Conyza canadensis (L.) Cronquist - syn. Erigeron canadensis L. - Asteraceae
Canadian horseweed, Canadian fleabane, Kanadisches Berufkraut
Annual plant,native to North America, „… spread to inhabited areas of most of the temperate zone of the northern hemisphere, …up to 1.5m tall, with sparsely hairy stems. The leaves are unstalked, slender, 2–10 cm long and up to 1 cm broad, with a coarsely toothed margin.“ http://en.wikipedia.org/wiki/Conyza_canadensis
Main components of the essential oil of Erigeron canadensis L. growing in west Japan were limonene (31.2%), camphene (14.2%) and germacrene D (11.3%).
[Miyazawa, Mitsuo, Keiichi Yamamoto, and Hiromu Kameoka. „The essential oil of Erigeron canadensis L.“ Journal of Essential Oil Research 4.3 (1992): 227-230]
„The essential oils from different botanical parts (herb, leaves, flowers, stems, roots) of Conyza canadensis Cronq. were analysed at various ontogenesis phases. R-(+)-limonene and trans-α-bergamotene were the main constituents of the herb, leaf and flower oil at all phases of vegetation. The early flowering phases are the best time for harvesting C. canadensis herb, because the oil yield is the highest (0.7-0.8%) and its chemical composition is constant (limonene 80-81%, trans-α-bergamotene 6-8%). Limonene was the dominating compound of the oils of European origin (French, Italian, Spanish, Belgian, Bulgarian and Lithuanian).“
[Chemical composition variability of the essential oil of Conyza canadensis Cronq., Lis, A., Piggott, J. R., & Góra, J., Flavour and fragrance journal, Vol.18(5), 2003, 364-367]
Conyza canadensis, CC BY-SA 3.0, Author: Andreas Kraska