I sniffed it and detected a most unusual odor that nevertheless was not unpleasant. It resembled a cross between a tiny evergreen tree and an egg or pineapple. It was not a pineapple, but it was wild chamomile or the pineapple weed (Matricaria discoidea).
Research cited below, by Daise Lopes & Paul P. Kolodziejczyk references the essential oil composition of pineapple weed as containing the following major fractions:
- myrcene (28.5%)
- (E)-β-farnesene (23.4%)
- germacrene D (6.8%)
- geranyl isovalerate (6.4%)
- (Z)-en-yn-dicycloether (8.1%)
MyrceneMyrcene is a monoterpene. That is, it can be derived from just two small isoprene units. Its primary function may be to impart a pleasant fragrance.
β-Farneseneβ-farnesene is a sesquiterpene. It is composed of three isoprene units. It appears it may primarily serve as an insect repellant.
Germacrene DGermacrene D is well-known as the prevalent essential oil component of the all-too-abundant lawn weed Deadnettle (Lamium purpureum). It renders two, perhaps three, useful services to the Pineapple Weed. It is antimicrobial and insecticidal. And it may act as a plant pheromone.
Geranyl IsovalerateGeranyl isovalerate imparts an odor reminiscent of apples, pineapples, and roses. Among flavor enthusiasts, it has the reputation of offering distinctive blueberry notes.
Note: You might also enjoy reading Terpenes and Terpenoids: Isoprene Rule
- Journal of Essential Oil-Bearing Plants: Essential Oil Composition of Pineapple-Weed (Matricaria discoidea DC.) Grown in Canada, Daise Lopes & Paul P. Kolodziejczyk
- The Good Scents Company: geranyl isovalerate