Weed of the month: Sweetbriar Rose (Rosa rubiginosa)
The sweetbriar rose isn't as sweet as its name suggests. In the Argentinean Andes, it creates impenetrable thickets of torns and branches, transforming the valleys into veritable shrubberies.
By Ana Clara Mazzolari
Sweetbriar rose, or rosa mosqueta in Spanish (Rosa rubiginosa) is an erect, scrambling, deciduous shrub of variable height (up to 3 m). The stems have numerous curved thorns and present small clusters of pink flowers. This species is native to Europe and Asia, and was introduced to Argentina at the beginning of the twentieth century. Nowadays, sweetbriar rose is invading several natural environments of Argentina.
This species was introduced intentionally, as it is valued by gardeners because of its ornamental properties and for its sweet, apple-like fragrance. In addition, rosehips and seeds are rich in vitamin C and their essential oils are used for cosmetic purposes. In some places of Argentina, for example in Patagonia, R. rubiginosa is already accepted as part of the local flora and its rosehips and seeds are harvested for private use or by small producers.
However, this species can be very problematic when it colonizes natural environments. In the central Andes of Argentina, in Mendoza province, R. rubiginosa occupies large areas, generating monospecific thickets that preclude recreational use, and limit the access to streams and other water courses. The invasion occurs along valleys, where soil moisture and nutrients are greater than at higher surrounding sites. The sites more vulnerable to the invasion are water courses, which represent environments of high conservation value in these semi-arid systems.
The high success of sweetbriar rose can be attributed to its great versatility in their reproductive system. This species is capable of producing fruits by pollination and apomixes, and is able to reproduce clonally via roots. Given this broad range of reproductive strategies to produce fruits and seeds, it is likely to colonize new areas through dispersal vectors, such as birds or large mammals. This is why its management requires, besides reducing the number of plants in the invaded area, an intensive monitoring to prevent new invasion foci.