Limonene is a monoterpenoid and one of two major compounds formed from pinene. As the name suggests, varieties high in limonene have strong citrusy smells like oranges, lemons and limes. Strains high in limonene promote a general uplift in mood and attitude. This citrusy terpene is the major constituent in citrus fruit rinds, rosemary, juniper and peppermint, as well as in several pine needle oils. Limonene is highly absorbed by inhalation and quickly appears in the bloodstream. Clinical studies have shown that it assists in the absorption of other terpenes through the skin and other body tissue.