Often overlooked, grasses play a very important role in the ecology of West Texas. They provide forage for animals, nest material for birds, and stabilize soil with their mats of fine roots. Several species found in the Amistad area are invasive exotic species, and put native vegetation at risk of being overgrown. One example is the Arundo donax cane, growing along the edges of the lake. It out-competes native plants along the edges of waterways in thick, impassible walls.