Latin name: Mentha spicata L
Common names: Spearmint, common mint, garden mint
Family: Lamiaceae (deadnettle family)
Part used: Leaf - spearmint is so named because of its pointy spear-like leaf
Key constituents: Essential oil (1-4% w/w) including R-(–)-carvone, limonene, dihydrocarvone, and 1,8-cineol. Unlike peppermint essential oil, spearmint essential oil only contains minimal amounts of menthol and menthone; flavonoid tannins (6-12% w/w); triterpenes; and bitter principals.
Although it has a very similar aroma to peppermint, and shares many of the same digestive properties, spearmint contains a slightly different in balance of plant chemicals. Spearmint has less menthol than peppermint, but is rich in phyto (plant) chemicals such as limonene, dihydrocarvone and cineol.1 It has a distinctly aromatic, spearminty, mildly sweet flavour.
Spearmint contains antioxidant nutrients, including vitamin A, beta-carotene and vitamin C. It also provides folates and B vitamins, including riboflavin, thiamin and vitamin B6.2
2 http://www.nutrition-and-you.com/spearmint.html Date from USDA Nutrient Database.