Rosemary Essential Oil Latin Name : Rosmarinus Officinalis. Part of Plant Used : Flowering Tops. Source : Tunisia. Extraction Method : Steam Distillation. Used in aromatherapy, Rosemary Oil helps reduce stress levels and nervous tension, boost mental activity, encourage clarity and insight, relieve fatigue, and support respiratory function. It is used to improve alertness, eliminate negative moods, and increase the retention of information by enhancing concentration.