Sporobolus alterniflorus facts for kids
Quick facts for kids Sporobolus alterniflorus |
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Sporobolus alterniflorus, also known as Spartina alterniflora, is a type of grass. It has many common names like smooth cordgrass, saltmarsh cordgrass, or salt-water cordgrass. This grass grows year after year and loses its leaves in the fall. You can find it in wet areas that are covered by tides, especially in salt marshes near estuaries (where rivers meet the sea).
In 2014, scientists changed its official name to Sporobolus alterniflorus. But many people still call it Spartina alterniflora. It can grow about 1 to 1.5 meters (3 to 5 feet) tall. Its stems are smooth and hollow. The leaves can be 20 to 60 centimeters (8 to 24 inches) long and about 1.5 centimeters (half an inch) wide at the bottom. They are pointy and bend downwards at the tips.
Like its relative, saltmeadow cordgrass, this plant grows its flowers and seeds on only one side of the stalk. The flowers start yellowish-green and turn brown in winter. It has special roots called rhizomes. If a piece of a rhizome breaks off, it can grow into a new plant. These roots are also an important food for snow geese.
Smooth cordgrass can grow in both low marsh areas (often covered by the tide) and high marsh areas (less often covered). However, it usually stays in the low marsh. This is because saltmeadow cordgrass is better at competing for space in the high marsh. It can grow in water with different salt levels, from slightly salty to as salty as the ocean. In places like Chesapeake Bay, it's considered the most important marsh plant. This grass does not like shade.
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How Smooth Cordgrass Helps the Environment
Sporobolus alterniflorus is known as an "environmental engineer." This means it changes its environment in helpful ways. It grows out into the water at the edge of a salt marsh. As it grows, it helps trap mud and sand, which builds up the land. It also helps other creatures, like mussels, settle there.
This process of building up land slowly raises the marsh level. Then, other plants that prefer higher ground can move in. As the marsh grows, smooth cordgrass keeps moving further out into the water, creating a new edge. The tallest smooth cordgrass plants are found at the very edge of the marsh. Plants further inland are usually shorter.
Where Smooth Cordgrass Naturally Grows
S. alterniflorus is native to the Atlantic coast of the Americas. You can find it from Newfoundland, Canada, all the way south to northern Argentina. In these areas, it is a main plant in salty coastal saltmarshes.
The caterpillars of a butterfly called Aaron's skipper (Poanes aaroni) have only been found living on this type of grass so far.
Problems as an Invasive Species
Spartina alterniflora can become an invasive plant. This happens when it grows in places where it doesn't naturally belong. It can cause problems on its own or by mixing with native plants. When it mixes, it creates new types of grass that can harm the original native plants.
How Invasive Smooth Cordgrass Harms Habitats
This grass can slow down water flow and drainage. It can also block paths for boats. Large areas of S. alterniflora can push out native plant species. This reduces the variety of life, also known as biodiversity, and changes the environment. For example, small creatures called invertebrates that live in mud flats disappear when the grass takes over their habitat. This means birds that eat these invertebrates have less food.
The Spartina anglica Hybrid
One example of an invasive Spartina alterniflora hybrid is Spartina anglica. This new grass formed when American S. alterniflora was brought to southern England around 1870. There, it met the local native grass, S. maritima, and they created a hybrid. S. anglica is a very strong plant. It can handle very salty soil and can do photosynthesis (make its own food) well even in colder temperatures.
S. anglica can grow in more types of soil than other Spartina species. It can also survive being covered by salt water for longer periods. This strong hybrid has now spread across northwest Europe. It was also brought to eastern North America to help stop erosion (soil wearing away).
Major Invasions Around the World
The biggest invasion of Spartina alterniflora is in China. Starting in 1979, plants from North America were purposely planted there. The idea was to protect the shore and trap sediment. However, the grass has spread to over 34,000 hectares (about 84,000 acres) in ten provinces and Hong Kong.
In Willapa Bay in Washington state, Spartina alterniflora likely arrived by accident in the 1800s. This happened during oyster transplants. From there, it may have spread to other parts of the state. In 2003, it covered about 3,000 hectares (over 8,500 acres) of solid grass. It was spread across an area of 8,000 hectares (20,000 acres). By 2016, efforts had reduced the invasion to less than 3 solid hectares (7 acres).
In California, four types of non-native Spartina have been introduced to the San Francisco Bay area. These include S. alterniflora, S. densiflora, S. patens, and S. anglica. Spartina alterniflora has had the biggest impact in San Francisco Bay. It was brought there in 1973 by the Army Corps of Engineers to reclaim marshland. It was then spread to other areas for restoration projects. It quickly showed it could outcompete the native grass, S. foliosa. It even threatened to completely remove the native grass from the bay.
Hybridization with Native Species
Spartina alterniflora has also mixed with S. foliosa, creating a hybrid called Spartina alterniflora × S. foliosa. This hybrid might be even more dangerous than S. alterniflora alone. The hybrid can change the environment in ways that harm native species. These hybrid plants have spread into creeks, bays, and other coastal areas.
The hybrids produce a lot of pollen. This pollen can cover the flowers of the native S. foliosa, leading to even more hybrid offspring. This leaves the native Spartina with little chance to produce its own pure offspring. The hybrids also make many more fertile seeds than the native Spartina. This means the hybrid population can grow much faster. The hybrids may even be able to fertilize themselves, which the native Spartina cannot do. This helps the hybrid spread even more.
By 2014, efforts to remove S. alterniflora and its hybrids in the San Francisco Bay Area were very successful. The infestation was reduced by 96%, from 323 hectares (about 800 acres) to just 12 hectares (about 30 acres). The hybrid grass is taller than both parent species. This provides good shelter for the Ridgway's rail, a bird that sometimes makes it harder to remove the grass.
Controlling Invasive Smooth Cordgrass
Several methods are used to control and remove Spartina alterniflora where it has become a pest. Pulling it by hand doesn't work well. Even tiny pieces of its underground stems (rhizomes) that break off can grow new shoots.
A chemical called Imazapyr, which is an herbicide (weed killer), is approved for use in water. It is used effectively in Washington and California to kill the grass. In Willapa Bay, tiny bugs called leafhoppers (Prokelisia marginata) were used to try and kill the plants. These plants threaten the oyster industry there. However, this method did not stop the invasion. In areas near San Francisco, surveys are done by air, land, and sea. These surveys help track how much Spartina has spread.
See also
In Spanish: Spartina alterniflora para niños
