Health benefits of calamus essential oil. The health benefits of calamus essential oil can be attributed to its properties as an anti-rheumatic anti-spasmodic cephalic circulatory memory boosting nervine stimulant and tranquilizing substance. Calamus essential oil is extracted from a red-like aquatic plant that has sword-shaped leaves and small greenish-yellow flowers. All parts of the plant have peculiar agreeable fragrance. Calamus essential oil is extracted from fresh roots or unpeeled dried root by the steam distillation process.