California Cord Grass

Less than ten years ago, three small clumps of California cord grass first appeared in the salt marsh of San Elijo’s Central Basin. It was viewed with mixed feelings. Our native cord grass (Spartina foliosa) is the preferred habitat of the endangered Light-footed Clapper Rail (recently renamed Ridgway’s Rail). California cord grass is a welcome component of our saltmarsh ecosystem. However, several years ago, the East Coast species, smooth cord grass was introduced into San Francisco Bay where it quickly began hybridizing with the native species. The aggressive hybrids have out-competed the native cord grass and altered many acres of prime salt marsh. Morphological characteristics suggest that our recent arrival is the native species, but attempts to confirm this genetically have been inconclusive.

Since first seen, the cord grass has spread rapidly through West and Central Basin. Superficially it resembles bulrush and cattails, but it tolerates ocean salinities, and the flowers and seed heads are grass-like, rather than the tassels of bulrush or the hotdogs of cattails.

But what is it – friend, or hybrid foe? We are optimistic, but at this point, only the Ridgeway’s Rail knows for sure.

Description ^2,4,34,129

California cord grass is an upright grass that  is usually less than 3 feet (1 m) in height. There may be one to several stems from the base and many others arising nearby from rhizomes. Stems are round and hollow, 3/16-1/2 inch (0.5-1.4 cm) in diameter; they are finely veined. Leaf blades are 6-18 inches (15-45 cm) long and less than 1/2 inch (1.7 cm) wide; they clasp the stem at their base, flatten out along most of their length and may curl inward into a tube at the tip.

The flower structure of California cord grass, like that of all grasses, is highly specialized and is described with a technical vocabulary. Simple, illustrated descriptions of grass structure are available on line.¹³⁰ 

Flowers are born along the terminal part of the stem. Petals are absent. Three stamens and a pistil with two feathery stigmas, are enclosed in two small bracts, the lemma and palea. Beneath each floret are two additional bracts (glumes). The upper glume is longer than the lower. Since one or more florets, subtended by glumes define a spikelet, in California cord grass, there is a single floret per spikelet. Spikelets are arranged into clusters along the top of the stem.  The spikelets are overlapping and closely appressed to the stem, giving the cluster a narrow, nearly cylindrical appearance. The bloom time is June-November.⁷

Seeds are rarely produced. Reproduction is primarily vegetative, by means of the rhizomes, which move out from the parent plant or break off and drift to other locations.

Classification ^2,7

California cord grass is an herbaceous perennial monocot in the grass family (Poaceae, formerly Gramineae). The grass family is the fifth largest plant family and is considered to be the most economically important, containing such important food crops as wheat, rice, oats corn and sugar cane. Grass leaves elongate from the leaf base rather than the tip and this allows grasses to be repeated grazed without damaging the plant, making them excellent forage crops.^41,310

Grasses have a unique terminology. They are recognized by their cylindrical stems (culms), which are generally hollow or pith-filled with solid joints (nodes). Leaves(blades) are flat, attached to alternate nodes; leaf bases wrap the stem forming the leaf sheaths.

Grass are most likely to be mistaken for sedges (Cuperaceae) or rushes (Juncaceae) but the old jingle helps:³¹⁰

“Sedges have edges
and rushes are round.
Grasses have nodes
where the leaves are found.”

Grasses are wind pollinated, and this has resulted in a highly modified flower structure with a unique terminology. There are no petals or sepals. The pistil and stamens are enclosed in two specialized bracts (the palea and the lemma); together these make up a grass floret. One or more floret is grouped along an axis (rachilla) forming a spikelet; beneath each spikelet are two additional bracts (glumes). Spikelets may themselves be clustered into larger spikes or panicles. There are generally three stamens with long filaments and large anthers. The wind-born pollen is tiny. The pistil consists of a superior ovary and two plumose styles.

Two species of Spartina are native to California; California cord grass is the more common. In addition four non-native species have been introduced, The non-natives and their hybrids are considered invasive weeds with deleterious impacts on the native salt marsh ecosystems.^131,133

California cord grass is the only species of Spartina to occur in the Reserve. So far as we know, there has been no genetic contamination from the smooth stem cord grass (S. alterniflora) that has invaded areas in Central California, but genetic tests to prove this have been inconclusive.

Ecology  

California cord grass is adapted to the difficult habitat just below the high tide line, below other saltmarsh plants. In this zone, its roots are often submerged and the soil that anchors them is often low in oxygen. The leaves of California cord grass have a system of elongated, hollow cells. Together with a hollow stem these facilitate the exchange of oxygen and carbon dioxide between the leaves and the roots.^11,41 Analogous structures are found in cattails and bulrush (e.g. Typha domingensis and Schoenoplectus californicus).

Cord grass depends upon seawater for its water needs. Like other saltmarsh plants, the roots of cord grass have the ability to exclude salt.³¹ Additionally, stems and leaves are provided with salt glands that excrete absorbed salt;¹³² like salt grass (Distichlis spicata) and alkali heath (Frankenia salina), California cord grass is often bedecked with tiny salt crystals that sparkle in the sun.

Human Uses ¹⁶

The Kumeyaay made bundles from the stems and used these for house walls. The roots were also boiled into a baby medicine.

Interesting Facts  

In the 1970s the Army Corps of Engineers introduced the smooth cord grass (S. alterniflora) into San Francisco Bay as a component of a revegetation project. Smooth cord grass is native to the East Coast, not California. This species quickly hybridized with our native species and the aggressive hybrid swarms began displacing the native species¹³¹ and altering the surrounding ecosystem.¹³³ It is now thought that there are no pure stands of California cord grass in San Francisco Bay and the hybrids have spread into estuaries to the north and south.

Less than ten years ago, three small clumps of California cord grass first appeared in San Elijo Lagoon, in the salt marsh of Central Basin. To our knowledge cord grass had not grown in San Elijo Lagoon previously, although a population was established in Batiquitos Lagoon to the north. Since first seen in San Elijo, the cord grass has spread rapidly through West and Central Basin. Morphological characteristics suggest that our recent arrival is the pure native species, but attempts to confirm this genetically to rule out genetic contamination have been inconclusive.

Cord grass is the preferred habitat for the endangered Ridgway’s Rail.^34,40 Rails build their nests of the hollow stems, anchoring them around upright stems which allows nests to float on the tides without being rafted away. The upright portions of the cord grass are woven over the nest to camouflage it from above, while a ramp is constructed between the nest and the ground. “The limited extent of marsh dominated by cordgrass appears to be the primary current factor preventing the population’s recovery.”⁴⁰

Since California cord grass has become established in San Elijo Lagoon, our population of Ridgeway’s Rails has increased. In 2010, during the summer months (July-September, when Ridgeway’s Rail sightings are typically higher) the monthly bird surveys reported an average of 7 birds west of the freeway. Four years later this count exceeded 20 birds.