Pteronia incana (Burm.) DC - Asteraceae - T'kaibebos (Afrikaans), blue bush, ash-bush

Invasive shrub of South Africa.

"This species has small, light grey, woolly, fragrant leaves, and forms a low, dense bush. Its fragrant leaves have a variety of medicinal uses. " [[https://en.wikipedia.org/wiki/Pteronia_incana]]

"Pteronia incana produces a yellowish oil with a strong fragrance. Interest in this oil has been primarily due to its unique odour properties which make it suitable for use as a fragrance... Pteronia incana oil had a higher content of p-cymene as well as limonene + 1,8 cineole, and lower content of myrcene than that reported by [[http://www.thegoodscentscompany.com/gca/gc1543591.html|Bruns & Meiertoberens (1987)]]. Moreover, the oil contained o-cymene, which had not been reported... Pteronia incana oil also displayed a fairly broad spectrum of antibacterial activity, particularly at higher concentrations. However, it was less efficient than A. afra and R. officinalis oils. Enterobacter cloacae and Staph. aureus showed the highest sensitivity to P. incana oil." \\
[Comparative evaluation of the antimicrobial activities of essential oils of Artemisia afra, Pteronia incana and Rosmarinus officinalis on selected bacteria and yeast strains. Mangena, T., Muyima, N. Y. O., Letters in applied microbiology, Vol.28(4), 1999, 291-296]  [[http://onlinelibrary.wiley.com/doi/10.1046/j.1365-2672.1999.00525.x/ful]] 

"The essential oil of Pteronia incana was collected and was investigated on a monthly basis using GC-MS. The oil volume and its constituents vary greatly with different time of sampling and distillation. The oil contains a high percentage of myrcene, α-pinene, β-pinene with sabinene, α-terpinene, 1,8 cineole and limonene." \\
[Variation in the essential oil constituents of //Pteronia incana// (Asteraceae)., Mayekiso, B., Magwa, M. L., Coopoosamy, R. M., African Journal of Biotechnology, Vol.5(12), 2006, 1220-1226.] [[http://www.academicjournals.org/article/article1379772552_Mayekiso%20%20et%20al.pdf]]

"In common with other species of Pteronia, the plant contains an essential oil reminiscent of pine turpentine oil with β-pinene, limonene, 1,8-cineole, myrcene, spathulenol, p-cymene and methyleugenol as main compounds present in all or most of the samples, with smaller amounts of α-pinene, sabinene, γ-terpinene, terpinen-4-ol, biclogermacrene, globulol and α-bisabolol in some of the distillates." 

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[Hulley, I. M., et al. "The ethnobotany, leaf anatomy, essential oil variation and biological activity of Pteronia incana (Asteraceae)." South African Journal of Botany 76.4 (2010): 668-675.] [[https://www.sciencedirect.com/science/article/pii/S0254629910002097]]