It appears that the potential risks of biofuel crops becoming invasive is being overlooked in an effort to increase production and meet the growing demand for biodiesel. Jatropha curcus (dubbed the wonder plant, see for example http://www.jatrophaworld.org) is an example of a species that has many characteristics of a weed (quick growth; resistance to adverse conditions such as drought and light frost; thrives on poor soils with low nutrient status; evidence of naturalization in new habitats etc.). Some species in the genus for which a weed risk assessment has been carried out are assessed as "high risk" (see for example http://www.hear.org/Pier/wra/pacific/jatropha_gossypiifolia_htmlwra.htm). Yet, there is little evidence of precautionary measures being taken in countries where Jatropha is being introduced as an economic plant, including in sensitive ecosystems (e.g. Madagascar).

I would second this concern, as some of the desired properties of biofuels (fast growing, hardy, drought-resistance, etc.) also correspond with traits common to invasive plants. In the US, concerns about use of arundo donax, phalaris arundinacea and species of miscanthes are cases in point.

For a brief overview of the issue, see S. Raghu, et al. (2006) Adding Biofuels to the Invasive Species Fire? Science, 313, 1742.

http://www.sciencemag.org/cgi/content/full/313/5794/1742/DC1

Regards

Stas Burgiel
The Nature Conservancy