EPPO Global Database

EPPO Reporting Service no. 09 - 2021 Num. article: 2021/206

Baccharis halimifolia phenotypic variation between native and introduced ranges

Over the last few centuries, humans have greatly influenced species distributions by modifying the environment and by dispersing species beyond their natural ranges. Baccharis halimifolia (Asteraceae: EPPO A2 List), is native to North America and is found within the EPPO region in Belgium, France, Georgia, Italy, Netherlands, Spain and the United Kingdom. It is also invasive in Australia and New Zealand. Within the EPPO region, the species was widely introduced for ornamental purposes, windbreaks and soil stabilization around the 1800s. On the Atlantic coast, B. halimifolia became naturalised in the early 1900s and considered invasive in the 1940s. Along the Mediterranean coast, it did not naturalise until the early 1980s. In Australia, the species was introduced in 1888 and became naturalised around the 1930s. Populations in the invasive range may exhibit different traits compared to native populations due to adaptation to different selection pressures between the ranges. Eighty populations were selected from the United States, Europe (France, Italy, Spain) and Australia where morphological data (height, canopy width and basal stem diameter) and achenes from two shrubs were collected. A total of 18 240 seeds were sown under the same controlled conditions (saline and non-saline) and seed germination, seedling emergence, survival and early growth were measured. Seeds collected from the European Atlantic coast (Spain and France) grew faster than those from the native range but the same was not shown for the Mediterranean coast (France and Italy) populations. The Australian populations grew faster than native populations under non-saline conditions but had lower survival in saline conditions. Germination also differed from populations within the USA, where expansive inland populations germinated faster than coastal native populations in non-saline environments but grew and germinated more slowly in saline environments. The results show that B. halimifolia exhibits phenotypic variation from across its area of distribution which may contribute to the success of the species when expanding its native range or naturalising in non-native regions.


Lázaro-Lobo A, Moles AT, Fried G, Verloove F, Antonio Campos J, Herrera M, Goñi E, Bioret F, Buffa G, Fantinato E, Sentinella A, Zalucki MP, Mayfield M, Smith T, Catling A, Zalucki JM, Lucardi RD, Shoemaker CM, Mason DS, Ervin GN (2021) Phenotypic differentiation among native, expansive and introduced populations influences invasion success. Journal of Biogeography, 1–12. https://doi.org/10.1111/jbi.14252