Online Google Dictionary

witches broom wordnet sense
  1. A Witch's broom is a disease or deformity in a woody plant, typically a tree, where the natural structure of the plant is changed. A dense mass of shoots grows from a single point, with the resulting structure resembling a broom or a bird's nest.
  2. (Witches’ brooms) Abnormal proliferations of shoots or branches caused by a pathogen (e.g., from dwarf mistletoe).
  3. An abnormally profuse, dense mass of host branches. This is a common symptom induced by dwarf mistletoe infection, as well as other parasites and abiotic agents.