BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES : Yucca baccata | Banana Yucca 


GENERAL BOTANICAL CHARACTERISTICS : 
Banana yucca is a native evergreen shrub from 1 to 3 feet (0.3-0.9 m) in
length [31,43,48].  The flower is a panicle on an erect stem [14,23].
The fruit is an indehiscent, fleshy capsule containing hundreds of small
seeds with tough, waxy seedcoats [23,43,48,51].

Banana yucca stems extend 8 to 16 inches (20-40 cm) into soil [51].
Growth form is variable.  Plants are typically acaulescent or more
rarely, caulescent with short upright to procumbent stems.  Caulescent
plants may be unbranched to highly branched [43,48].  Stems of all
growth forms have basal buds beneath the soil surface.  Additonally,
some banana yucca have short, thick rhizomes.  Rhizomatous plants often
grow in clumps, while nonrhizomatous plants are generally solitary [43].
Rhizomes are apparently long lived.  Roots are fibrous and highly
branched.  Physiology studies suggest that banana yucca roots are
shallow; however, little is known of the extent of the banana yucca root
system [56].  Procumbent plants often produce aerial roots [51].



RAUNKIAER LIFE FORM : 
   Stem succulent
   Geophyte


REGENERATION PROCESSES : 
Banana yucca reproduces vegetatively and by seed.  Vegetative
reproduction is more common [43,51].

Vegetative reproduction:  Banana yucca reproduces by sprouting from
basal buds and/or rhizomes and by layering [43,51].  All banana yucca
have a few buds located on the stem base.  After top-kill,
nonrhizomatous plants generally produce three or four vigorous basal
sprouts.  Rhizomatous plants generally produce numerous rhizome sprouts
after top-kill; some plants may also produce a few basal sprouts
[30],43,51].  Layering is an important method of regeneration in plants
with procumbent stems [51].

Sexual reproduction:  Banana yucca is pollinated solely by the female
yucca moth (Tegeticula yuccasella).  After pollinating a banana yucca
flower, the yucca moth flies to a different flower and deposits her eggs
in the new flower's ovary.  Most flowers are pollinated, and pollination
typically results in production of a large number of banana yucca seeds.
The seeds and fruit are consumed by yucca moth larvae [1,52].  Addicot
[1] found that banana yucca fruits collected in Arizona, Utah, and
Colorado produced a mean of 116 viable seeds per fruit.  Number of
viable seeds consumed by yucca moth larvae was low; larvae tended to
consume inviable seeds near the fruit apex.  In a similar study, Keeley
and others [27] reported a 10 to 12 percent loss of seeds due to yucca
moth larvae.  Larvae of other insects may also damage fruits or seeds.
Wallen and Ludwig [49] reported that fruits infested with Tenebrionidae
beetle larvae were usually aborted.

Seeds are dispersed by frugivorous animals.  In desert shrubland of New
Mexico, woodrats and lagomorphs were primary seed dispersers [49].

Webber [51] found that in the laboratory, germination rates of seeds of
eight species of yucca were good:  seed collections of all species showed
80 to 90 percent germination.  (Germination rate of banana yucca seed
was not tested.)  In the field, seedling establishment of yuccas,
including banana yucca, is limited.  Moisture and temperature conditions
are rarely adequate for seedling survivorship in the environments in
which banana yucca occurs [28].  During 4 years of field research in New
Mexico, Webber [51] recorded establishment of only 25 banana yucca
seedlings:  9 in southern New Mexico and 16 in relatively less arid
northern New Mexico.

Age at first reproduction and years between subsequent seed set are
undocumented.  An Apache elder reported that banana yucca first flowers
at 2 to 3 years of age, and mature plants flower approximately every 2
years if rainfall is sufficient [39].  (Smith [44] reported that
soaptree yucca sets seed only after plentiful winter and spring rains.)
A computer model based upon average annual carbohydrate storage predicts
a 3-year cycle of seed production for banana yucca [49].


SITE CHARACTERISTICS : 
Banana yucca occurs in canyons and on dry plains, washes, and slopes
[23,50].  Soils may be loamy, sandy, or clayey, and are sometimes
alkaline [50,57].  Banana yucca is common on rocky soils and occurs over
pans and gravels.  Soils are characteristically dry [45,50].  In Nevada,
banana yucca grows on soils that receive less than 6 inches (150 mm) of
annual precipitation [45].

Aspect upon which banana yucca occurs varies.  In Arizona chaparral,
shrub live oak-banana yucca-yellowleaf silktassel (Garrya flavescens)
communties tend to occur on north and east slopes [12].  In the Organ
Mountains of New Mexico, banana yucca occurs mainly on south-facing
slopes at high elevations (>7,600 feet (2,300 m)) and on east and west
exposures at intermediate elevations (6,700-7,600 feet (2,000-2,300 m))
[16].

Elevational range of banana yucca by state follows.

California   2,600 to 4,300 feet   (800-1,300 m) [23]
Colorado     5,300 to 7,500 feet (1,600-2,300 m) [22]
New Mexico   2,000 to 8,000 feet   (600-2,400 m)
Texas        2,000 to 8,000 feet   (600-2,400 m) [48]
Utah         2,460 to 7,870 feet   (750-2,400 m) [53]


SUCCESSIONAL STATUS : 
Banana yucca occurs on disturbed and undisturbed sites [12,37,19].  In
Mesa Verde National Park, Colorado, banana yucca was common in both
early postfire and mature twoneedle pinyon-Utah juniper (Juniperus
osteosperma) communities [19].


SEASONAL DEVELOPMENT : 
Phenology of banana yucca is poorly documented.  The flowering period is
generally from April to June depending upon latitude and elevation
[56].

Related categories for SPECIES : Yucca baccata | Banana Yucca