BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Pleurozium schreberi | Schreber's Moss 



GENERAL BOTANICAL CHARACTERISTICS : 
Schreber's moss is a perennial, relatively large, robust moss with a
weave growth form.  It is usually prostrate or partly erect, freely
branched, and grows in mats rather than tufts [24].  The stems are 2.4
to 4.5 inches (6-15 cm) long, and the leaves loosely imbricate [16].


RAUNKIAER LIFE FORM : 
NO-ENTRY


REGENERATION PROCESSES : 
Sexual reproduction:  Schreber's moss is a dioecious, pleurocarpous
(producing the sporophytes laterally from short, lateral, specialized
branches rather that at the stem tip) moss.  The spores are shed 9 to 12
months after fertilization [24].  The period of gametangial (structure
containing the gametes) development in Schreber's moss is approximately
7 months for archegonia (female gametophyte) and 9 months for antheridia
(male gametophtye).  The timing of gametangial development in spring may
be influenced by the duration or severity of the winter [24].

Vegetative reproduction:  Schreber's moss reproduces vegetatively by
branching laterally.  The main stems of this moss are perennial and
appear to be capable of indefinite growth.  There is a growth resting
phase in the winter [24].


SITE CHARACTERISTICS : 
Schreber's moss often occurs in closed to semi-open coniferous forests
predominantly in boreal and cool temperate climates.  It also occurs in
damp woods, swamps, or margins of bogs.  Although Schreber's moss is
most abundant in old, closed, mesic stands, it is also found in dry,
nutrient-poor, open, black spruce-lichen stands in suitable areas at the
base of birch (Betula spp.) and black spruce [19,21,35].  In Alabama,
Schreber's moss is found growing abundantly on a large soil island over
granite beneath Georgia oak (Quercus georgiana) [35].

Soils:  Schreber's moss occurs on humus and exposed mineral soil and
coarse fragments or rocks [21].  It is often abundant on nitrogen-poor,
acidic soils throughout much of its range and is sometimes used as an
indicator of acidic soils [24,35].  The pH at one Schreber moss site is
5.7 [35].  Soil textures range from course to fine sand, loam, or
clay-loam [17].  It normally does not grow on calcareous soils [2].

Plant associates:  Schreber's moss is often associated with the
following species:  mountain fern moss (Hylocomium splendens), salal
(Gaultheria shallon), big huckleberry (Vaccinium membranaceum),
pachistima (Pachistima myrsinites), queencup beadlily (Clintonia
uniflora), ptilium (Ptilium crista-castrensis), Labrador-tea, mountain
cranberry (Vaccinium vitis-idaea minus), bog blueberry, black crowberry
(Empetrum nigra), and peat mosses (Sphagnum spp.) [12,21].


SUCCESSIONAL STATUS : 
Obligate Climax Species

Schreber's moss is very shade tolerant and typically occurs in stable
late stages of succession.  After the canopy closes, Schreber's moss
will generally form a continuous carpet on the forest floor [5].  Given
a shady, humid, high-nutrient environment as is found on the cool, basal
slopes of black spruce-white spruce-feather moss stands, Schreber's moss
is a very effective competitor against other species.  It can quickly
spread over and eliminate other ground cover such as lichens [19].


SEASONAL DEVELOPMENT : 
The beginning of blooming in mosses occurs when one or two archegonia
open.  In North America, Schreber's moss blooms in August and September
[24].  The gametangial develop in spring of the following year.  In
Germany, fertilization generally occurs in May, while in Sweden it is
delayed until July.  The spores are shed throughout the year following
fertilization.  The dates given for capsule dehiscence in three
countries are as follows [24]:

        Sweden: May
        Holland: February to May
        Germany: February to March or March to April

Capsules may persist on stems for at least twelve months after dehiscing
[24].

Related categories for Species: Pleurozium schreberi | Schreber's Moss