Sporobolus foliosus (Trin.) P. M. Peterson & Saarela

Spartina foliosa is distributed In coastal southwest North America along the Pacific Ocean shoreline and estuaries of Mexico and California. This aquatic plant grows in shallow near-shore waters, salt marshes or on mudflats in the intertidal zone. The species is severely restricted to elevations less than five meters above mean sea level.

The plant, also known by its common name California cordgrass, grows from rhizomes which are typically bedded in shallow coastal muds below mean sea level. Leaves are emergent, and stems are generally 60 to 150 meters in length. The species in threatened due to introduction of the alien species Spartina alternifolia, which hybridizes with the native, which process is sometimes known as genetic pollution, in cases such as this where the native stock then declines in population, due to a hardier hybrid.

California cordgrass is threatened in the heart of its native range, due to the U.S. Federal Government's ill-advised scheme to introduce an alien species genus relative into the San Francisco Bay perimeter, under the guise of erosion control.

Specifically, California cordgrass is threatened with extinction due to introduction of the alien species Spartina alternifolia, which hybridizes with the native, which process is sometimes known as genetic pollution, in cases such as this where the native stock then declines in population, due to a hardier hybrid.

After the introduction of the Atlantic coast alien in 1973, hybrid swarms have spread rapidly into other areas of the coast and penetrating to tidal creek tributaries of San Francisco Bay. Currently the great majority of the native California cordgrass has been extirpated from San Francisco Bay, and threat continue into the balance of the range.

Spartina foliosa Trin. M6m. Acad. St.-P^tersb. VI 6^ 114. 1840.
Spartina leiantha Benth. Bot. Voy. Sulph. 56. 1844. (Type from Baja California.) Spartina densiflora subvar. Brongniarti f. acuta St. Yves, CandoUea 5; 76, 81. 1932. (Tvpe from Eureka, California, Heller 13871.)
Culms 70-100 cm. tall, erect from comparatively slender spreading rhizomes, rooting at the lower nodes, leafy to the summit; sheaths crowded, much longer than the internodes, rounded, usually succulent; ligule ciliate, 1-2 mm. long; blades 15-40 cm. long, 5-10 mm. wide at the base, usually stiffly ascending, glabrous on both surfaces, the margins scaberulous; panicle spikelike, cylindric, 15-20 cm. long, usually partly enclosed in the upper sheath; spikes several to numerous, sessile, crowded, at least at the summit of the panicle, the lower ones 5-7 cm. long, the rachis glabrous; spikelets distant, at least in the lower spikes, closely appressed; first glume half to three fourths as long as the floret, the keel hirsute in the lower half; second glume acute, as long as or distinctly exceeding the lemma, the keel hirsute, the margins ciliate in the lower half; lemma 8-10 mm. long, rather thin, subobtuse, obscurely lobed, glabrous except for the sparsely ciliate margins; palea narrowed at the summit, exceeding the lemma.
Type locality: California.
Distribution: Salt marshes near the Pacific coast, San Francisco to Baja California.

Perennials, Aquatic, leaves emergent, Terrestrial, not aquatic, Rhizomes present, Rhizome elongate, creeping, stems distant, Stolons or runners present, Stems nodes swollen or brittle, Stems erect or ascending, Stems geniculate, decumbent, or lax, sometimes rooting at nodes, Stems solitary, Stems caespitose, tufted, or clustered, Stems terete, round in cross section, or polygonal, Stem internodes solid or spongy, Stem internodes hollow, Stems with inflorescence less than 1 m tall, Stems with inflorescence 1-2 m tall, Stems, culms, or scapes exceeding basal leaves, Leaves mostly cauline, Leaves conspicuously 2-ranked, distichous, Leaves sheathing at base, Leaf sheath mostly open, or loose, Leaf sheath smooth, glabrous, Leaf sheath hairy at summit, throat, or collar, Leaf sheath and blade differentiated, Leaf blades linear, Leaf blades 2-10 mm w ide, Leaf blades mostly flat, Leaf blade margins folded, involute, or conduplicate, Leaf blades mostly glabrous, Ligule present, Ligule a fringe of hairs, Inflorescence terminal, Inflorescence solitary, with 1 spike, fascicle, glomerule, head, or cluster per stem or culm, Inflorescence curved, twisted or nodding, Inflorescence a panicle with narrowly racemose or spicate branches, Inflorescence with 2-10 branches, Inflorescence branches more than 10 to numerous, Inflorescence branches 1-sided, Rachis angular, Flowers bisexual, Spikelets pedicellate, Spikelets sessile or subsessile, Spikelets laterally compressed, Spikelet less than 3 mm wide, Spikelets with 1 fertile floret, Spikelets solitary at rachis nodes, Spikelets all alike and fertille, Spikelets bisexual, Spikelets disarticulating below the glumes, Spikelets secund, in rows on one side of rachis, Rachilla or pedicel glabrous, Glumes present, empty bracts, Glumes 2 clearly present, Glumes distinctly unequal, Glumes equ al to or longer than adjacent lemma, Glume equal to or longer than spikelet, Glumes keeled or winged, Glume surface hairy, villous or pilose, Glumes 1 nerved, Glumes 3 nerved, Lemmas thin, chartaceous, hyaline, cartilaginous, or membranous, Lemma 3 nerved, Lemma glabrous, Lemma body or surface hairy, Lemma apex truncate, rounded, or obtuse, Lemma awnless, Lemma margins thin, lying flat, Lemma straight, Palea present, well developed, Palea membranous, hyaline, Palea longer than lemma, Palea 2 nerved or 2 keeled, Stamens 3, Styles 2-fid, deeply 2-branched, Stigmas 2, Fruit - caryopsis.

Sporobolus foliosus is a species of grass known by the common name California cordgrass. It was reclassified from Spartina foliosa after a taxonomic revision in 2014. It is native to the salt marshes and mudflats of coastal California and Baja California, especially San Francisco Bay. It is a perennial grass growing from short rhizomes. It produces single stems or clumps of thick, fleshy stems that 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 North American Atlantic coast relative smooth cordgrass (Sporobolus alterniflorus), which is not native to the Pacific coast. S. alterniflorus was introduced to San Francisco Bay in the 1970s and it quickly began to hybridize with S. foliosus. Hybrids generally outcompete the native plant and spread rapidly, threatening S. foliosus with localized extirpation. 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 an affected native plant's offspring are hybrids. This is an example of genetic pollution. S. alterniflorus × foliosus hybrids have spread rapidly because they are much more genetically fit than either parental species, an example of hybrid vigor. However, S. foliosus is still the dominant plant at lower tidal elevations in most salt marshes around San Francisco Bay, and numerous locations within the Bay have remained uninfested during ongoing efforts to eradicate S. alterniflorus and hybrids. Restoration of tidal marsh habitat is in progress at multiple sites, including the planting of cultivated S. foliosus harvested from uninfested locations and propagated in a nursery.