Palmarosa is a grass, not a rose, and the surprise is how convincingly it reads as one: soft, green and rosy, with none of the weight a true rose oil carries. It is the reason perfumers reach for it, and the reason a bottle this size goes a long way in a blend.

This is the certified organic version, whose ingredient line reads Cymbopogon Martini (Palmarosa) Oil with the organic asterisk. Plant Therapy has since dropped the organic listing, so this is the last of that run. Diffuse three to four drops per 100 mL of water, or dilute to 2 to 4 percent in a carrier for skin. The bottle carries the maker's KidSafe mark.