rootery

Century Dictionary and Cyclopedia

1. n. A mound or pile formed with the roots of trees, in which plants are set as in a rockery.

Wiktionary

1. n. A pile of roots, set with plants, mosses, etc., and used as a garden decoration.

GNU Webster's 1913

1. n. A pile of roots, set with plants, mosses, etc., and used as an ornamental object in gardening.