BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Cupressus macnabiana | Macnab Cypress 



GENERAL BOTANICAL CHARACTERISTICS : 
MacNab cypress is a native, evergreen tree with a broad crown and
lacking a main trunk [10,24].  It grows from 9.9 to 33 feet (3-10 m)
tall [8].  It is unique among North American cypress because of the
flat, sprayed arrangement of its branches [2,24].  Mature leaves are
generally about 0.06 inch (1.5 mm) long, although they can be up to 0.4
inch (10 mm) on vigorous shoots [8,24].  Ovulate cones are solitary, up
to 1.0 inch (25 mm) long.  Staminate cones are 0.08 to 0.12 inch (2-3
mm) long [8,24].  The bark is furrowed and fibrous, 2.54 to 5.1 inches
(1-2 cm) thick, and not exfoliating [24].  A well-defined taproot and
numerous laterals are formed the first year [10].


RAUNKIAER LIFE FORM : 
   Phanerophyte


REGENERATION PROCESSES : 

MacNab cypress reproduces exclusively from seed.  Cone production is
abundant.  Staminate cones are produced on trees that are 6 to 7 years
old [24].  Ovulate cones are produced on trees that are 14 years of age
or older.  The cones require 2 years to mature [2].  They contain from
75 to 105 seeds each [10,24].  The cones are closed; they persist on the
tree until opened by the heat of a fire or from desiccation due to age
[10,27].  Seeds are shed gradually over several months after the cones
are opened [27].  Detached cones will open, but they rarely result in
seedling establishment, usually due to the lack of a suitable seedbed
[2].  Seed dispersal is primarily by wind and rain [27].

MacNab cypress germination rates are extremely low, less than 5 percent
[16].  Seeds require bare mineral soil for germination and
establishment.  Seedling mortality is greater on shaded sites with
abundant litter because of damping-off fungi [2,27].  Seedlings are
sensitive to excessive moisture [24].


SITE CHARACTERISTICS : 
In many areas MacNab cypress is restricted to serpentine soils, but in
other locations it occurs on clay loam (up to 5.0 feet [1.5 m] deep),
silty loam, alluvial, granitic, and volcanic soils [13,16,27].  It is
found on dry slopes, exposed hillsides, and ridgetops [8,16,20].  It
occurs at elevations from 1,000 to 2,800 feet (300-850 m) on north- to
northeast-facing slopes [8,20].
            


SUCCESSIONAL STATUS : 
Facultative Seral Species

Site requirements for cypress seedlings are typical of those for pioneer
conifers.  Seedlings are shade intolerant and survive best in full
sunlight on bare mineral soil [27].  Perhaps due to its shorter, bushier
habit, MacNab cypress is found on more exposed sites than Sargent
cypress where the two species occur together [16]. 


SEASONAL DEVELOPMENT : 
MacNab cypress starts shedding its pollen around October 28 [24].  Seeds
mature 15 to 18 months after pollination.  Ovulate cones remain closed
until opened by heat or age [10,24].

Related categories for Species: Cupressus macnabiana | Macnab Cypress