assumes prominence in the overstory canopy with cedar
elm, great leadtree (Leucaena pulverulenta), sugarberry, honey mesquite
(Prosopis glandulosa), and anacua [43].  Western soapberry occurs in
many southwestern riparian woodlands which are considered climax or
postclimax communities [6].

Western soapberry also grows well on infertile waste ground and may
occur in some early seral communities.


SEASONAL DEVELOPMENT : 
Fruits and flowers develop annually in a "characteristic growth flush"
[34].  New vegetative shoots subsequently arise from an axillary bud
located behind the site of the previous year's flowers and fruit [34].
Fruit ripens during September and October [40] and commonly persists
until late winter or spring [16].  Generalized flowering and fruiting
dates of western soapberry by geographic location are as follows:

   location          flowering     fruit ripe    authority

   NM                May-August    ----          Lamb 1971
   Southwest         May-June      ----          Vines 1960
n Great Plains       mid-June      October       Stephens 1973
se CO                March-June    ----          Shaw & others 1989
Trans-Pecos, TX      March-July    ----          Powell 1988
   TX                May-June      ----          Simpson 1988
   Great Plains      March-July    ----          Great Plains Flora
                                                 Association 1986
   AZ                May-August    ----          Kearney & others 1960

Related categories for Species: Sapindus saponaria var. drummondii | Western Soapberry