BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Arctostaphylos patula | Greenleaf Manzanita 



GENERAL BOTANICAL CHARACTERISTICS : 
Greenleaf manzanita is an erect native perennial shrub, approximately 3
to 7 feet (1-2 m) tall.  Its limbs are crooked, many branched, stout,
and rigid.  The twigs are covered with fine hairs.  The bark is smooth,
shiny, and reddish brown.  On older stems the bark becomes "shreddy".
Stripping occurs and exposes the light colored whitish-green wood
underneath.  Those stems that are stripped of their bark become
especially twisted and gnarled.  The evergreen leaves are bright green
to yellow-green, simple, alternate, leathery, broadly oval, hairless,
entire, and have distinct petioles.  The pinkish flowers are borne on
nodding terminal clusters.  The petals are fused together in an urn
shape.  The manzanita fruit is a berrylike drupe that looks like a small
apple.  It is dark reddish-brown to black and has a thin mealy pulp
enclosing 4 to 10 stony seeds.  The seeds may be separate or variously
coalesced [3,26,43,44,49,59,69].

Greenleaf manzanita has a heavy, turnip-shaped or globular lignotuber
which may include a tabular platform [24,26,76].  Its roots generally
reach 10 feet (3 m) or more in depth [24].  

Stands of greenleaf manzanita may reach 20 to 100 hundred years of age
[20,32,58].  Lignotuber age is rarely documented.  It is difficult to
determine the age of a burl by its annual rings because the wood tissue
is swirled and arranged in an irregular pattern.  Carbon-dating
techniques have shown that burls may persist in some species of
chaparral brush for 200 hundred years or more [24].


RAUNKIAER LIFE FORM : 
   Phanerophyte


REGENERATION PROCESSES : 
Sexual:  Greenleaf manzanita reproduces sexually by seed.  These seeds
have an extremely thick endocarp and will not germinate unless
scarified.  Seed coat scarification may occur naturally by the high
temperatures associated with fire, mechanically by soil disturbances,
such as those associated with logging activities, or chemically
[3,28,51].  A recent laboratory study suggested that exposure to light
inhibited the germination of greenleaf manzanita seeds [35].

Seeds stored in the soil appear to have a great longevity as evidenced
by the synchronous establishment of large numbers of seedlings after
fire in 400-year-old forests [36].  Seed longevity is also illustrated
by the fact that there is little difference in the number of seedlings
after fires in 100-year-old stands of chaparral than after fires in
20-year-old stands [32].

Greenleaf manzanita produces heavy seed crops nearly every year ( 10,000
seeds per acre [24,710 seeds/ha]) [51].  These seeds can tolerate soil
temperatures in excess of 200 degrees F (93 degrees C) [66].  Animals
are the primary mode of seed dispersal [41].  Insects are primarily
responsible for the pollination of greenleaf manzanita flowers [41].
The flowers occurring on one individual are usually noncompatible [43].
Outcrossing and hybridization are common within this species [2,24].

Vegetative:  Greenleaf manzanita regenerates vegetatively through
sprouting and layering.  Sprouting occurs from dormant buds located
within the root burl or lignotuber [75].  These buds are stimulated to
sprout after the removal of the aboveground crown [23,24,43,51].  This
type of new growth occurs rather rapidly and may be observed in as
little as 10 days to 3 weeks [23,24,43].  Greenleaf manzanita is
generally able to sprout when the plant reaches approximately 2 years of
age, as it takes about this long for the root burl to fully develop
[24].  Fire may promote an increase in the size of the root burl [26].
Forma platyphylla does not have a root burl and is not able to sprout
[71].

Layering may occur when manzanita branches are forced to the ground and
kept there for long periods of time, such as may occur with a heavy
snowfall.  Under conditions such as these, the branches may sprout roots
and develop into separate plants [24,43,69].


SITE CHARACTERISTICS : 
Greenleaf manzanita is typically found on dry sites. It
characteristically grows in full sunlight on well-drained soils.  It is
found in the openings of coniferous forests, on old burns, and in arid
chaparral belts [59].  It is found on a variety of aspects and at
elevations ranging between 3,100 and 10,000 feet (945 and 3,048 m)
throughout its range [1,5,11,40,56,64,74].

Soil:  Greenleaf manzanita typically occurs on soils that are
well-drained, shallow to moderately deep, and sandy loam to silty loam
in texture.  Parent materials may include sandstones, limestones, and
granite types [5,11,40,64,74].  In Utah greenleaf manzanita shows a
preference for acidic and saline soils over sodic-saline and organic
soils [12].

Climate:  Greeenleaf manzanita usually occurs within warm, dry, semiarid
climes [5,40,56,74]. 

Elevation:  Elevational ranges for greenleaf manzanita in several
western locations follow:

Location                     Elevation                 Reference

w Colorado      7,500 to  9,000 feet (2,286-2,743 m)   [59]
Utah            3,700 to 10,000 feet (1,128-3,048 m)   [12,40,72]
n Arizona       7,000 to  8,500 feet (2,134-2,591 m)   [31]
Sierra Nevada   2,500 to  9,000 feet (  762-2,743 m)   [59]


SUCCESSIONAL STATUS : 
Facultative Seral Species

Greenleaf manzanita-dominated communities have been variously referred
to as grassland climax, true climax, pyric climax, and transitional
vegetation [19,51].

Greenleaf manzanita displays characteristics common to shade intolerant
pioneer species [73,59].  It begins to die back when overtopped by
trees, preferring open areas in full sunlight [53].  It is often one of
the first plants to become established on disturbed sites, especially
after fire [59].
 
When this plant occurs in locations susceptible to frequent fires, it
has the ability to regenerate quickly, allowing it to perpetually
dominate a site [8,59,65,73].  On sites where fire is excluded for long
periods of time, greenleaf manzanita may provide a better microclimate
for some tree seedlings than would exist on harsh sites in full
sunlight, and it may enhance soil conditions through the addition of
organic material [51].  This would allow for the relatively slow but
sure establishment of the seedlings of some species of pine.  Several
authors have noted that conifers may regain site dominance from
chaparral within 10 to 30 years [51].


SEASONAL DEVELOPMENT : 
Greenleaf manzanita flowers from late March to June, depending on
location [59].  In California flowering occurs from April to June
[44,49], in the Great Basin from May to June [43].  Flowering of this
species may be triggered by summer moisture stress [3].  The number of
flowers produced by a shrub is dependent upon the amount of the previous
year's precipitation.  The flower buds form 1 year prior to the time
they mature.  They are dormant the following summer, fall, and winter,
and bloom the next spring [43].

The fruits ripen in late summer to early fall [59].  Generally, this
species fruits over its entire range between July and October [3,67].
In Nevada, fruiting occurs from May to September [67].  The fruits may
occasionally persist on the shrub year-round [62].  The seeds are
generally dispersed in the summer and fall [3,34].

Most chaparral species experience the greatest amount of growth in May
and June.  Growth ceases in mid-July, due to high air temperatures and
low soil-moisture [24].

Related categories for Species: Arctostaphylos patula | Greenleaf Manzanita