Spartina densiflora
Spartina densiflora is a species of grass known by the common name denseflower cordgrass. It has been reclassified as "Sporobolus montevidensis" after a taxonomic revision in 2014, but "Spartina densiflora" is still in common usage. It is native to the coastline of southern South America, where it is a resident of salt marshes. It is also known on the west coast of the North America and parts of the Mediterranean coast as an introduced species and in some areas a noxious weed. In California it is a troublesome invasive species of marshes in San Francisco Bay and in  Humboldt Bay, where it was introduced during the 19th century from Chile in ballast. Description. This perennial grass generally lacks rhizomes. It grows in erect clumps of slender stems that can reach 1.5 meters tall. The long, narrow, gray-green leaves are rolled inward, especially when new. The inflorescence is a narrow, dense, spike-like stick of branches appressed together, the unit reaching up to 30 centimeters long. The flowers are colorless and the spikelets are tipped with bristles. Invasive species. This plant has negative impacts on the salt marsh habitat of the California coast. It forms tight clumps of  herbage that raise the elevation of the plants in the marsh, keeping the water from flowing in as far as it naturally would, and increasing sediment accumulation. It competes with its native relative, California cordgrass ("Spartina foliosa"), and other marsh plants such as pickleweed ("Salicornia pacifica"). The net coverage of "Spartina densiflora" and "S. densiflora" × "foliosa" was reduced to approximately 41 square meters in 2014, down from about 1.7 hectares (4.2 acres) in 2005. However, it continues to expand in the Humboldt Bay region.