Beach grass (Ammophila breviligulata) grows along the Atlantic coast of the United States in dune areas. It has been introduced to numerous other locations, such as the Pacific coastline and the Great Lakes, where it serves as a valuable dune erosion control grass. During its life the grass can withstand extreme coastal storms and will remain alive even after being buried in up to 1 foot of sand from heavy drifting.
A vigorous perennial, beach grass has a rhizome root system that can spread up to 8 feet per year. It requires full sunlight for optimum growth. Beach grass flourishes in sand with virtually no soil. It grows a large rhizome-based mat that is up to 20 feet deep. The roots spread out horizontally and vertically.
When drifting sand begins to build up around the beach grass stems, the plant simply sends up longer shoots. The stem that is buried in the sand becomes a root, thus ensuring the ongoing life of the beach grass in the shifting sand. Each blade of grass usually towers 2 to 4 feet in height. The grass is highly susceptible to nematodes, so it does not do well in soil and rarely survives transplant. It requires sandy conditions to thrive and continue its life span.
From spring to summer the beach grass produces long spikes of yellow flowers. Each spike holds one flower head. At the base of each yellow flower head is a light fur covering. Pollination is wind driven. Following flowering the grass produces seed heads which are carried by the wind to new locations. Despite its seed production, the predominant way that beach grass spreads is through its root system, which forms huge, firmly established colonies. The seeds of beach grass are rarely viable.
The root system of beach grass has a symbiotic relationship with mycorrhizal fungi. The fungi can successfully extract even trace amounts of nutrients from the nutrient-poor sand. The nutrients are readily consumed by the beach grass. Beach grass requires mycorrhizal fungi to flourish, according to the Compost Gardener. If beach grass is not planted with the fungi, the results are poor and the grass fails to grow or dies.
Insects and Dangers
Both the beach grass scale (Eriococcus carolinae) and the gall midge (Mayetiola ammophilae) feed on beach grass. The beach grass scale sucks the nutrients from the grass blades, which cause them to yellow and die. The midge eats the base of the grass stems. The voracious feeding can cause the grass to rot. Man also poses a serious danger to large colonies of beach grass, which are easily killed by all-terrain vehicles or other motorized transports in the sand.