Secretiveness (hiding behind the bush). Protection from an unreasonable public or fear of openness. Female emotions, penchants, and desires (Merlin being seduced behind the white thornbush by Viviane). Is the bush bare or in bloom? Is something behind or inside the bush? (God was revealed to Moses in the form of a burning bush.)
Symbol of the personality of the dreamer. Hiding place.
According to Freud, the female genitalia.... Little Giant Encyclopedia