Spike grass (Distichlis spicata) is a resilient perennial grass that thrives in some of the most challenging environments on Earth. This plant is widespread across North America, found in coastal salt marshes, inland salt flats, and alkaline meadows where few other species can survive. Its ability to tolerate highly saline and alkaline soils makes it a powerful colonizer. Distichlis spicata is a foundational species, utilizing biological adaptations that allow it to persist where fresh water is scarce and salt concentrations are toxic.
How to Identify Spike Grass
Identifying spike grass involves observing its low-growing habit and characteristic leaf structure. The plant typically forms dense, sod-like mats or extensive clonal colonies, rarely exceeding half a meter in height. Its stems are solid and stiff, bearing narrow, sharp leaves arranged in two opposing rows, giving the foliage a distinct, symmetrical appearance.
The dark green leaves often have a crusty texture due to visible salt crystals excreted onto the surface. A distinguishing feature is that the plant is dioecious, meaning individual plants bear either male or female flowers, but not both. The common name originates from the inflorescence, as the flowers are gathered in short, dense, spike-like clusters at the top of the stem.
Surviving High Salt Environments
The survival of spike grass in highly saline environments stems from a specialized physiological mechanism known as salt excretion. Distichlis spicata is a recretohalophyte that actively pushes salt out of its tissues, unlike some plants that store salt in old leaves to be shed. This process occurs through tiny, two-celled salt glands located on the leaf surface. These glands transport and excrete excess ions. The salt is forced onto the leaf surface, where it crystallizes as the water evaporates, maintaining a stable, non-toxic salt concentration within the plant’s cells.
Furthermore, the plant possesses an extensive network of sharp-tipped, scaly rhizomes that function as robust underground stems. These rhizomes contain aerenchymatous tissues, which create air passages that allow the plant to survive temporary flooding and saturated, oxygen-poor soils.
Ecological Significance and Uses
Spike grass plays a significant role in stabilizing fragile coastal and inland ecosystems. The dense, interwoven nature of its rhizome network binds soil particles together, which is effective in preventing erosion on shorelines and tidal banks. This ability to stabilize shifting substrates makes it a natural engineer in its environment.
The plant also holds value as a forage source, especially in arid or saline rangelands. It retains its green color and nutritional value for longer periods during drought conditions when other grasses have become dormant. For this reason, it is utilized as a grazing source and winter feed for livestock like cattle and horses. Historically, the excreted salt crystals were scraped from the leaves by Native American tribes, who used the harvested salt for seasoning and trade. Spike grass continues to be used today in land reclamation and restoration projects due to its tolerance for high salinity.