A noticeable feature of the Texas Hill Country and Lyndon B. Johnson National Historial Park is Ball Moss (Tillandsia recurvata), found clinging to branches in the understories of trees. Ball moss is closely related to the better known Spanish moss. It is not actually a moss, but rather an epiphyte, or air plant. It attaches to the trees, but derives its nutrition from the air, making it non-parasitic.

Epiphytes are plants that attach themselves to limbs, shrubs, power lines, fences, and other above-ground structures with pseudo-roots. These are not true roots; they do not absorb water and minerals, but anchor the plant to aerial structures.