BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Spartina alterniflora | Smooth Cordgrass 



GENERAL BOTANICAL CHARACTERISTICS : 
Smooth cordgrass is a large, coarse, warm-season grass, which is
physiologically adapted to the salt marsh habitat [26,27].  Plants
growing under good conditions reach 8 feet (2.5 m) tall, while those
growing in the high salt marshes, especially at edges of salt pans, may
be only 16 inches (40 cm) tall, including the inflorescence [6].  A
dense stand of this tall grass is like a small forest of dark green
plants.  Almost no light gets through to the mud beneath the stand.
Tidal currents are strong where the best growth occurs and wash away
dead leaves, leaving stands clean and free of debris most of the year
[26].


RAUNKIAER LIFE FORM : 
   Helophyte


REGENERATION PROCESSES : 
Smooth cordgrass reproduces both sexually and vegetatively.  Sexual
reproduction contributes little to maintenance of established stands but
may be important in the establishment of large disturbance-generated
patches.

Sexual:  Germination in New England marshes occurs from April until the
end of June [18].  Germination response to salinity has an inverse
curvilinear relationship, with the maximum tolerance limit for
germination between 6 and 8 percent sodium chloride [19].  Competition
from mature plants prevents seedling establishment.  Maximum
establishment occurs on bare patches; seedling survival increases as
bare patch size increases.  Tillers appear soon after germination and
spatial location of tillers may be important in determining seedling
success [18].

Vegetative:  Vegetative shoots grow in tussocks consisting of a parent
tiller plus daughter tillers developed from axillary buds at the base of
the parent shoot.  Tussocks are connected by underground rhizomes [18].
Approximately 40 percent of rhizome growth occurs in the upper 2 inches
(5 cm) of soil from April to October.  Over the whole year 74 percent of
the rhizome growth occurs in the upper 5.9 inches (15 cm) [9].


SITE CHARACTERISTICS : 
Smooth cordgrass forms dense, monospecific stands in salt and brackish
marshes with mid to high tide levels [6,27,30].  It dominates where
salinities range from 3 to 5 percent and the average water table is 4
inches (10.2 cm) above ground level.  Plants may be inundated with salt
water for up to 20 hours per day.  Unlike most other marsh plants, the
salt-tolerance of cordgrass is directly proportional to water depth [1].

Smooth cordgrass thrives in anoxic, low marsh habitats due to its
ability to oxygenate its roots and rhizospere.  Rhizospere oxidation is
not evident in seedlings and small colonizing patches.  Both of these
groups are stunted in anoxic low marsh substrates.  This suggests that
success of smooth cordgrass in anoxic habitats is size dependent and may
be driven by group benefits of rhizosphere oxidation [5].


SUCCESSIONAL STATUS : 
Facultative Seral Species

Smooth cordgrass dominates the low marsh habitat in New England, and is
restricted to this habitat by the competitive dominance of marshhay
(Spartina patens) on the seaward border of the high marsh.  In the
absence of marshhay, smooth cordgrass will grow vigorously in the high
marsh [4].

Smooth cordgrass is a pioneer species bordering tidal inlets and lagoons
in the saline portions of Texas and Louisiana marshes [15].  It also
invades brackish areas, ditches, and ponds with silt or clay bottoms,
and shallow water in saline areas.  After organic matter builds up in
the ponds, brackish marsh dominants such as other cordgrasses (Spartina
spp.), saltgrass (Distichlis spp.), and rushes (Juncus spp.) replace
smooth cordgrass.  Smooth cordgrass remains the major dominant in saline
areas, unless they are aggraded by inorganic sediments, which promotes
the establishment of communities of inland saltgrass or marshhay [21].


SEASONAL DEVELOPMENT : 
In the North, smooth cordgrass plants have a short active period.
Shoots that develop during the summer die completely in the fall and are
often removed before mid-winter by ice and the tides.  In the south, the
growing season is longer and fall senescence is slower.  Many young
culms initiated in the fall live through the winter.  Culms initiated
the previous spring do not complete senescence until the end of winter
[8].  Flowering occurs from June until October [6,12,22].  Variety
pilosa flowers later than the typical form [24].

Related categories for Species: Spartina alterniflora | Smooth Cordgrass