As long as the bottom is at least temporarily saturated with water and is saline to some degree, sea arrowgrass has no problem growing. That can mean high up as well as lower down in salt marshes and inland of the dike where there is seepage or remnants of salt still in the soil. Compared to its family member marsh arrowgrass, sea arrowgrass forms fuller clusters, is less delicate and its inconspicuous flowers are bunched close together along the stem. In addition, the foot of the stems and leaves grow slanted out of the ground. Sometimes, the plants in the middle of the cluster die so that the remaining plants seem to form a fairy ring, just like some mushrooms.