BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Malosma laurina | Laurel Sumac 



GENERAL BOTANICAL CHARACTERISTICS : 
Laurel sumac is a fast-growing, native, sclerophyllous shrub from 6.6 to
16 feet (2-5 m) in height at maturity [7,46,56].  The evergreen leaves
are aromatic and somewhat glaucous.  Flowers are borne on terminal
panicles.  The fruit is a drupe containing a single, hard-coated seed
[5,7].  The lignotuber is large and massive, measuring as much as 2.6
feet (0.8 m) in diameter [11,52].  Laurel sumac roots are deep and
extensive; vertical root depth of one individual in the Santa Monica
Mountains exceeded 43.6 feet (13.2 m) [11].  The shrubs are at least
moderately long-lived.  Ring counts of the branches of larger
individuals on the San Gabriel River floodplain reveiled ages of 35 to
47 years.  The massive lignotubers and roots were undoubtedly much older
but could not be aged due to extensive rot [51].  Little information is
available on age distribution in a typical stand.  Mixed laurel
sumac-lemonadeberry stands on Santa Catalina Island are uneven-aged
[34].


RAUNKIAER LIFE FORM : 
   Phanerophyte


REGENERATION PROCESSES : 
Sexual:  The honeybee is an important laurel sumac pollinator [7,9,23].
Seed production is low but consistent [62]; some seed is produced each
year.  Seed falls beneath the parent plant or is disseminated by
frugivorous animals.  Soil-stored seed is probably sound for many years
[5], but long-term viability studies are lacking.  Scarification by
hydrochloric acid, heat, or mechanical means breaks dormancy.
Temperatures for optimal heat scarification are from 200 to 240 degrees
Fahrenheit (93-115 deg C) [6,47].  A study was conducted to test the
germination capacity of fresh seed of seven chaparral species after
exposure to elevated temperatures.  It showed that laural sumac and the
taxonomically related sugarberry required higher temperatures for
germination than all other species tested.  Germination capacity of
laurel sumac seed was 52 percent following five minute dry heat exposure
at 220 to 240 degrees (104-115 deg C) but lowered to 20 percent at the
140- to 160-degree (60-71 deg C) range [61].

Drought sensitivity is a major factor inhibiting recruitment.  Laurel
sumac seedlings appear approximately 1 month later than most chaparral
shrub seedlings, and their taproots grow slowly [50,52].  Germination
and growth are favored on sites with summer microshade.  Mortalilty is
usually greatest the first summer following germination [14].  Seedlings
are also sensitive to cold.  They grow slowly at near-freezing
temperatures, and frost kills them [7].  The preponderance of laurel
sumac on southern aspects is probably due to the more rapid growth of
seedlings on these warmer sites during years of high precipitation [35].

Vegetative:  Laurel sumac sprouts from the lignotuber following damage
to aboveground portions of the plant [11,55,60,61,62].  


SITE CHARACTERISTICS : 
Laurel sumac occurs in maritime, Mediterranean, and semiarid climates
[37,39,58,65].  Insular populations, exposed to the maritime climate,
undergo little seasonal fluctuation in the mild temperatures.  Summer
drought occurs, but the effects are moderated by frequent fog and low
clouds [65].  Populations in Mediterranean and semiarid climates receive
90 percent of annual rainfall from November to April.  Precipitation in
the Santa Monica Mountains, where a Mediterranean climate predominates,
averages 30 inches per year (762 mm/yr) [2].  Hot, dry Santa Ana foehn
winds occur in coastal mountains during fall [35].

Soils supporting laurel sumac are acidic to neutral, well-drained, dry,
and often rocky or gravelly [2,18].  In riparian zones laurel sumac is
most common on gravelly outwash areas [18,51].  Soil textures in which
laurel sumac is found are sand or sandy loam [24,51].  Parent materials
include diorite, shale, sandstone, and sandstone with conglomerate.
Laurel sumac does not occur on unconsolidated sand, limestone-, or
serpentine-derived soils [24,32,58].  It is favored on soils with high
exchangable potassium levels.  Peak abundance occurs on coastal sites
with heavy litter layers.  Laurel sumac is less frequent inland [29,58].
Slope varies from 0 to 80 degrees; it is most common on southern
exposures [24,29].  Laurel sumac occurs at elevations below 3,000 feet
(914 m) [34.35.38]


SUCCESSIONAL STATUS : 
Facultative Seral Species

Laurel sumac is a moderately successful initial colonizer of disturbed
sites and a strong residual colonizer [47,55,62].  Sprouts and surviving
seedlings persist through climax in coastal sage scrub and mixed
chaparral communities [8,50,58].  In alluvial scrub communities, laurel
sumac usually establishes from seed from mid-seres through climax.  When
seasonal floods do not excavate the roots, however, it quickly
establishes dominance in the initial community [51].


SEASONAL DEVELOPMENT : 
New leaf growth is initiated in February, and leaves are retained for
about 12 months [20,56].  Maximum stem elongation occurs in June [11],
but stems continue to grow throughout the year [67].  Flora primordia
develop directly prior to flowering, which begins in May.  Peak
flowering ends in July, but blooming sometimes continues into December
[5,26,56].  Fully ripened fruits first appear in September.  The fruits
often remain on the parent plant until spring [5,55].

Related categories for Species: Malosma laurina | Laurel Sumac