Heterotheca subaxillaris, known by the common name camphorweed, is a North American species of flowering plant in the family Asteraceae.Discover Life, Heterotheca subaxillaris (Lam. ) Britton &. Rusby, camphorweed Distribution and habitat It is widespread across much of the United States (from California to Massachusetts) as well as Mexico and Belize.SEINet, Southwestern Biodiversity, Arizona chapter photos, description, partial distribution mapBiota of North America Program 2014 county distribution map
H. subaxillaris may be found in habitats such as upper beaches, longleaf pine-wiregrass savannas, and pine-scrub oak sand ridges.Lonard, Robert I., Frank W. Judd, and Richard Stalter. “Biological Flora of Coastal Dunes and Wetlands: Heterotheca Subaxillaris (J. De Lamarck) N. Britton & H. Rusby”. Journal of Coastal Research 27.6 (2011): 1052–1058. Description Heterotheca subaxillaris is a perennial, aromatic herb up to 203 centimeters (80 inches or 6 2/3 feet) in height, often with several erect stems. The stems are hairy to bristly. The inflorescence contains 3-180 flower heads in a flat-topped array. Each head contains 15–35; yellow ray florets surrounding 25–60 disc florets at the center.Flora of North America, Heterotheca subaxillaris (Lamarck) Britton & Rusby, 1887.
Ecology
Sandy parts are common habitat for H. subaxillaris. They thrive in prairies with high sand content. Human-disturbed areas are also preferred, such as roadsides or waste areas. Camphorweed florets are adapted to suit generalist pollinators to an equal or greater extent than specialists, such as plasterer bees. Other bees are the most common of these generalist visitors, collecting nectar and pollen in exchange for transferal of male gametes between flowers. Larvae of insects such as brown flower moths and agromyzid flies feed on the stems and/or flower heads of the camphorweed. Olsen KM. Pollination effectiveness and pollinator importance in a population of Heterotheca subaxillaris (Asteraceae). Oecologia. 1996 Dec;109(1):114-121. doi: 10.1007/PL00008811. PMID: 28307601.Camphorweed. Illinois Wildflowers.
Chemistry The leaf volatiles from which the name "camphorweed" is derived include camphor, but as a minor constituent (less than 2%); of 41 documented volatiles, for example, caryophyllene, pinene, borneol, myrcene, and limonene each comprised over 5% of the total.Lincoln, D.E., B.M. Lawrence. 1984. The volatile constituents of camphorweed, Heterotheca subaxillaris. Phytochemistry 23(4):933-934
References
External links Photo of herbarium specimen collected in Nuevo León in Mexico in 2003