Natura - nature
   actualia - actual entities
     Mundus Plinius - physical world
       Astra Plinius - celestial bodies
         Universe
           (Supercluster) Virgo-Hydra-Centaurus Supercluster
             (Supercluster) Virgo Supercluster
               (Cluster) Local Group
                 (Galaxy) Milky Way Galaxy veter.
                   (Spiral arm) Orion Arm
                     (Region) Local Bubble
                       Local Interstellar Cloud
                         (Planetary system) Solar System
                           (Planet-satellite system) Earth System
                             (Planet) Earth veter.
                               "spheres" (Earth)
                                 (Sphere) Hydrosphere (Earth) - layer of water
                                   (Drainage system) Atlantic Ocean Basin
                                     (Drainage system) American Mediterranean Sea Basin (America)
                                       (Drainage system) Gulf of Mexico Basin
                                         (Drainage system) Mississippi River Basin (United States, Canada)
                                           (Drainage system) Red River Basin (North America)
                                             (Drainage system) Little River Basin (United States: Oklahoma, Arkansas)
                                               (Stream) Mountain Fork (United States: Arkansas, Oklahoma)