Spartina foliosa
Encyclopedia
Spartina foliosa is a species of grass
known by the common name California cordgrass. It is native to the salt marsh
es and mudflat
s of coastal California
and Baja California
, especially San Francisco Bay
. It is a perennial grass growing from short rhizome
s. It produces single stems or clumps of thick, fleshy stems which grow up to 1.5 meters tall. They are green or purple-tinged. The long, narrow leaves are flat or rolled inward. The inflorescence
is a narrow, dense, spike-like stick of branches appressed together, the unit reaching up to 25 centimeters long. The lower spikelets are sometimes enclosed in the basal sheaths of upper leaves.
This native plant is seriously threatened by the invasion of its non-native relative smooth cordgrass
(Spartina alterniflora). The latter was introduced
to San Francisco Bay in the 1970s and it quickly began to hybridize with S. foliosa, leading to the near-extirpation
of the once-common native plant. The two species reproduce at the same time of year, and the invader sheds large amounts of pollen
that fertilize the flowers of the native, so that the majority of the native plant's offspring are hybrids. There are almost no pure individuals of S. foliosa left, as most plants in the area are hybrids: this is an example of genetic pollution
. Hybrids of the two species have spread rapidly because they are much more genetically fit
than either parent, an example of hybrid vigor. Pure S. foliosa will probably become extirpated from San Francisco Bay, and only its hybrids will remain.
Poaceae
The Poaceae is a large and nearly ubiquitous family of flowering plants. Members of this family are commonly called grasses, although the term "grass" is also applied to plants that are not in the Poaceae lineage, including the rushes and sedges...
known by the common name California cordgrass. It is native to the salt marsh
Salt marsh
A salt marsh is an environment in the upper coastal intertidal zone between land and salt water or brackish water, it is dominated by dense stands of halophytic plants such as herbs, grasses, or low shrubs. These plants are terrestrial in origin and are essential to the stability of the salt marsh...
es and mudflat
Mudflat
Mudflats or mud flats, also known as tidal flats, are coastal wetlands that form when mud is deposited by tides or rivers. They are found in sheltered areas such as bays, bayous, lagoons, and estuaries. Mudflats may be viewed geologically as exposed layers of bay mud, resulting from deposition of...
s of coastal California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
and Baja California
Baja California
Baja California officially Estado Libre y Soberano de Baja California is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is both the northernmost and westernmost state of Mexico. Before becoming a state in 1953, the area was known as the North...
, especially San Francisco Bay
San Francisco Bay
San Francisco Bay is a shallow, productive estuary through which water draining from approximately forty percent of California, flowing in the Sacramento and San Joaquin rivers from the Sierra Nevada mountains, enters the Pacific Ocean...
. It is a perennial grass growing from short rhizome
Rhizome
In botany and dendrology, a rhizome is a characteristically horizontal stem of a plant that is usually found underground, often sending out roots and shoots from its nodes...
s. It produces single stems or clumps of thick, fleshy stems which grow up to 1.5 meters tall. They are green or purple-tinged. The long, narrow leaves are flat or rolled inward. The inflorescence
Inflorescence
An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Strictly, it is the part of the shoot of seed plants where flowers are formed and which is accordingly modified...
is a narrow, dense, spike-like stick of branches appressed together, the unit reaching up to 25 centimeters long. The lower spikelets are sometimes enclosed in the basal sheaths of upper leaves.
This native plant is seriously threatened by the invasion of its non-native relative smooth cordgrass
Spartina alterniflora
Spartina alterniflora is a perennial deciduous grass which is found in intertidal wetlands, especially estuarine salt marshes. It grows 1-1.5 m tall, and has smooth, hollow stems which bear leaves up to 20-60 cm long and 1.5 cm wide at their base, which are sharply tapered and bend down...
(Spartina alterniflora). The latter was introduced
Introduced species
An introduced species — or neozoon, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its indigenous or native distributional range, and has arrived in an ecosystem or plant community by human activity, either deliberate or accidental...
to San Francisco Bay in the 1970s and it quickly began to hybridize with S. foliosa, leading to the near-extirpation
Local extinction
Local extinction, also known as extirpation, is the condition of a species which ceases to exist in the chosen geographic area of study, though it still exists elsewhere...
of the once-common native plant. The two species reproduce at the same time of year, and the invader sheds large amounts of pollen
Pollen
Pollen is a fine to coarse powder containing the microgametophytes of seed plants, which produce the male gametes . Pollen grains have a hard coat that protects the sperm cells during the process of their movement from the stamens to the pistil of flowering plants or from the male cone to the...
that fertilize the flowers of the native, so that the majority of the native plant's offspring are hybrids. There are almost no pure individuals of S. foliosa left, as most plants in the area are hybrids: this is an example of genetic pollution
Genetic pollution
Genetic pollution is a controversial term for uncontrolled gene flow into wild populations. This gene flow is undesirable according to some environmentalists and conservationists, including groups such as Greenpeace, TRAFFIC, and GeneWatch UK.-Usage:...
. Hybrids of the two species have spread rapidly because they are much more genetically fit
Fitness (biology)
Fitness is a central idea in evolutionary theory. It can be defined either with respect to a genotype or to a phenotype in a given environment...
than either parent, an example of hybrid vigor. Pure S. foliosa will probably become extirpated from San Francisco Bay, and only its hybrids will remain.